Thanks for the replies Jack and Dee
I appreciate that boards are getting denser, and part of my problem is that
many
of my footprints were created for high speed video boards where space is at
a
premium, and produced at fairly low volume. However, most of my current
boards
are for the lighting industry and tend to have a mixture of high power
components
and signal level sections. The high power stuff is determined to a large
extent by
the current requirements, but on the signal side I often get comments about
the
pads sizes looking a bit small. I am confident that they meet the IPC
requirements,
but I would be much happier if I could produce some sort of documentation
that
proves they will solder well.
I am trying to produce some company guidelines which is why I am going back
to 'first principles' to try and obtain the current facts and figures to
back up our
methods.
Again, I would be most interested in any information from anyone out-there
regarding pad sizes for the ideal solder joint (for through hole parts). I
know this
is a fundamental issue, but I just can't find and info on the subject.
Best regards,
Mark
Mark Holmes PCB Designer
Helvar Lighting Control
mailto:[log in to unmask]
> -----Original Message-----
> From: Jack Olson [SMTP:[log in to unmask]]
> Sent: Friday, September 24, 1999 5:17 PM
> To: [log in to unmask]
> Subject: Re: [DC] Pad Sizes for good solder Joints
>
> That is a really good question, but I don't know how much response you
> will
> get, because in my experience it is usually the opposite that happens. The
> assembler wants to reduce the pad size and corresponding amount of solder
> paste applied. I've never thought about how IPC says minimum, and how that
> could be interpreted to mean that you should make everything bigger if you
> can, because nobody does that! Everyone wants smaller smaller smaller
> (except maybe big pads on through-hole for high-power components, or
> something like that). So maybe you should take that "land sizes should be
> maximized" statement with a grain of salt, since I believe the IPC
> recommendations are already bigger than anyone else's out there. (correct
> me
> if I'm wrong you guys, I'm just a lowly layout guy)
>
>
>
> -----Original Message-----
> From: Mark Holmes [mailto:[log in to unmask]]
> Sent: Friday, September 24, 1999 1:09 AM
> Subject: Pad Sizes for good solder Joints
>
>
> All the data I have regarding pad sizes (e.g. IPC-2221
> 9.1.1) give examples
> on how to calculate Minimum pad sizes, usually from a PCB
> fabrication
> standpoint. IPC-2221 states that all lands and annular
> ring
> shall maximised
> wherever feasible, consistent with good design
> requirements
> and electrical
> clearance requirements.
>
> My questions are: How do I determine the pad size that
> will
> give me the best
> soldered joint?
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