Introduction

Metal core printed circuit boards (MCPCB) refer to boards which incorporate a metal plate or substrate as the central layer instead of the typical FR4 dielectric. Metals like aluminum, copper or iron alloys can be used as the core material in MCPCBs.

The high thermal conductivity of the metal core enables heat dissipation from mounted electronic components. This makes MCPCBs well suited for thermal management in applications with high power devices.

This article provides a detailed comparison between the different metal core materials used in PCBs covering properties, performance, applications, pros/cons and costs.

Aluminum Core MCPCB

Aluminum is the most common metal base material used in metal core PCBs due to its combination of good thermal performance, ease of fabrication and lower cost:

Typical properties:

• Thermal conductivity: 130 W/mK
• Coefficient of thermal expansion (CTE): 23 ppm/°C
• Density: 2.7 g/cm3
• Specific heat capacity: 0.9 J/g°C
• Availability of alloys like 6061, 5052, 2024 etc.

Key attributes:

• Excellent heat dissipation performance
• Cost effective material and processing
• Lightweight
• Well-established PCB technology
• Can be easily machined or punched
• Recyclable

Typical thickness range:

• 0.5mm to 6mm plates
• 1mm to 2mm is common

Applications:

• LED lighting
• Power converters
• Motor drives
• Power supplies
• Solar inverters
• Automotive electronics

Aluminum MCPCBs offer the best balance of thermal performance, manufacturability and cost for most mid-to-high power electronic circuits.

Copper Core MCPCB

Copper provides significantly higher thermal conductivity than aluminum. This makes it useful for very demanding thermal applications:

Properties:

• Thermal conductivity: 400 W/mK
• CTE: 17 ppm/°C
• Density: 8.9 g/cm3
• Specific heat capacity: 0.39 J/g°C

Benefits:

• Extremely high thermal conductivity
• Well-established PCB technology
• Widely available
• Can be fabricated using standard FR4 processes
• Solderable and recyclable

Typical thickness range:

• 0.25mm to 4mm
• 0.5mm to 2mm common

Applications:

• High power LED lighting
• RF power amplifiers
• Power modules
• Solar microinverters
• High density computer systems

The excellent thermal performance of copper MCPCB justifies its higher cost in applications where thermal dissipation is critical for reliability.

Iron Alloy Core MCPCB

Iron alloys containing nickel, cobalt, aluminum etc. offer a lower cost alternative to copper for improved thermal conductivity over aluminum:

Properties vary by composition:

• Thermal conductivity: Up to 65 W/mK
• CTE: 10-15 ppm/°C
• Density: 7-8 g/cm3
• Specific heat capacity: 0.44-0.46 J/g°C

Benefits:

• Higher thermal conductivity than aluminum
• Lower cost than copper
• Compatible with FR4 fabrication
• High strength for thin cores

Typical thickness range:

• 0.1mm to 3mm plates
• 0.2mm to 0.5mm common

Applications:

• LED lighting
• Industrial electronics
• Telecom systems
• Automotive

Iron alloys like iron-nickel-cobalt provide a good compromise between performance and cost for an intermediate thermal conductivity core material.

Comparing Metal Core PCB Materials

Key properties of the main metal core PCB base materials:

General material selection guidelines:

• Aluminum – Cost-driven applications where thermal conductivity >130 W/mK is sufficient
• Copper – Where maximum heat dissipation is critical
• Iron alloy – Applications constrained by weight or cost but need higher thermal performance than aluminum

Metal Core MCPCB Fabrication

Fabricating metal core PCBs requires specialized processes compared to standard FR4 PCB construction:

Base Metal Preparation

The metal is cut into specified panel sizes and thicknesses. Holes are punched for mounting components if needed. The surfaces are chemically cleaned.

Dielectric Layer Lamination

Thin dielectric films like polyimide or FR4 prepregs are laminated onto the metal core under pressure and temperature. Bonding agents help adhesion.

Circuit Formation

Similar to rigid PCB fabrication, the circuit layers are formed on the dielectric layers using processes like photolithography, plating and etching.

Component Assembly

Components can be conventionally soldered. For higher heat tolerance, sintering of silver paste or transient liquid phase bonding is used.

Enclosure Integration

The metal core MCPCB can sometimes directly serve as a housing or enclosure surface for mechanical stiffness, shielding and heat spreading.<img src=”https://drive.google.com/uc?export=view&id=1pNpZjav6MG438K0wGShZbZ8eqy3llH-S” alt=”metal core PCB fabrication” style=”width:500px;height:300px;”>

The specialized materials, processes and integration considerations involved in metal core PCB manufacturing demand working with an expert supplier.

Aluminum MCPCB Pros and Cons

Benefits of aluminum metal core PCBs:

• Excellent thermal conductivity for heat dissipation
• Cost-effective material and fabrication
• Lightweight construction
• Mature, established manufacturing processes
• Readily machinable or punchable
• Solderable and recyclable

Limitations of aluminum MCPCBs:

• Lower thermal conductivity than copper or alloy cores
• Higher CTE than copper causes greater component warping stresses
• Susceptible to corrosion in harsh environments
• Lower stiffness than steel or copper cores when very thin
• Not suitable for high frequency or precision circuits

Aluminum strikes the best balance between cost, performance and manufacturability for most commercial thermal management PCB applications.

Copper MCPCB Pros and Cons

Advantages of copper metal core PCBs:

• Extremely high thermal conductivity
• Well-established PCB manufacturing processes
• Widely available material supply
• Can often reuse fabrication lines for rigid FR4 PCBs
• High temperature soldering capability
• Recyclable material

Drawbacks of using copper as metal core:

• Substantially higher cost than aluminum
• Heavy weight increases product weight
• Thermal expansion issues when paired with non-CTE matched components
• Lower brilliance compared to aluminum with LEDs
• Lower dielectric strength than aluminum at thinner gauges
• Requires nickel plating for solderability

The unmatched thermal performance of copper justifies its usage where removing heat is absolutely critical for application success.

Iron Alloy MCPCB Pros and Cons

Benefits of iron alloy metal core PCBs:

• Higher thermal conductivity than aluminum
• Lower density than copper provides weight savings
• Cost is between aluminum and copper
• High yield and tensile strengths when thin
• Manufacturing processes similar to FR4 PCBs

Challenges with iron alloys for metal core PCBs:

• Thermal conductivity still lower than copper
• Material options not as diverse as aluminum or copper alloys
• More difficult to fully recycle
• Higher loss at high frequencies than aluminum or copper
• Lower stiffness than aluminum or copper at identical thickness

Iron alloys offer a viable intermediate option where cost or weight are key constraints but thermal performance must exceed aluminum.

