Microwave Tech - Understand what factors affect the quality of high-frequency board PCB steel mesh?

Understand what factors affect the quality of high-frequency board PCB steel mesh?

PCB factory: 1. Before the production process, we discussed the manufacturing process of the steel mesh. We know that the best process should be laser cutting and electropolishing. In chemical etching and electroforming, there are some processes that are prone to errors, such as film reduction, exposure, and development. Electroforming is also affected by the non-uniformity of the substrate.

2. The materials used include PCB frame, wire mesh, steel plate, adhesive, etc. The PCB frame must be able to withstand a certain program relay and have a good level; polyester mesh is most suitable for wire mesh, which can maintain tension stability for a long time; steel plate is best used with No. 304, and matte is more beneficial to tin than mirror . Rolling of the slurry (adhesive); the adhesive must be strong enough to withstand some corrosion.

3. The hole design has the greatest impact on the quality of the PCB stencil. As mentioned earlier, the design of the opening should consider factors such as manufacturing process, aspect ratio, area ratio, and empirical values.

4. The integrity of the production data will also affect the quality of the PCB template. The more complete the information, the better. At the same time, when data coexists, it should be clear which data should prevail. In addition, generally speaking, the use of data files to make stencils can reduce errors.

5. The correct printing method can maintain the quality of the steel mesh. On the contrary, improper printing methods, such as excessive pressure, poor PCB template or PCB network, can cause damage to the stencil.

6. Solder paste (adhesive) cleaning is easier to solidify. If it is not cleaned in time, it will block the opening of the template. The next edition is difficult. Therefore, the PCB template should be cleaned in time after being removed from the machine, or should not be printed on the printing machine for one hour.

7. The storage network should be used in a specific storage location and should not be placed randomly to avoid accidental damage to the storage network. At the same time, the PCB stencil should not overlap and be difficult to handle, which may cause the frame to bend.

Steel mesh introduction:

SMT mold: A special SMT mold whose main function is to help deposit solder paste, and the purpose is to transfer the precise amount of solder paste to the precise position of the empty PCB.

SMT process development: SMT steel mesh (SMT template) has also been applied to the bonding process. The evolution of steel mesh was originally composed of steel mesh, so it was called a mask at the time. The first is nylon (polyester) mesh. Later, due to durability, metal wire mesh, copper wire mesh, and finally stainless steel wire mesh appeared. However, no matter what material is used, there are disadvantages of poor molding and low precision.

With the development of SMT technology, the requirements for the network are getting higher and higher, and the steel mesh has emerged as the times require. Due to the material cost and difficulty of the production process, the original steel mesh is made of iron/copper plate, but because the stainless steel mesh is easy to rust, it is replaced, that is, the current steel mesh (SMT).

Steel mesh classification

According to the manufacturing process of SMT steel mesh, it can be divided into laser template, electropolishing template, electroforming template, step template, bonding template, nickel-plating template and etching template. Laser mold template is currently the most commonly used template in the SMT mold industry. Its characteristics are: direct use of data files for production, reducing errors in the manufacturing process; high accuracy of the opening position of the SMT template: the overall process error is less than (+4 microns); the opening of the SMT template has a geometric pattern, which is beneficial to the solder paste print.

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