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Pad Sizing

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ibwev

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I am creating my first PCB layout. I am using a 14 position connector terminal block (Digikey 277-1731-ND). I don't fully understand the datasheet. It mentions a hole diameter of 1.2 mm and a pin dimension of 0.9 mm. Currently, I have noted 2.92 mm round pad with a 1.32 mm hole.

1) What size pad would be best.

2) Using the above pad size only leaves about .635 mm in between pads. Is that too close to solder?

3) What is the minimum suggested width between pads?
 

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hi,
I make that 25thou of an inch spacing which is OK
Its advisable to have some clearance on the pin/hole diameters, so 0.9mm dia pin and 1.2mm dia hole is OK
If you need a better 'mechanical' support for the connector you could consider rectangular pads.
 
Pad size has many faces.
I agree with Eric that larger pads are stronger. You need to keep some distance between the pads. Your PCB maker might need 0.01 inch between copper.
If you need to run a trace between the pins you need smaller pads. Example: PAD, 0.01 space, 0.01 TRACE, 0.01 space, PAD
Some times connectors have oblong pads or rectangle pads so the pad is large in two directions and small in two directions to allow a trace between pins.
 
One thing to watch out for when sizing holes for pins is the shape of the pin. Some part, including many connectors, have square or rectangular pins. So you need to size a round drilled hole for the the diagonal distance between opposite corners of the pin.
 
I am creating my first PCB layout. I am using a 14 position connector terminal block (Digikey 277-1731-ND). I don't fully understand the datasheet. It mentions a hole diameter of 1.2 mm and a pin dimension of 0.9 mm. Currently, I have noted 2.92 mm round pad with a 1.32 mm hole.

1) What size pad would be best.

2) Using the above pad size only leaves about .635 mm in between pads. Is that too close to solder?

3) What is the minimum suggested width between pads?

Hi

Are you planning on having a board fab house make your board?
If so, they usually have PCB design specifications that the PCB design must meet before they can fabricate it.
I'd check online with a fab house, they provide this info for free.

They usually have a minimum hole diameter and a minimum annular ring specification.
Also, the choice of hole size can be a cost factor. If the hole size is a standard size, the cost may be less.

If this is your first board, its a good habit to review board house specifications so your familiar with them.
You may need to tailor your pcb parts library, traces, etc., to accommodate the spec.

Here's a link to a typical spec:

https://www.pcbfabexpress.com/preview_specs.jsp

eT
 
Hi,
A very useful free download tool for checking PCB artworks I use, before submitting them for production is the GC-Prevue 21.3.6

Get the free version.
https://www.graphicode.com/

E
 
If you are using a board house to etch the board you need to follow their rules. In eagle the rules are contained in a file. You load this into eagle and the board you design will be forced to their rules when you do the DRC or design rule check. Some companies like OSHpark have tools that let you upload you eagle .brd file and will do a rendering from it to show you what you PCB will look like as well as do the needed checking.

As others have said larger pads are stronger. This is because the copper is glued to the substrate and the more copper you have on a pad the more glue you have holding it.
 
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