2024.05.20

Flux Frequently Asked Questions and Answers 2

Empty welding 
  1. Printing: bias, 
  2. Path: bias, mounting pressure, poor thimble positioning
  3. Reflow welding: the temperature setting is not good, the component is not heated enough.
  4. Materials:1. Poor weldability of components. 2. The activity of solder paste is not good.
Offset
  1. The is a displacement in the position of the imported components of the reflow welding furnace: check the positioning of the patch machine method and accuracy, adjust the patching machine; check the adhesion of solder paste; smooth transmission expedite; observe the transmission status when the tin furnace.
  2. The displacement of the component occurred in the process of reflow welding; when checking the heating curve and preheating time it complies with the regulations; the track operation is smooth and clear.
  3. Whether the printing volume of solder paste is too much; adjust the printing volume of solder paste.
  4. Whether the design of the substrate welding area is correct; re-check according to the design requirements of the welding area.
  5. Whether the activity of solder paste is qualified; it can change the use of strong solder paste.
Empty
  1. Printing
A) The printing of solder paste is too thick, and the amount of solder paste is too much.
B) The ambient temperature and humidity exceed the standard, and the solder paste or PCB, BGA are damp.
C) The solder paste is dry and does not roll.
2. Reflow welding: the temperature setting is not appropriate.
3. PCB: The position of the PCB through hole is not right or the bubbles in the buried hole.
4. PCB, components: unbaked.
5. Material: a) The quality of solder paste is poor; b) There are bubbles in the BGA tin ball.
Continuous tin electrodeposit
  1. Printing: offset, bridge connection, uneven surface, solder projection, too thick, excessive amount of solder paste.
  2. Patch:The installation is biased or the pressure is too high, resulting in the post-bridge connection.
  3. Reflow welding: improper temperature setting, uneven heating or too fast heating.
  4. PCB, steel mesh design: steel mesh thickness or opening discomfort.
  5. Material: Thixotropy, Collapse and Viscosity changes of solder paste.
Residual
  1. Printing: a) The solder paste is printed too thick, and the amount of solder paste is too much. b) The solder paste is not fully stirred.
  2. Reflow welding: The temperature setting is not appropriate, the preheating is not enough, the temperature is too high.
  3. Steel mesh design: Large PAD does not have a diversion design.
  4. Material: The quality of solder paste is not good.
Standing piece
  1. Printing
  1. The printing thickness is uneven or the amount of tin at one end is small;
  2. Printing offset
Patch: Offset
Reflow welding
  1. Improper temperature setting;
  2. Unbalanced heating of components;
  3. The stove triangle T is too large;
PCB: PCB solder pad design is not good;
Materials
  1. Poor weldability of one-end solder pads or components
  2. The solder paste is too active
Solder bead
  • Printing
  1. After printing, there is too much solder paste.
  2. There is solder paste at the bottom of the mesh board that has not been cleaned.
  3. The ambient temperature exceeds the standard, and the solder paste or PCB is damp.
  • Reflow welding: Improper temperature setting, insufficient preheating, too fast heating.
  • PCB, steel mesh design:
  1. Improper management method of solder paste, absorbing too much water.
  2. The quality of solder paste is not good.
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