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April 2018

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From:
Dwight Mattix <[log in to unmask]>
Reply To:
TechNet E-Mail Forum <[log in to unmask]>, Dwight Mattix <[log in to unmask]>
Date:
Thu, 19 Apr 2018 17:39:24 +0000
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Holy Post-Sep Batman!



Concur, that's not assembly heat. Well yeah it likely is but an afternoon in the sun on the dashboard of your car might have been enough heat to pull that interconnect apart.



IMAO (in my arrogant opinion), that's just a poorly fab'd PTH.



For starters Sherlock Holmes:

1. Does the supplier have sections from this lot (both inprocess plating and final Met lab QC and solder float eval)?  Review those

2.Do you or the supplier have any "as-is" boards that have not as yet been through reflow?

If yes, get busy sectioning those and look for precursors.  Go crazy and do some vertical grinds down to look at the post interconnect in the horizontal. I'll lay you odds you'll see dark rings and/or gaps at the hole/foil plating interface.



Be prepared to go deeper into process logs, looking at actual working travelers, and chem lab info. They either had a recipe they dropped the ball on, or they don't have a recipe that's worth the paper it's written on.  (once again, that's IMAO)>







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

From: TechNet [mailto:[log in to unmask]] On Behalf Of Guy Ramsey

Sent: Thursday, April 19, 2018 10:20 AM

To: [log in to unmask]

Subject: Re: [TN] R: [TN] R: [TN] PCB failure



I would like to see an image of the full via, top to bottom. But, I see no evidence that the failure was caused by excessive heat from hand soldering.. Obviously, they failure could be heat induced, but the board structures show no signs of heat stress. They didn't put up much of a fight from what  is visible in the photo.



On Thu, Apr 19, 2018 at 12:49 PM, Zilber Gil <[log in to unmask]> wrote:



> We require 0-5 micron etch back.

> Gave the explanation previously.

> Regards,

> Gil

>

>

>

> נשלח מסמארטפון ה-Samsung Galaxy שלי.

>

>

> -------- הודעה מקורית --------

> מאת: David Hillman <[log in to unmask]>

> תאריך: 19.4.2018 16:43 (GMT+01:00)

> אל: [log in to unmask]

> נושא: Re: [TN] R: [TN] R: [TN] PCB failure

>

> Hi Wayne - etchback isn't necessary for acceptable PTH reliability for 

> some products and product use environments so that may not be a 

> contributing issue. With that being said, I like etchback as it always 

> makes the inner connections better/more robust and in some product use 

> environments having etchback is necessary for long term product life. 

> One question we haven't asked as a group is " was etchback required in 

> the fabrication requirements?"

>

> Dave

>

> On Thu, Apr 19, 2018 at 9:11 AM, Wayne Showers < 

> [log in to unmask]

> > wrote:

>

> > The real problem is that this PCB has no etchback, positive or 

> > negative (PCBs are defective).  As far as resin recession, yes the 

> > processing probably caused the separation, but once again, the PCB has no etchback.

> >

> > I would send that cross-section image to the PCB supplier and asked 

> > them if this is typical.  I suspect that they will realize it is a 

> > trap and either offer a crazy answer or admit that their is no 

> > etchback and offer

> to

> > re-run/replace the PCBs.

> >

> The information contained in this communication is proprietary to 

> Israel Aerospace Industries Ltd. and/or third parties, may contain 

> confidential or privileged information, and is intended only for the 

> use of the intended addressee thereof. If you are not the intended 

> addressee, please be aware that any use, disclosure, distribution 

> and/or copying of this communication is strictly prohibited. If you 

> receive this communication in error, please notify the sender immediately and delete it from your computer.

>


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