PCB has developed for the past few years. It has developed from the regular board for components to the circuit board with complex components.
As PCB designer or manufacturer, you constantly face challenges on how to achieve a better outcome. You want to provide a new solution or breakthrough to problems. In some cases these problems may require new functionality. It could also be a choice between a module-based or custom PCB design. In any of these cases, you need special PCB types. The ever-growing demand to provide electronic capabilities like high speed or high power into odd spaces made special circuit board types crucial.
There may be reasons for this apprehension. Your PCB assembly and fabrication will become successful if you work with right contract manufacturer (CM). To have a clear knowledge of what a special PCB is, we will first define printed circuit boards according to their mechanical and electrical properties which you can use to define your board requirements. Furthermore, we will discuss how manufacturing printed circuit boards with special materials affect turnaround time and cost.
What is a Special PCB?
If PCB was classified based on its material, special PCB can be FR4 PCB or metal core PCB. Special PCBs have special requirements. This is a reason they are known as special PCBs. For instance, special PCBs like buried and blind unique, 10 oz heavy copper, and high frequency boards have special requirements.
Special PCB can realize both electrical and mechanical functions. Furthermore, extreme factors like copper thickness, precision, and the PCB thickness are becoming the focus.
Special PCB Types
Impedance controlled PCB: This circuit board is available in 100 ohms, 50 ohms. The tolerance can be +-10%.
Heavy copper PCB: The copper weight of heavy copper boards is 4~10 OZ/ft2. Extreme heavy copper PCB has a copper weight of 20~200 OZ/ft2.
How to Optimize Special PCB Board Manufacturing Process
The materials used for printed circuit boards primarily define their properties. Therefore, it is crucial to choose the best PCB material. The choice of the PCB material is an aspect of PCB design. However, PCB designers need to explore the properties of a board if the PCB board material doesn’t satisfy the board requirements.
Furthermore, there are parameters you CM must consider during the manufacturing process of special PCBs. These parameters include type of material, light copper weight, trace width, size, heavy copper weight, surface finish, and more. These parameters can affect the manufacturing process as regards cost and turnaround time.
As PCB designer or manufacturer, you constantly face challenges on how to achieve a better outcome. You want to provide a new solution or breakthrough to problems. In some cases these problems may require new functionality. It could also be a choice between a module-based or custom PCB design. In any of these cases, you need special PCB types.
Special PCB Technologies
HDI blind buried hole
You can only see blind holes on the top or bottom layers. This means that blind holes are usually created from the PCB surface. On the other hand, both sides of buried holes are inside the PCB layers. Buried holes are usually drilled in the inner layer. This means that a buried hole is a type of hole inside circuit boards. Blind buried holes have helped in reducing the quality and size of High-Density Interconnect (HDI) PCBs. Also, these holes help in enhancing electromagnetic compatibility, minimizing the number of layers, making PCB design faster, and reducing costs.
The integration of blind buried hole in the FR-4 prototype has advanced to the highest level of 20 layers. Also, the board thickness is ≤6.0mm, blind holes stage is 1~4, and laser drilling technology is integrated.
Multi-layer special stack-up structure
The ever-growing demands for high-speed circuits have made the complexity of PCB boards become higher. There is a need to separate the power layer and the signal layer to prevent the interruption of electrical factors. Therefore, multiple layers are involved in this process.
Furthermore, the stack-up structure is plays a significant role in electromagnetic compatibility (EMC) performance of the circuit boards. Also, it is a critical way to reduce electromagnetic interference. For the number of signal networks, the PIN density will be greater if the device density is greater. In this case, a special stack-up structure is needed.
Characteristic impedance refers to the resistance electromagnetic waves or high-frequency signals encounter in the transmission signal lines of components. The PCB characteristic impedance value must correspond with the tail and head components’ electronic impedance when transmitting the digital signal on the circuit board.
In a case where mismatch occurs, there will be reflection, delay, attenuation, and scattering of transmitted signal energy. In this case, the PCB designer must carry out impedance control. For FR-4, flexible circuit board, a rigid-flex board, the process of impedance control can help achieve 2–20 layers.
Thick copper PCB
A thick copper PCB is a type of printed circuit board in which the thickness of the copper is 2 oz or beyond. Also, the thick copper circuit board features corrosion resistance, low temperature resistance, high temperature resistance, and great extension performance. These properties enable electronic devices to have a longer life span. Also, they help in simplifying the size of electronic equipment. Some PCB designers can achieve 2~6 layers in thick copper PCB technology. 10 oz is the maximum copper thickness.
Electroless Nickel Electroless Palladium Immersion Gold(ENEPIG)
The Electroless Nickel Electroless Palladium Immersion Gold(ENEPIG) is a commonly used surface finish type used in circuit boards. The ENEPIG process involves depositing nickel, palladium, and gold on the PCB surface by chemical methods. This surface finish technology is non-selective.
This surface finish option integrates 50 nm thick palladium plating and 10 nm thick gold plating. The integration of these plating helps in achieving anti-friction, corrosion resistance, and good electrical conductivity. The copper layer thickness will impact the different appearance and physical properties mentioned above. ENEPIG is the most recent surface finish technology integrated in the PCB prototype. plated pad
Electroplated nickel gold/gold finger
Nickel electroplating is also known as electrolytic gold. This surface finish type attaches gold particles to the circuit board by integrating electroplating. It is usually called hard gold since its strong adhesion. This process of attaching gold particles can help to improve the wear resistance and the hardness the circuit board. Also, it can prevent copper and other metals from diffusing. Furthermore, it can meet the requirements of brazing and hot press welding. The coating can have good ductility, low stress, and low porosity. Therefore, coating is widely integrated in PCB proofing.
Considerations for Choosing a Manufacturer for your Special PCB
There are several special PCB manufacturers. When choosing a manufacturer for your special board, it is crucial you consider some factors.
Special PCBs like heavy copper board, ceramic PCB, and high frequency board require great skill and knowledge during their manufacturing process. Your manufacturer must have a vast knowledge in the design and production of this PCB. Also, you can get more information from review of customers.
Your special PCB manufacturer must adhere to certain standards in the industry. Also, ensure the company you are hiring has the right certification. Certification implies that your PCB manufacturer adheres to certain standards in the industry. Also, it indicates the quality of the printed circuit board your manufacturer supplies. The right certification assures you your manufacturer is on the right track.
This is another factor you need to consider when choosing a manufacturer for your special PCB project. Some manufacturers have a long standing experience in fabricating special PCBs. The years of experience your PCB manufacturer has acquired indicates how well they have been performing.
Turnaround time is an essential factor to consider when choosing a special PCB manufacturer. This factor describes the time it takes to complete the fabrication of a printed circuit board. Before you request for a circuit board, make enquiry about your manufacturer’s turnaround time.
This is an important factor you need to consider when choosing a manufacturer for your special PCB. Your manufacturer should be attentive to all your needs and details. Also, some PCB manufacturers offer after sale services to their clients. Consider a manufacturer who puts your interest first.
Some PCB manufacturers offer customers special PCBs. If you have decided to go for special printed circuit boards. Cart buy The ever-growing demand to provide electronic capabilities like high speed or high power into odd spaces made special circuit board types crucial.