Difference between solder paste screen and red glue screen
1、 I believe that many customers do not know how to choose when they go off the grid with the laser grid system. Today, let's share with you briefly!
1. The most important thing is the selection of steel mesh process:
Generally, SMT processing manufacturers will determine whether to make solder paste steel mesh or red glue steel mesh based on different component designs of PCB boards. Generally, if there are many pieces, red glue mesh technology will be used for wave soldering. There are few components, but they are wave soldering. Solder paste mesh process is adopted for manual welding. Of course, this is decided by the customer according to the patch processing and production.
2. Difference of steel mesh:
Red glue screen - first print the red glue, then print the components. After the components are firmly bonded to the PCB, insert the components to pass the wave soldering uniformly.
Solder paste mesh - directly print solder paste on the bonding pad, paste the SMD components, and then conduct reflow soldering uniformly. The solder components are manually welded.
3. Of course, the most fundamental and simple difference is that the perforated pipes are different:
The red glue screen, such as a resistor, normally has two pads, and the red glue hole is the position between the pads. In this way, the red glue is applied to stick and tin.
Holes are opened at the pad position, so that the solder paste is directly brushed at the pad position.
2、 Understand red glue and solder paste
Red glue is a kind of polydilute compound, which is different from solder paste in that it will solidify after being heated, and its freezing point temperature is 150 ℃. At this time, red glue starts to directly change from paste to solid. Properties of red glue: red glue has viscosity fluidity, temperature characteristics, wetting characteristics, etc. According to this characteristic of red glue, the purpose of using red glue in production is to make parts stick firmly to PCB surface to prevent them from falling
Solder paste is an indispensable data in SMT. After it is cooked and melted, SMT parts can be welded on PCB copper foil for connection and conductivity. Its role is similar to that of tin wire and wave soldering tin water we often see, but their inherent states are different
1) From the perspective of process:
When the red glue dispensing process is adopted, when there are many points on the board, the dispensing will become the bottleneck of the whole SMT line;  
When the red glue adopts the printing glue process, it is required to AI first and then patch, and the printing glue position is required to be very accurate;  
Solder paste process requires the use of furnace pass bracket;  
2) From the perspective of quality:
Red glue is easy to drop parts for cylinder or glass encapsulated parts;  
Compared with solder paste, red glue plate is more affected by storage conditions, and the problem caused by moisture is also part loss;  
Compared with solder paste, the defective rate of red glue plate after wave soldering will be higher. Typical problems include solder skips;  
3) In terms of manufacturing cost:-
The furnace passage bracket in the solder paste process is a large investment;  
For solder on solder joints, solder paste is more expensive than tin bar;  
Glue is a special cost in red glue process;  
4) In terms of use:
The red glue shall be stored in the freezer at 2~8 ℃ to prevent the characteristics from being affected by temperature changes
The red glue shall be heated for 4 hours at room temperature, and used in the first in first out order
For dispensing, the red glue in the rubber tube should be de bubbled, and the red glue that is not used up at one time should be stored in the freezer. Old glue and new glue cannot be mixed
Fill in the temperature recovery record form, the temperature recovery person and the temperature recovery time accurately. The user must confirm that the temperature recovery is OK before use. Generally, neither solder paste nor red glue can be used after expiration. Once the solder paste is oxidized, it will be rejected immediately. The solder paste can be stored for 30 days at room temperature and 120 days at 2~8 ℃. Solder paste: used on the printing machine. The ingredients of the solder paste are: tin powder (63%), lead powder (37%) Flux (accounting for 5% of the total composition). The eutectic point of the solder paste is 183 ℃. At this time, the solder paste starts to melt from the paste and becomes solid when it is cold. The role of the solder paste is that it is deformed by heat, and it is the medium for the part and PCB PAD welding.
Hongqiao Technology Co., Ltd. is a high-tech enterprise specializing in the research, development and production of cutting fluid, electronic hardware cleaner, surface treatment agent, welding materials: solder paste, tin rod, tin wire, BGA solder ball, SMT tin, electronic flux and thinner, electronic welding equipment and accessories, electroplating anode plate (rod), semi tin ball and other products.