More SMD vs fewer DIPs

[Grant Richter]

That is true, one of our distributor told me that about 90% of all parts
shipped today are surface mount.
One thing I have not seen discussed is why surface mount is attractive.
Aside from being small, they require NO LEAD PREPARATION.
If you have ever spent many nights bending leads for stuffing thru hole
boards,
this will mean a lot to you.

SMD is not that bad to work with. Here is my list of tips from the
technicians
at a big board rework house.

1. You need a bottle of liquid water soluble flux with a needle applicator.
Use LOTS of flux and wash it off the same day.
2. Solder braid is absolutely required for removing solder bridges between
pins. Suckers will just rip up pads.
3. Use two soldering irons to heat both sides of the part to lift it.
4. Get a good pair of stainless steel needle point CURVED tweezers to place
parts.
5. Remove SO parts (small outline - like tiny dips) by heating one pin at a
time and carefully prying it up with the point of an Xacto blade.
6. Wet one of the pads, place the part aligned to the one side, then solder
the other side.
7. Use resistors in 0805 packages and caps in 1206 packages. These are the
easiest package sizes to work with
and to get most common values in. (0805 caps are more difficult to obtain)
8. Most of the rework guys use regular size irons. They don't like the tiny
irons because they deliver less heat.
But a temperature controlled iron is absolutely essential.
9. Don't be afraid to short pins and then solder braid the excess off.
Assuming you have a solder masked board.

An example is placing a 244 pin quad flat pack (like a SHARC DSP) this has
pins on 20 mil centers.
Place two corner pins to get the chip on the pattern (this will take about
an hour),
then flood the whole thing with flux and use a spade tip to apply solder to
all the pins, don't worry about shorts.
Now go back with solder braid and wick up any excess between pins. Done
correctly, you can't tell it from a reflow job.

Required disclaimer: These are tips from people who do this every day.
They do work, but depending on your skill and finger size, may not work for
you.

----------
> From: John Speth <johns at oei.com>
> To: Synth-DIY List (E-mail) <synth-diy at mailhost.bpa.nl>
> Subject: More SMD vs fewer DIPs
> Date: Thursday, May 20, 1999 12:28 PM
> 
> I think that DIP format devices are slowly giving way to SMD format 
> devices.  Quite a few newer and better devices are being released by IC 
> houses in SMD format only.  SMD is not very friendly to us experimenters.
> 
> Does anyone know if any vendor or supplier sells any kind of SMD-to-DIP 
> carriers so us non-capital endowed peons can benefit from these new SMD 
> devices?
> 
> John Speth
> Object Engineering, Inc
> mailto:johns at oei.com
>