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Residues of non-conducting substances in general

more examples

Poor dispensing of adhesive

Description:
In this case poor dispensing of adhesive before placing the components led to the following defects:
a) depots of different sizes
b) movement of dispensing machine caused strings of adhesive

Causes/Remedy:
  • poor machine paramenter for dispensing of adhesive
  • unsuitable adhesive (viscosity)
  • process conditions (temperature)
  • poor teaching of machine (sequence of motions)


Source: visual, optical inspection - general view
Poor ispensing of adhesive

Description:
Classical fault during dispensing of adhesive before placing components. The example clearly shows the string of adhesive which sticks out from the main depot and even reaches the pad. This would lead to opens.

Causes/Remedy:
  • poor machine paramenter for dispensing of adhesive
  • unsuitable adhesive (viscosity)
  • process conditions (temperature)
  • poor teaching of machine (sequence of motions)


Source: visual, optical inspection - general view
faulty application of adhesive

Description:
Misplaced depots of adhesive. Since the dispensing machine did not move accurately, the area where adhesive can be deposited were left. Adhesive is clearly visible on the pads.

Causes/Remedy:
  • poor machine paramenter for dispensing of adhesive
  • unsuitable adhesive (viscosity)
  • process conditions (temperature)
  • poor teaching of machine (sequence of motions)


Source: visual, optical inspection - general view
misplaced adhesive depots

Contamination

Description:
This example shows contamination on the uncovered, wettable studs of conductors. Since this defect was detected on bare-boards, the contamination must be due to particles from the galvanic processes. Contamination through inexpert storing or transport cannot be ruled out either. This contamination can lead to defects during soldering (opens due to non-wetting).

Causes/Remedy:
  • manufacturing fault during galvanizing process
  • contamination as a consequence of inexpert storage/transport (cover foil)
  • cleaning necessary
  • contamination during preceding production processes


Source: visual, optical inspection - general view
Contamination on wettable studs of conductors
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