I'll make one other suggestion: You can use our Board Talk bulletin board
if you'd like. You can start a topic and upload any attachments as needed.
That way, no one has to ask for or wait on a password, and anyone can
upload reports/attachments at any time.

It's at www.theprintedcircuitboard.com.

Best,

Mike

Mike Buetow
PCD&F/Circuits Assembly
w/m: 617-327-4702
@mikebuetow

BOARD TALK: The online community for the PCB industry
www.theprintedcircuitboard.com

PCB CHAT: A new way to engage the experts: www.pcbchat.com

The 2012 CIRCUITS ASSEMBLY Directory of EMS Companies:
circuitsassembly.com/dems

-----Original Message-----
From: TechNet [mailto:[log in to unmask]] On Behalf Of Inge Hernefjord
Sent: Friday, December 14, 2012 9:16 AM
To: [log in to unmask]
Subject: Re: [TN] Component issue - epoxy die attach

Thanks Steve, good idea. I already have Dropbox I will drop the first
little paper there today, the title is: " Do we need bother about humidity
on inside of the packages."
TNetters who are interested in downloading "my" reports, install:

.dropbox.com/install <https://www.dropbox.com/install>

Inge

On 14 December 2012 13:12, Steven Creswick
<[log in to unmask]>wrote:

> Inge,
>
>
>
> Thanks, but I still feel there is room for more than one at that level!
>
>
>
> I had a thought, if Steve G is limited in space, or time at the
> moment.  I believe that Box.net [as well as others allows] for online
> storage that you can share with others.  You would have to establish
yourself there [free],
> but you could put up whatever you desired.    Just a thought.
>
>
>
> PS – Thanks for sending over the meteor shower and clear skies.  I
> believe it was better yesterday morning, but I was more prepared this
> morning.  I bundled up nice and warm, placed a couple layers of
> cardboard down on the ground [no lasting snow yet] and laid down to
> enjoy the show.  Had some really nice ones!  Had many wisps as well.
> At 25°F/-3°C, after about 40 minutes I figured that I had better get
> up while I still could.  What would you recommend I drink to warm up?
>
>
>
> Didn’t see Santa though [too early], …. maybe after my warm-up drink….
>
>
>
> Steve C
>
>
>
> From: Inge Hernefjord [mailto:[log in to unmask]]
> Sent: Friday, December 14, 2012 6:54 AM
>  To: TechNet E-Mail Forum; Steven Creswick
> Subject: Re: [TN] Component issue - epoxy die attach
>
>
>
> Yes, Steve, you are the unquestionable King of Microelectronics in TN.
> Am sure all agree.  Basta!
>
>
>
> I've sent a rather good article to Howard with the title 'Issues in
> Hermetic Sealing of Medical Products' . The author briefs some common
> matters, no academic, endless argumentation. I will even prepare for
> shareing  some deeper papers for downloading, if someone wish to learn
> more. Maybe I could let Steve Gregory 'administrate' .?
>
> Inge
>
>
>
>
>
>
>
> On 14 December 2012 11:51, Steven Creswick <[log in to unmask]>
> wrote:
>
> Inge,
>
>
>
> Not so sure I desire / deserve that title.
> mew
>
>
>               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]]
> 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
>
>
>
>
>
> -----Original Message-----
>
> From: Joyce Koo [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]]
> 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
>
>
>
>
> -----Original Message-----
> From: TechNet [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. Any use of this information by anyone other
> than the intended recipient is prohibited. If you have received this
> transmission in error, please immediately reply to the sender and
> delete this information from your system. Use, dissemination,
> distribution, or reproduction of this transmission by unintended
> recipients is not authorized and may be unlawful.
>
>
> ______________________________________________________________________
> 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] 
______________________________________________________________________