Cost Comparison

Metal core PCB cost considerations:

• Metal core PCBs have higher fabrication cost than FR4 PCBs due to specialized materials, processes and lower panel utilization.
• However, the ability to remove heat from high power components results in overall system cost savings.
• Aluminum core is the most economical metal base material. Iron alloy adds moderate cost increment over aluminum. Copper core can double the cost over aluminum.
• But metal core PCB cost is typically a small fraction of overall system cost for an electronic product. The thermal and reliability benefits justify the premium.
• Cost reduces in high production volumes due to improved material utilization and manufacturing efficiency.

Applications of Metal Core PCBs

Some common application areas where metal core PCBs provide benefits include:

LED Lighting

The high power LEDs used require metal core PCBs for heat extraction. Aluminum is widely used but copper or iron allows driving LEDs at higher currents for greater luminosity.

Power Converters

Switching converters and inverters for power electronics require metal core PCBs to manage substantial heat dissipation from components like inductors and FETs.

Motor Drives

Motor drives work under challenging operating temperatures. Metal core PCBs allow efficient thermal management in the tightly packed drives.

Servers

Within data centers, high compute density server blades need effective cooling to maintain reliability.

RF Power Amplifiers

High frequency RF amplifiers using GaAs or GaN ICs benefit from the electrical and thermal conductivity of copper metal core PCBs.

Aerospace & Defense

Rugged aluminum or copper core PCBs meet demanding thermal and mechanical performance requirements in aerospace and military applications.

Conclusion

Metal core PCB technology enables integration of electronic components and systems with higher power densities by effectively managing dissipated heat. Aluminum, copper and iron alloys provide a range of core material options to suit different design constraints and applications. Aluminum MCPCBs offer the best value for most cost-driven commercial applications demanding higher thermal conductivity than standard FR4 PCBs. Where maximum heat transfer is critical for product functioning, the highest performing copper MCPCBs are the optimal choice despite increased cost. Iron alloys provide a middle ground alternative. With each material having unique benefits and tradeoffs, designers must make informed selections to match the metal PCB technology used to the specific thermal, weight, frequency, mechanical and cost requirements of the application.

FAQs

What are some key considerations when selecting metal core PCB thickness?

Some guidelines for choosing thickness:

• Thicker cores allow mounting larger, higher power components
• Thinner cores weigh less but have reduced stiffness
• Thicker cores increase trace lengths if routing on outer layers
• Optimal thickness balances weight, cost and layout space

What fabrication challenges are common with metal core PCBs?

Some potential issues include:

• Delamination or cracking due to CTE mismatches
• Voids or lack of adhesion with dielectric bonding
• Drilling precision on thicker metal cores
• Higher scrap rates and lower panel utilization
• Warping when cooling after lamination

How are components assembled on MCPCBs?

Assembly options:

• Conventional SMT soldering for moderate temperature parts
• Sintered silver joints for high power devices
• Transient liquid phase soldering where high heat capacity is required
• Press fit pins, clips or thermal adhesives for selective mounting

What alternatives exist to using metal core PCBs for thermal management?

Some options are:

• Thick copper planes within conventional PCBs
• Thermal cladding, gap pads or vias for heat extraction
• Heat sinks, heat pipes or cold plates attached to PCBs
• Liquid cooled plates with internal fluid circulation
• Insulated metal substrate PCBs

Are electrically insulating coatings required on metal cores?

Yes, the metal core must be coated with insulating dielectric films on both sides to avoid electrical shorts. This adds material cost but allows routing signals like conventional PCBs.

Printed Circuit Board Manufacturing and Aluminum-Based PCBs

A tremendous changing everywhere can be seen as the concept of everything and work has been changed completely. Nowadays, electronic appliances are not an exception to this changing. Today, the electronic manufacturing heavily depends on the quality of printed circuit board and its manufacturing. Because of the broad use of these innovative boards in electronic appliances like television, computer cell phones and even in tiny cables has persuaded renowned manufacturers to get involved in PCB manufacturing.

Since their inception, a tremendous changing can also be seen in the printed circuit manufacturing as previously they were manufactured by using polyester as well as polyimide materials. But, today aluminum based PCBs have captured the market. Apart from this they also have the first choice, when it comes to electronic manufacturing. There are a number of benefits associated with aluminum-based PCBs as aluminum is safe and durable. Apart from this, it is lightweight that can be used for any purpose.

Moreover, it can also afford the heat and electricity conductivity in those electronic applications that are more prone to get quick heat. Moreover, in PCB manufacturing, using a base that should have excellent heat as well as electrical conductivity is vital. And aluminum is the metal that is a perfect base for PCB manufacturing for the dissipation of heat devoid of extra heat sinks. In addition the aforesaid benefits of aluminum, there are also a number of other benefits associated with it. It is a common fact that aluminum is the most commonly used metal used in power transmission lines globally and it eliminates the effect of thermal stress on all the modules.

In this way, aluminum-based PCBs are very helpful in increasing the life of electronic manufacturing and appliances. Reducing the temperature of component operating, improving reliability and also improving thermal conductions are some of the added advantages of aluminum-based PCB manufacturing. Because of having a number of benefits of aluminum-based PCB, they are also called metal core printed circuit boards. A doctor to thermal conduction that leads to versatility in component tracking layout, aluminum-based PCB manufacturing also make them more useful.

The PCB Manufacture, Manufacturing, and the Aluminum PCB

PCB stands for the printed circuit board. The manufacturing of this printed board specializes in the prototype to medium production volumes. There is a wide range of products that are the latest in the industry of the PCB. These products are accompanied by the latest model of the equipment’s to produce precise boards and meet the requirements. No matter what one’s special needs and applications are the printed circuit board will work to meet them. The circuit boards that come from the printed board are good and they exceed the expectations of the user. A printed circuit board is a mechanically devised path, track or pathway leading to the electronic receipt and connection of electronic devices.

PCB: How to Choose the Right One

It is very important to choose the right manufacturer while selecting an electric board for a device. One-sided; two-sided as well as multi-layered circuit boards are available and are utilized in different devices these days. The multilayered boards are usually used in small devices and they are settled one upon another. Some of these boards are also available with aluminum plating or hot air leveling.

A number of companies have a knowhow of designing electronic boards of different sizes and they also provide with several materials used for the production purpose. These materials are tested and verified time and again so that the customers can get smooth working devices. It takes a lot of time and effort to learn about the designing of a printed circuit board. Thus, instead of going through such a complex process, it is always advisable to order them from a trustworthy and experienced company or resource.

Aluminum is one of the world’s widely used metal. Its use is not limited to industrial purposes alone, and can also be seen in homes, offices, and highways. This metal is also used in building vehicles due to its remarkable ability to withstand corrosion. The metal is also renowned for its low-density characteristic.

Since aluminum is malleable, using it for various purposes is not difficult. It is perfect for vehicles and can be used in machinery since it does not ignite easily unlike other metals. Apart from this, it is also a hundred percent recyclable, which makes it a favorite among recycling centers and junkyards. This metal also maintains its physical properties even after it is recycled.

