I thought I responded this this a while ago, guess NOT!!!
Wow, Dano yagot Entek boards that are that old!!!! Coo.
Sounds kwazy that you�d end-up with that volume of old boards, but it�s probably one of those deals where correcting the problem keeps getting put off and keeps getting put off, until it gets smelling SO bad!!! Er, did the fine person that gave you those lousy 0402 dump these boards on you also? [What the hey, let�s blame it on �em anywho.]
We have never re-Entek�d our boards. [�Bout 5 er 6 years ago our lazy behind, good fer nuthin buyer was getting BIG bonuses because she was lowering the cost of bought in parts by volume buying. Unfortunately, all this buying has little to do with the build plan or customer demand. So the production manager got fired, because he couldn't hit cost bogies when trying to economically solder these nasty boards that had been sitting around on the shelf for a cuppla years, humm.] After we figured-out what was happening, we started buying in littie bittie batches when we ship littie bittie volume of products. [And the buyer got another bonus for lying that she figuring that out too!!! Some people just think with the wrong head. I don�t get it!!!]
If I had yer Entek boards, I�d make-up a special stencil for each part number, reflow the pups with the hi-test flux, contract wash �em, test for cleanliness, bake �em, bag �em, and clean-up the messes on the bench, when that day came.
You�re correct the degraded Entek will crater your through holes. This begs the side question: Has the copper plating been damaged enough to compromise the reliability of the product? [Ummm, probably not. Although my concern about this would increase with the wimpiness of the flux I expected to be using when I worked through this inventory backlog.]
That aside, it�s fairly easy to strip Entek with alcohol, but howdya know that ya removed all of the Entek? Dunno.
On the other hand, Entek is applied by dipping or spraying and it wouldn�t surprise me if the re-coating process didn�t strip the old the coating. BUT, none of that Entek re-processing does anything to remove the underlying corrosion of the copper surface that must be removed prior to applying a new solderability protection, be it OSP or HASL. [Kinda like that brass lamp on your front stoop, beside the front door. It�s been lacquer coated, but still corrodes because the porosity of the coating allows moisture in the air to pass to the metal.]
Given the volume of inventory you have to build-down, yer likely looking at something with greater shelf longevity than OSP. There�s no reason why you can�t HASL your Entek boards. Issues are: 1 Board layout 2 Getting the job done.
BOARD LAYOUT. Never heard of anyone laying-out a board for OSP. Generally, OSP boards are converted HASL boards.
GETTING THE JOB DONE. Your fabricator will probably tell you how tough it is going to be to do the job. Hey, it�s not like we�re taking pictures of worms hanging-out by the vents in the Marianis Trench. Or digging-up the streets of Boston for 10 years and blowing the original $3-billion dollar budget: now approaching 12 or 15, on the way to 20-billion dollars. [Then again, liberals are always looking for new ways to take money from people.] Your fabricator could have issues with the fixturing of your boards to match-up with their processes. [Continuing with that thought, your fabricator may not be the proper shop for the job. A specialist may be in order.]
Oooo, let me get a side issue on the table, before I forget. There is no reason not to expect that these boards haven�t been sopping-up moisture, like a Redbone at a bigo puddle on a July after noon. So beyond your primary concern of restoring solderability, there should be the concern of moisture venting from the boards during soldering process.
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I have thousands of old datecode PCBs which has an Entek and...
- Jul 04, 2001
by
Yngwie
I thought I responded this this a while ago, guess NOT!!!
...
- Jul 04, 2001
by
davef
