Good mornin' Afng-

    The first thing I would do is test  bare PCB for cleanliness.  I am sure you will get more advice, but
this is where I would start.  How long are the boards stored before you use them?

Ryan Jennens

afng wrote:

> Message :  I have a problem on solder joint reliability. It was detected
> that some of the solder joint was having minute solder crack on the DIP IC
> joints. I believe some might call it solder creep. The crack is so severe
> that it cause 'open' joint. It only happened after many temperature cycle
> or the board was on the field for more than 6 months. The board is a
> through-hole single sided board,substrate is FR1. Apart from the IC joints,
> we also detect similar problems on other joints. The crack is only visible
> with close inspection, the crack seems to separate the fillet away from the
> pad. The board goes through wave soldering once, and no touch up on the
> joints. Initially we though it could be due to crack in the thickened
> intermetallic layer. But, as know we suspect it could be due to creep on
> the solder itself. WE are using eutectic solder composition, and would not
> likely to change to other type of solder composition and substrate
> materials due to cost impact. I hope someone with similar problem can
> enlighten us on any possible solution.
>
> Thank you
>
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