Thanks Shawn

-----Original Message-----
From: Upton, Shawn [mailto:[log in to unmask]] 
Sent: Friday, February 05, 2016 10:28 AM
To: TechNet E-Mail Forum; Nutting, Phil
Subject: RE: [TN] developing thermal profile without a populated board

Run one, visual inspect, manual rework as necessary, run a second one.  Repeat until satisfactory results are obtained.

I don't think for small runs one can expect much better.

For some small runs I wonder if more manual soldering is easier/faster than attempting to figure out the "best" production solution.  10 boards is not much of a production run.  Run what is known to work (standard 0603's, TSSOP's, etc), and manually add anything that is questionable.

Shawn Upton
Section Head, Test Engineering
Sensors Business Unit
Allegro MicroSystems, LLC
[log in to unmask]
603.626.2429/fax: 603.641.5336


-----Original Message-----
From: TechNet [mailto:[log in to unmask]] On Behalf Of Nutting, Phil
Sent: Friday, February 05, 2016 9:42 AM
To: [log in to unmask]
Subject: Re: [TN] developing thermal profile without a populated board

This thread leads me to a slight variation.  We have a 4 layer board, copper planes on both sides with a bunch of 0603 and SOIC components in two small areas and some large ferrite transformers that are about 1 inch square and 1/2 inch high.  I can't believe this would use the same profile.  Do you run this to mount the big parts and follow with a different profile that will reflow just the small parts leaving the big parts untouched?

I'm in disagreement with other engineers on how to handle this.  And no I have not yet looked at the manufacturer's recommended profiles of the important and different parts.  Other fires to put out first.

Also, how do you handle a profile for a batch of ten boards where you don't have the luxury of having a populated test board?  The ten boards could potentially be the run for the entire year.

Phil Nutting

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