Andre,
I was bitten by the same problem. My last company used water soluble
and I could run 1:1 with no solderballs, but water soluble is so aggressive
it will solder to wood...almost. Anyway, then I came to Hella to help
setup this new plant and we implemented NC, I went 1:1 and boom, big time
solder balls. I went to homeplate patterns and cut down the number of
solderballs significantly. Then I went through two more iterations of
stencils, reducing the aperture size each time until now I have no solder
balls and great solder joints. You just have to find the size that
balances no solderballs, but still enough paste to get a good fillet and
lap joint.
Brad Kendall
Hella Electronics Corp.
[log in to unmask] on 07/13/98 02:49:46 PM
Please respond to [log in to unmask]; Please respond to
[log in to unmask]
To: [log in to unmask]
cc: (bcc: Brad Kendall/Hella North America Inc.)
Subject: Re: [TN] Solder ball ussues with NC paste -Reply
Mr. Park
I read you article and I agree with you. I Understand that many people use
the homeplate or equivalent shape. My question is, in the company I work
before, I was using a reduction of 2 mils from the pad size using Water
soluble paste and the result was no solder ball at all (really no solder
ball).
Now here we are using NC with the homeplate opening and sometime we still
have some solder ball, same thing if we use the water soluble solder paste.
I did conduct a test, just for fun, using a Topline board with (NC paste):
- 2 rows with 1:1 (pad vs aperture)
- 4 rows with 2 mils less
- 4 rows with homeplate
we assembled 8 boards and the result was respectively 122, 58 and 2 solder
balls.
So what is confusing me is why before I did not see solder ball and now I'm
facing the solder ball problem?
The answer is probably the placing equipment but why? Or maybe something
else!
Any others help will be appreciate.
Thank you,
At 10:18 98-07-13 -0700, Matthew Park wrote:
>Mr. Bisson
>
>Please get hold of a March issue of Circuit Assembly. There is
>an article that might help you with solderball problem. I am
>available to discuss with you if you have further questions.
>
>regards
>
>matthew
>SMT Manufacturing Engineer
>NII Norsat International Inc.
>604-597-6200, ext 254
>
>>>> Andre Bisson <[log in to unmask]> July 10,
>1998 10:40 am >>>
>Hello,
>
>I need help from people who assembled board using NC solder
>paste. I'm
>presently facing some issues with solder balling after reflow
>using NC paste.
>
>Our parameter are:
>
>NC paste
>Good standard profile
>Homeplate opening for chip (mpm printer)
>Panasonic equipment for pick and place
>
>I'm use to run board with the following parameter with any solder
>ball
>(different company):
>
>Water paste
>Good standard profile
>Opening reduce by 0.002" than the pad size (mpm printer)
>Contact system or Fuji Cp pick and place
>
>I will like to have comment from people who use NC paste and
>don't have
>this problem. If possible can you tell me why I have solder ball. I
>take a
>close look of the board and they are built with the ipc standard.
>
>Thank you very much,
>
>
>
>________________________________
>
>Andre Bisson
>Process Engineering
>Matrox Electronic Systems
>Tel.: (514) 969-6000 Ext: 2462
>E-mail: [log in to unmask]
>________________________________
>
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________________________________
Andre Bisson
Process Engineering
Matrox Electronic Systems
Tel.: (514) 969-6000 Ext: 2462
E-mail: [log in to unmask]
________________________________
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