Components with POSTS?

Community PCB Design
1

Hi there,

I have a SD memory card socket. However, this socket, in addition to pins for electrical connections, has two plastic posts(or legs) that I think is meant to fix the socket to PCB more securely.

How to handle these posts? If they are long enough, you could make just a hole on pCB. But they are not long enough. They just extend half the thickness of the PCB. Plus, I do not want to make a hole all the way. How to take care of this? Thanks

Regards

.

2

Hi,

I’m afraid you still need to make an unplated hole through the PCB. You often find these alignment posts on parts with iregular pinout such as connectors and buttons.

3

olivier_p:
Hi,

I’m afraid you still need to make an unplated hole through the PCB. You often find these alignment posts on parts with iregular pinout such as connectors and buttons.

Thanks. But what is “unplated hole”? Thanks

.

4

One without copper plating. Most PCB suppliers plate all holes by default and you have to specify unplated holes. The software I use allows holes to be designated as unplated. In this case the holes could be plated.

Leon

5

why does the hole have to be unplated?

6

I can’t see why, I said as much in my post.

Leon

7

Greetings Phil,

Philba:
why does the hole have to be unplated?

Depending upon the component, plating may short

electrical contacts or PCB traces on the component.

A plated-through-hole can always be redrilled to

remove the plating (going the other way is harder…)

A blind hole, counter-bored hole, or counter-sunk hole

is not impossible but usually increases the PCB’s cost.

These are not allowed by BatchPCB, BTW.

A plated through hole is just that, its up to the PCB

designer to specify whether a plated through hole

has an annular ring or not. The software I use allows

holes to be designated as unplated.

Comments Welcome!

8

This all seems like common sense to me.

Shorting - this would be an issue if the part has a metal shield and the designer is stupid. When faced with a metal shield, I simply add “pins” to the part and connect them to ground in the circuit. If the shield isn’t grounded (kind of a stretch), don’t connect them to anything. Seems like a non-issue to me. Either way, you can solder the part down for mechanical integrity. If there are traces on the part or under the metal area of the part, the designer should create a restrict area.

Leon, I reread your posting - it wasn’t totally obvious when I first read it as it looked like you were agreeing. Though in context of your response, I see.