Has Steve pasted the photos? Seen nothing at the moment. Am curious, have
inspected hundred thousands wire bonds (that's the disadvantage of being
expert on something)
Inge
--------------------------------------------------
From: "Chris Mahanna" <[log in to unmask]>
Sent: den 10 June 2010 20:56
To: <[log in to unmask]>
Subject: Re: [TN] LED wiring bonding
> Au. No necking or breaking was noted. We believe that there may be some
> correlation to the increased CTE of “optically clear” encapsulation vs.
> not so clear or tinted. But the underwriting of my project is gone, for
> now.
> Chris
>
> From: Werner Engelmaier [mailto:[log in to unmask]]
> Sent: Thursday, June 10, 2010 2:34 PM
> To: [log in to unmask]; Chris Mahanna
> Subject: Re: [TN] LED wiring bonding
>
> Hi,
> Are we sure it is the bond and not the wire itself that is breaking? We
> eed to know whether we are dealing with Au or AlSi wire.
> Been working on a wire break case.
> Werner
>
>
>
> -----Original Message-----
> From: Chris Mahanna <[log in to unmask]>
> To: [log in to unmask]
> Sent: Thu, Jun 10, 2010 1:13 pm
> Subject: Re: [TN] LED wiring bonding
>
> I forwarded some optical pictures to Steve.
>
>
>
>
>
>
>
> Steve, you're welcome to post them.
>
>
>
>
>
>
>
> Chris
>
>
>
>
>
>
>
>
>
>
>
>
>
>
> -----Original Message-----
>
>
>
>
>
>
>
> From: TechNet [mailto:[log in to unmask]<mailto:[log in to unmask]>] On Behalf
> Of Victor Hernandez
>
>
>
>
>
>
>
> Sent: Thursday, June 10, 2010 8:04 AM
>
>
>
>
>
>
>
> To: [log in to unmask]<mailto:[log in to unmask]>
>
>
>
>
>
>
>
> Subject: Re: [TN] LED wiring bonding
>
>
>
>
>
>
>
>
>
>
>
>
>
>
> Fellow TechNetters:
>
>
>
>
>
>
>
>
>
>
>
>
>
>
> Was anyone able to provide a photo(s) of this LED bonding issue.
>
>
>
>
>
>
>
>
>
>
>
>
>
>
> Victor,
>
>
>
>
>
>
>
>
>
>
>
>
>
>
> -----Original Message-----
>
>
>
>
>
>
>
> From: TechNet [mailto:[log in to unmask]<mailto:[log in to unmask]>] On Behalf
> Of Steven Creswick
>
>
>
>
>
>
>
> Sent: Tuesday, May 11, 2010 5:32 AM
>
>
>
>
>
>
>
> To: [log in to unmask]<mailto:[log in to unmask]>
>
>
>
>
>
>
>
> Subject: Re: [TN] LED wiring bonding
>
>
>
>
>
>
>
>
>
>
>
>
>
>
> Chris,
>
>
>
>
>
>
>
>
>
>
>
>
>
>
> I get the shivers when people say they have a bond lift, because my
> instinct
>
>
>
>
>
>
>
> tells me the process was not where it should have been, but there is still
>
>
>
>
>
>
>
> room for optimism.
>
>
>
>
>
>
>
>
>
>
>
>
>
>
> If properly bonded, and subsequently torn or sheared apart, I expect to
> see
>
>
>
>
>
>
>
> a good deal of viable intermetallic beneath the bond. If there is little
>
>
>
>
>
>
>
> sign of intermetallic formation, there was little bonding taking place -
>
>
>
>
>
>
>
> read as not a very good bond in the first place.
>
>
>
>
>
>
>
>
>
>
>
>
>
>
> By analogy, if one is crafting with wood and gluing panels together with a
>
>
>
>
>
>
>
> good glue, then subsequently breaks the panel - the break should occur
>
>
>
>
>
>
>
> somewhere other than at the glue line. The glue should be stronger than
> the
>
>
>
>
>
>
>
> wood. As it is with wire bonding. The bond should be stronger than the
>
>
>
>
>
>
>
> wire itself.
>
>
>
>
>
>
>
>
>
>
>
>
>
>
> Regarding the blue dye. Not sure of the specific mold compound being used
>
>
>
>
>
>
>
> [you could at least ask to see the data sheet ...], but it has been my
>
>
>
>
>
>
>
> experience that the amount of dye used is actually extremely little. I
>
>
>
>
>
>
>
> doubt that it would have significant effect on CTE, but you could be on to
>
>
>
>
>
>
>
> something. Normally one tosses in a bunch of fumed silica, etc to help
>
>
>
>
>
>
>
> control CTE. This doesn't do too well for maintaining light transmission,
>
>
>
>
>
>
>
> however. I would also check to see if the clear and blue were actually
>
>
>
>
>
>
>
> cured the same way, etc. That may have more effect on the result than the
>
>
>
>
>
>
>
> pigmentation alone.
