Printed circuit boards are without doubt the core materials for manufacturing electronic devices. There are several PCB manufacturers today as the use of these boards has become popular. Bergquist PCB is a high-quality PCB with great properties. Bergquist PCB features great flame-retardant, exceptional mechanical strength, and dimension stability.
Asides from that, this PCB features a good heat sink and electromagnetic protection. Bergquist gap filler is a material that features great benefits for engineers. In this article, we will be discussing everything you need to know about Bergquist PCB.
Bergquist PCB – What Does It Mean?
Bergquist PCB is a laminate class with aluminum base copper. This laminate features great thermal and mechanical properties. Bergquist thermal clad provides a thermal management solution for applications. Especially those in need a high watt-density surface mount.
This thermal clad laminate conducts heat more. This substrate features better mechanical properties than direct bond copper constructions. It can remove components and enable the production processes of smaller devices.
Bergquist MCPCB features optimum durability, lower operating temperatures, and longer component life. Bergquist thermal clads aren’t only incorporated with metal base layers. These substrates can boost their function by replacing FR-4 in multilayer assemblies. The thermal clad’s thermal performance can reduce the copper circuit layer’s thickness.
Bergquist thermal clad PCB allows low-cost manufacturing. This happens by removing the need for expensive manual assemblies.
Rayming Support BERGQUIST thermal clad material list :
1.bergquist Thermally Conductive Silicone Film Series （Sil Pad= SILPADTSP）
2.bergquist Thermal silica film series （Gap Pad= GAPPADTGP）
(Abbreviation: GPVO, GPVOSOFT, GPVOUS, GP1500, GP2000S40, GP1500R, GP3000S30, GPHC3.0, GP2500S20, GP5000S35)
3.bergquist Thermally conductive solid glue series double grouping (GapFiller= GAPFILLERTGF):
4. bergquist phase change material series (Hi Flow = HIFLOWTHF):
HiFlow105, HiFlow225UT, HiFlow300P (HIFLOWTHF1600P)
5.bergquist Thermally conductive double-sided adhesive series (Bond Ply):
Benefits of Bergquist Thermal Clad PCB
There are several benefits of the Bergquist thermal clad. These benefits include:
Increased performance and durability
Bergquist PCB feature low thermal impedance which outperforms other insulators. This allows cooler operation. These thermal clad PCBs increase the level of durability. This is because the designs are simple and components are cool.
The thermal clad removes the thermal interface and uses thermal solder joints. This makes the assemblies cool. These thermal clad PCBs allow automated pick-and-place for SMD’s which minimize production costs.
Board size reduction and hardware replacement
Bergquist thermal clad minimizes board space and replaces other components like heat sinks. It also helps to get rid of rubber or mica insulators under power devices. Heat transfer becomes better when it removes this hardware.
With the use of etched traces on the board, interconnects can be removed. This thermal clad helps to replace discrete devices at the board level.
Increased power density: The use of Bergquist PCBs allows more efficient electricity conduction. This means that these metal PCBs can conduct more efficient power.
Long term reliability
In the PCB world, new materials often go through a thorough qualification program. After this program, these materials can be launched in the market. Bergquist Company features state-of-the-art test facilities. It ensures that all their materials go through extensive testing. This is to verify their electrical integrity. Bergquist makes use of strict development procedures.
This U-L-approved company has ISO 9001:2000 certified production facilities. Qualification testing includes temperature recycling, electrical and thermal stress. It also involves adhesion and mechanical property validation. Bergquist combines up-front qualification tests with audits. This helps to ensure the materials offer consistent performance. Electrical testing takes place at selected intervals.
Extends dies life: One great thing about Bergquist PCB is that it prolongs dies shelf life. These PCBs guarantee you the components’ life extension. This company ensures the fragile components are replaced. This is with more durable and stronger parts.
Bergquist Thermal Clad PCB Applications
Bergquist thermal clad are useful in several applications. This is because of their thermal and mechanical properties.
Motor drives: Bergquist thermal clad are ideal for use in motor drive applications. These thermal clad are good dielectric material and feature high watt density. With these materials, you can fabricate and install form factors into motor drives. The compact motor drives on these thermal clad ensure high watt density. Bergquist PCBs are ideal for high-temperature applications.
