hi,

i'm not sure how to reply to your question which probably should be:  is there any chance to get this sucker to solder?  it's clear that the heat is getting sucked away in spite of the thermal relief.  perhaps there is more than one plane that the vias are attached to.  multiple reliefs would add up to the equivalent of one plane with no relief.  in any case, it seems that your only choice is to increase the preheated temperature of the panel and/or the solder and/or decrease the belt speed.  the designer was probably counting on voodoo physics to get this to solder.

phil

-----Original Message-----
From: Stephen R. Gregory [mailto:[log in to unmask]]
Sent: Thursday, August 10, 2000 11:00 AM
To: [log in to unmask]
Subject: [TN] Topside solder fillets after wave...


Hi all!

Been trying to dial a profile in on the wave today with a board that's fairly
thick, probably around .090", polyimide, all PTH with a fair amount of the
IC's being ceramic. We use a spray fluxer and a RMA flux.

The first boards have been coming off without the preferred topside fillets
at a number of locations. I've been playing with the pre-heat, belt speed,
and even did something that I don't like to do, which was to flux the topside
of the board.
All to no avail...I still had quite a few places that didn't have topside
fillets, and that is something that doesn't go over well here at all.

I started noticing that the places that didn't have topside fillets were at
the same locations. So I came back to my 'pooter and looked at the gerber for
the board. What's really weird was that everyplace there's a thermal for a
pin is where I have no topside fillet??? I thought that thermals were
supposed to help prevent that from happening? But it's true, every single
place there is a thermal= no top solder. Has anybody ever seen that before?

-Steve Gregory-

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