I do too. Sincerely, Paul Reid Program Coordinator PWB Interconnect Solutions Inc. 235 Stafford Rd., West, Unit 103 Nepean, Ontario Canada, K2H 9C1 613 596 4244 ext. 229 Skype paul_reid_pwb [log in to unmask] -----Original Message----- From: Dwight Mattix [mailto:[log in to unmask]] Sent: December 17, 2013 1:05 PM To: TechNet E-Mail Forum; Paul Reid; [log in to unmask] Subject: Re: [TN] Crazing +1 Paul In any case (and regardless of the spec), when out playing sourcing games... I look at crazing and wicking from fab to fab as a relative indicator of a) how skilled/disciplined they are at drill and b) how far along the accountants are into their destruction of the fabs technical capability. >:-} At 07:03 AM 12/17/2013, Paul Reid wrote: >Hi Gerry, > >Based on the responses from "everyone" I am sure that crazing is a >defect that is a concern. It is just that one company is playing >"specmanship" with IPC's rules and I don't like it. > >The rules state that a microsection is not needed to inspect for >crazing. Therefore, according to the fabricator, one cannot inspect for >crazing using a microsection. The specification does not state that a >microsection is prohibited in the inspection for crazing however. IPC A >600 states that crazing ".. does not require a microsection evaluation". > >Regardless of how I found the defect it is the intent of IPC to reject >this condition if it violates 50% spacing rules. > >I found this condition "along the way" and I raised the flag. That is >all I can do. > > >Sincerely, > > > >Paul Reid > >Program Coordinator > >PWB Interconnect Solutions Inc. >235 Stafford Rd., West, Unit 103 >Nepean, Ontario Canada, K2H 9C1 > >613 596 4244 ext. 229 > >Skype paul_reid_pwb >[log in to unmask] > > > > >-----Original Message----- >From: TechNet [mailto:[log in to unmask]] On Behalf Of Gerry Gagnon >Sent: December 13, 2013 8:49 PM >To: [log in to unmask] >Subject: Re: [TN] Crazing > >Hi Richard, > >Have enjoyed your posts over the years and agree with you frequently. > >The answer is that it "depends". > >Yes, the magnifications and switching rules are the "front matter" that >a lot of folks gloss over from time to time. > >I am sure that if you were looking to verify a certan non-conformance >and found something along the way that was lethal for your product or >application, you would have no problem raising that flag. > >By the way "along the way" is just a figure of speach I was using. >Definitely not proper specification language. > >Gerry > > > Date: Mon, 9 Dec 2013 12:52:28 +0000 > > From: [log in to unmask] > > Subject: Re: [TN] Crazing > > To: [log in to unmask] > > > > I am not sure I accept that "along the way" theory completely. > > Prevalent in all of the IPC standards, all defect categories are >provided a magnification level for inspection. For example, if a >non-metallic particle is seen on the PWB while inspecting solder joints >at 20X magnification on a conformal coated CCA, the inspector is >supposed to switch to the required magnification for the particulate >matter (4X-7X). If the particulate matter cannot be seen at that range, >it is not considered to be a defect. > > If you want to entertain your "along the way" theory, then have fun >counting up the rework hours to strip away the coating, remove the >particles, clean, dry, and re-coat. No matter what you do short of >building all product in a Class 10 clean room, this unnecessary rework >will never end. > > > > Of course, one must understand that there are certain exceptions to >this; I am just saying that you cannot allow an "along the way" >philosophy in the factory. It will put you out of business. > > In regards to your example, two questions come to mind: > > > > 1. What is the magnification required when inspecting for particulate >matter between conductors at the PWB level, and what is the minimum >electrical clearance between the two traces you describe? If the >material was visible at the required magnification, it was an escape, >and should have been caught at the higher magnification you describe >anyway, and is a real defect. > > 2. Did you measure the resistance again after the tiny piece of >material was removed, and did it make any difference? > > > > > > -----Original Message----- > > From: TechNet [mailto:[log in to unmask]] On Behalf Of Gerry Gagnon > > Sent: Friday, December 06, 2013 7:21 AM > > To: [log in to unmask] > > Subject: Re: [TN] Crazing > > > > Hi Paul, > > > > Hope you and Bill B. are doing fine. > > > > I am assuming that you you were looking for something else and >detected a "non-conforming" level of crazing. > > > > In my mind, this is an easy one because you found the non-conformance >"along the way" while examining your microsection. > > > > Let me give you an easier analogy. > > > > While examining a region of an IST test coupon in transverse mount, I >find a tiny piece of material bridging two conductors at high mag. > > Clearing away the conductor surfaces enough to measure if there is a >resistance, I get a value in the MegOhm range. > > > > Is it a short? > > > > Unless things gave changed, Bare board continuity thresholds will not >detect this phenomenon. > > Let's also say that innerlayer AOI (if performed) has a very high >escape rate for this type of phenomenon or may not even detect it at >all. > > > > Is the phenomonon a short per IPC A-610? > > My answer is yes, it is an unwanted connection, albeit a high >resistance connection, and is difficult to detect. > > > > Does the fact that I found this short in a cross section under high >magnification, while I was looking for something else, change anything? > > > > I don't think so, and I do not think IPC A-610 allows non-conformances >that are found "along the way". > > > > Have a good one. > > Gerry > > > > > > > > > > > Date: Thu, 5 Dec 2013 16:05:41 -0500 > > > From: [log in to unmask] > > > Subject: [TN] Crazing > > > To: [log in to unmask] > > > > > > I was just on a conference call where we found crazing (a separation > > > > between glass fibers and the epoxy system), in a microsection. The > > > fabricator stated that this had to be evaluated looking at a board > > > macroscopically and could not be evaluated microscopically. > > > > > > > > > > > > Crazing is called out in IPC-A- 600 in section 2, paragraph 2.3.2 >page > > > 18, which is "Externally Observable Characteristics". In A-600 there > > > > is picture of a microsection showing the defect but it states that a > > > > microsection is not required. > > > > > > > > > > > > In IPC 6012-2010 crazing is call out in 3.3.2.2, page 12, which >states > > > (I am paraphrasing), "Crazing shall not violate greater than 50% of > > > the distance between adjacent conductors..." The document then >refers > > > to IPC A 600. > > > > > > > > > > > > What is your take on their argument that crazing should not be > > > evaluated microscopically as per IPC? > > > > > > > > > > > > Sincerely, > > > > > > > > > > > > Paul Reid > > > > > > Program Coordinator > > > > > > PWB Interconnect Solutions Inc. > > > 235 Stafford Rd., West, Unit 103 > > > Nepean, Ontario Canada, K2H 9C1 > > > > > > 613 596 4244 ext. 229 > > > > > > Skype paul_reid_pwb > > > [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] > > > >______________________________________________________________________ > > > > > > ______________________________________________________________________ > > 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] > > ______________________________________________________________________ > > >______________________________________________________________________ >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] >______________________________________________________________________ ______________________________________________________________________ This email has been scanned by the Symantec Email Security.cloud service. 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