Current sense resistor PCB pads?

[treez]

Hello,
The CSM3637 current sense resistor has different size pads depending on the resistance value.
The lower resistance values have much wider pads.

CSM series datasheet:
http://www.vishaypg.com/docs/63089/csm.pdf

Our prototype boards need to be able to have either the low resistance version or the higher resistance version.
Therefore, do you think it will be ok to just use the "wide-pad" land pattern, and fit the "narrow-pad" resistor to this "wide-pad" footprint in those cases where we do use the higher resitance values?

 

[FvM]

Use commen sense.

I suggest two objectives
- power pads should be fully connected
- sense pads must be separated from power circuit

 

[treez]

If I use the wider power pad footprints, then the power pads will always be connected, no matter which resistor is used.
So why have they specified two different footprints when one would appear to be allright for all?
-Is it because the narrow pad resistor could in theory slide about on the wider pads whilst in the solder bath (we will be hand soldering them on our few prototypes)?

 

[FvM]

I don't know what you want to achieve. This are high precision resistors that must be connected in 4-wire circuit to achieve the specified accuracy. The CSM3637 and CSM2512 are obviously incompatible, I don't see how to connect both types 4-wire with the same footprint.

The resisistor price is about tenfold that of standard precision types, so nobody would use it for simple current sense applications.

 

[treez]

Thanks forgive me for not explaining in full.
The CSM3637 has two footprints, one for resistances below 1.9mR, and one for footprints above 1.9mR.....what I am saying is, if I just do the "wider-pad" version, then can I solder either of the CSM36367 types to it?

 

[FvM]

Sorry, I didn't read your post thoroughly. Using larger pads is definitely no problem in hand soldering, probably not even in reflow. Take care that the solder doesn't wet the resistance element.