[time-nuts] Parts Selection

Bob Camp lists at rtty.us
Fri Mar 25 17:26:50 UTC 2011


Hi

You can indeed to it with a soldering iron. You need to have the right iron
and some skill to do it without messing things up. There are many other ways
you could do it.

To clarify a bit:

The layout will not be very forgiving of re-doing stuff a couple of times.
It's likely there would be narrow traces and stuff going between leads. To
make it work you would want to get it right the first time on the vast
majority of the connections.  

Bob


-----Original Message-----
From: time-nuts-bounces at febo.com [mailto:time-nuts-bounces at febo.com] On
Behalf Of Brooke Clarke
Sent: Friday, March 25, 2011 1:18 PM
To: Discussion of precise time and frequency measurement
Subject: Re: [time-nuts] Parts Selection

Hi Bob:

Done it before - No.
	Have done 0.05" (1.27mm) pitch and it's easy.
Done it / last 2 years - No.
Set up to do it  - No.

I don't have a feel for the level of difficulty in working with 0.5mm 
pitch parts.  For example can you do it with a soldering iron (like I 
use for 0.05" pitch parts), or is some other method needed?  Will hot 
air work or is an oven necessary?
http://www.prc68.com/I/SMT.shtml

Have Fun,

Brooke Clarke
http://www.PRC68.com


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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