What Is Custom PCB?
Custom PCB services those customers who have not found the suitable PCB from the common types, or have their own unique requirements for PCB fabrication. On the other hand, you can design the custom PCBs in some special steps that will make your PCB fabrication and assembly process more flexible and suitable for your purpose. Design custom PCBs can also have a lower price than the full custom one.
Wanted a full-custom PCBs or just design custom PCBs, you need to have PCB basic, such as the process of PCB fabrication and assembly, the right material of PCBs, types of PCBs and the characteristics of each of them, PCB component, PCB design, PCB layout, and PCB reverse engineering software.
Why You Need Custom PCB?
Custom PCB can be divided into full custom PCB or design custom PCB.
The full custom PCB is more flexible and advanced than the design custom PCBS, and usually used in high-standard industries such as the medical industry, or aerospace industry where need a totally special design for their devices.
Design custom PCB has a lower cost than the full custom PCB and more complex and flexible than the normal type. It hasn’t a comprehensive custom PCB design but has a complex design than the normal. It also provides a unique and professional appearance. Compare with the full custom PCBs, the design custom boards have a lower cost and fast production circle.
Custom PCB boards are mainly made of four processes: PCB fabrication, PCB assembly, PCB coating, and PCB inspection. PCB coating and inspection are specialized that will be provided by your PCB manufacturers. You can select the type, material, and production technology for your unique PCBs in the PCB fabrication and assembly process.
There is the basic of the process of PCBs fabrication and assembly:
8 steps of PCB fabrication:
- Step 1: Creating a designed layout on the copper-clad laminate.
- Step 2: PCB manufacturers will etch or remove excess material from inner layers to reveal images and pads.
- Step 3: Laminating printed circuit board materials at high temperatures for creating the PCB layer stack up.
- Step 4: Creating mounting holes, through-hole pins, and vias on PCB.
- Step 5: Etch and remove the excess copper of the surface layer to reveal images and pads.
- Step 6: Placing plating pin holes and via holes.
- Step 7: Creating a protective coating or solder masking on the surface.
- Step 8: Printing silkscreen printing, logos or other markings, and installing polarity indicators on the surface.
5 steps of PCB assembly:
- Step 1: Adding solder paste
- Step 2: PCB pick and place
- Step 3: Soldering
- Step 4: Inspection
- Step 5: Testing
Material is the second core during the PCB manufacturing process. PCB designers usually have various considerations to ensure the normal function and wear resistance of PCBs. Different electronic products should match different PCBs for the mixture utilization of the PCB function. These factors include dielectric constant, flame retardance, higher glass transition temperatures, mitigated loss factors, thermal performance, dimensional stability, etc.
Therefore, there are some excellent materials that are most popular to use as the material of PCB fabrication:
FR4 epoxy laminate and prepreg: Features with good electrical, thermal, and mechanical characteristics, as well as an excellent strength-to-weight ratio, FR4 has become the ideal materials for most electronic applications. This kind of material meets certain requirements of NEMA LI 1-1998 standards. FR4 laminates and prepreg usually used for the PCB with lower layer counts generally less than 14 layers.
Polyimide laminates and prepreg: Compare with FR4, the excellent resistance in harsh and higher temperature environments made this kind of PCB materials have a higher cost and improved electrical performance properties. It also is stable during the thermal cycling with less expansion property that is very suitable for higher layer count constructions.
Teflon laminates and bonding plies: This kind of PCB material is ideal for custom PCB manufacturing because of its excellent electrical properties. Teflon laminates and bonding plies can provide high-speed capabilities to the designers and become the ideal material for high-speed circuitry applications, so it is expensive more than polyimide.
Flexible laminates: This kind of PCB material is thin and can be used for the electronic design that needs to fold the PCB. Generally, this kind of material is made from higher temperature materials such as polyimide, or low-cost materials such as PEN and polyester.
Other PCB materials also include BT, ceramics, cyanate ester.