PCB manufacturing involves many materials and many procedures that come with it. The PCB manufacturer makes sure that when they manufacture this board they are accompanied by the safety measures that they need to be followed when you are handling this printed board. The dimensions of the board, including the entire diameter, copper wire thickness, and material length, are closely monitored in the manufacture of these products. Before the printed circuit, there was the point to point constructions were used. Originally the electronic components had wire leads and the printed circuit board had holes drilled for each wire of each component. There are many types of the aluminum-based PCB that exist. All these types are useful to you as an individual. Their makes are unique and hence they are long-lasting. There are many types of the aluminum base PCB that are there in the market today depending on what you want. There are the aluminum printed boards for led, the aluminum PCB for high power led, led street light, high thermal led and the aluminum board for the garden lamp.

Supporting the military is something RayMing is very proud of, and we were contracted to assemble a PCB for use in a military communications application. The RF prototype PCB assembly used Rogers 4350B material, and the board required surface mount technology for the double-sided assembly that featured 250 placements. Board specs included 3 layers, standard vias, and 1 panelization. Final measurements came to 8 x 5.75 in. We performed final testing using automated optical inspections and x-ray inspection before delivering product to the customer.

Introduction

Rogers RO4350B laminates are widely used for manufacturing high frequency PCBs for defense and aerospace applications like radars, electronic warfare systems, satellite communications, etc. This high performance PCB material enables circuits to operate reliably at microwave and mm-wave frequencies beyond 10 GHz.

However, assembling PCBs using RO4350B substrates requires special considerations during fabrication, component selection and assembly processes owing to its unique properties. This article provides guidelines on how to assemble RO4350B PCBs for mission-critical military applications.

RO4350B PCB Material Properties

RO4350B is a glass reinforced fluoropolymer composite circuit board material designed for exacting microwave and mm-wave circuit needs. Here are some of its key properties:

• Dielectric constant (Dk) of 3.48 at 10 GHz
• Low loss tangent of 0.0037 at 10 GHz
• Woven glass reinforced hydrocarbon/ceramic filled PTFE composite
• Good thermal conductivity of 0.69 W/m/K
• Low Z-axis CTE of 41 ppm/°C
• Glass transition temperature of 280°C

RO4350B’s electrical and mechanical attributes make it suitable for aerospace RADARs, satellite communication, electronic warfare systems and radio communications.

Design Considerations

The PCB layout for an RO4350B board destined for military usage must account for the following:

Controlled Impedance

• Maintain tight impedance control over traces and match to RF IC terminations

RF Shielding

• Incorporate adequate shielding enclosures for emission control

Minimal Passives

• Limit passive components to reduce losses at high frequencies

RF Transitions

• Carefully design components/connectors interfaces

Thermal Management

• Use thermal vias and/or metal backing to spread heat

Reliability Testing

• Subject prototype to thermal cycling, vibration and shock tests

PCB Fabrication Process

RO4350B PCBs require specialized fabrication to meet military specifications:

• Material – Use RO4350B laminates from Rogers or equivalent suppliers
• Layer Count – Typical stackups have 4 to 32 layers depending on complexity
• Dielectrics – Combination of RO4350 prepregs and bondplies
• Trace width – RF traces down to 3 mils line with 3 mil spacing
• Hole walls – Copper plated through holes with 1 oz copper
• Surface finish – Immersion silver or ENIG surface finish
• Testing – Full electrical testing and quality inspection per IPC standards

Component Selection

The active and passive components used on the PCB assembly must also conform to RF application needs:

RF Transistors

• Gallium arsenide (GaAs) RF power transistors with operating frequency > 10 GHz

Power Amplifiers

• GaN or GaAs MMIC power amplifiers from suppliers like Qorvo, Microchip, etc.

RF Connectors

• High frequency SMP, SMPM, SSMP connectors rated for microwave bands

Passive Components

• Chip resistors, capacitors and inductors with tight tolerances rated for high frequency use

EMI Suppression

• Multi-layer ceramic capacitors, ferrite chip beads for noise filtering

Assembly Process Steps

Assembling the RO4350B PCB requires precision SMT assembly and inspection:

Solder Paste Printing

• Use solder paste suitable for small RF components. Dispense accurate volumes.

Component Placement

• Use pick and place machine with capability to handle small chip components.

Reflow Soldering

• Follow the thermal profile recommended by solder paste vendor. Use nitrogen if possible.

Conformal Coating

• Select coating suitable for high frequency. Apply selectively near components.

Testing

• Carry out RF measurements like insertion loss, VSWR etc.

Thermal Cycling

• Cycle over temperature range of product use environment.

Vibration and Shock

• Subject PCB assembly to vibration and shock pulses expected during deployment. Verify performance.

Conformal Coating

• Environmentally seal assembly with conformal coating compatible with operating temperatures.

Quality Inspection

Thorough inspection procedures must validate assembly integrity:

• Visual Inspection – Verify component placement, orientation, solder joints, coating coverage.
• Microscope Inspection – Check solder fillet wetting, bridging under high magnification.
• AXI Inspection – Confirm assembly defects, alignment issues are within limits.
• X-Ray – Employ x-ray imaging to inspect BGA/CSP hidden solder joints.
• RF Testing – Validate transmission fidelity at circuit operating frequencies.
• Environmental Testing – Subject samples to expected temperature, humidity, vibration levels.

FAQs

Q: What is the dielectric constant of RO4350B at 1 GHz?

A: The dielectric constant (Dk) of RO4350B at 1 GHz is 3.48.

Q: What finish is preferred for assembling RO4350B military PCBs?

A: Immersion silver and electroless nickel immersion gold (ENIG) offer the best finish for assembling RO4350B boards.

Q: What is the glass transition temperature of RO4350B material?

A: RO4350B has a high glass transition temperature of 280°C.

Q: What RF connectors work best with RO4350B boards?

A: SMP, SSMP and SMPM connectors rated for microwave frequencies beyond 10 GHz work well.

Q: What solder mask color is typically used on military PCBs?

A: Olive drab green colored solder mask is frequently used on military PCB assemblies.

Printed circuit boards (PCBs) that operate reliably at high frequencies are critical for applications like 5G, satellites, radars, avionics and other wireless communications systems. Manufacturing such high frequency PCBs requires expertise in specialized materials, stackups, fabrication processes and quality control. This article profiles the top 10 manufacturers of high frequency PCBs based on their capabilities.

1. RayMing Technology

Headquarter Location: Shenzhen, China

RayMing Technology is an expert in high frequency PCB prototyping and volume production using cutting edge fabrication technologies and testing. They manufacture boards up to 24 layers for RF frequencies above 10 GHz such as mmWave antennas, radar systems, satellite communication, electronic warfare and aerospace/defense electronics.

