This is why very few engineers and scientists are politicians. See what happened when they asked Einstein to "rule" Israel. http://www.youtube.com/watch?v=Dtk_gChLchw&feature=related -----Original Message----- From: TechNet [mailto:[log in to unmask]] On Behalf Of Graham Collins Sent: Friday, December 14, 2012 1:40 PM To: [log in to unmask] Subject: Re: [TN] Component issue - epoxy die attach Wait a minute here! If Doug is Emperor, why does he say "it depends" so much??? For royalty all pronouncements are supposed to be absolute truths! Imposter, I say. regards, Graham Collins Senior Process Engineer Sunsel Systems (902) 444-7867 ext 211 On 12/14/2012 12:33 PM, Steven Creswick wrote: > Is "Mountain Dew" related to moonshine in its effects upon the human body? > > -----Original Message----- > From: TechNet [mailto:[log in to unmask]] On Behalf Of Stadem, Richard D. > Sent: Friday, December 14, 2012 11:28 AM > To: [log in to unmask] > Subject: Re: [TN] Component issue - epoxy die attach > > Well, maybe not a Coke, but I have seen the masses arriving at the > Technet expos and forums toting cases of Mountain Dew in order to pay > appropriate tribute to Emperor Pauls. > > -----Original Message----- > From: TechNet [mailto:[log in to unmask]] On Behalf Of Douglas Pauls > Sent: Friday, December 14, 2012 10:09 AM > To: [log in to unmask] > Subject: Re: [TN] Component issue - epoxy die attach > > Well, I have been Emporer now for 8 years and have yet to get a burger > and coke out of it. > > Doug Pauls > > > > From: Steven Creswick <[log in to unmask]> > To: <[log in to unmask]> > Date: 12/14/2012 10:07 AM > Subject: Re: [TN] Component issue - epoxy die attach > Sent by: TechNet <[log in to unmask]> > > > > Emperor Doug, > > > > Wow! TechNet is so wonderful! > > > > Not only can you get all kinds of information and opinions on just > about everything under the sun, but you can get titles too!! > > > > How much more do I need to get a burger & coke? > > > > Steve C > > > > From: [log in to unmask] [mailto:[log in to unmask]] > Sent: Friday, December 14, 2012 9:12 AM > To: TechNet E-Mail Forum; Steven Creswick > Subject: Re: [TN] Component issue - epoxy die attach > > > > Steve, > Hell, take the Title and have some fun with it. > > At IPC, I decided that General Chairman, Cleaning and Coating > Committees was too boring a title. So I bestowed the Title of Emporer on myself. > Debbie Obitz became Vice Empress. > Graham Naisbitt is the head of the Jedi Council John Perry and Kris > Roberson are now Grand Moffs. > We have a few System Lords running around. > > We definitely have more fun than the other General Committees. > > So have fun. Maybe Inge can be the Marquis of Micro. Mr. Stadem can > be Duke of DRAMS........ > > Doug Pauls > > > > From: Steven Creswick <[log in to unmask]> > To: <[log in to unmask]> > Date: 12/14/2012 04:53 AM > Subject: Re: [TN] Component issue - epoxy die attach > Sent by: TechNet <[log in to unmask]> > > _____ > > > > > Inge, > > > > Not so sure I desire / deserve that title. > > > > I would submit it to you instead. > > > > > > Howard, you have asked a few questions for which there likely are no > perfect answers except, "it all depends". > > > > "Back in the day", I was familiar with some commercial 'hermetic' > parts that I would not recommend anyone use. > > > > I agree with Inge that processes have improved [and most of the really > bad suppliers no longer exist], but I view RGA results as a planned > goal related to adhesive processing, overall component cleanliness, > and pre-seal processing conditions. The RGA results are only as good > as your process leading up to the sealing operation. Once the package > is sealed, it is a done deal. You cannot screen out for RGA on a > piece by piece basis, as you can with electrical test. Die attach, > wire pull and electrical test results should be almost transparent > across the spectrum from COM, MIL, to Space. > The only difference is that one normally imposses greater > requirements, and increased testing frequency on MIL/Space than on the > COM product. And for reference, with the exception of radiation > hardness, Implantable Medical devices were as tight, or tighter than > Mil/Space > > > > Now then, many manufacturers that make both Commercial and Mil product > will often share a great deal of processes, but sometimes Production, > is Production.. If a Mil pre-seal bake was 24-36 hrs, a corresponding > Com bake may have only been 8-12 hrs. Pre-seal bake and vacuum bake > ovens attached to the sealing chambers are limited in size, so one > would not generally allow a Com grade part to unnecessarily take up > resources. Maybe 8-12 hrs is not quite good enough to meet Mil specs. > that's why it is processed as a Com part. > > > > Sorry we are not giving you a clean answer to your questions. > > > > Inge's wealth of documents will be helpful in your education, however. > > > > > > > > Still time for me to bundle up and check out the meteor shower!!! > > > > Best