Power Conversion: Bergquist thermal clad is a preferred choice for engineers. This is because of its watt-density and size. This material features various thermal performances and is highly reliable. You can utilize this thermal clad in most form factors. Engineers also fabricate it in various substrate metals and copper foil weights. Bergquist sil pad is another material useful in this application.
LEDs: Thermal clad has been useful in LED applications for a long time. It is without a doubt that this material features great thermal properties. It is an ideal solution for designers who are considering reliability and quality. Bergquist thermal clad can be used for special bends and shapes. This enables the designer to make use of LED light engines in any application.
Heat-rail and forming: Thermal clad has become popular in heat-rail and forming. The use of this material has increased. It is used in other applications like automotive. Fabricators can remove the dielectric and form the metal with three-dimensional substrate. This material provides surface mount assemblies. It also gives attachment abilities in heat rails and forming applications.
What Does a Thermal Clad Comprise of?
This material is a dielectric metal base that features a bonded copper. Bergquist thermal clad consists of three different layers.
Dielectric layer: Bergquist thermal clad consists of a dielectric layer. This layer is at the middle of the clad and it ensures electrical isolation. Furthermore, this dielectric layer helps to minimize thermal resistance. This layer also provides electrical isolation. Any dielectric layer should be glass-free. This helps the thermal performance of the thermal clad.
This layer is the major element of Bergquist thermal clad. It bonds the circuit metal with the base metal together. Dielectric layers of a thermal clad sets the foundation. One great benefit of this layer is that it is U.L-certified.
Circuit layer: During the fabrication of a thermal clad, the circuit layer is the top layer. The circuit layer allows heat transfer and electric current conduction. For a thermal clad, there are various sizes of circuit layers. This size is between 0.5 oz and 10 oz. Furthermore, you can request a specific size that suits the intended application.
Base layer: The base layer is often made of aluminum. But, copper can also be used. The thickness of the material also varies. 1.57mm is the most common base material thickness. Designers are free to decide the thickness of this base layer. Ensure you select a base layer thickness that is ideal for your applications. Some applications don’t need base layer materials.
What to Consider When Choosing Dielectric Materials
When choosing dielectric materials, you have to consider some factors. You will need to evaluate your options and consider the application requirements. We will be discussing the primary factors you should consider.
Thermal conductivity: This is an important factor you should not overlook. The Bergquist thermal clad’s thermal conductivity clad determines thermal performance. This is important especially when interfacial area and resistance are considered.
Thermal Impedance: This helps to determine the watt density of any application. This is because thermal impedance measures how temperature declines. This decline is checked across each watt’s stack-up. Lower thermal impedance indicates that more heat moves out of the components.
Dielectric layer type: It is no doubt that a dielectric layer is very important in a thermal clad. This dielectric layer helps to increase an application’s performance. This layer is a ceramic/polymer combination. It makes thermal clad have great properties of electrical isolation.
Polymers are great materials that can withstand high bond strengths and thermal aging. The ceramic filler helps to boost thermal conductivity. High-frequency applications need the best dielectric material.
Electric isolation: The thickness of dielectric material falls within a range. This is from 0.003 inches to 0.009 inches. Your isolation requirement will determine the thickness of your dielectrics. It is important you choose the right thickness for your dielectric material.
How to Measure the Thermal Conductivity of a Thermal Clad
Bergquist thermal clads’ thermal conductivity determines a lot of things. There are two major ways to know this material’s thermal conductivity. The value of the thermal conductivity can vary. This depends on the method you use.
Standard test method:
This method uses ASTM E1461 and ASTM D5470. The steady-state method is ASTM D5470. This method doesn’t utilize approximations. More so, it offers derived value. Engineers refer to ASTM E1461 as the diffusivity of Laser Flash. You calculate thermal conductivity and the thermal diffusivity refers to the test output.
Non-standard test methods are another way to determine thermal conductivity. When you use this non-standard method, the thermal conductivity values can be different. For example, if you select the same dielectric methods, then you can get different values.
