Multiple SMD pads for the same signal

Ville wrote:

 

I need to use a SMD connector which requires two pads per contact (Molex

52610). The problem is how to make Eagle aware of multi-part SMD pads.

I have a 10-contact connector which has 20 pads in two rows (2x10 pads).

Each contact in the connector is shaped so that it uses two separate

pads, on in each end of the contact. I know I could solve the problem by

making a 20-contact connector and then connecting the contacts pairwise

in the schematic editor. Unfortunately, this would lead to a messy

schematic and also ruin interchangeability with 10-pin FPC connectors.

Is there some smd pad naming trick which would help here? I have named

the pads 1,2,...10 and 1b,2b,...10b, but is there some way to name the

pads so that Eagle would recognize them to belong to the same potential?

Or is there some other way to connect several pads to one signal?

I do not think this problem is unique. For example, many dfn packages

have an exposed ground pad in the middle (either for better heat

conduction or for better GND contact), and that pad is seldom drawn in the

schematic.

TIA,

 

- Ville

 

Symbol pins and pads have to be 1 to 1. You can make the solder stop and

cream outlines so they match the required outline and (not knowing the

shape) use a long smd pad to bridge the two pins.

Paul R.

Symbol pins and pads have to be 1 to 1. You can make the solder stop and

cream outlines so they match the required outline and (not knowing the

shape) use a long smd pad to bridge the two pins.

A good idea! Unfortunately, this has the problem that I would like to

have traces going in between the two rows of pads. If there are long pads,

this is not possible (and DRC might have some complaints about vias, as

well).

I tried another approach. I made "hidden" pins into the schematic symbol

(one contact symbol having two pins). This is something that at least

some transistor symbols have in the library. However, I had to abandon

that approach for two reasons. First, ERC had a lot of complaints about

missing junctions. Second, even this did not enable me to make the two

connectors (horizontal which has 10 pads and right angle with 20 pads)

interchangeable, as Eagle refused to use the 20-pin symbol with 10-pin

packages.

So, the outcome was that I made a connector with 20 pins. It looks ugly

in the schematic but the PCB is fine.

However, this would be nice to have in future versions of Eagle. It

would be useful to be able to have several connections to one pad and

several pads to one connection. Without knowing anything about the internal

structure of Eagle, this may be either rather simple or horrendously

difficult.

- Ville

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