Mark.

It sounds like the adjustments that they are trying to make are to the 'Chip
Wave' height. Increasing this will eliminate some of the skips that you are
getting but it will tend to force solder up through tooling holes and slots.
What about a wave solder carrier for the board that will cover the breakout
slot?

Mark Austin

===== Original Message from [log in to unmask] (TechNet E-Mail Forum.) at
29/09/00 15:41
>Hi all,
>
>We are currently having problems with one of our boards which requires SMT
>parts on the underside to be wave soldered.
>The problems include solder bridges and solder skips. All the components are
>orientated as IPC-782-3-9, although they do
>appear to be pretty closely placed. The board was designed some 5 years ago
>by an outside contractor, and at the moment
>I don't have the design data available to modify. Although the board is an
>old design, we have had many changes at our
>manufacturing plant, both with equipment and personnel, and the new operator
>is struggling to get good results with this
>particular board.
>
>One point raised in a recent meeting was that they were unable to make
>certain adjustments to the wave, which might
>solve the problem, because the solder was being pushed through the routed
>gap between the board and the panel.
>
>Our routed gap between boards tend to be 2.4mm, which from my experience
>seems to be fairly standard.
>
>My questions are:
>
>*       Should a 2.4mm routed gap around a board cause problems when wave
>soldering?
>*       What standards detail component to component spacing for wave
>soldering SMT?
>
>I have the IPC standards which details land to land clearances (IPC-782-3-8)
>but these only appear to be for reflow.
>
>My design guidelines state that the minimum distance between shadowed
>components should be no less than the
>height of the component next to it. What about parts that are not shadowed?
>- ie end to end clearance of chip components
>(assuming orientation is as IPC-782-3-9)
>
>Any thoughts or comments would be most appreciated.
>
>Thanks in advance,
>
>Mark
>
>
>Mark Holmes PCB Designer
>Helvar Merca Ltd.
>Hawley Mill, Hawley Road,
>Dartford Kent.
>DA2 7SY England.
>Tel: +44 (0)1322 222211
>Fax: +44 (0)1322 282286
>mailto:[log in to unmask]
>http://www.helvar.com
>
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