[time-nuts] Parts Selection

[paul swed]

My first answer would be heck no. Enough trouble with 16 pin chips.
BUT now you have set the bait. A cesium standard.
That would grab my attention. So indeed if there were not a time limit, I
would invest in a very small tip iron and the correct solder. I have come to
the conclusion also that the tips Greg suggests can work. I simply have
equipment thats to large. (Funny I stayed clear of that hair size solder at
the Flea markets) This will be resolved I hope at the first MIT flea or
heaven forbid really ordering new.
Second those days of soldering might be non-coffee days. :-)
I have done some crazy stuff if the price to value ratio is correct.
Regards
Paul

On Fri, Mar 25, 2011 at 1:56 PM, Bob Camp <lists at rtty.us> wrote:

> Hi
>
> I'm guessing that's a yes to each of the questions in the poll.
>
> Bob
>
> -----Original Message-----
> From: time-nuts-bounces at febo.com [mailto:time-nuts-bounces at febo.com] On
> Behalf Of Greg Broburg
> Sent: Friday, March 25, 2011 2:53 PM
> To: Discussion of precise time and frequency measurement
> Subject: Re: [time-nuts] Parts Selection
>
> I have assembled hundreds of such parts using only a
> low cost Antex 15W soldering iron, some fine diameter
> solder and some solder wick. A hot air gun makes
> removal very easy and I have never damaged a PCB
> using the hot air removal method.
>
> Solder diameter should be .010 - .015 mils Large
> diameter solder is a problem with this method.
>
> To put a .5mm pitch part down without any fancy stuff
>
> 1: Carefully align the part with the pads, double check
> that Pin 1 is in the correct alignment. Now solder a
> couple of pads at two opposite corners to stabilize the
> part. Expect to solder two to four pads at the corners
> and that they will be shorted. Do not worry if you have
> shorts between closely spaced pads. We will fix that later.
>
> 2: If the pad alignments are not perfect then reheat one
> of the two opposite corner pad (s) and move the part
> until it is correctly aligned.
>
> 3: When all pads are aligned then carefully solder all of
> the leads to all of the pads. Do not worry if some pads
> are shorted. do not worry if all pads are shorted.
>
> 4: Using .025 mil solder wick dipped in RMA solder flux
> if not already fluxed, desolder all of the pads. In other
> words, the solder wick is not effective at removing all of
> the solder. What is left from surface tension will be the
> correct amount.
>
> 5: Using a QTip with alcohol / acetone / dope thinner
> clean all pads of flux. Do this twice or more each time
> with a fresh QTip tip.
>
> 6: Inspect using magnification if necessary, to verify no
> shorts or solder balls between pads. If so, use the solder
> wick to remove the short.
>
> I have done this hundreds of times.
>
> Greg
>
>
>
> > With regards to soldering .5mm pitch parts:
> >
> > I've never done that professionally or as a hobby.
> >
> > I don't see myself doing this at home.
>
>
> On 3/25/2011 11:07 AM, Bob Camp wrote:
> > Hi
> >
> >
> >
> > Just a show of hands sort of thing. It comes up each time we talk about
> > projects and never really gets answered. Rather than trying to work it
> out
> > as a part of a project, let's see if it can be addressed by it's self.
> >
> >
> >
> > How many people are willing to solder up a project with multiple 0.5mm
> > spacing>=144 pin package IC's on it? There's a typical package drawing at
> > the end of:
> >
> >
> >
> > http://www.national.com/ds/DP/DP83816EX.pdf
> >
> >
> >
> > I'm sure it's a "what's in it for me?" sort of question. Let's assume
> it's
> > just neat piece of bench gear rather than a home grown cesium standard
> for
> > $100.
> >
> >
> >
> > I don't think this part really matters, but it might to some people. Say
> > each chip is well below $100, but above $20 each. There might be only one
> > part like this on some projects, but for the sake of this poll, let's say
> > there are two or three of them. Net is roughly 250 to 500 pins like this
> to
> > solder, on some number of packages. It's part of a project that will cost
> > you $250 to $500.
> >
> >
> >
> > I'm not talking about opinions on weather it can or can't be done. It
> > certainly can be done and is done every day. What I'm asking is - would
> you
> > buy a bag with the parts all in it? If you do are you going to put it
> > together in a reasonable amount of time?  Reasonable time might mean
> > different things to different people. For the sake of completeness, yes
> you
> > also need to get it working after you assemble it.
> >
> >
> >
> > Next layer (you knew there had to be more) - have you done it before
> > (anywhere)? / done it in the last 2 years (at home)? / are you set up to
> do
> > it today (at home)?
> >
> >
> >
> > I'm not trying to get into "how would you do it / what would you need /
> > could you farm it out". Those are also neat questions, but not part of
> this.
> >
> >
> >
> >
> > I'll start off the voting (and yes the answers are out of order):
> >
> >
> >
> > Done it in the before - yes.
> >
> >
> >
> > Done it in the basement / last 2 years - no.
> >
> >
> >
> > Set up to do it in the basement - yes, but not set up well.
> >
> >
> >
> > Would I buy one - done that before. Likely would again. (counts as a
> yes).
> >
> >
> >
> > Would actually do it in a reasonable amount of time - unlikely.  (That
> > counts as a no).
> >
> >
> >
> > Any more votes?
> >
> >
> >
> >
> >
> > Bob
> >
> >
> >
> >
> >
> >
> >
> > _______________________________________________
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> >
>
>
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