>
>
>
>
>
>
>
>
>
>
>
>
>
>
> If you have intermittent bonds due to delamination, etc. sometimes you
> can
>
>
>
>
>
>
>
> simply press on the device and get it to work again. You might also try a
>
>
>
>
>
>
>
> bit of gentle heat/cold - say refrig to room, etc. Am not a fan of the
>
>
>
>
>
>
>
> freeze spray stuff.
>
>
>
>
>
>
>
>
>
>
>
>
>
>
> Wire necking will come about after many temp cycles - aka hundreds
> depending
>
>
>
>
>
>
>
> on temp limits. It had better not occur after 1-4 reflow cycles!
>
>
>
>
>
>
>
>
>
>
>
>
>
>
> I may also have a pic of delam if Vlad can not locate his.
>
>
>
>
>
>
>
>
>
>
>
>
>
>
> Best wishes,
>
>
>
>
>
>
>
>
>
>
>
>
>
>
> Steve Creswick
>
>
>
>
>
>
>
> http://www.linkedin.com/in/stevencreswick
>
>
>
>
>
>
>
>
>
>
>
>
>
>
>
>
>
>
>
>
>
>
>
>
>
>
>
>
> -----Original Message-----
>
>
>
>
>
>
>
> From: Chris Mahanna
> [mailto:[log in to unmask]<mailto:[log in to unmask]>]
>
>
>
>
>
>
>
> Sent: Monday, May 10, 2010 10:33 PM
>
>
>
>
>
>
>
> To: TechNet E-Mail Forum; Steven Creswick
>
>
>
>
>
>
>
> Subject: RE: [TN] LED wiring bonding
>
>
>
>
>
>
>
>
>
>
>
>
>
>
> Steve,
>
>
>
>
>
>
>
> Awesome. Now that you've walked me through it, I think our customer has a
>
>
>
>
>
>
>
> mixed bag- some bond lifts and delam, all damaged by excessive soldering
>
>
>
>
>
>
>
> excursions. I guess maybe part of my question was whether delam was a
>
>
>
>
>
>
>
> latent defect from poor bonding.? Haven't found significantly necked down
>
>
>
>
>
>
>
> Au wires yet.
>
>
>
>
>
>
>
> Do you think they can get significantly better CTE, Tg out of blue lenses?
>
>
>
>
>
>
>
> On our job, the blue had half the failure rate of the clear, even though
>
>
>
>
>
>
>
> they are rated the same for soldering. BTW they are both really Ir
>
>
>
>
>
>
>
> emitters; clear lenses with the better spectrum.
>
>
>
>
>
>
>
>
>
>
>
>
>
>
> Thanks for the help. I will certainly try to get permission to post the
>
>
>
>
>
>
>
> pictures. I'd like to see Vladimir's SEM image. Is there further FA to
> be
>
>
>
>
>
>
>
> gleaned from SEM?
>
>
>
>
>
>
>
>
>
>
>
>
>
>
> Thanks Werner!
>
>
>
>
>
>
>
>
>
>
>
>
>
>
> Wayne, yes I believe that was the official blame game from the component
>
>
>
>
>
>
>
> manufacturer. What do they look like when you burn them up? I'd expect
> to
>
>
>
>
>
>
>
> see burnt plastic too.??
>
>
>
>
>
>
>
>
>
>
>
>
>
>
> Chris
>
>
>
>
>
>
>
>
>
>
>
>
>
>
> -----Original Message-----
>
>
>
>
>
>
>
> From: TechNet [mailto:[log in to unmask]<mailto:[log in to unmask]>] On Behalf
> Of Steven Creswick
>
>
>
>
>
>
>
> Sent: Monday, May 10, 2010 6:49 PM
>
>
>
>
>
>
>
> To: [log in to unmask]<mailto:[log in to unmask]>
>
>
>
>
>
>
>
> Subject: Re: [TN] LED wiring bonding
>
>
>
>
>
>
>
>
>
>
>
>
>
>
> Chris,
>
>
>
>
>
>
>
>
>
>
>
>
>
>
> Ahh! Something I can help out with.
>
>
>
>
>
>
>
>
>
>
>
>
>
>
> A great deal depends on the package structure, obviously wire bonding
>
>
>
>
>
>
>
> process control, and whether it is Au or Al wire.
>
>
>
>
>
>
>
>
>
>
>
>
>
>
> Wire bonding defects are rare, if the materials and process is under
>
>
>
>
>
>
>
> control.
