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How To Inspect PCB Assembly Board?

(I) let’s learn about the standard shortcomings of quality testing.

  1. Serious shortcomings (in CR): any shortcoming enough to harm the human body or machine or to endanger the safety of life, such as unconformity / burning / electric shock, etc.
  2. The main shortcomings (in MA): can cause damage to the product, abnormal function, or the defects of the life of the product because of the material.
  3. Minor defects (in MI): does not affect the function and service life of the product, there are some shortcomings in appearance defects and slight defects or differences in the mechanism assembly.

(II) Test conditions for PCBA board:

  1. In order to prevent the pollution of parts or components, must be selected with EOS/ESD full protection gloves or fingerstall and wear anti-static ring operation, light white fluorescent lamp, the light intensity must be above 100Lux, 10 seconds visible.
  2. Test methods: will be quarantined at about 40cm away from the eyes, up and down about 45 degrees, or three times the magnifying glass by visual inspection.
  3. Inspection criteria: (according to QS9000 C=0 AQL=0.4% sampling level;)
  4. Sampling plan: MIL-STD-105E LEVEL II normal single sampling.
  5. Criteria: serious shortcomings (CR) AQL 0%.
  6. Main shortcomings (MA) AQL 0.4%.
  7. Secondary shortcoming (MI) AQL 0.65%.

(III) SMT patch workshop PCBA board inspection project standard

  1. Welding miss welding of SMT parts
  2. SMT parts: cold welding
  3. SMT part (solder joint) short circuit (tin bridge)
  4. Missing parts of SMT parts
  5. SMT parts error
  6. SMT parts are polar opposite or wrong to cause combustion or explosion
  7. More parts of SMT parts
  8. SMT parts turning: text face down
  9. SMT parts: long side chip length is less than 3mm, width is less than 1.5mm, qty are not more than five (MI)
  10. SMT parts tombstone: the end of the piece element is warped
  11. SMT part offset: the side offset is less than or equal to the 1/2 of the weldable end.
  12. SMT parts float high: the distance between the base of the component and the base plate is <1mm
  13. SMT parts with high warping: the height of warping is greater than the thickness of the part’s foot
  14. The heel of SMT parts did not stick to the heel without stannic.
  15. SMT parts cannot be identified (print blurred)
  16. SMT parts foot or body oxidation
  17. SMT part body breakage: capacitance breakage (MA); resistance damage is less than 1/4 of component width or thickness (MI); IC is damaged in any direction <1.5mm <1.5mm (MI), exposing internal material (MA).
  18. SMT parts use non designated suppliers: according to BOM, ECN
  19. Tin tip of SMT part welding point: the height of tin tip is greater than the height of part body
  20. Eat too little tin SMT parts: the minimum height is less than the thickness of the solder joints and welding end 25% of the height or thickness of solder and 0.5mm, which is smaller (MA)
  21. SMT parts eat too much tin: the maximum solder joint height exceeds the pad or climbing to the top of the metal coating end cap is acceptable, solder contact element body (MA)
  22. The ball / tin slag: every 600mm2 more than 5 solder or solder splash (0.13MM or less) for (MA)
  23. There is a pinhole / hole in the solder joint: a solder joint has one (MI) or more.
  24. Crystallization: on the surface of the PCB plate, there is a white residue around the welding terminal or terminal, and the surface of the metal is white.
  25. Unclean: unclean for 30 seconds in the arm
  26. Bad glue: viscose is located in the area to be welded to reduce the width of the welding end more than 50%.
  27. PCB copper exposure: the line (gold finger) width of copper is greater than 0.5mm (MA).
  28. PCB scraping: no bottom material is not seen in scraping
  29. PCB burnt: PCB after reflow oven or after maintenance is burnt yellow and PCB color is not the same
  30. PCB bending: the deformation of any direction in each 300mm is more than 1mm (300:1) (MA).
  31. PCB inner layer separation (bubble): the area of bubbling and stratification does not exceed 25% (MI) of the distance between the plated holes or inner conductors, and the bubbles between the coated holes or inner conductors (MA).
  32. PCB stained foreign objects: conducting (MA); non conducting (MI)
  33. PCB version error: according to BOM, ECN
  34. Gold finger tin: Tin position falls on the edge of the plate to count 80% (MA)

(IV) DIP post welding workshop PCBA board inspection project standard

  1. Welding point welding of DIP parts
  2. DIP parts: cold welding solder joint with a toothpick light dial pin parts, if clicked is cold
  3. DIP part (solder joint) short circuit (tin bridge)
  4. Missing parts of DIP parts
  5. DIP parts: Phi = 0.8mm, long molding molding length is less than or equal to 1.5mm, Phi > 0.8mm molding length is less than or equal to 2.0mm special requirements except shear pin
  6. DIP parts error
  7. DIP parts are polar opposite or wrong to cause combustion or explosion
  8. DIP part foot deformation: pin more than 50% of pin thickness
  9. DIP parts are high or warped: reference IPC-A-610E, depending on the special condition of the assembly
  10. Tin tip of DIP part welding point: the height of tin tip is greater than 1.5mm
  11. DIP parts cannot be identified: (blurred print)
  12. DIP parts foot or body oxidation
  13. DIP parts are damaged: the surface of the component is damaged, but it does not reveal the metal material inside the element.
  14. DIP parts use non designated suppliers: according to BOM, ECN
  15. PTH vertical hole filling and surrounding wetting: at least 75% vertical filling, pin and hole wall at least 270 degrees of wetting.
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