Author Topic: 'riser' DIP socket for adding a piggyback PCB?  (Read 349 times)

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Offline TERRA Operative

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'riser' DIP socket for adding a piggyback PCB?
« on: July 07, 2018, 05:13:33 pm »
I got a bit of a project I am toying with and I am looking for a particular part that seems a bit hard to find (Or my Google-fu is weak..)

I have a chip on a PCB that I have removed and put a socket in it's place.
I want to install a kind of piggyback daughter board with something like a wirewrap DIP socket to lift the daughter board up to clear other components on the main board but then also put the IC into the wirewrap style socket on the daughter board. (The attached picture will make that all make sense)

The problem is that wire wrap pins are too large to insert into a DIP socket, and the headers I used are too large to make contact with thin DIP chip pins.

Does anyone know where I can find what I am looking for? I need it to suit a 28 pin (2x14) chip with 0.510" (12.95mm) lead width.

 

Online blueskull

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Re: 'riser' DIP socket for adding a piggyback PCB?
« Reply #1 on: July 07, 2018, 05:17:13 pm »
Do the socket and pins HAVE to be at the same place? If you can shift the socket a few mm from the pins, you can use 2 separate connectors, one pin and one socket. Now with just a socket, not socket-pin combo, you will have much more selections.
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Offline Benta

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Online Ian.M

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Re: 'riser' DIP socket for adding a piggyback PCB?
« Reply #3 on: July 07, 2018, 06:06:50 pm »
I've done that before with turned pin sockets -  take two and crop any pins you need to intercept  on the top one and file flat enough that they wont touch the bottom socket, then solder Kynar wirewrapping wire into the bottom socket, using them as solder cups, and round the base of the  shoulder of the pin for connections to the top socket, then  take the wires to a daughterboard mounted nearby on 3M VHB foam tape.

If you put solder paste in each individual socket of a 28 pin turned pin DIP socket, you could reflow it SMD style onto the protruding pins of another one, already soldered through your PCB leaving its pins free to plug into the main board. If you need more height, you could reflow it onto the ends of the pins of a wirewrap socket, previously soldered through your PCB.    A fillet of epoxy to mechanically reinforce the joint may be a good idea.

However as Blueskull has pointed out,  as m-m turned pin headers are readily commercially available, if you can tolerate as little as 0.1" lateral offset, its best to put footprints for the socket and the header, separate, but overlapping.

Hint:  if its ever going to be removed, put a sacrificial 28 pin turned pin socket  between it and the main board.  If any pins get damaged, you've then got the chance to gently pry off the sacrificial socket and press it into a new one.
 
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Offline TERRA Operative

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Re: 'riser' DIP socket for adding a piggyback PCB?
« Reply #4 on: July 07, 2018, 07:26:31 pm »
Do the socket and pins HAVE to be at the same place? If you can shift the socket a few mm from the pins, you can use 2 separate connectors, one pin and one socket. Now with just a socket, not socket-pin combo, you will have much more selections.

Nah no reason for no offset except for my OCD and having to respin boards. :)


http://www.precidip.com/AppHost/9698,1/Scripts/Modules/Catalog/Default.aspx?c=15

Cool, thanks for the link, I'll have a look and see what they have.


I've done that before with turned pin sockets -  take two and crop any pins you need to intercept  on the top one and file flat enough that they wont touch the bottom socket, then solder Kynar wirewrapping wire into the bottom socket, using them as solder cups, and round the base of the  shoulder of the pin for connections to the top socket, then  take the wires to a daughterboard mounted nearby on 3M VHB foam tape.

If you put solder paste in each individual socket of a 28 pin turned pin DIP socket, you could reflow it SMD style onto the protruding pins of another one, already soldered through your PCB leaving its pins free to plug into the main board. If you need more height, you could reflow it onto the ends of the pins of a wirewrap socket, previously soldered through your PCB.    A fillet of epoxy to mechanically reinforce the joint may be a good idea.

However as Blueskull has pointed out,  as m-m turned pin headers are readily commercially available, if you can tolerate as little as 0.1" lateral offset, its best to put footprints for the socket and the header, separate, but overlapping.

Hint:  if its ever going to be removed, put a sacrificial 28 pin turned pin socket  between it and the main board.  If any pins get damaged, you've then got the chance to gently pry off the sacrificial socket and press it into a new one.

Nice technique, I might steal that idea... I want to try to keep the board as 'Plug-in' as possible so there's a minimum of flappy bits around though.
 

Offline tooki

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Re: 'riser' DIP socket for adding a piggyback PCB?
« Reply #5 on: July 07, 2018, 11:16:07 pm »
Take a look at Mill-Max, for example their Series 116 DIP sockets. (Catalog page 111: https://www.mill-max.com/catalog)

But also you could just use two single-row sockets, which come in far more options from Mill-Max. I also bet they can custom make something for you if it's absolutely unavoidable.
 
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Offline TERRA Operative

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Re: 'riser' DIP socket for adding a piggyback PCB?
« Reply #6 on: July 08, 2018, 01:50:15 pm »
 
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