You can utilize other substrate’s materials. This will help you arrive at different results. It is important to know that this method doesn’t give the best results of thermal conductivity.
Connection Techniques for Bergquist PCB
There are several connection techniques used on Bergquist PCB. These techniques are discussed below:
Power connections are lead frame assemblies. This connection attaches to the printed circuit pads. Engineers bend these assemblies to give room for the shell utilized for encapsulation. Some designs employ a plastic retainer ideal for high amperage. You will need to adhere to design rules and regulations for IMS PWBs.
This is very important in designing packages that feature Chip-On-Board architecture. Wire bonding is a connection technique that utilizes the surface mount ability of a PCB.
In thermal clad assembly, pin headers and pin connectors are very useful. These connections are important when you attach an FR-4 panel to a thermal clad assembly. The most developed designs make use of stress relief when fabricating the pin. You can achieve current carrying capacity when you make use of redundant header pins.
Custom connectors address mechanical and electrical fastening. The holes enable great soldering without errors. In addition, the shoulder washer helps the base plate. Custom connectors are not available commercially. Most times, they are custom-made.
Designers should finish the interfacing conductors with sulfamate nickel plating. This is very important when the edge connectors are part of the printed wiring pattern of the thermal clad. A 45-degree chamfer is the best for an edge connector. To avoid shorting, always sustain the minimum edge to conductor distance.
Considerations for Base Metal Layer Design
For the base layer of Bergquist thermal clad, there are certain considerations to look at.
Solder joints & the thermal expansion coefficient
Designers can reduce solder joint stress in a thermal clad. Select the appropriate base layer to match the expansion of the component to get this. The fatigue the solder joint undergoes in cycling or power is a major concern.
Cooling and heating may stress the joint. Solder joints are not rigid in terms of their mechanical capability. Mismatched materials, large devices, and extreme temperature may cause strain on solder joints. Device termination and ceramic-based components are causes of solder joint fatigue.
Electrical connections to the base plate
Copper is an ideal material for the layer if the connection to the base plate is important. You should match the base and circuit coefficients of thermal TCE expansion. Failure to do this may cause excess plated-hole fatigue during thermal cycles.
The base’s thickness
For aluminum and copper thermal clad, there is a standard thickness of the gauge. There are also non-standard thicknesses. The base layer’s thickness is an important factor to consider.
For Bergquist thermal clad, copper and aluminum are the most common base layers. However, there are other metals you can utilize. Some applications consider CTE mismatch as a factor and as such, use other metals.
Without any doubt, copper and aluminum are cost-effective base layers. These materials are the industry standards. When design consideration is a factor, copper is the right option. Copper is costlier than aluminum. For instance, an aluminum material of 0.125 has similar costs to a copper of 0.040 inches.
This is another important consideration for the base metal layer design. Copper and aluminum base layers feature similar quality brushed surfaces. Aluminum comes in different colors such as blue, clear, red, and black.
How to Select a Circuit Layer
There are factors you should consider when selecting a circuit layer. The circuit layer of Bergquist material is very important. We will discuss these factors in this section.
Heat spreading capability
In materials of thermal clad, the dielectric thickness affects the way heat spreads. The foil thickness also influences heat spreading ability. Heat spreading is a great advantage. This can increase when you increase the thickness of the copper conductor. When the copper conductor thicknesses increase, it reduces junction temperature.
Engineers use heavy copper with bare die to remove any need for a packaged component. Sil pad 400 helps to isolate the sources of power from heat sinks.
Current carrying capabilities
This is an important consideration in selecting a circuit layer. In a thermal clad, the circuit layer represents the component-mounting layer. This layer interconnects the assembly’s components. The circuit trace that links up the components can convey greater currents. This is because it can dissipate heat.
Considerations for Electrical Design
There are several things that play a significant role in an electrical design of a thermal clad. These things include:
Proof testing is an important aspect. After the fabrication of PCBs, engineers ensure these materials undergo rigorous testing. The essence of proof testing is to ensure there are no defects in the materials. The materials for thermal clad usually undergo testing. This is to confirm the potency of the dielectric material. For testing the voltages need to be higher than the beginning of partial discharge.
Experts suggest that the number of proof tests should be at a minimum. This will help to prevent some issues from occurring.