wishes, > > > > Steve Creswick > > > > From: Inge Hernefjord [ <mailto:[log in to unmask]> > mailto:[log in to unmask]] > Sent: Friday, December 14, 2012 3:08 AM > To: TechNet E-Mail Forum; Steven Creswick > Subject: Re: [TN] Component issue - epoxy die attach > > > > Howard, > > I'm afraid we do bombard you with facts so will be choked. Therefore, > I'll take it slowly. > > 1. Steve is King of Micro, listen to him > 2. Nothing wrong with upgrading commercial to MIL or SPACE. JAN, QL, > etc > too expensive, will disappear. Semi processing been so good today, > that there is nearly no difference between commercial and MIL production. > 3. I send offline to you an article, that is a good one to start > with. No meaning to complicate the question. Suitable drink for this > paper: 4 cl Isle of Jura 4. Epoxy hysteria was initially because its > outgassing caused trouble for all optics in SPACE parts. Agree with > the King, well processed epoxies do no harm. > > > > Inge > > On 14 December 2012 03:14, Steven Creswick <[log in to unmask]> > wrote: > > Joyce - Agree, but so do the Ni & Au platings. > > If the package had a hole so large that the helium was absorbed enmass > in the adhesive, it should have failed hermeticity due to the presence > of He > - > or gross leak testing. > > I hope that he can at least trust that the hermeticity test was > done properly. You are right though, if that is not done correctly, > all is lost. > > Without being privy to the manufactures methods, it appears as though > one is attempting to make a silk purse from sow's ear. > > It is my opinion that meeting RGA requirements is not a 'will test later' > kind of requirement - unless you plan to do 100% [destructive] testing. > Meeting RGA requirements is something that one needs to plan for, and > process accordingly, from the beginning. > > > > Steve Creswick > Sr Associate - Balanced Enterprise Solutions > <http://www.linkedin.com/in/stevencreswick> > http://www.linkedin.com/in/stevencreswick > > > > > > -----Original Message----- > > From: Joyce Koo [ <mailto:[log in to unmask]> mailto:[log in to unmask]] > Sent: Thursday, December 13, 2012 9:02 PM > To: [log in to unmask]; [log in to unmask] > Subject: Re: [TN] Component issue - epoxy die attach > > Steven, epoxy absorb He. If he did He leak test, pass hermidicity > means nothing. My 2 cents. > -------------------------- > Sent using BlackBerry > > > ----- Original Message ----- > From: Steven Creswick [ <mailto:[log in to unmask]> > mailto:[log in to unmask]] > Sent: Thursday, December 13, 2012 08:58 PM > To: [log in to unmask] <[log in to unmask]> > Subject: Re: [TN] Component issue - epoxy die attach > > Howard, > > Sorry, this will be a bit long. > > I am glad you stated that the packages passed hermeticity testing. > That would have been the first item to check. > > I assume this is TO-5 or smaller style package. The smaller volume > packages can be problematic if there is a leak during puncture of the > package because the available tested volume is so small compared to a > potential leak. > > Different labs used to test for RGA in different manners, with > different style equipment. > > On one style of test equipment, the sample package would be placed > into the evacuated test chamber and punctured/broken. The sample gas > would then flow into the chamber and subsequently be taken into the > mass spec. > > Other equipment relied upon placing the package up against the > sampling port, sealing it via an o-ring [of sorts]. Once fixed > against the evacuated sampling port, a needle would protrude through > the center of the o-ring and puncture the package lid, allowing the > test gas to enter the mass spec. > > Both methods have pro and cons. The chamber method is most convenient > for all-ceramic style packages where there is no metal lid to > puncture. A problem with it is that the entire exterior of the > package must be thoroughly cleaned, but can still carry ad/absorbed > species into the test chamber. Plated surfaces also can contain a > great deal of trapped hydrogen put down during plating. Some systems > would see Hydrogen, and log it as H2O. > > With the puncture method, if the lid is too robust, the act of > puncturing could displace the sample from the seal and allow > atmosphere to be introduced, thereby squirreling up the data. Most > hybrids had 0.010-0.020" > thick lids and what WE often did was to take a small end mill [~0.050" > dia] > and mill a small recess in the lid, leaving only about 0.005" of metal > thickness. The lab would than center this in the seal. Generally, > this gave us more consistent data. > > Variance of data - either approach is prone to variation if everything > is not absolutely perfectly cleaned and performed. You did not say > how many samples you ran at each lab. Hopefully, you ran 4-6 at each. > As a minimum, 3, so you could throw out the low and high, and keep the > middle. I am sorry, but to test 1 or 2 is almost fruitless due to > variance. > > To the adhesive - Two major