PCB process edge function, production method and design

Edge in the SMT patch machine nozzle to absorb components and mount to the PCB board, there may be collision phenomenon. As a result, production cannot be completed, so a certain process edge must be reserved, and the general width is 2-5mm. This method is also suitable for some plug-in components to prevent similar phenomena when undergoing wave soldering.

The process edge is not part of the PCB board and can be removed after the PCBA manufacturing is completed.

PCB process edge production method

1, V-CUT: a process connection between the process edge and the board, slightly cut on both sides of the PCB board, but not cut!

2, connecting ribs: the use of several ribs to connect the PCB board, in the middle of some stamp holes, so that the hand can be broken or washed off with the machine.

PCB process side design requirements

Not all PCB boards need to add process edge, if the PCB board space is very large, on both sides of the PCB set aside 5mm without any patch components, this situation does not need to add process edge, there is another case is the pcb board side within 5mm without patch components, as long as the other side of the process edge can be added, These need the attention of PCB engineers. The plate consumed by the process side will increase the overall cost of the PCB, so when designing the PCB process side, it is necessary to balance economy and manufacturability.

For some special shape PCB boards, the PCB boards that were originally left with 2 process edges or 4 process edges can be greatly simplified by cleverly assembling them.

When designing the assembly method in SMT processing, it is necessary to fully consider the track width of the SMT mounter. For the assembly with a width exceeding 350mm, it is necessary to communicate with the process engineer of the SMT supplier.

OSP is an organic welding film, also known as copper protection agent, which is mainly to protect copper exposed to the air, which is a common surface treatment process in PCB processing. All things are not perfect, OSP is no exception, then Shenzhen PCB board factory - Honglijie Electronics to introduce the advantages and disadvantages of PCB board surface treatment process OSP.

OSP acts as a barrier between copper and air, which is different from other surface treatment processes, OSP is organic, not metal, so it is cheaper than the tin spray process. The principle is to grow a layer of organic film on the clean bare copper surface by chemical method, and many computer motherboards use the OSP process.

This layer of organic film can make the circuit board before welding to ensure that the inner layer of copper foil will not be oxidized, welding, once heated, this layer of film will evaporate, solder can solder the copper wire and components together.

With all the advantages of bare copper plate welding, expired plates can also be re-finished.

Disadvantages: 

1, OSP transparent colorless, more difficult to check, it is difficult to distinguish whether the OSP processing.

2, the OSP itself is insulated, non-conductive, will affect the electrical test. In this way, the test point must open the steel mesh and print the solder paste to remove the original OSP layer, and then contact the needle point for electrical testing. OSP cannot be used as an electrical contact surface, such as a keyboard surface for keys.

3, OSP is not corrosion resistant, easy to be affected by acid and temperature. When used in secondary reflow welding, it needs to be completed within a certain time, usually the second reflow welding effect will be relatively poor. If the storage time exceeds three months, it must be resurfaced and used within 24 hours after opening the package.

An OSP circuit board, exposed to the air for more than ten days, will not be able to weld components.