Core Capabilities:

• PCB materials including Rogers, Taconic, Arlon for mw and mmWaves
• Stackups with signal-power-ground layer sequencing
• Fine line PCB fabrication down to 2 mil line/space
• Laser drilling to create microvias for HDI
• Immersion silver plating for optimal HF performance
• Rigid-flex PCBs
• 100% testing for electricals and quality

Industry Segments Served: Defense, avionics, telecom, space, automotive

2. TTM Technologies

Headquarter Location: California, United States

TTM Technologies is among the top high frequency PCB manufacturers in the world headquartered in the United States. They fabricate RF/microwave boards for defense and aerospace applications including radars, electronic warfare systems, satellite communications, telemetry systems etc.

Core Capabilities:

• PTFE, ceramic and hydrocarbon based laminates
• Complex multilayer and HDI boards
• Fine line capabilities down to 2/2 mils
• Laser microvias and back drilling
• ENIG, immersion silver and IPC coatings
• Rigid-flex PCBs
• Testing for HF parameters

Industry Segments Served: Defense, aerospace, industrial

3. AT&S

Headquarter Location: Leoben, Austria

AT&S is Europe’s largest high frequency PCB manufacturer serving the automotive, industrial, medical and aerospace sectors. They produce advanced HDI, multilayer and rigid-flex boards capable of over 100 GHz frequencies.

Core Capabilities:

• PTFE, ceramic, polyimide based materials
• HDI structures with 3 um vias/lines
• Stackups for mmWave applications
• Laser drilling and backplane technology
• AOI, microsectioning and electrical testing
• Prototyping to mass production
• Global manufacturing footprint

Industry Segments Served: Automotive, industrial, medical, aerospace

4. Compeq Manufacturing

Headquarter Location: Taiwan

Compeq Manufacturing is a leading high frequency PCB manufacturer in Asia. They fabricate boards using FR4, Rogers, Teflon, Polyimide for wireless communication applications up to 77 GHz. Their key expertise is in automotive radar PCBs.

Core Capabilities:

• Materials including Rogers 4350, 4003C, TMM 3
• Stackups for 77GHz automotive radars
• HDI with 2 mil lines and 4 mil microvias
• Sequential lamination process
• Fine line printing down to 4 mil
• Rigid-flex PCBs
• IATF 16949 automotive qualified

Industry Segments Served: Automotive, communication

5. Elec & Eltek

Headquarter Location: Taiwan

Elec & Eltek specialize in making high frequency PCBs for communication infrastructure applications including 5G antennas, base stations, small cells and satellite communications. They offer advanced HDI and RF boards.

Core Capabilities:

• Key laminates – Rogers RO4003C, RO4835, Taconic RF-60
• PCBs rated up to 76GHz frequency
• Fractional microvia in pad technology
• 1Oz to 2Oz copper on high TG substrates
• ENIG surface finish for fine pitch components
• RF characterization and testing
• Prototypes through volume production

Industry Segments Served: Communication infrastructure, aerospace

6. Hillmancurtis Technologies

Headquarter Location: Stafford Springs, Connecticut, United States

The Defense and Aerospace division of Hillmancurtis specializes in fabricating complex, high reliability PCBs and substrates for defense electronics operating in extreme environments. They manufacture rigid, rigid-flex and ceramic boards for mission-critical applications.

Core Capabilities:

• High speed digital, RF and thermal management PCBs
• Rigid-flex boards for constrained spaces
• Multilayer build up boards for advanced RADAR
• Ruggedized boards meeting Mil-P and AS standards
• Specialty coatings like parylene conformal coating
• Assembly and testing services
• ITAR registered and AS9100 certified

Industry Segments Served: Defense, military aerospace

7. Park Electrochemical

Headquarter Location: Melville, New York, United States

Park Electrochemical develops advanced materials and designs cutting-edge RF/digital multilayer boards catering specifically to aerospace and defense markets. They also build PCBs for satellite antennae applications.

Core Capabilities:

• PTFE composite materials
• Multilayer RF PCBs with complex routing
• PTFE-based RF antenna boards
• Multilayer digital boards for avionics
• Ruggedized for harsh environments
• Design services leveraging RF expertise
• Testing capabilities like shock, vibration

Industry Segments Served: Defense, aerospace, satellite

8. San Francisco Circuits

Headquarter Location: San Francisco Bay Area, California, United States

San Francisco Circuits manufactures advanced RF, microwave and millimeter wave PCBs for communications infrastructure and aerospace/defense applications. Their high frequency PCBs range up to 90 GHz.

Core Capabilities:

• PTFE, quartz and hydrocarbon ceramic materials
• Multilayer RF/digital/mixed signal designs
• Modeling and signal integrity analysis
• ENIG surface finish on exposed pads
• Via stub elimination techniques
• 100% electrical testing
• Low to mid volume production

Industry Segments Served: Aerospace, communication infrastructure

9. Cicor Group

Headquarter Location: Boudry, Switzerland

Cicor Group provides sophisticated PCBs and microelectronics solutions for industries including aerospace, defense, medical and industrial automation. Their PCB technologies support high frequency applications.

Core Capabilities:

• RF designs on substrates like Rogers RO4003
• Multilayer and HDI circuit boards
• Flex and rigid-flex PCB solutions
• Advanced assembly on ceramic substrates
• Clean room assembly and testing
• Prototyping to medium volume production

Industry Segments Served: Aerospace, defense, industrial

10. Probe Test Solutions

Headquarter Location: Irvine, California, United States

Probe Test Solutions offers advanced probe card technologies and HF PCB solutions catering to 5G communications, satellite RF testing and aerospace/defense test.

Core Capabilities:

• High frequency materials including PTFE composites
• Multilayer digital and RF designs
• Micro coax interface on boards
• Millimeter wave antenna in package
• Custom probe cards for IC testing
• Design, fabrication and testing services

Industry Segments Served: 5G infrastructure, aerospace/defense

Comparison of High Frequency PCB Manufacturers

This comparison shows that leading high frequency PCB manufacturers leverage materials like PTFE composites and ceramics along with processes like laser drilling to achieve very high operating frequencies demanded by modern RF/wireless applications.

How to Choose a High Frequency PCB Manufacturer?

Here are some tips on selecting the right PCB manufacturer for high frequency applications:

• Frequency range – Ensure they can support the target frequency range like >10 GHz mmWave boards.
• Materials expertise – Use of substrates like Rogers, Taconic demonstrating high frequency knowledge.
• HDI capabilities – Availability of HDI technology with microvias, fine features.
• Stackup experience – Ability to design optimal layer stacks separating digital and RF signals.
• Design services – End-to-end design support from schematic to fabrication.
• Modeling and analysis – Simulation of signal, power integrity, impedance and EMI.
• Quality systems – Certifications like IPC, ISO, AS9100 demonstrate disciplined quality.
• Testing capabilities – Range of electrical, RF and functional tests offered.
• Prototyping abilities – Capability for both low volume prototyping and volume production.
• Applications experience – Expertise for the specific product application like radars or 5G.
• Cost effectiveness – Competitive pricing combined with strong technical capabilities.

