Re: pick 'n' place machines (was: OT 0805 resistor noise)

On 8 Sep 2005 12:52:26 -0700, Winfield Hill
<Winfield_member@xxxxxxxxxxx> wrote:

>John Larkin wrote...
>>
>> We recently did our first 456-pin BGAs... and it worked!
>
> Preheat with hot air from below, heat it with hot air from
> above, and after a while it just "sits down" all of a sudden?


It went through the conveyer on the reflow oven, deep dark tunnel, so
we couldn't see what happened! They do ride a thermocouple through the
oven, attached to a data-logging Fluke, to get the time-temp profile
right. That's apparently the most important thing. They've done maybe
20 boards so far, with 100% success. They prefer BGAs to TSOPs now,
although they may change their mind after they have to rework one.

It's sure nice to toss all your logic into one huge chip. No
interconnect problems, and massively inefficient logic works just
fine. Multipliers, adders, fifos, PID controllers, serial bangers,
phase detectors, DPMs, whatever, just heap them on. It's almost
obscene.

John



.

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