[time-nuts] Parts Selection

[Bob Bownes]

Here are my answers:

Done it before? - yes.

Done it in the basement / last 2 years? - Yes. In last 24 hours actually.

Set up to do it in the basement? - Yes. Can do by hand, hot air rework
tools, or reflow oven.

Would I buy one? - done that before. Likely would again. (counts as a yes).

Would actually do it in a reasonable amount of time? - Yes, other
projects pending of course.

And a +1 on the solder paste mask. 7-15x microscope makes it easy.

Bob



On Fri, Mar 25, 2011 at 1:19 PM, David C. Partridge
<david.partridge at perdrix.co.uk> wrote:
> Well, if you ship a paste mask with the PCB I've no problem at all, but that's not likely to happen, so it's down to hand work.  I've done that before now and while it's not the easiest job, it's quite doable with a microscope or the eyes of an eagle.
>
> Dave
> -----Original Message-----
> From: time-nuts-bounces at febo.com [mailto:time-nuts-bounces at febo.com] On Behalf Of Bob Camp
> Sent: 25 March 2011 17:08
> To: 'Discussion of precise time and frequency measurement'
> Subject: [time-nuts] Parts Selection
>
> Hi
>
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> 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.
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> 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:
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> http://www.national.com/ds/DP/DP83816EX.pdf
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> 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.
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> 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.
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> 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.
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> 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)?
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> 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.
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> I'll start off the voting (and yes the answers are out of order):
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> Done it in the before - yes.
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> Done it in the basement / last 2 years - no.
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> Set up to do it in the basement - yes, but not set up well.
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> Would I buy one - done that before. Likely would again. (counts as a yes).
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> Would actually do it in a reasonable amount of time - unlikely.  (That counts as a no).
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> Any more votes?
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> Bob
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