Future Outlook for High Frequency PCBs

The market for high frequency PCBs will witness strong growth in the coming years driven by:

• 5G infrastructure – mmWave PCBs for 5G base stations, small cells, test equipment
• Aerospace/defense – Satcom, electronic warfare, radar, guidance systems
• Automotive – Radar PCBs for collision detection and autonomous driving
• High speed computing – High bandwidth data centers, supercomputers, AI/ML
• IoT proliferation – Connecting appliances, wearables, sensors wirelessly
• Space communications – Satellite constellations for global broadband access
• Technology advances – Innovations in materials, fabrication and assembly enabling higher performance

To cater to this surging demand, high frequency PCB manufacturers are expanding production capacity, capabilities and forming strategic customer partnerships.

Frequently Asked Questions

Q: What frequencies do high frequency PCBs support?

A: High frequency PCBs operate reliably from microwave bands (~3-30 GHz) up to mmWave frequencies >30 GHz. Materials and processes enable these high frequencies.

Q: What are some key materials used in high frequency PCBs?

A: Common materials are PTFE composites like Rogers 4000, Taconic RF materials, Arlon, Isola Astra. Ceramics like aluminum nitride are also used.

Q: What fabrication processes are critical for high frequency PCBs?

A: Laser drilling, photolithography to achieve fine features, sequential lamination, controlled impedance traces, SI analysis and modeling are key processes.

Q: What are some challenges in high frequency PCB manufacturing?

A: Maintaining signal integrity at high speeds, impedance control, thermal management, PCB distortion control and reliability are some key challenges.

Q: How are high frequency PCBs tested?

A: They undergo electrical testing focused on insertion loss, VSWR, time domain reflectometry, impedance and functional RF testing.

LED LIGHTING PCB

Printed circuit boards(PCB), are everywhere in our technology-based society. Everything from computers to medical equipment to cars contains these PCB in one form or another. However, not all PCB are the same— many of them use different designs or materials to suit a unique purpose. The base material is especially important for the circuit board, which helps determine how effectively the circuit board transfers heat.

Some applications require specific properties in their circuit boards. This is especially true for temperature-sensitive applications, one of which is LED lighting. The LED lighting industry is expanding rapidly in response to increased interest in the more efficient and cost-effective lighting method, but much of the functionality of LED lights depends on the temperature of its system. For many companies, the solution to this problem is in aluminum-based PCBs,We call it LED PCB.

To help you understand why the LED lighting industry uses Led PCB, we’ve outlined the nature of PCB base layers, the attractive qualities of aluminum PCBs and why they work well in the LED lighting industry.

LED PCB now widely used in more and more areas because of it’s Energy Saving and Environmental Protection. With over years experience in turnkey service from PCB,Components Sourcing and oem prototype pcb assembly, RayMing Could you provide the LED PCB, LED Chips and OEM LED PCB Assembly Service. If you have some inquiries with the LED PCB

PCB Cores

Engineers design printed circuit boards to work best within their particular application. The designs can specify the nature of the circuit, the PCB coating material, the size of the PCB and a variety of other qualities. One of the most basic qualities to change, however, is the core of the circuit board.

PCB bases come in a variety of materials, including:

FR-4: Most common of these materials is FR-4, a base composed of glass and epoxy. While fire-retardant, FR-4 tends to be relatively inefficient at transferring heat.

Epoxies: Another, albeit less common substrate for PCBs is a material known as an epoxy. While less durable than other options, epoxy-based PCBs are much cheaper to manufacture.

Metal-core: Metal-core PCBs are very effective for a variety of applications, specifically those involving heat transfers. These bases consist of metal, usually aluminum, laminated with copper. These metals give the circuit board improved electrical insulation and thermal conductivity.
When thermal qualities are not as important, FR-4 or epoxy bases are more common, as these tend to be relatively less expensive. However, when thermal qualities are important for the proper function of the end product, metal-core printed circuit boards are likely the solution.

How to Make a LED Board or LED Circuit Board?

Making a LED (light emitting diode) circuit board is a good exercise for those new to electronics. It does not require a lot of components or expertise, and it is a useful circuit to know. When making a LED PCB, LED circuit board, you should be familiar with how a circuit board works. Columns of holes are electrically connected with exceptions for the first and last rows of holes. The first and last rows (rather than columns) of holes are electrically connected and are slightly offset from the main grid. This property of a circuit board makes the job of building a LED circuit board much simpler.

Things You’ll Need

Circuit board

9-volt battery
1″ wire, 2 pieces

100 ohm resistor
LED

Make a LED Board or LED Circuit Board Instructions

1.Wrap an end of your first wire around the positive terminal of your 9-volt battery.
2.Insert the other end of your first wire into the hole of your circuit board located in the first row and the first column.
3.Insert one end of your 100 ohm resistor into the same row as your wire,but this time in the second column of your circuit board.
4.Place the other end of your 100 ohm resistor in the hole of your circuit board located in the second row and second column.
5.Insert the anode (long wire) of your LED into the hole located in the third row, second column of your circuit board.
6.Insert the cathode (short wire) of your LED into the hole located in the third row, third column of your circuit board.
7.Wrap an end of your second wire around the negative terminal of your 9-volt battery.
8.Insert the other end of your second wire into the hole of your circuit board located in the fourth row, third column. You now have a completed LED circuit board and your light emitting diode will illuminate.

Introduction

A printed circuit board (PCB) prototype is an early sample version of a PCB designed to test the viability of the PCB design before full-scale manufacturing. Building a high-quality PCB prototype is a crucial step in the electronics design process, allowing the designer to verify the PCB’s functionality and catch any errors before committing to mass production. This guide will walk through the key steps involved in creating a functional PCB prototype.

Overview of PCB Prototyping Process

The typical workflow for building a PCB prototype assembly is:

1. Create schematic and PCB layout files
2. Choose PCB fabrication process
3. Select PCB materials
4. Submit Gerber files to PCB manufacturer
5. Assemble PCB components
6. Test prototype board
7. Iterate on design as needed

The following sections will explore each of these steps in greater detail, from designing the board to testing the finished prototype.

Schematic Capture and PCB Layout

The first step is to design the schematic and PCB layout files that define the structure of the board. This is done using EDA (electronic design automation) software such as Eagle, Altium, OrCAD, KiCad, etc.

