A truly sweet, small, new SMD power FET package

What a coincidence! I am in the middle of a design right now where I am considering the Si7157DP and the SiRA00DP devices in that package. I would use two of each in a non-PWM H-bridge configuration and spread them out a bit on the board. I think they will have longer life than an automotive relay.

JohnS

Right. Ignore errors that you know are OK. Show that CAD program who's boss.

Some fine-pitch parts throw tons of errors if you set the clearance checks to be useful.

Lead-free solders vary by nearly 2:1 in thermal conductivity. I think that would throw off your calculations.

You can easily compute the thermal conductivity of the solder from my table, then substitute any solder you'd like.

Why didn't you just do that, and if it made a worthwhile difference, share? You know, contribute.

Cheers, James Arthur

On the business side of the firewall, a good 30A auto relay is hard to beat.

It's sure getting close though, and some day soon we'll be clacking silicon instead of copper and steel. Best of luck at it.

Cheers, James Arthur

Because I'm not designing a thermally constrained board. I was just trying to point out a limitation of your spread sheet as presented. You presented your calculated data without explaining the basis. No intent to get your hackles up. Just trying to set the record straight.

I spent hours over the years refining a spreadsheet to estimate these exact things--thermal performance of filled / unfilled vias--for designs, and a bit of time posting some example data here that others might benefit.

In ten minutes you could've calculated what kind of solder is in there, noted the solders possible, noted any effects on the overall result, and generally made any statements, improvements, and added any worth you wanted to the original presentation, saved for posterity.

You've spent thrice that in my time quibbling about I should've done or still should do.

Pitch in some time. It feels good.

Cheers, James Arthur

You are complaining about how much time you spend replying to my posts? Why do you continue this conversation? I don't think I am the one who is acting a bit strange.