Eric,
The fracture is between the component and the adhesive.
But that problem is already solved.
We dispense 3 dots adhesive at the two ends of the component.
Half the dot is underneath the component and the other half sticks to the
side.
It looks strange but it works for us.
I was wondering if anyone has some documents/papers saying that TSOP's
(SRAM's ,DRAM's etc.) are not really suitable for gluing and/or
wavesoldering.
With such a document it is much easier for me to convince the customer to
change their design.
Regards
Jowan Iven
-----Original Message-----
From: TechNet [mailto:[log in to unmask]] On Behalf Of Eric Dawson
Sent: vrijdag 25 april 2003 14:26
To: [log in to unmask]
Subject: Re: [TN] SRAM on bottomside
Hi Jowen,
At the risk of offending the wave soldering fraternity, I have two aims in
life. The second is to remove wave soldering from the production process.
My opinion is that reflow soldering gives better quality so I promote double
sided reflow where I can . If this involves pin in hole reflow then so be
it. The problem is with older designs that have a lot of leaded components
so I have to accept wave soldering.
It may be an obvious question, but since the area of these SRAMS is larger
than the usual SM components, are you printing/dispensing a larger area of
adhesive? Also, when the components become detached, is the fracture surface
between the adhesive and the board or between the adhesive and the
component. The answer to this may point you in the direction of the cause of
the failure.
Regards
Eric Dawson
PS tappity tappity tappity. As somebody observed on this forum a year or so
ago, this is my Friday dance. (With acknowledgements to Snoopy).
> -----Original Message-----
> From: Jowan Iven [SMTP:[log in to unmask]]
> Sent: Friday, April 25, 2003 12:26 PM
> To: [log in to unmask]
> Subject: [TN] SRAM on bottomside
>
> Hi there,
>
> One of our customers has put a SRAM (TSOP-54 NEC) on the bottomside of
a
> board.
> It is necessary to wavesolder this side so we have to glue this component
> along with the other smd's
> The problem is that these components are very susceptible for
boardhandling
> and fall off the board to often before the wavesolderprocess.
> In one way or another the adhesion is not as strong as with "normal"
> components.
> In the past we had the same problem with similar shapes from different
> manufacturers.
> Luckily we were able to solve those problems.
> And I think we can solve this one in the same way.
>
> What then is your problem, I hear you thinking.
> It looks to me that these components are not really designed for
> (glueing,curing and) wavesoldering.
> And I'm looking for some sort of proof or testresults.
> Wether I'm right or wrong, I just would like to know.
>
>
>
> Jowan Iven
>
>
>
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