Partial discharge includes the following:
- Surface tracking and treeing
- Surface emission at interfaces
- Inner discharges in cavities or void
- Corona discharge
During the proof test, engineers test several circuit boards at once. Proof test helps to ascertain that the dielectric insulation has no degradation. Degradation can occur due to any defects in the material or the fabrication process.
The proof testing at some voltage levels can reduce the life span of the dielectric. Poof testing above 1200 or 700 VAC shows defects in the dielectric insulation of the material.
Micro-voids, delaminations, and micro-fractures in the dielectric can break down during the test. Experts recommend using the DC proof test to ensure safety. The levels of voltage should be around 1500 VDC to 2250 VDC.
You have to control the voltage’s ramp to prevent tripping. This will also help to control the test effectively.
Operators have to take safety considerations during DC testing. They must ensure that the board is fully discharged before they remove it from the test fixture.
Dielectric breakdown voltage refers to the possible difference that dielectric failure can happen. Dielectric failure may happen in an insulating material between two electrodes. Such breakdown is irrecoverable and permanent. ASTM maintains that the results from this test can help to detect the dielectric characteristics of a material.
This is different from the proof test. Experts recommend proof testing below 50% of the actual dielectric breakdown voltage. It as well involves providing for creepage distance to prevent surface arcing.
Dielectric materials come in different thicknesses and types. Not all boards yield the same result. During Hipot testing, metal substrates that are insulated look like capacitors of parallel plates.
The value of the capacitance varies. This difference is with the configurations of board layouts and materials. This happens when a board passes the tests and another fails. However, both boards pass when you test for their leakage current and dielectric strength in a controlled environment.
It is very important to consider material characteristics when testing parameters. Parameters and test setup that don’t consider the necessary factors can cause false failures of the board.
The charge and leakage current is another test characteristic that raises concerns. You can only detect leakage current measurements once you bring the board to DC voltage.
Read about Multilayer PCB here
How to Choose Dielectric Materials for Thermal Clad PCBs
Bergquist thermal clad uses dielectric materials that feature great properties. However, when choosing these dielectric materials, Bergquist considers certain factors. These factors include:
Now, Peel strength of thermal clad works in line with the temperature you expose them to. Peel strength measures the strength of the bond between the dielectric material and copper conductor.
When the temperature rises, the peel strength of a thermal clad is weaker. The temperature of the thermal clad application will determine the peel strength.
Coefficient of thermal expansion:
The operating environment of thermal clad will determine the coefficient of thermal expansion. This value increases with the temperature.
The temperature of the operating environment determines a lot. It doesn’t only determine the peel strength and CTE, but it also determines storage modulus. When there is an increase in temperature, the storage modulus decreases. You can choose the ideal Bergquist material for your operating environment.
Frequently Asked Questions
What factors determine the cost of Bergquist thermal clad? The cost of a Bergquist thermal clad varies. Several factors determine the cost of these materials. The material quality plays a significant role in the cost of this thermal clad. Aluminum and copper are the best materials for the base layer.
The size of the material also determines the cost. If the aluminum or copper is bigger, the cost will be higher. The material’s thickness is also an important factor. These factors determine the price of the thermal clad.
What are the risks of operating Bergquist thermal clad above glass transitions? The mechanical and electrical properties of this thermal clad will change. You will notice that the CTE increases and the peel strength reduces. The storage modulus of the thermal clad also declines.
What is the ideal operating temperature of a Bergquist PCB? The type of dielectric will determine bergquist PCBs’ operating temperature. If you will utilize this PCB in high-temperature applications, HT Bergquist PCB is the best.
What does a Bergquist gap pad do? A Bergquist gap pad is a material that helps to fill the air gaps between devices’ heat spreaders. It offers a thermal interface between devices and heat sinks.
Bergquist material features great thermal and electrical properties. This material is ideal in several high-temperature applications. The dielectric material of Bergquist PCB plays a significant role. Henkel Bergquist is gaining popularity in the PCB industry.
Bergquist produces electrical and mechanical stable thermal clad. Bergquist PCB has its unique benefits and this makes it stand out in the industry.