How to judge the quality of solder paste? How to identify and handle it?

How to judgeSolder pasteGood or bad? Everyone is well aware that this situation can also occur with common solder paste, but they don't know how to identify it. If we look at the appearance, it's only the surface. Engineers should pay more attention to the quality performance of the solder paste. The soldering quality,AOITest performance, long-term reliability, etc., and also test according to standards. If all the data meet the requirements, it is a good solder paste. The use of a solder paste brand and model must go through a series of preliminary tests and actual production tests. Now, let's have JJY solder Paste Manufacturer introduce how to detect and handle it?

It can be used generally.SMTFor trial use suggestions, observe the following items:

1Observe under a microscope whether the tin powder particles are uniform and the surface smoothness.

2Smell the solder paste.

3For the printing position, observe the demolding effect and the forming effect. Special attention should be paid to the effect after three hours. Many poor-quality solder pastes start to deteriorate very poorly after three hours of printing.

4Check the welding effect of the weld points behind the furnace.FLUXThe residue should not be excessive.

In fact, the above solder paste tests are general tests. For some items, the test results are already available in the test reports attached by the solder paste suppliers. As a user, we can only look at the data in the attached test reports. What we actually do is only the tests of the solder paste's characteristics and the post-soldering effect verification. However, it is rather one-sided to evaluate the quality of a brand model based on this. Moreover, the application or usage effect of each product needs to go through a series of tests and stability tests in the later stage of welding before a conclusion can be made. There is no such thing as good or bad; there is only whether it is suitable or better.

The most common problems in solder paste printing are soldering, solder seepage, collapse, sharpening and powdering.

I. Diagnosis and Treatment of Tin Soldering

1Phenomenon description: There is a small amount of solder paste connecting between the two solder pads. During high-temperature welding, it is often pulled back by the main solder bodies on each pad. Once it cannot be pulled back, it will cause a short circuit in the solder balls or the circuit, resulting in poor welding.

2Soldering diagnosis: insufficient tin powder, low tin powder viscosity, large tin powder particle size, high room temperature, too thick printing, high placement pressure, etc.

3Soldering treatment: Increase the proportion of metal components in the solder paste; Increase the viscosity of the solder paste; Reduce the particle size of tin powder; Reduce the ambient temperature; Reduce the thickness of the printed solder paste; Enhance the accuracy when printing solder paste; Adjust various construction parameters of solder paste; Reduce the pressure applied to the parts; Adjust the temperature curves of preheating and fusion welding.

Ii. Diagnosis and Treatment of Tin Infiltration

1Phenomenon description: After printing, there are burrs or excess solder paste near the solder paste.

2Tin seepage diagnosis: Insufficient pressure of the scraper, too small scraper Angle, excessive opening of the steel mesh.PCBandPADThe size is too small, the printing is not aligned properly, the parameters of the printing machine are set incorrectly, and the steel mesh andPCBThe bonding is not tight and the viscosity of the solder paste is insufficient.PCBOr the bottom of the steel mesh is not clean, etc.

3Tin infiltration treatment: Adjust the parameters of the solder paste printer; Clean or replace the template, clean or replacePCB; Improve the accuracy of the printing press; Increase the viscosity of the solder paste.

Iii. Diagnosis and Treatment of Solder Paste Sharpening

1Phenomenon description: Solder paste is presentPCBThe molding on it is poor, the coating area is too large, and the distance between the weld points is too small.

2Diagnosis of solder paste sharpening: The holes in the steel mesh are not smooth, the size of the holes in the steel mesh is too small, and the demolding speed is unreasonable.PCBThe solder joints are contaminated, the solder paste quality is abnormal, and the steel mesh is not wiped clean, etc.

3Solder paste sharpening treatment: Clean or replace the steel mesh; Clean or replacePCB; Adjust the printing parameters; Replace the solder paste with better quality.

Iv. Diagnosis and Treatment of Solder Paste Collapse and Powdering

1Phenomenon description: Solder paste is presentPCBThe molding on it is poor, the printing height is inconsistent, and the solder paste is in powder or granular form.

2Diagnosis of solder paste collapse and powdering: Excessive solvent in the solder paste, excessive solvent when wiping the bottom of the steel mesh, solder paste dissolving in the solvent, the wiping paper not rotating, poor quality of solder pastePCBThe printing was left in the air for too long.PCBExcessively high temperatures, etc.

3tinPaste collapse and powder treatment of solder paste: Increase the proportion of metal components in solder paste; Increase the viscosity of the solder paste; Reduce the particle size of tin powder; Reduce the ambient temperature; Reduce the thickness of the printed solder paste; Enhance the accuracy of the seal paste; Adjust various construction parameters of solder paste; Reduce the pressure applied when the parts are placed; Avoid using solder paste and after printingPCBLeft in damp air for a long time; Reduce the activity of the flux in the solder paste; Reduce the lead content in metals.

To sum up: Regarding the requirements for solder paste: I would like to tell everyone that it should have excellent rolling properties. It has low viscosity during the printing process and high viscosity after printing is completed. The flux paste of Shenzhen JJY, a well-known brand, has a very good separation effect from steel mesh and scraper. It also has the characteristic of not drying easily at indoor temperature but drying easily at preheating temperature12A manufacturer of solder paste and solder wire with a year of product research and development, specializing in solder paste, solder wire, lead-free solder paste, leaded solder paste, solder rods, leaded solder paste, etc.