On 09:18 PM 7/03/2002 +0100, Peder K. Hellegaard said:

>Anybody who knows where to find SMD footprints for wavesoldering ?
>If anyone already has Protel-libraries containing such footprints I would be
>most appreciated to receive a copy.


I think there was supposed to be a commercial library supplier that had 
soldering technology aware libraries - it was stated to me as a better 
alternative to the IPC libraries.  Sorry but I can't remember their name - 
something like SMC-plus or SBC-plus or something from very vague 
memory.  Maybe someone else who gets the PCB design magazines will know 
what the name is.

I have built my wave and reflow libraries up mostly from the Philips data 
books (for the passives and small semis) and some other sources over time 
and a bit of trial and error.  They are not, unfortunately, in an organised 
fashion that they could be released.

The Philips info I used is possibly somewhat dated now days - I am not sure 
if they have kept it up to date.  The main thing about the SO packages is 
the solder thieves - in order to minimise the space taken up by the thieves 
my libraries have the last pad on each row double in width and its centre 
adjusted to keep the pad spacing the same as the other inter-pad 
gaps.  This has worked well for many years and all the manufacturers have 
said it worked OK.  But...the pain is that when you rotate a package 180 
degrees for layout reasons you have to manually twiddle four pads (two to 
make thinner and bring back in, and fatten and move out two).  But since it 
is a fairly simple process to do I s'pose a server could be written to do 
it if I ever had enough of them to do to worry about it.

A long time ago I was suggesting that Protel had improved support for 
soldering technologies - including automatic switching of thieves as one 
rotated a component.  The design rule that restricts component rotation is 
useful for checking that wave solder side component orientation is correct 
.. as long as you have designed your library components with some 
consistency.  I would like extended rules that include wave solder side(s), 
solder direction, automatic indication of any components with poor 
orientations, possibly even rules that check for shadowing by tall 
components (if the 3D viewer is to be improved then component heights can 
be entered into the system) etc.

I would like the ability in the PCB library to have multiple decal designs 
associated with one footprint which can then be associated with layers so 
as a component was swapped from one layer to another it (optionally of 
course) automatically choose the correct decal and oriented the thieves 
according to the nominated wave direction (if the component is on a wave 
solder side) etc.

But as wave soldering becomes less common maybe all this is not so much an 
issue as it was a few years ago.

Ian Wilson

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