Solder pastePrintingMTCommon problems in processing technology: The quality of solder paste printing is very important. Solder paste printing is an important process flow. inSMTIn the surface mount technology (SMT) production process, the solder paste printing processing technology is a unified stage because it is due to the installation defects of many printed power circuits. When close intervals are applied, the problem is complex, resulting in tin Bridges between adjacent feet.

Regulations for printing base steel plates 

1The specifications are precise and stable. And the steel mesh can have an excellent surface. It is suitable and firmly positioned relatively accurately in the printing machine. The solder mask layer and oil marks do not harm the solder mask layer.
2The base steel plate must have sufficient strength and flatness
3The components at the bottom edge of the double-sided panel must take into account the relative density of the components (the support points should be considered)
4Surface cleanliness: The surface must not be contaminated with floating dust or dirt.
5The solder mask should be prevented from being higher than the solder mask. 

 With the development trend of electronic devices towards miniaturization and high functionality, in order to better meet the application requirements of high-density micro-interval components and achieve the printing of fine interval components, technological innovations have been carried out on traditional fiber laser cutting steel mesh, which has emergedFGNew types of steel mesh manufacturing methods such as steel mesh and nano-coated steel mesh. 

FGSteel mesh: Laser steel mesh processed from special stainless steel plates and fine crystal stainless steel. Its advantage lies in the addition of a niobium element in the steel sheet processing technology,Niobium elements can optimize the crystal, reduce the over-temperature sensitivity and fire ductility of steel, and improve the compressive strength of steel sheets during production and processing. The production and processing shape of the hole edge gloss is better than that of ordinary steel mesh and fine crystal stainless steel plate304Compared with stainless steel plates, it has the advantages of high compressive strength, good flexibility and wear resistance. The laser template thus produced features stable and consistent characteristics, excellent printability, durability and longevity, and can effectively increase the one-time success rate of printing.

Nanotechnology steel mesh: Nanotechnology steel mesh inherits the advantages of laser steel mesh such as high precision and shorter production and processing time. It is based on the application of nanomaterials in andPCB The outer surface of the plate and the inner cavity of the mesh are coated with nanocomposite materials, and by altering the structure of the nanocomposite materials, they are made to be compatible with stainless steel sheets Excellent experience    The strength of the steel sheet will also be further enhanced. Because the nanocomposite material has a resistant effect on the solder paste in the solder paste, it reduces the adhesion between the solder paste and its solder paste, Reducing the residue of solder paste on the inner wall of the hole improves the demolding quality and the transfer rate of solder paste.
3.2 Steel mesh design

Steel mesh design is the key to processing technology design. Steel mesh design includes opening design and thickness design. 

Thickness design: The thickness of the steel mesh should be determined based on the relative density of the printed circuit board assembly, the size of the electronic components, and the spacing between the pins (or solder balls). General Application0.1 mm～0.13 mmThin and thick steel sheets. When assembling with high density, it can be selected0.1 mmThe following thicknesses.0.4 PITCHtheQFP,020For a component, the suitable thickness is0.1 mm,0.4PITCH CSPFor components, the suitable thickness is0.08 mm.
    Opening design: This includes the opening specification and opening shape. Both the opening specification and opening shape can affect the filling and release of solder paste (demolding), thereby influencing the print volume of the solder paste. The three major factors that harm the release of solder paste are: the ratio of thickness and the ratio of total area. The geometric shape of the hole edge Surface roughness of the hole edge.

Main regulations for the opening design of steel mesh:IPC-7525The basic definition of drilling holes in steel mesh stipulates that the openings of the steel mesh must meet a certain thickness ratio and total area ratio so that the solder paste can smoothly migrate through the meshPCBIn terms of the defined design, the range ratio and thickness ratio of the steel mesh openings are respectively exceeded0.66and1.5However, when designing specifically, the relatively small width of the opening should also be taken into consideration＞5*solder ball size,The transfer rate of the solder paste will reach the above level70%Above. When designing steel mesh, ifL＞5 WTaking into account the ratio of kindness; Otherwise, the total area ratio should be taken into account to determine whether the design of the mesh is beneficial for the release of solder paste.

Summary

Solder paste printing processing technology is a dynamic processing technology. There are many factors that affect the quality of solder paste printed products, which are related to solder paste, base steel plate, steel mesh, squeegee, printing support points and the main printing parameters, etc. To achieve continuous and stable printing quality, it is first necessary to ensure that the printing machine has excellent reliability. Appropriate solder paste, base steel plate, steel mesh, and squeegee must be selected, and reasonable basic parameters of the printing machine should be set. Corresponding supervision regulations should be formulated to ensure that solder paste printing operates under controlled conditions.

The brand of Shenzhen JJYSolder pasteAfter all12A solder paste and wire manufacturer specializing in the annual research and development of solder paste, solder wire, solder wire, lead-free solder paste, leaded solder paste, solder rods, leaded solder paste, etc. Choose the solder paste manufacturer of JJY brand for solder paste.