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From: - Wed May 08 19:31:50 2002
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Date: Wed, 08 May 2002 19:31:50 -0700
From: "David L. Miller" <
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To:
Homebrew_PCBs@yahoogroups.comSubject: Re: [Homebrew_PCBs] Re: hot air soldering comments
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I don't know what the "proper" preheat temperature is, but I can tell
you that when our contract manufacturer re-works a board for us at work,
they bake it at 125C (~250F) for 24 hours before they touch a chip. So,
you should be able to heat to 200F "forever" without damaging anything...
tedinoue wrote:
> Hi Guys,
>
> Thanks for replying. I have referenced Hans' links and the others in
> the past and made the hot-air-pencil -- that works fine. My real
> questions lie elsewhere
> Hans indicates that preheating is necessary. ok, one question down.
>
> The outstanding questions are:
> What is the proper preheating temperature?
> Is there a maximum time you should preheat the board/components
> before damage can set in?
> What can I do about unmelted solder paste that has moved under
> surface mount caps?
> What do you do about the tiny cap components blowing away, even under
> very minimal air flow? I've read a tiny dab of epoxy. What do others
> do?
>
> Thanks,
> Ted
>
> --- In Homebrew_PCBs@y..., Steve Greenfield wrote:
> > Yup, Hans, your page has been in the bookmarks of the Group home
> > page for weeks!
> >
> > Hint, hint, everyone, check out the Bookmarks at the Group home
> > page once in a while. Also a reminder to add useful links.
> >
> > http://groups.yahoo.com/group/Homebrew_PCBs/links
> >
> > Do you think one of those warmer plates would work? Not a hotplate,
> > I mean those glass warmer things. I was just figuring they are
> > pretty cheap at the thrift store.
> >
> > Also a reminder that when you do this, the solder paste must be dry
> > before you start trying to solder, or any fluids will boil and push
> > the parts off the pads. Should be able to do that by warming it up
> > on your pre-warmer for a bit.
> >
> > Steve Greenfield
> >
> > --- hans@c... wrote:
> > > Ted,
> > > I made a Hot Air Pencil and published the idea several years ago
> > > at my
> > > web site.
> > > The single most important item is the heat exchanger. In my
> > > design I
> > > filled it with stainless steel
> > > wool and that made a vast difference.
> > > Pre-heating the board is required.
> > > http://hans-w.com/surfacem.htm
> > > hansw
> >
> >
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