Hi Jorge,
I've been thinking that I should use a couple of round apertures putting solderpaste just at the castellated terminations, this would solder the castellations and allow and squeezed paste to adhere to the pads. Just wondering if anyone else has had this problem.....
Larry
-----Original Message-----
From: [log in to unmask]
[mailto:[log in to unmask]]
Sent: Thursday, August 07, 2003 5:07 PM
To: [log in to unmask]
Subject: Re: [TN] 43%] [TN] solderballs from components with zero
standoff
Larry,
While back ago, we had the same issue with a similar crystal. We
were able to eliminate the problem by reducing the apertures a great deal,
50%. The paste is indeed getting squeezed under the component and forming a
small solder bead during reflow. You might want to check the placement
height and force, that could also be a contributing factor. I agree with
you, sometimes component manufacturers don't know very much of the process,
and make erroneous recommendations. The other option, I did try it in a S016
with a heat slug, is to modify the rectangular pad with a series of spaced
round apertures, this way the flux/paste have somewhere to go during reflow.
My grain of salt
Jorge Rodriguez
Process Engineer
Varian, Inc
[log in to unmask]
-----Original Message-----
From: Larry Koens [mailto:[log in to unmask]]
Sent: Thursday, August 07, 2003 1:18 PM
To: [log in to unmask]
Subject: [SP: 43%] [TN] solderballs from components with zero standoff
Techneters
Steve was good enough to post a picture of my problem on his website. It's
titled "solderball beside crystal."
This crystal has two Castellated terminations at each end of the component.
These two terminations are tied together underneath the component. Our pads
and paste are per the manufacture's suggestions (not that is always a good
thing)But as you can see, we have a solderball problem. My feeling this that
the paste is getting squeezed out under the component and forming the
solderballs. What type of paste aperture reductions do you all use for this
type of component that really doesn't have any standoff height? I know most
companies use a standard 10% reduction. Just not sure if it's enough.
thanks,
Larry Koens
E.I. Microcircuits
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