Pete,

The soldering process yield depends upon many factors:

1.      Temperature set up including ramp rates, temperature hold and cool
down rates.

2.      Type of solder and flux

3.      Cleanliness of component leads and PCB surfaces

4.      Moisture control for components, PCB and assembly area.

Use of inspection tools helps to set up process window at the beginning and
then to monitor the process stability.

If you have poor yields at soldering, the process engineer has to
investigate the source of poor joints. Using inspection

tools is just part of that process improvement.

 

pratap singh

___________________________________

Tel/Fax: 512-255-6820; Cell: 512-663-8903

email: [log in to unmask]


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I just got back from another trip to our (captive) PCB plant, and before I
vent 
more frustrations, I need to ask if I'm off base.

As part of our switch to the more difficult lead free at the same time we 
started BGAs and moved to a new facility in a new country, we purchased x-
ray and solder paste inspections systems.  After asking about the gathering 
dust on them, I was told the SPI was used on a 1 panel/hour sample for each 
of 2 lines, the x-ray is used only on failed boards suspected of a BGA
problem.

I'm not a process engineer, don't even play one on the internet, but this 
doesn't seem normal to me.   We still aren't getting good yields, I think
these 
tools should be more utilized.  I don't want to press the issue without a
better 
idea of normal use.

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