Luis,
In all my years with Lucent Technologies and Andrew Corp. we've always asked our board vendors to provide cross section samples. I can't ever remember asking a PCB fabricator to provide every cross section they have made. If I were a PCB fabricator I would certainly want to retain cross sections for my archive. Once in a while when we do a lot of business with "big" PCB fabricators we find they have the capability to take acceptable photomicrographs but for the most part the typical PCB fabricators don't have the optical systems to capture good optical photomicrographs. The cross sections thee PCB fabricators make are good enough for them to measure and confirm plating and solder mask thickness and to see if their drilled PTH and vias are straight and have uniform plating. The first thing we do with cross sections provided by PCB fabricators is to re-polish and micro-etch them to see details and we'll do photomicrographs for our own internal reports. To be honest there are many times we ask a PCB Fabricator to provide cross sections whenever they make some change in their fabrication process or laminate material just so we have the cross sections in case there an issue comes up at solder assembly or test and we can go back and check the cross sections. Unless it is a really new complicated design, or hot project that our customers need us to guarantee the reliability we probably would only file the cross sections along with the First Article report the PCB fabricator provides. In some cases we would not only re=polish and photograph the PCB fabricators cross sections but we would do reliability measurements on a fully assembled PCBA and then do our own cross sections.
I think in general it isn't worth asking a PCB Fabricator to provide photomicrographs because they will probably not be good enough quality to tell anything useful.
Regards,
George
George M. Wenger
Failure Signature & Characterization Lab LLC
609 Cokesbury Road, High Bridge, NJ 08829
(908) 638-8771 Home (732) 309-8964 Mobile
E-mail [log in to unmask]
[log in to unmask]
-----Original Message-----
From: TechNet [mailto:[log in to unmask]] On Behalf Of Louis Hart
Sent: Tuesday, April 01, 2014 7:04 PM
To: [log in to unmask]
Subject: Re: [TN] PWB Microsection Report - Photos
Phil, interesting the questions you ask.
As someone who works on PCB fabrication, I have often wondered if any customers looked at the coupons and sections we send them.
Personally, I have been reluctant to send Compunetics' sections as I have told colleagues that these sections are the documents showing that, to all indications, the boards were built in conformance with requirements. For that reason, if a customer requests a section of a single coupon, I tell our folks that we will prepare an extra one for the customer and keep our usual complement. During the past few months a customer has been requiring all of our formerly internal sections, the sectioning and analysis by an external lab, plus any remaining coupons. (We have been sending everything - G, E, M, etc - in the face of these imprecise requirements.) Then we note in the microsection archive, and on the production records, that all coupons and sections went to the customer in accordance with the purchase order requirements.
The semiconductor detectors in the common lab microscopes cannot get an image of much more than one hole, and maybe not even that in a thick board, at the standard 100X magnification. The CCDs used in the big astronomical telescopes like those at Mauna Kea, the Canary Islands, or the European Southern Observatory high in the Chilean Andes, could capture more area, maybe. But the last I heard, which was 11 years ago, the price for one of those chips by itself was upwards of $70 000.
If I had the sections themselves, I would not bother with any photos.
I notice Vladimir at Sentec just posted something. Let's see what he thinks....Louis Hart
-----Original Message-----
From: TechNet [mailto:[log in to unmask]] On Behalf Of Phil Bavaro
Sent: Tuesday, April 01, 2014 6:40 PM
To: [log in to unmask]
Subject: [TN] PWB Microsection Report - Photos
I have been trying to get my PWB Fabricators to include photographs of the cross sections that come in with our PWBs but have encountered resistance from some of them. Some even say they cannot do this as they don't have the camera equipment. They always include a mount with a cert and spare coupons but no picture of what is already polished in the mount.
In my opinion, looking over a spreadsheet of check marked boxes for compliance to 6012 is important, but a picture of the mount(s) reveals more information. And in my experience, when I go to a third party lab, I always get photos.
Am I asking for something that is not normally provided from a PWB Fabricator?
What do the rest of you do when it comes to inspection of microsection mounts?
Thanks in advance,
Phil
________________________________
This message and any attachments are solely for the use of the addressee and may contain L-3 proprietary information that may also be defined as USG export controlled technical data. If you are not the intended recipient, any disclosure, use or distribution of its content is prohibited. Please notify the sender by reply e-mail and immediately delete this message and any attachments.
______________________________________________________________________
This email has been scanned by the Symantec Email Security.cloud service.
For more information please contact helpdesk at x2960 or [log in to unmask] ______________________________________________________________________
______________________________________________________________________
This email has been scanned by the Symantec Email Security.cloud service.
For more information please contact helpdesk at x2960 or [log in to unmask]
______________________________________________________________________
|
