>Date: Sat, 02 Nov 1996 22:19:47
>To: [log in to unmask] (MR MARK A WARYCKA)
>From: Poh Kong Hui <[log in to unmask]>
>Subject: Re: wavesoldering mixed tech boards
>
>Hello Mark,
>
>First, let me try to answer your second question.
>There are only one way to "temperory" cure the blow hole issue, that's to bake
>the board, hopefully before auto-inserting process.. Try bake around 100 deg.C
> for 4 to 6 hrs -- it's long time, but it gives better guarantee...
>
>Now, after baking, you still have the blow-hole problem, try lower the solder
>pot temperature to maybe 235 deg.C. , to reduce the thermal shock..
>
>That's all I could tell you so much..
>
>Next, go back to your PCB supplier or whoever consigned to you, ask them
>to plate wall of the PTHs and via-holes, and drill them properly..And maybe
>their incoming raw material has some problem..
>
>I don'r think incoming inspection can tell whether the board going to have
>void or blow-hole, unless you test physically. Which's "destroy one raw card".
>
>
>To answer your second question, is slightly tougher.
>Let me ask you a couple of questions; before able to troubleshoot for
>you..
>
>1. Does it happen randomly from time to time ?
>2. Does it happen on the same location.
>3. Does surface mount IC has coplanarity issue, that your operator
> press down the lead of the IC during Touch-up, before wave-soldering?
>4. Is the solder paste sufficient on the location where the IC
de-solders ?
>5. Is the surface mount IC's solder joint is properly formed before wave
> solder..?
>6. Is the lead of the Surface mount oxidised ?
>7. Is the SMT pads (of the PCB) dirty or comtaminated with mask
> or other foreign material.
>8. What is your top side actual temperature ??
>
>You mentioned when you use solder pallet, the issue seems to be decreased.
>Why not try operating at the lower solder pot's temperature -
>let's say 235 - 240 deg. C.
>
>I guess the pallet must has absorbed some the heat away from the board.
>
>
>
+====================================+
Kong Hui Poh
Process/Equipment Engineering Advisor..
Techgate Electronics
Email: [log in to unmask]
=-=-=-=-=-= -=-=-=-.=.=.=.=.=.=.=.=.=.=.=.=. =.=.=.
***************************************************************************
* TechNet mail list is provided as a service by IPC using SmartList v3.05 *
***************************************************************************
* To unsubscribe from this list at any time, send a message to: *
* [log in to unmask] with <subject: unsubscribe> and no text. *
***************************************************************************
|