The schematic will include all the components and connectivity on the board. The PCB layout will take the schematic and lay out the traces, pads, silkscreen, drill holes, etc. Some key considerations when designing the board:

• Ensure the schematic follows best practices for readability and manufacturability. Pay attention to conventions for symbols, net names, etc.
• Make the PCB layout match the schematic exactly. Any discrepancies will lead to an non-functional board.
• Follow manufacturer design rules and capabilities. For example, trace widths, hole sizes, clearance rules.
• Minimize traces lengths for better performance, especially for high-speed signals
• Include test points, programming headers, and other features to support prototyping

Selecting PCB Fabrication Process

There are several options for manufacturing PCB prototypes in low volumes. Each has tradeoffs between cost, quality, and turnaround time.

Milling/Engraving

A mechanical process that uses a small end mill or laser to cut away copper on the board. Best for very fast turnarounds but lower precision.

Pros:

• Extremely fast turnaround, usually 1-2 days
• Low cost for basic boards

Cons:

• Limited features and design rules
• Lower precision and accuracy

Chemical Etching

Uses chemicals to etch away unwanted copper on blank PCB laminate. Provides good quality for prototyping.

Pros:

• Fast turnaround, around 2-4 days
• Good quality and resolution
• Low to moderate cost

Cons:

• Limited on fine features below 8 mil line/space

Photolithography

The traditional PCB fabrication technique that uses light-sensitive photoresist and etchants. Provides excellent quality and capabilities.

Pros:

• High precision down to extremely fine geometries
• Excellent for high complexity boards
• Wide range of material options

Cons:

• Slower turnaround time, 5-10 days
• Higher costs as complexity increases

Choosing PCB Materials

The substrates and coatings used in the PCB fabrication process impact the cost, capabilities, and characteristics of the finished board.

Substrate (Core) Material

This forms the base laminate material for the PCB. Common options:

• FR-4 Glass Epoxy – Most common, inexpensive but good performance for prototyping
• CEM-1 Paper Epoxy – Cheaper but lower performance than FR-4
• FR-4 High Tg – Improves heat resistance for enhanced thermal/mechanical capabilities
• Rogers RO4003 – High frequency circuit material
• Polyimide – Extremely heat resistant flexible material

Copper Thickness

Thicker copper increases current handling and thermal dissipation. Common options:

• 1 oz – Standard weight for signal traces
• 2 oz – Heavier copper for power traces
• 1/2 oz – Thinner copper to save cost, allow for finer traces

Soldermask and Silkscreen

Colored lacquers applied over copper for insulation and labeling. Options:

• LPI Soldermask – Liquid PhotoImageable soldermask for high resolution
• SR Green Soldermask – Most common and inexpensive mask color
• Glossy vs. Matte Finish – Glossy better for denser designs
• Silkscreen Legends – Printed labels, often white

Surface Finishes

Applied to exposed pads/traces to facilitate soldering. Options:

• HASL (Lead) – Common finish, allows leaded soldering
• ENIG – Gold immersion finish for high reliability leaded/lead-free soldering
• Hard Gold Plating – Excellent wear resistance, ideal for test points/probes
• OSP – Organic Solderability Preservative, lead-free compatible

Submitting Gerber and Drill Files

To fabricate the board, the PCB layout data must be converted to a standard format called Gerber files along with drill data. These files provide all the info needed to produce the bare PCB.

Most EDA tools can generate Gerber files and Excellon drill files from the PCB layout. Double check for errors before submitting to your board house.

Standard Gerber files required:

• Copper layers – Top, Bottom, Internal layers
• Soldermask top and bottom
• Silkscreen layers top and bottom
• Board outline/profile layer
• Drill drawing and Excellon drill file

Zip the files and upload to your chosen manufacturer. Be sure to order any specified surface finishes.

Assembling Components onto the PCB

Once the bare PCBs come back from fabrication, the next step is populating the boards with components by soldering. This can be done manually or by using SMT assembly equipment for high volume production.

Bill of Materials

You’ll need a complete bill of materials (BOM) specifying all required components before assembling the board. Ensure you order the correct parts specified in the BOM and extra spares.

Manual Assembly

For prototyping it’s common to manually assemble boards. Some tips:

• Use a soldering iron, solder, and basic tools like tweezers. Use flux for easier soldering.
• Solder components in order of profile height, lowest first.
• Double check values and orientations as you populate.
• Inspect joints under magnification for potential bridges or cold joints.
• Take care when soldering sensitive components like ICs to avoid damage. Use sockets.

SMT Assembly

For higher quantity assembly, SMT equipment can place and solder surface mount components much faster and more reliably than manual work. Some options for small prototype runs:

• DIY Reflow Oven – Modified toaster oven with thermal profile
• Desktop SMT Prototyping Machine – Small pick and place + reflow oven combo units
• SMT Assembly Service – Machine assembly services for quick turnaround

Testing the Prototype

Once all components are soldered in place, the prototype board can be validated by testing. This may involve:

• Visual Inspection – Check for correct assembly, no short circuits
• Continuity Testing – Verify electrical connectivity matches circuit design
• Functional Testing – Power up board and test operation against requirements
• Debugging – Identify and fix any functional or design issues

Testing will determine if the board functions correctly or requires another design iteration. Use any issues found to improve the design before final production.

Frequently Asked Questions

What are the key benefits of building a PCB prototype?

The main benefits of prototyping a PCB design are:

• Validates the design by testing it works correctly
• Allows debugging issues before large scale manufacturing
• Tests manufacturability and tolerances for the design
• Provides something to evaluate for potential customers
• Reduces project risk by ensuring quality before high volume production

What are some tips for designing a good PCB layout?

Some best practices for PCB layout:

• Follow manufacturer design rules and capabilities
• Minimize trace lengths for better signal integrity
• Provide adequate spacing and clearance for routing and components
• Incorporate test points and programming connectors to assist testing
• Clearly label layers with silkscreen and use legible text sizes
• Double check footprints match chosen component packages

How many PCB prototypes should be ordered?

As an initial test run, 5-10 boards is generally recommended. This allows distributing prototypes for evaluation and provides spare boards for rework if needed. For simple boards, starting with 3-5 is reasonable. Order extras if producing complex boards or still debugging the design.

What are common SMT assembly techniques for PCB prototyping?

Typical assembly options for SMT prototyping include:

• Reflow soldering with a DIY modified toaster oven
• Small desktop SMT assembly machines optimized for prototyping
• Using stencil + solder paste + hot air rework station
• Full assembly services using professional SMT pick-and-place equipment

How should PCB prototypes be tested?

Recommended ways to test a prototype PCB:

• Visual inspection of the board for errors
• Verify power and ground connectivity
• Check basic I/O operation for components
• Validate core functionality against requirements
• Stress test inputs/outputs and environmental performance
• Try intentional fault injection to check robustness
• Inspect solder joints and connections under a microscope

How to Fabricate a PCB With DIY Methods?

