Leonel I have experienced parts (capnets) rotating during reflow when they
were placed perfectly on the wet paste. This was because of the layout of
the parts. What is your part size and approximate height; the pad size and
pad gap?
It could also be a heating/cooling imbalance though ususally that results in
tombstoning which you have said was not the problem. Is there an imbalance
in trace size that goes to the pads? Is one pad compared to the other have
an imbalance in thermal cooling in reflow. How fast is your cooling in the
oven and how many chanbers do you have? Is your PCA large?
As always: what is your process, paste, stencil thickness and stencil
aperature design for these locations?
Dorothy Lush
> ----------
> From: <Leonel Jay J. Manuel>[SMTP:[log in to unmask]]
> Reply To: TechNet E-Mail Forum.
> Sent: Thursday, August 16, 2001 7:49 PM
> To: [log in to unmask]
> Subject: Re: AW: [TN] Misplace component
>
> Dorothy and Wolfgang,
>
> The misplacement is actually misalignment of one of the component
> terminal with respect to the solder land and it usually occurs after
> reflow soldering. Note that we performed 100% inspection prior reflow to
> check the component placement and found it
> to be correct. We maintain a humidity level between 40 to 60 %.
>
> Leonel Jay J. Manuel
> Process Engineer
> RF PCC Engineering
> Philips Semiconductors Phils. Inc.
> Office Tel: (6349) 5430001 to 25
> : (632) 8445139 ext. 288
> Fax No. : (632) 8445248 / (6349) 5430027
> E-mail :[log in to unmask]
>
>
>
>
>
>
> "Busko, Wolfgang" <[log in to unmask]>@IPC.ORG> on 08/16/2001
> 04:33:53 PM
>
> Please respond to "TechNet E-Mail Forum." <[log in to unmask]>
>
> Sent by: TechNet <[log in to unmask]>
>
>
> To: [log in to unmask]
> cc: (bcc: Leonel Jay J Manuel/CUB/SC/PHILIPS)
> Subject: [TN] AW: [TN] Misplace component
> Classification:
>
>
>
> Hi Dorothy,
>
> you should have asked Leonel. I just tried to give some hints what could
> be
> checked in addition to avoid "misplace".
> I also don´t know how that actually looks like in his special case, a
> picture in this case would be worth a thousand words.
>
> It´s obvious that without seeing the problem live all our guessing is like
> paddling in fog.
>
> Have a nice day
>
> Wolfgang
>
> -----Ursprüngliche Nachricht-----
> Von: Dorothy M. Lush [mailto:[log in to unmask]]
> Gesendet am: Mittwoch, 15. August 2001 19:46
> An: [log in to unmask]
> Betreff: Re: [TN] Misplace component
>
> Wolfgang,
>
> What do you mean by "misplaced"?
> Do you mean it is missing?
> Do you mean it is tombstoning?
> Do you mean it is misaligned?
> Do you mean it is in the wrong location?
>
> Dorothy Lush
>
> > ----------
> > From: Busko, Wolfgang[SMTP:[log in to unmask]]
> > Reply To: TechNet E-Mail Forum.
> > Sent: Wednesday, August 15, 2001 4:22 AM
> > To: [log in to unmask]
> > Subject: AW: [TN] Misplace component
> >
> > Hi Leonel,
> >
> > if the processes are checked already and there seems to be no cause you
> > might check your checks and focus on the results, if they clearly show
> > that
> > the particular process is definetly not the cause.
> >
> > For the solderability of bare boards and parts, there´s always a good
> > portion of trust in solderability of a whole batch after checking some
> > samples.
> >
> > Cleanliness is another major factor in this game, how is the handling
> > done,
> > is the dust removed prior to paste print (there´s always some of it
> right
> > out of the sealed package), for how long do the printed boards wait
> until
> > beeing reflowed, and what about temperature and humidity at these hot
> > summer
> > days, does your paste like it as it is now?
> >
> > Just a couple of things which I think can contribute to that what you´re
> > seeing.
> > If it happened suddenly, can you find out what has changed?
> >
> > Good luck
> > Wolfgang
> >
> >
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