Victor, Technet is fine, I for one received all of your emails on the subject.

It is kind of a chore to go into TMs, find the method you are describing, and see exactly what it states. 

I imagine that is why a lot of people cannot respond, as they are quite busy.

So if I understand your question correctly, you are discussing the Dip and Look method of determining solderability, and you want to know if you should dip both sides?

I think what you are trying to achieve is to see if there are any wetting issues for a given solder sample or samples.

If that is the case, then wouldn't you wish to perform this test as closely as the real production process, which I assume is a wave solder process? For that is the only process that this test replicates.

Once you have performed the test on side one (the normal solder source side), I see no value in flipping it over and dipping or floating the opposite side. You do not normally wave solder both sides of a CCA. Second, because I know of no PWB HASL fab process (or plating process if some other finish is used) that would cause solderability issues on only one side of the PWB, although I suppose it is possible.

If you plan on using selective solder and/or SMT reflow, then you may wish to run the sample through those processes to test for solderability. Dip-and-look test results can be notoriously misleading. Just because the PWB retains solder does not mean it will solder up with good wetting action, although it is an indicator.

Like Werner Engelmaier used to say, "I can get solder to completely coat a toothpick, but that does not mean I will be able to solder to it successfully, ie, no IMF is formed".



If I were performing that test, I would put some non-pretinned PTH scrap parts on the test sample(s) as well, as a fully loaded CCA can greatly affect the amount of wetting that takes place versus an empty PCB.

I believe there are new Test Methods for determining SMT and Selective Solder process solderability, and they outline a close duplication to the reflow or SS process. 

That is what I do to test PWB solderbility; running the test sample(s) through a process that is as close to actual production as I can get it.

I hope this helps you.

dean





-----Original Message-----

From: TechNet <[log in to unmask]> On Behalf Of [log in to unmask]

Sent: Monday, August 26, 2019 1:30 PM

To: [log in to unmask]

Subject: [TN] FW: TM-650 2.6.8, Thermal Stress, Plated Through Holes, 2x thru 6x.



Fellow TechNetters:



   Requesting clarification on the above stated TM.



   Section 5.6  Using tongs, carefully remove the test specimen from the solder and place it on a piece of insulator to cool to room temperature ( see 6.3).

Question:       Is the test specimen FLIP after each 10 second excursion as to ensure that both sides of the test specimen touch the molten solder surface.

                I did not see any reference this this remark…………



Victor,