Testin g finished PCB's

[Stan F.]

I recently ran into a problem with poor solder joints (mine) causing a
problem with finished circuits. The circuits would often work fine right
away, but after 12 hours would be giving errors. I've improved my technique,
but don't want to wait 12 hours to finish testing each circuit. I PLAN on
using a hot/cold water bath to "shock" the circuit connections to create a
problem before a customer finds it. Is this OK, or do you have a better
idea?

Thanks in advance!!
Stan F.

 

[EEng]

I recently ran into a problem with poor solder joints (mine) causing a
problem with finished circuits. The circuits would often work fine right
away, but after 12 hours would be giving errors. I've improved my technique,
but don't want to wait 12 hours to finish testing each circuit. I PLAN on
using a hot/cold water bath to "shock" the circuit connections to create a
problem before a customer finds it. Is this OK, or do you have a better
idea?

Thanks in advance!!
Stan F.

1. Ensure the solder joints are good from the start.

2. Thermal testing is a good idea if its done properly. Improper
testing would be when you go from extreme hot/cold to the other
extreme very fast. This will cause fractures where none would have
ever occurred. Proper therm tests ramp the temperatures over time
from one extreme to the other so as not to fracture. Therm Testing is
not designed to find bad solder joints, its designed to test the
thermal dynamics of the components themselves.

 

[j.b. miller]

We used to run finished boards through the 'normal' +"dry mode' cycles of
the Dishwasher to clean and 'thermal shock' the boards.
Did that for 20 years....

hth
jay

 

[EEng]

We used to run finished boards through the 'normal' +"dry mode' cycles of
the Dishwasher to clean and 'thermal shock' the boards.
Did that for 20 years....

hth
jay

We still do. Sometimes the best answer to a hi-tech problem is a
low-tech solution

 

[John Woodgate]

I read in sci.electronics.design that Stan F.
ews.snet.sbcglobal.net>) about 'Testin g finished PCB's', on Wed, 7 Jan
2004:

I recently ran into a problem with poor solder joints (mine) causing a
problem with finished circuits. The circuits would often work fine right
away, but after 12 hours would be giving errors. I've improved my technique,
but don't want to wait 12 hours to finish testing each circuit. I PLAN on
using a hot/cold water bath to "shock" the circuit connections to create a
problem before a customer finds it. Is this OK, or do you have a better
idea?

Yes. Learn to solder properly. You should get 99.9% reliability without
ANY effort if you just learn how to do it.

Heat the WORK, not the solder.

Be PATIENT.

Use the best iron you can afford. Temperature control is not a luxury
these days.

Use good quality cored solder that is no thicker than the work.

Use a bit comparable with the joint size and with a temperature suitable
for the solder you are using (probably lead-free these days).

Keep the joint STILL until the solder surface dulls, especially with
lead-free solder.

Using a holding device ('third hand' or whatever) ISN'T an admission of
defeat.