Homebrew PCBs

Stefan Trethan wrote:
> What would that help? sitting them on foam would require you to build some  
> kind of machine vision, which is a vast amount more difficult than just  
> pick here place there.

Indeed -- I'm that machine.

My interest wasn't in fully automated pick and
place.  Rather a tool to allow more accurate
manual placement.  Even in the case of feeding
components from tape/carrier there are situations
where enough play exists in the carrier well to
cause significant variation between successive
component picks and some form of additional
alignment/registration is needed.

Especially in the case of ICs which will be
reflow soldered, it makes sense to keep them
discrete.  If the packages have any moisture
content they require baking before reflow
to avoid popcorn damage.  And the number of
baking cycles per unit should be minimal
(eg: 1) to avoid tarnishing the leads.  So I
pre-pick all ICs destined for a single board
onto a metal tray for preassembly baking.

I don't disagree keeping components in tape/
carrier won't buy locating precision.  But the
overhead of mounting and unmounting bits of
tape or IC carrier in a prototype scenario
doesn't seem to be worth the effort.

The scope of the tools being discussed here I'd
hazard apply to the >10 unit prototype scenarios.
While it is a common characteristic of a well
engineered design to scale beyond the original
application it is unlikely needed in this case.
For higher volume assembly runs it would typically
make more sense to farm-out the work to an
assembly shop.

-- 
uhmgawa@...        www.gnu.org