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Subject:
From:
Jorge Santana <[log in to unmask]>
Reply To:
TechNet E-Mail Forum.
Date:
Tue, 30 Dec 2003 16:21:53 -0600
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text/plain (124 lines)
Just a little history ...

  We had a high volume assembly that uses a DPACK package that get hot
during normal operation, by design a heatsink was provided by the board
using large copper pads. One beautiful day there were missing solder paste
to that particular device ( not sufficient coverage ) and the amount of
solder were not enough to make a good thermal contact with the board
heatsink and to make things worst visually were very hard to detect
insufficient solder because the big void were under the part. This
particular module failed at the costumer, and then started a chain reaction
from our customer CEO down to the poor manufacturers guy ( was me on that
time )
  Given a high volume manufacturing operation only few options could be used
to solve this problem, and one of the options were to use automated solder
inspection after screen printer. After that we bought a Screen printer with
2D inspection and we never had a problem like that again!
  This tools are not used only for process control but to avoid problems in
the field, so the investment depends who are your customers and how much
cost to you field failures ...

Thanks
Jorge Santana

-----Original Message-----
From: TechNet [mailto:[log in to unmask]]On Behalf Of 27782
Sent: Tuesday, December 30, 2003 12:56 PM
To: [log in to unmask]
Subject: Re: [TN] Paste Deposition


Hi Steve,

Thanks for the response.

Your response was the premise behind my question and as to why I presented
the question.

Most folks I talked to due measure the first board and then again at some
quantity or time after and as you put it is there a benefit to the
investment?

Lets see what we get!

Thanks
Dan mauro


Steve Gregory writes:

> Hi Tom!
>
> Yes, and those systems aren't that cheap either!
>
> Let me just throw this question out to everybody; let's assume that the
> stencil has been ordered correctly (correct thickness for the type and
pitch of the
> components being placed), the printer has been set-up correctly (correct
> squeegee speed, pressure, and separation speed, along with proper board
support),
> is there REALLY any value added, or will things vary THAT much when using
> METAL squeegee blades, that thickness measurements need to be done every
25 boards
> or whatever, during a run?
>
> I have my own opinion, and experiences about this...but I would like to
hear
> what everybody else thinks.
>
> -Steve Gregory-
>
>> Use ASC212 for solder paste thickness and volume. Currently check the
first
>> two boards at beginning of the run and every hour thereafter. Have
>> experience with CyberOptics LSMII and Sentry- running a gage R&R will
reveal a lot
>> about the measuring system. Depending on the system the GR&R ranged from
5 to
>> 25% .
>>
>> Tom Gervascio
>> Senior Process Engineer
>> Sparton Electronics
>> (352) 540-4040
>>
>
>
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