Stuffing boards with pulled QFP chips

[allison]

On 03/31/2017 02:00 PM, Paul Koning wrote:
>> On Mar 31, 2017, at 1:51 PM, allison via cctech <cctech at classiccmp.org> wrote:
>>
>> On 03/31/2017 06:32 AM, David Griffith via cctalk wrote:
>>>> I'm down to the last few P112 boards for sale and am pondering
>>>> another run of them because demand is steady.  One of the biggest
>>>> challenges for the last run was getting the QFP-packaged 100-pin
>>>> chips[1] in a state such that the pick-and-place robot wouldn't throw
>>>> a fit about slight differences in lead position.  The stuffing house
>>>> insisted that I send them new chips.  Pulls, though they looked
>>>> perfectly okay to me, were not acceptable.  Does anyone here know
>>>> anything about pick-and-place robots using pulled 100-pin QFPs,
>>>> particularly a stuffing house that can work with such chips and not
>>>> screw up?
>>>>
>>>> [1] The now-obsolete super-io chips
>>>>
>>>>
>> Is this something that an experienced hand can manually do?
> Yes, definitely.  100 lead PQFP is perfectly doable if the lead pitch is not insanely small.  It takes a good fine tip soldering iron (mine is a Weller with a PTS tip), fine solder (preferably real, i.e., 63/37 non-PC solder).  Liquid flux is a big help, as is a magnifier and bright light or modest magnification microscope.
>
> If you have to do a couple of dozen boards this gets very tedious, but for 5-ish it isn't a big deal.
>
> 	paul
>
So happens I'm fully equipped on all counts.  Including the PTS tip. 
However my preference
for years has been the PTA7K (WTCP60) which is 1/4" wide!  Gets a few
pins done at a time... ;)

I've not gone over to the Rohs side, most of the solders are not fun to
work with though a
few have very active fluxes and solder aluminium well.   So its Kester
44 in 10 and
20 mil (inch mil) diameters.

I've done more than a few AD537 and similar Blackfin CPUs with their 288
BGA package that's
a challenge to pull and replace.

Allison