Method 1#:

1. Cut the copper-clad laminate to the size required by the pcb fabrication
2. Put the stencilpaper on the steel plate, use a pen to draw the circuit diagram on the stencil paper (diagram size should be 1:1), cut it out according to the PCB size, and place it on the copper-clad laminate. Take a small amount of paint and talcum powder into a suitable printing material, dip the printing material with a brush, and evenly apply it to stencil paper. Repeat it several times. Then the circuit can be printed on the printed board. This printed board can be used repeatedly and is suitable for small batch production.
3. Use 1g of potassium chlorate and 40ml of 15% hydrochloric acid to prepare a corrosive solution, and then apply it to the printed board where it needs to be corroded for corrosion.
4. Wash corroded printed boards repeatedly with water. Wipe off the paint with banana oil, and then wash it several times to clean theprinted board without leaving corrosive liquids. Apply a layer of rosin solution. Let it dry before drilling.

PCB fabrication Method 2#:

There are many ways amateurs can create PCB, but they are either time-consuming, complex in “craftsmanship,” or low quality. My method of making PCB is one of the methods with a better overall effect. The method is as follows:

1. Printed circuit board diagram. The pads in the figure are represented by dots, and the connection can be a single line, but the position and size must be accurate.
2. Cut the printed circuit board according to the circuit diagram’s sizeand clean the surface of the copper foil.
3. Use carbon paper to copy the diagram to the printing board. If the circuit is simple and the producer has extensive board-making experience, this step can be omitted.
4. Depending on the components, paste standard pre-cut symbols (pads) with different inner and outer diameters. Then stick tape lines of different widths according to the current. Electronic stores provide standard pre-cut symbols and tape. Common specifications of pre-cut symbols include basic materials such as D373 (0D-2.79, ID-0.79), D266 (0D-2.00, ID-0.80), D237 (OD-3.50, ID-1.50). Try not to use (black) and plastic (red) materials. The general specifications of tape are 0.3, 0.9, 1.8, 2.3, 3.7, etc. The unit is millimeters.
5. Use a softer hammer, such as smooth rubber, plastic, etc.,to hit the sticker to make it fully adhere to the copper foil. Focus on the turning and overlapping of the line. It is best to use a heater in cold weather to heat the surface to enhance the adhesion effect.
6. Put it in ferric chloride to start the corrosionprocess. Be noted that the liquid temperature cannot be higher than 40° After corrosion, it should be taken out and rinsed at the correct time, especially if there are thin lines.
7. Make holes, polish the copper foil with fine sandpaper, apply rosin alcohol solution, and let it dry. The quality of this printed board is very close to that of a conventional printed board. The 0.3 mm tape can be passed between the two legs of the IC, which can greatly reduce the short jumpers on the front of the circuit board, thus saving trouble and time.

PCB fabrication Method 3#:

1. Dissolve lacquer flakes (namely shellac, available from chemical stores) in three parts of absolute alcohol, and stir appropriately. After all the flakes dissolve, add a few drops of medical purple potion (gentian violet) to make it show a particular After evenly mixing, it can be used as protective paint for the pcb fabrication.
2. First,polish the copper-clad board with fine sandpaper. Then use the duckbill pen in the drawing instrument (or the ink duckbill pen used to draw graphics on the compass) for drawing. There are nuts on the duckbill pen to adjust the thickness of the stroke. You can also use a triangle ruler to draw thin straight lines. The drawn line should be smooth, uniform, without jagged edges, giving people a smooth and fluent feeling. You can also write Chinese characters, English, pinyin, and symbols in the free space of the circuit board.
3. If the drawing line penetrates the surrounding environment, the concentration is too small,and you can add some paint chips. If the drawing line does not stretch smoothly and becomes too thick, you need to drop a few drops of absolute alcohol. It doesn’t matter if you make a mistake. Just wipe it off with a small cotton swab dipped in absolute alcohol, and then redraw. After drawing the circuit board, it may corrode in the ferric chloride solution. After the circuit board is corroded, it is very convenient to remove the paint. Dip a cotton ball in absolute alcohol to wipe the protective paint to dry, and then apply rosin.
4. Because the alcohol evaporates quickly, the prepared protective paint should be sealed and stored in a small bottle,such as an ink bottle. Cover the bottle cap after use. If the concentration becomes thicker in the next use, add the appropriate amount of anhydrous alcohol to dilute the solution.

Fabrication PCB Method 4#:

1. Paste the self-adhesive labels on the copper foil of the copper-clad laminate, then draw the circuit on the veneer. Use a cutter to cut the veneer to form the required circuit prototype, remove the non-circuit parts, and finally use ferric chloride to corrode theideal circuit board.
2. The corrosion temperature can be performed at about 55°C, and the corrosion rate is more rapid. Rinse the corroded circuit board with clean water, remove the self-adhesive labels on the circuit board, make holes, wipe clean, and then apply rosin alcohol solution prior to

Method 5#:

1. Arrange the components’ density and positionaccording to the shape of the components used in the schematic circuit diagram and the size of the printed board area. The components‘ location should be determined according to the principle of large first, then small, first overall, and then local. The adjacent components in the circuit are placed nearby and arranged neatly and evenly.
2. The connecting tracebetween components cannot be bent at right angles at the corners or intersections of the two traces. They must transition through a curve, and they cannot cross each other and turn too far. When certain traces cannot achieve this, you can consider placing printed trace on the back of the printed board and then using stud bolts to connect to the front circuit. Another solution is to use insulated trace when soldering components.
3. The distance between the input part and the output part is better to avoid mutual interference.

Method 6#:

1. Print the circuit board diagram on the printer at a ratio of 1:1 on 80 grams of copy paper. Hand drawing is also possible, but the bottom paper should be flat.
2. Find a fax machine, take out the fax paper from the machine, and replace it with a hot-melt plastic film. Put the circuit diagram into the fax machine’s outgoing fax trayand use the copy button to copy the circuit diagram on the hot-melt plastic film. At this time, the “printed manuscript” of the printed circuit board is ready.
3. Use double-sided adhesive tape to affix the drawn plastic film to the copper-clad board evenly. The plastic film and board shouldbe flat and not wrinkled. The tape paper can not cover the melted part. Otherwise, it will affect the production quality of the circuit board.
4. Use a paintbrush to brush the paint on the plastic film evenly. Note: Only brush in one direction. Otherwise,the plastic film will wrinkle, and the lines on the copper plate will overlap. After the circuit diagrams have been brushed, carefully remove the plastic film. At this time, a printed circuit board is finished. After drying, it can be corroded.
5. If you want to print manypieces, you can make a wooden frame that is a little larger than the circuit board, lay the PCB stencil (our company sells it) flat on the wooden frame, and fix it. Then use double-sided tape to stick the fixed plastic film under the screen. Put the copper-clad board on the table, close the screen frame (the printed image and the copper-clad board should be aligned left and right), use a paintbrush to paint in one direction, and remove the screen frame. The printed circuit board is printed. If there is any defect, it can be modified with paint and bamboo.