potential issues come to mind. > > First - if you take a great adhesive and improperly process it, you > end up with garbage. The 84-1LMI is a very good adhesive which has > been used by many firms in Space, Mil, and Implantable medical > applications. It can meet the requirements of Mil Std 883, TM 5011 > when properly processed. That is a very good material to use - if > properly processed!! Depending upon the date of assembly, it was THE > material to use. [I am not in any way associated with Ablestik/Henkel, > but I have indeed used this material on many hybrids, including many > space applications, one of which is still in the Saturnian system] > > Second - No matter how well you process the adhesive, if the pre-seal > conditioning [pre-seal bakes, vac bakes, package [and lid] cleanliness > [and bakes] is not adequate, one will end up trapping trash inside a > hermetic package. > > Yes the limit is 5000PPM. The real issue is [if the RGA testing is > accurate] what other ionics and corruption do you have inside the > package to combine with the water?? > > Whether adhesive is allowed or dis-allowed is generally addressed by > the detail specification for the device. I do indeed know of quite a > few Space level parts that have adhesive inside.... properly processed > adhesives... > > No one can really give you a definitive answer, at arms length, such > as this, but here are my free two bits ... > > > I would have to go back and review my dew point knowledge, but I > strongly suspect the 28000 PPM is bogus [unless device assembly is > really sloppy - see below]. You should be able to achieve well under > 2000 PPM without too much grief if it is a TO-5 or smaller package [properly processed]. > > My fear is that you are buying a commercial grade device, that was > assembled and processed as a commercial grade device, having no RGA > requirements. > Therefore, the adhesives were likely not processed in a manner which > would give you good RGA results. To make a poor analogy, it is like > you are buying a standard 75W incandescent bulb and banging it around > as though it were a Rough Service bulb. Yes, some will survive the > abuse, but most will have the filament destroyed almost immediately > because they were not constructed in a manner which would offer a much > greater likelihood that they would pass testing. That may be the > situation you are in. Sorry. > > Hopefully Inge is eyes-open and he can add a few comments as well. > > > Steve Creswick > Sr Associate - Balanced Enterprise Solutions > <http://www.linkedin.com/in/stevencreswick> > http://www.linkedin.com/in/stevencreswick > > > > > -----Original Message----- > From: TechNet [ <mailto:[log in to unmask]> mailto:[log in to unmask]] On > Behalf Of Watson, Howard A > Sent: Thursday, December 13, 2012 6:24 PM > To: [log in to unmask] > Subject: [TN] Component issue - epoxy die attach > > Hello 'netters, > > I debated posting this, as it seems to me to be an obscure problem, > but then, I'm always amazed at your knowledge base. I have a JFET > 2N6550 component to be used for space application. Unfortunately, it > is not manufactured at JANS space quality, so we buy the commercial > grade, plus an option 2 screening, which upscreens the part to "like" > JANTXV. I think this is called re-branding. Then, we send it to a lab > for further upscreening to JANS. The problem is that the parts are > failing the moisture test of the residual gas analysis (RGA). I found > out that epoxy is used for the die attach, and likely the epoxy is > outgasing during subsequent baking as part of the testing. My first > question is who knows of a standard for die attach of this component > type stating that epoxy is forbidden for military and space use? The > epoxy used by the manufacturer is Ablestik p/n 84-1LMI; Material # > 1119570. I just found out today that they do have the capability of > eutectic die attach, and I'm pursing this option, expecting a huge > expense and lead time. > > Secondly, I had two independent labs perform the RGA. The first lab > had results averaging ~28,000 PPM. The second lab results averaged ~5600 PPM. > The standard is no more than 5000 PPM. They both performed the > testing to the same MIL-STD-750. I can't understand the wide range of > results, but my second question is who knows of any studies related to > the negative effects of excessive (>5000 PPM) moisture inside > hermetically sealed devices used in space? By the way, they all > passed the seal tests. Perhaps some of you are knowledgeable in this > area. Thanks in advance for your help. > > Howard Watson > > ______________________________________________________________________ > 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 transmission (including any attachments) may contain confidential > information, privileged material (including material protected by the > solicitor-client or other applicable privileges), or constitute > non-public information. 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