What are the causes and solutions for the appearance of solder beads during solder paste printing? During the general reprinting process, many skilled technicians will encounter the situation of tin beads. The occurrence of this phenomenon is the result of the combined effect of many factors in the production process. The reasons for the appearance of tin beads include the product itself, environmental protection issues during welding, and the fact that the welding material itself contains a certain amount of moisture and problems in the formulation. So, what are the reasons for the appearance of tin beads during the production process? Also, if you want to know how to solve this kind of problem, let's talk about Youjia Jinyuan belowSolder paste manufacturerLet me introduce it to you all

1,Solder pasteThe warming time was insufficient, resulting in moisture after printing.PCBImproper storage of the board caused it to get damp. When passing through the reflow oven, tin explosion occurred, resulting in tin beads.

Answer: Extend the warming time of the solder paste.3-4Hours, strengthenPCBThe preservation and use of the boardPCBBake the board.

2The solder paste printing steel mesh is not clean and contaminatedPCBBoard The steel mesh is too thick, resulting in excessive solder paste printing. The openings of the steel mesh are improper, causing the solder pads to overflow during reflow and solder beads to appear after passing through the furnace.

Answer: Clean the steel mesh more frequently, adjust the thickness of the steel mesh, use anti-tin bead steel mesh, and change the openings of the steel mesh.

3During the solder paste printing process, the force and Angle of the squeegee were adjusted incorrectly, resulting in excessive solder paste on the solder pads. After passing through the reflow oven, the molten solder overflowed the solder pads, causing solder beads to appear.

Answer: Adjust the Angle and force of the scraper.

4The viscosity of the solder paste is high, the printing performance is poor, and the sphericity of the solder powder is not good, which leads to an uneven amount of solder paste on the pad after printing. When passing through the reflow oven, the flux in the solder paste of the pad evaporates quickly, resulting in insufficient cleaning force of the pad and excessive surface tension, and the appearance of solder beads.

Answer: Reduce the viscosity of the solder paste, improve its printing performance (thixotropic coefficient), and use high-quality solder powder. If the metal content in the solder paste is high, the alloy ratio in the solder paste needs to be reduced.

5The placement accuracy of the surface mount machine is insufficient, the placement pressure is too high, the solder paste overflows the pad after placement, and solder beads appear after passing through the reflow oven.

Answer: Adjust the placement accuracy and pressure of the placement machine.

6The collapse of solder paste is not good. When passing through the reflow oven, the solder paste collapses due to heat and overflows the solder pads, resulting in solder beads.

Answer: Adjust the collapse performance of the solder paste.

AIf the activity of the solder paste is insufficient, enhance the activity of the solder paste formula.BIf the viscosity is low, adjust the viscosity of the solder paste, adjust the flux paste formula, and increase the metal content of the solder paste.

7The furnace temperature curve, the chain speed is too fast, and the chain shakes severely.

Answer: Adjust the furnace temperature curve, reduce the chain speed, and repair the chain vibration.

8The solder paste activity is insufficient, the solder pads are severely oxidized, and the solder pads are not cleaned properly when passing through the reflow oven, resulting in uneven surface tension between the solder pads and the solder, and the appearance of solder beads.

Answer: To enhance the activity of solder paste, factors such as its lifespan and printing lifespan should be taken into account when increasing the activity of solder paste.

9After the solder paste was printed, the demolding was not done well, causing the solder paste to tip. During the surface mount process, the solder paste overflowed the solder pad, and after reflow, solder beads appeared.

Answer: Adjust the printing performance of the solder paste (adjust the thixotropic coefficient of the solder paste)

Summary: As can be seen from this, the higher the preheating temperature and the more rapidly the preheating zone heats up, the greater the vaporization phenomenon and the more likely it is to form tin beads. If you still have any questions, you can consult Shenzhen JJY Industrial Technology Co., LTD. Let's learn and grow together!