Pay attention to the above process. When painting, the hand force should be light and heavy. If there is too much paint or the film is too thick, the lines will be smudged. If the force is too light, the lines will break. And the plastic film must face up.

What is the Industrial PCB fabrication Process?

1. Board cut

Board cutting is the process of cutting the original copper-clad laminate into boards that can be made on the production line.

First, let’s understand a few concepts:

• UNIT: Refers to the unit graphics designed by PCB design engineers.
• SET: Refers to multiple units that engineers put together to improve production efficiency and facilitate production. This is what we often call the puzzle, which includes unit graphics, process edges,etc.
• PANEL: Refers to a pcb fabrication composed of multiple sets. It is added with tool board edges to improve efficiency and facilitate production when PCB manufacturers producethe product.

2. Innerdry film

The inner layer dry film is the process of transferring the inner layer circuit pattern to the pcb manufacturing board.

In PCB production, we will mention the concept of graphics transfer because the production of conductive graphics is the basis of PCB production. Therefore, the graphics transfer process is of great significance to pcb fabrication process.

The inner dry film application includes many processes such as inner layer filming, exposure, development, and etching. The inner film is to paste a special photosensitive film on the copper plate’s surface, which we call a dry film. This film will cure when exposed to light, forming a protective film on the board. Exposure and development expose the board with the film, the transparent part is cured, and the non-transparent part is still the dry film. After developing, the uncured dry film is removed, and the board with the cured protective film is etched. After removing the film, the inner circuit pattern is transferred to the board. The whole process flow is shown in the picture below.

For designers, our main consideration is the minimum line width, spacing control, and wiring uniformity. If the distance is too small, it will cause film clamping. If this occurs, the film cannot be removed entirely and will cause a short circuit. If the line width is too small, the film’s adhesion is insufficient, resulting in an open circuit. Therefore, the safety spacing during circuit design (including line to line, line to pad, pad to pad, line to the copper surface, etc.) must be considered during pcb manufacturing.

• Grinding board

The primary function of the grinding plate: The basic pretreatment is mainly to solve the problems of surface cleanliness and roughness. Remove oxidation and increase the copper surface’s roughness, which will increase the film’s adhesion effect to the copper surface.

• Filming

Paste the processed substrate with dry film or wet film by hot pressing or coating to facilitate subsequent exposure production.

• Exposure

Align the negative film with the substrate on which the dry film is pressed, and use ultraviolet light on the exposure machine to transfer the negative film pattern to the photosensitive dry film.

• Development

Use the weak alkalinity of sodium carbonate to dissolve and rinse the unexposed dry film/wet film, leaving the exposed part.

• Etching

After the unexposed dry film and wet film are removed, the copper surface will be exposed. Use acid copper chloride to dissolve and corrode the exposed copper surface to obtain the required circuit.

• Film stripping

Use sodium hydroxide solution to peel off the exposed dry film that protects the copper surface to expose the circuit pattern.

3. Brown oxidation

Purpose: To form a microscopic roughness and organic metal layer on the inner copper surface to enhance the adhesion between the layers.

Process principle: Through chemical treatment, a uniform and good adhesion characteristic of the organic metal layer structure is produced. The copper layer’s surface, which is before the inner layer, is roughened in a controlled matter. This is to strengthen the inner copper layer and the prepreg after pressing the plate strength.

4.Stack up

Stack up is the process of bonding each layer into a whole utilizing the PP sheet’s adhesiveness. This bonding is achieved by mutual diffusion, penetration between macromolecules on the interface, and interweaving. The multi-layer pcb manufacturing and PP sheets are pressed together to form a multi-layer board with the required number of layers and thickness. In actual operation, the copper foil, bonding sheet (prepreg), inner layer, stainless steel, isolation board, kraft paper, outer layer, and other materials are laminated according to the process requirements.

For designers, the first consideration for stack up is symmetry. Because the pcb fabrication will be affected by pressure and temperature during the lamination process, stress will remain on the board after the lamination is completed. Therefore, if the two sides of the laminated board are not uniform, the stress on the two sides will be different, causing the board to bend to one side, which greatly affects the PCB’s performance.

In addition, even in the same layer, if the copper distribution is uneven, the resin flow rate at each point will be different. As a result, the area with less copper will be slightly thinner, and the area with more copper will be slightly thicker.

In order to avoid these problems, various factors such as the uniformity of the copper distribution, the symmetry of the stack, the design and layout of the blind and buried holes, etc., must be considered in detail during the design.

5.Drilling

Drilling is the process of creating through-holes between the layers to connect the layers.

6.Plated through holes(PTH) and plating

• Plated through holes(PTH)

Plated through-holes are also called chemical copper. After drilling, the PCB board undergoes redox reactions in the sinking copper cylinder to form a copper layer to metalize the holes. Copper is deposited on the surface of the original insulating substrate to achieve an interlayer electrical connection.

• Plating

Plating creates the PCB board surface that has just been copper-immersed. The copper in the hole is thickened to 5-8um to prevent the thin copper in the hole from being oxidized or micro-etched and leaking the substrate before pattern plating.

(1) Outer dry film

The process is the same as the inner dry film.

8.Outer layer pattern plating, SES

The copper layer of the hole and circuit is plated to a specific thickness (20-25um) to meet the copper thickness requirements of the final PCB board. The useless copper on the board surface is etched away, exposing useful circuit patterns.

9. Solder mask

Solder mask, also called and green oil, is one of the most critical PCB fabrication processes. Solder mask is achieved mainly through screen printing or coating solder mask ink, coating a layer of solder mask on the board surface, and developing through exposure. The processes also expose the disk and hole to be soldered and cover other areas with solder mask to prevent short circuit during soldering.

10. Silkscreen

The required text, trademark, or part symbol is printed on the board surface by screen printing. Afterward, it is exposed on the board surface by ultraviolet radiation.

11. Surface treatment

The solderability of bare copper itself is very good, but long-term exposure to the air can cause oxidation and saturation. It tends to exist in the form of oxides and is unlikely to remain as the original copper for an extended period. Therefore, surface treatment of the copper surface is required. The primary purpose of surface treatment is to ensure good solderability or electrical properties.

Regular surface treatments: HASL, immersion gold(ENIG), OSP, immersion tin, immersion silver, electric hard gold, electric gold fingers, etc.

12. Forming

The pcb fabrication process is cut into the required dimensions with a CNC molding machine.

13. Electrical test(E-test)

Simulate the status of the pcb fabrication and check the electrical performance after power on to see if there is an open or short circuit.

14. Final inspection, sampling test, packaging

Check the appearance, size, hole diameter, thickness, and marking of the pcb fabrication process to meet customer requirements. The qualified products are packed into bundles, which are easy to store and transport.