Introduction of small and medium batch SMT patch process
- 2020-01-30-

Small and medium batch SMT patches can be made from a variety of different materials. The most widely used form of glass fiber substrate called FR4. This provides a reasonable degree of stability under temperature changes and is not as severe as the breakdown, although not being overly expensive. Other less expensive materials can be used for printed circuit boards in low-cost commercial products. For high-performance RF designs, the dielectric constant of the substrate is important, and a low level of loss is required, and then PTFE-based printed circuit boards can be used, although they are more difficult to handle.


In order to make the track with the components in the small and medium batch SMT patch, first obtain the copper clad board. This includes the substrate material, usually FR4, and the usual copper cladding on both sides. The copper coating is connected to a thin layer of copper on the motherboard. This combination is usually very good for FR4, but the properties of PTFE make this more difficult, which increases the difficulty of processing small and medium batches of PTFE SMT patches.

versusSmall and medium batch SMT patchBoard selection and provision The next step is to create the required tracks on the circuit board and remove the unwanted copper. The manufacturing of small and medium batches of SMT patches is usually achieved using a chemical etching process. The most common form of PCB etching used is ferric chloride.

In order to obtain the correct pattern of the track, the photographic process is used. Usually the copper of the bare printed circuit board is covered with a thin layer of photoresist. It then passes through a photographic film or photomask to specify the required track exposure. In this way the image of the track is transferred to the photoresist. With this completed, the photoresist is placed in the developer so that only those areas of the track plate that are needed are covered in the resist.

The next stage in the process is to place the printed circuit board into areas that are etched with ferric chloride in areas that do not require tracks or copper. Knowing the concentration of ferric chloride and the thickness of copper on the circuit board, it is placed into the amount of time required to etch the bubble e-commerce. If the printed circuit board is placed in the etching for too long, then some definition is lost as the ferric chloride will tend to weaken the photoresist.

Although most of the small and medium-volume SMT patch panels use the manufacturing method of photographic processing, other methods are also available. One is to use a specialized highly accurate milling machine. Then the machine is controlled to grind the copper far away in areas where it is not needed. The control is obviously automatic, driven from files generated by SMT patch design software for small and medium batches. This form of small and medium batch SMT chip manufacturing is not suitable for large quantities, but it is an ideal choice in many cases where the number of small and medium batch SMT chip prototypes is very small.

In the manufacture of multilayer printed circuit boards, although the same process is used, as a single-layer board, a considerable degree of precision and manufacturing process control is required.

The board is made by using much thinner individual boards, one for each layer, and then these are combined together to produce a whole circuit board. As the number of layers increases, each board must become thinner to prevent the finished board from becoming too thick. In addition, the registration between the layers must be very accurate to ensure that any holes are aligned.

To combine the different layers together the board is heated to cure the adhesive material. This may cause some problems with the warp. Large multi-layer circuit boards can have a unique bend on them if they are not designed correctly. This can happen especially if, for example, one of the inner layers is a power plane or a ground plane. Although this in itself is good, if some reasonably significant areas have been unwound copper.