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I am looking for an eagle footprint that can accept both a standard 40 pin DIP socket or a ZIF socket. Alternatively, if you have tried this and found it to be impractical I'd like to hear that too.

update: thanks for the contributions. I had not realised that different brands of ZIF sockets can be very different in pin spacing. The ZIFs I have is marked 3M (although it is more likely a clone). The two rows are definitely not at the standard distance from each other, yet close enough to the standard distance that two holes is out of the question, the holes would overlap which AFAIK is frowned upon by boardhouses. I now made the holes larger, I'll see whether this works out OK (the file was sent to the PCB house today). The holes are now so large that no trace will fit between two pins, but the autorouter did not mind :)

update 2: larger holes worked OK. It is a bit of a compromise now, I would never use such large holes for a normal DIP socket, but is still fits OK.

supercat's answer was the most usefull to me, but it is in a comment :( I have one of those black ZIFs too, I like it much better than my '3M clone', but it costed maybe 10 times as much...

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    \$\begingroup\$ I can't see a problem. It would only take me a few minutes to create one for the PCB software I use. \$\endgroup\$
    – Leon Heller
    Commented Oct 30, 2011 at 11:37
  • \$\begingroup\$ I don't see the problem. The ZIF socket will be a bit wider and longer than the normal DIP, so it looks like you can use the ZIF footprint for both. \$\endgroup\$
    – stevenvh
    Commented Oct 30, 2011 at 11:38
  • \$\begingroup\$ For those who say: use a normal DIP footprint: are you speaking from practice? Maybe the ZIF I have is atypical (Chinese 3M clone), but it has 14.5 mm (centre-centre) between the two rows of pin, versus 15,2 for a normal DIP socket. So I'd have to make the holes very large to fit both. \$\endgroup\$
    – Wouter van Ooijen
    Commented Oct 30, 2011 at 13:00
  • \$\begingroup\$ @Wouter - IIRC I used 3M/Textool ZIF sockets in normal 40-pins IC sockets in the past, so I presume the row spacing will have been close to 15.24mm. Can't you space the rows at 14.85mm (average of 14.5 and 15.2) and make the holes slightly larger, so that the pins may touch the edges of the holes? \$\endgroup\$
    – stevenvh
    Commented Oct 30, 2011 at 14:57

4 Answers 4

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The pins of a 40-pin ZIF will have the same spacing as a 40-pin DIP. The issues to watch out for are: (1) some ZIF sockets have pins which require larger holes than would be required for most sockets, and (2) nearly all ZIF sockets are wider or longer than ordinary sockets; many are significantly longer. If you wish to solder a ZIF socket directly into a board, you should leave room for this. My normal preference, however, is to solder an "ordinary" socket into the board and plug a ZIF socket into that. If you take that approach, it may be possible for the ZIF socket to overhang some low-clearance components.

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  • \$\begingroup\$ You must have ZIF sockets that are very different from mine. Mine has flat pins, flat in the 'short' direction of the socket, exactly opposite to the flatness of IC pins. No chance at all to force my ZIF pins in either a low-cost ('dual swipe') socket, even less in a machined (round pin) socket. \$\endgroup\$
    – Wouter van Ooijen
    Commented Oct 30, 2011 at 22:02
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    \$\begingroup\$ Sounds like you have 3M Textool sockets. I don't know what sockets are available these days, but I've used at least three different styles: the green 3M Textool ones, some black ones by Aries which have round pins and are a bit bulky at one end, and some blue ones which have a release lever on one end, rather than on the side, and have pins which are flat in the proper direction to fit leaf-spring sockets. \$\endgroup\$
    – supercat
    Commented Oct 30, 2011 at 22:30
  • \$\begingroup\$ @Wouter van Ooijen: See above comment. Also, note that Aries sockets (my favorites) can accept chips with 0.3"-0.6" spacing. As shipped from the factory, the pins are 0.6" apart, but it is (or at least used to be) possible to disassemble the socket, swap the contacts from the left half and right half, and then reassemble the socket with 0.3" spacing. Older sockets used a screws and nuts to hold them together. The newest ones I saw used rivets. I've never disassembled a riveted one, but they look as though, if you find the right nut+screw for reassembly, they should work the same. \$\endgroup\$
    – supercat
    Commented Oct 31, 2011 at 15:35
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Use large pads with two holes, or two overlapping pads, for each pin.

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Whether what you want is possible depends on the ZIF socket. Normal 40 pin DIPs have .6 inch spacing between the two rows. If the ZIF socket doesn't, then you'll need at least one extra row of holes.

However, most 40 pin ZIF sockets do use the same spacing as 40 pin DIP packages. I moved my Eagle 40 pin ZIF footprint into the PACKAGE library and updated the Eagle Tools release at http://www.embedinc.com/pic/dload.htm. This wasn't intended to be a dual purpose footprint and was made for the particular model (some kind of Aries, I think) of ZIF socket I happened to have at the time. You may have to make the drill size a little larger but otherwise I don't see a reason this shouldn't work fine with a bare 40 pin DIP or other 40 pin DIP socket.

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The only differences between a ZIF 40-pin socket and a normal 40-pin socket is the outer dimensions of the socket, and the size and shape of the pins. The pin spacings are the same.

Just use the ZIF socket footprint (as it is the bigger of the two in all respects) and the normal 40-pin one will fit in it fine.

It's hard to see on my poor quality photo, but the pins of this chip and the ZIF socket line up fine, and I have used a standard 40 pin DIP socket footprint and enlarged the holes slightly to take a ZIF socket before now.

Of course, it all depends on your ZIF socket. Mine is a 3M one, and others may vary.

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