Hi Richard,

Now you know why some assemblers request test coupons.
For the age of the boards, you might have a DATE CODE on
the board. It's usually 4 digits, 2 of them are the week number
and the other 2 are the fabrication year. (example: 99-12 or
12-99 represent the 12th week of 1999).

Boards older then 6 months may start to have a substantial
amount of water absorbed into the laminate. They may also
have a fair amount of oxidised tin forming on the surface of
traces and inside the PTH.

Do NOT bake the boards unless necessary, it slightly reduces
the reliability and life expectancy of the board.

You might have to sacrifice a board to microsection it and see
any problems with the internal structure (mostly the plating).

If you are scrapping any boards, use the area affected.

If the failures are always at the same component, the batch of
components may need to be looked at for solderability.

Finally check the wave and preheat temperature. (You could do
this first actually).

Good luck,

Alain Savard, B.Sc.
Chemical Process Analyst
CAE Electronics Ltd.
e-mail: [log in to unmask]

-----Original Message-----

Hello Richard,

HELLO ALAIN

A few things to look at:
- Did you perform a solderability test on the test coupons?
NO COUPONS WERE SUPPLIED.

- How old are these boards?
NOT ENTIRELY SURE - WE GET THEM FROM AN EXTERNAL SUPPLIER.

- Did you verify plating thickness and voiding in the test coupons?
NO COUPONS SUPPLIED.

- are your components pre-tinned?
NOT BY US. FITTED AS SUPPLIED.

RICHARD TILBROOK

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