米6体育平台手机版

SLDA021B March 2014 – February 2020 AM3892 , AM3894

1
1. 2
2. 3
  1. 4
    1. 5
  2. 6
3. 7
  1. 8
    1. 9
  2. 10
    1. 11
    2. 12
      1. 13
  3. 14
  4. 15
4. 16
  1. 17
  2. 18
  3. 19
  4. 20
5. 21
  1. 22
    1. 23
  2. 24
  3. 25
  4. 26
  5. 27
  6. 28
  7. 29
  8. 30
6. 31
  1. 32
  2. 33
  3. 34
  4. 35
  5. 36
  6. 37
7. 38
  1. 39
  2. 40
  3. 41
  4. 42
8. 43
  1. 44
  2. 45
  3. 46
  4. 47
9. 48
  1. 49
  2. 50
  3. 51
  4. 52
  5. 53
  6. 54
  7. 55
    1. 56
    2. 57
  8. 58
  9. 59
  10. 60
10. 61
11. 62
  1. 63
  2. 64
12. 65
66

9 Troubleshooting Guide

The troubleshooting guide shown as Table 4 lists some common assembly defects and typical causes for each. It is possible that other factors may cause these defects – if none of the recommended solutions resolves the defect, more extensive failure analysis may be required to determine the root cause.

Table 4. Troubleshooting Guide

Defect	Recommended Solutions
Head on Pillow	●	Check Solder Paste Volumes to ensure that there are no insufficient prints
	●	Check the temperature gradient across the BGA. It should be 10°C or less, with lower temperature gradients preferred
	●	Check with the solder paste manufacturer to ensure that the solder paste is designed to minimize head in pillow defects
	●	Check that the reflow profile meets the paste manufacturer’s guidelines. Generally, the time to peak temperature should be less than 6 minutes and the soak should be less than 2 minutes, but these guidelines may vary by paste. Incorrect profiling may exhaust the flux, or may insufficiently activate it.
	●	Use nitrogen as a reflow environment. Ensure that the oxygen levels are within specification when using nitrogen
	●	Check the lot number, date code and storage conditions for the component
	●	Ensure that the maximum recommended bakeout time has not been exceeded.
Solder Shorts or Bridges	●	Check solder paste prints for excessive volume or mis-registration
	●	Check that the stencil underwiping frequency is adequate and the wiping process is effective
	●	Verify placement accuracy and ensure that placement pressure is not excessive
	●	Ensure that the printed circuit assemblies do not experience sudden acceleration or deceleration prior to reflow
Opens or Insufficients	●	Check Stencil for apertures clogged with solder paste
	●	Verify that the stencil apertures and the PCB pads are within the designed specification.
	●	Check the temperature gradient across the BGA and ensure that it is 10°C or less, with lower temperature gradients preferred
Voids	●	Check to ensure that the reflow profile matches the paste supplier’s recommendations
	●	Ensure that microvias are filled. If microvia filling does not meet specification, contact the PCB manufacturer.
	●	If planar microvoids near the printed circuit board are detected, contact the PCB manufacturer, as these may be signs of a surface finish defect