3 types of SMT stencil production process
According to the processing methods, basically the classification of SMT stencil can be divided into three categories, that is: chemical etching process, laser cutting process, electroforming process.
These are the differences in production methods, but the preliminary steps are basically the same. For example, customers provide ready-made PCB circuit boards, which are scanned and drawn into production files; or they are directly provided with drawings (i.e. PCB design files or Gerber files etc. that can be processed by computers), these are sent to the SMT stencil manufacturer, and then the engineering department of the SMT stencil manufacturer conducts pre-production design processing to make finished documents suitable for final processing, and then get it to the production department for production.
solder paste printing principle
With the development of SMT stencil, more than 95% of the stencil in the SMT processing industry is made by laser cutting. Next, let's briefly introduce the three production methods, advantages and disadvantages of corresponding SMT stencil:
1. Chemical etching: Apply a layer of acid-proof glue on the steel plate, remove the glue where the opening is needed, exposing the steel plate, and corrode the steel plate with acid to form an opening. The effect of using this kind of stencil is not very good.
2. Laser cutting: It is very simple to use laser to directly drill holes in the place where the opening is needed. This kind of steel plate is the most used and the price is relatively cheap.
3. Electroforming: This kind of stencil is based on laser cutting. Then inner wall and the opening chamfer are electroformed at the opening, so that the inner wall of the opening is very smooth, which is good for solder paste printing. This kind of steel plate is very expensive and is not used much, unless there are special requirements for the SMT process, it is generally not used.
If you need SMT stencil, it is best to purchase SMT stencil according to your actual situation. If the opening is very simple, you do not need to mount very precise components (including 0.5mm or below pitch IC, 0201 chip material, etc.), chemical etching method can fully meet your needs.
So what are the advantages and disadvantages of laser stencil compared with other type stencils?
(1) Advantages:
Compared with etched stencil and electroformed stencil. Laser SMT stencil is simple to make, fast, accurate, easy to use, and affordable. After the laser stencil is electropolished, the quality is better and the effect is better. At present, most stencil of SMT processing on the market use laser cutting.
(2) Disadvantages:
The thickness is fixed one, the ladder stencil cannot be made, and the treatment of irregular shapes of rounded corners and chamfers is not perfect.