Reply to:   RE>largest circuit board holes allowable...

Barry:

The size of the hole is not the issue.  A properly adjusted wave solder
machine will have the crest of the wave reach the middle of the board
thickness, allowing the solder to wick up the plated holes.  If the wave is
adjusted too high, the leading edge of the board and any large opening inside
the board outline will scoop the solder onto the top of the board and flood
it.  

Disk drive manufacturers have been building control PCAs for years with LARGE
holes for the spindle motors.  They don't have the problem, because they pay
close attention to the height of the wave itself as the board crosses the
wave..

Also, I assume that the holes for the clips are NOT plated holes.  Due to the
surface tension of the solder, bare unplated holes will discourage the solder
from trying to flow over the top of the board.

Hope this eases your mind.

Bill Fabry
Truevision, Inc.
--------------------------------------
Date: 10/2/96 6:20 PM
To: Bill Fabry
From: Barry Cavanaugh


I am designing an assembly that uses plastic molded clips to attach a circuit
board to a button matrix. The design requires that holes (for the clips) be
incorporated within the body of the board...

My question is:

for a board that is wave soldered, how large can I make these square openings
before solder starts to pour over onto the top of the board...

Please share any experiences that you have had...

Thanks...

Barry Cavanaugh
Hughes Network Systems
Div. of Hughes Electronics
San Diego, CA USA

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