SMT chip processing reflow welding welding defect inspection checklist
1. Pickaxe bead checklist
(1) Is the temperature rise rate in the initial stage of preheating too large?
(2) Is the temperature rise rate during the reflow phase too large?
(3) In order to avoid tin bead, has the template opening size been reduced or the template opening has been specially designed?
(4) Are there any additives in the solder paste to prevent the formation of tin beads?
(5) Is the mounting pressure too high?
(6) Is the temperature in the production workshop too high or the humidity too high?
(7) Check other printing parameters.
2. Solder ball inspection checklist
(1) Is the temperature rise rate too high during the initial stage of preheating?
(2) Is the holding time long enough?
(3) Is there a nitrogen protection device?
(4) Is the mounting pressure too high?
(5) Has the size of the template opening been reduced?
(6) Is the printing press aligned?
(7) Is the position of the solder mask correct?
(8) Is the storage life of solder paste suitable?
(9) Is the solder paste exposed to the air for too long?
(10) Is the temperature or humidity in the production workshop too high?
(11) Check other printing parameters.
3. Tombstone inspection checklist
(1) Is the temperature rise rate in the recirculation zone too high?
(2) Is the solderability of the metallized end of the component good?
⑶Is the PCB solderability good?
(3) Has the solder mask been damaged?
(4) Is the mounting pressure too low?
(5) Is the size of the solder paste alloy powder correct?
(6) Is the solder paste alloy a standard eutectic composition?
(7) The quality of the solder paste is qualified?
4. Bridging checklist
(1) Is the temperature rise rate too high during the initial stage of preheating?
(2) Is there a nitrogen protection device?
(3) Has the size of the template opening been reduced?
(4) Is the thickness of the template too thick?
(5) Is the pad width greater than 1/2 of the lead pitch?
(6) Check whether the collapsibility of solder paste is qualified?
(7) Check other printing parameters.
5. Checklist for poor or semi-wetting
(1) Is the temperature in the recirculation zone correct?
(2) Is the cooling rate too high?
(3) Is there a nitrogen protection device?
(4) Is the solderability of the components good?
(5) Is the solderability of the PCB good?
(6) Is the solder mask damaged?
(7) Is the quality of the solder paste qualified?
6. Void checklist
(1) Is the temperature rise rate in the recirculation zone too large?
(2) Is the holding time too short?
(3) Is the temperature in the recirculation zone too high?
(4) Does the thixotropy of solder paste change?
7. Checklist for component offset
(1) Is the mounting pressure too low?
(2) Is the mounting acceleration too high?
(3) Is the placement accuracy sufficient?
(4) Is the solder paste sticky enough?
(5) Is the solder paste exposed to the air for too long?
8. Welding inspection checklist
(1) Is the mounting pressure too low?
(2) Is the land coplanarity good?
(3) Is the coplanarity of the metal ends or pins of the components good?
(4) The solderability of the components is very good?
(5) Is the PCB solderability good?
(6) Is the temperature rise rate too high during the initial stage of preheating?
9. Checklist for component damage
(1) Is the temperature rise rate too high during the initial stage of preheating?
(2) Is the holding time too short?
(3) Is the temperature in the recirculation zone too high?
(4) Is the cooling rate correct?
(5) Evaluate the packaging materials and filling materials of SMT equipment;
(6) Determine whether the filling of the solder paste on the bending radius of the wing-shaped and J-shaped pins reduces the flexibility of the pins;
(7) Use accelerated stress test to evaluate long-term reliability (thermal cycle, power cycle, etc.);
(8) Reduce the deformation of the substrate in the process of operation, installation, sub-board, electrical testing, etc.;
(9) Reduce the residual stress of rigid packaging materials;
(10) Optimize the operation process of components to prevent chip-outs and sharp fragments, broken edges;
(11) A thin copper layer is added to increase the hardness of the epoxy stubborn glass substrate, thereby reducing the bending of the central axis;
(12) The pad size and solder paste volume should match to ensure satisfactory solder filling;
(13) Use accelerated stress test (impact, vibration, etc.) to evaluate long-term reliability.
10. Excessive intermetallic compound checklist
(1) Is the peak temperature too high?
(2) Is the temperature rising too fast during the warm-up phase?
(3) Is the reflow soldering time too long?
(4) Is the holding time too short?
(5) Is the cooling rate correct?
11. Checklist for Flux Spatter
(1) Is the temperature rise rate too fast in the initial stage of warm-up?
(2) Is the temperature rise rate in the recirculation zone too fast?
(3) Is the temperature setting of the recirculation zone correct?
(4) Is the temperature in the production workshop too high or the humidity too high?
(5) Is the quality of the solder paste qualified?
12. Excessive residue checklist
(1) Is the temperature curve time long enough?
(2) Has the size of the template opening been reduced?
(3) Is the correct solder paste used?
(4) Is the quality of the solder paste qualified?