>
>
>
>
>
>
>
>
>
>
>
>
>
>
> The caveat is that Pb-free reflow temps may cause extra expansion in the
>
>
>
>
>
>
>
> molding compound as the material goes above it Tg during reflow/s.
>
>
>
>
>
>
>
> Many/most clear mold compounds have Tg's in the <135-155°C range. Can't
> put
>
>
>
>
>
>
>
> silica in there to help modify the CTE...
>
>
>
>
>
>
>
>
>
>
>
>
>
>
> Moving mold compound during temp cycles can often break the bond wire near
>
>
>
>
>
>
>
> mid-span. The wire will actually neck down to the shape of an hour-glass
>
>
>
>
>
>
>
> funnel as it stretches. ... then breaks. Oops.
>
>
>
>
>
>
>
>
>
>
>
>
>
>
> You can also get bond lifts, but if that is the case you may also see
>
>
>
>
>
>
>
> delamination from the bonding surface. Hard to describe what it looks
> like
>
>
>
>
>
>
>
> other than to say that you can see an air-gap there.. If you don't see
> the
>
>
>
>
>
>
>
> delam, one just may have a poor bond.
>
>
>
>
>
>
>
>
>
>
>
>
>
>
> You can also shear the ball/bond off the die, but many times one will
> place
>
>
>
>
>
>
>
> a low modulus material on top of the chip to mechanically de-couple from
> the
>
>
>
>
>
>
>
> higher modulus molding compound in an attempt to alleviate this.
>
>
>
>
>
>
>
>
>
>
>
>
>
>
> First thing to do is x-ray to find where the discontinuity is. If that
>
>
>
>
>
>
>
> fails, then move on to selectively polishing the device down so that you
> can
>
>
>
>
>
>
>
> see inside clearly.
>
>
>
>
>
>
>
>
>
>
>
>
>
>
> I have been known to take a really tiny 0.010-0.015" dia drill bit in a
> pin
>
>
>
>
>
>
>
> vise to gain access to the interior for dye testing to check for
>
>
>
>
>
>
>
> delamination [but that can be classified as destructive - although
> certainly
>
>
>
>
>
>
>
> illustrative!]
>
>
>
>
>
>
>
>
>
>
>
>
>
>
> Lastly, it may also be possible to shear the die off, but like you, I
> would
>
>
>
>
>
>
>
> look at the wire first. A quick look at the bonds can often tell you if
>
>
>
>
>
>
>
> they are over bonded, or something was moving during bonding. Once you
> get
>
>
>
>
>
>
>
> it polished flat, you may be able to get a reasonable picture.
>
>
>
>
>
>
>
>
>
>
>
>
>
>
>
>
>
>
>
>
>
> Steve Creswick
>
>
>
>
>
>
>
> http://www.linkedin.com/in/stevencreswick
>
>
>
>
>
>
>
>
>
>
>
>
>
>
>
>
>
>
>
>
>
>
>
>
>
>
>
>
> -----Original Message-----
>
>
>
>
>
>
>
> From: TechNet [mailto:[log in to unmask]<mailto:[log in to unmask]>] On Behalf
> Of Chris Mahanna
>
>
>
>
>
>
>
> Sent: Monday, May 10, 2010 5:49 PM
>
>
>
>
>
>
>
> To: [log in to unmask]<mailto:[log in to unmask]>
>
>
>
>
>
>
>
> Subject: [TN] LED wiring bonding
>
>
>
>
>
>
>
>
>
>
>
>
>
>
> It's all LEDs these days!
>
>
>
>
>
>
>
>
>
>
>
>
>
>
> We have an FA that shows poor wire bonds to GaAlAs/GaAs in microsection
>
>
>
>
>
>
>
> after assembly. The failure is seen in the parts per hundred across
>
>
>
>
>
>
>
> different lots and slightly different part numbers of LEDs.
>
>
>
>
>
>
>
> The assumption would be that LED wiring bonding defects are very rare.
> Is
>
>
>
>
>
>
>
> there something particular about these? Or is it the crimping and/or
>
>
>
>
>
>
>
> Pb-free assembly that is pulling them apart?
>
>
>
>
>
>
>
> The ones that seem more susceptible are GaAlAs Double Heteros.
>
>
>
>
>
>
>
>
>
>
>
>
>
>
> Thanks.
>
>
>
>
>
>
>
>
>
>
>
>
>
>
> Chris
>
>
>
>
>
>
>
>
>
>
>
>
>
>
>
>
>
>
>
>
>
> ______________________________________________________________________
>
>
>
>
>
>
>
> This email has been scanned by the MessageLabs Email Security System.
>
>
>
>
>
>
>
> For more information please contact helpdesk at x2960 or
> [log in to unmask]<mailto:[log in to unmask]>
>
>
>
>
>
>
>
> ______________________________________________________________________
>
>
>
>
>
>
>
>
>
>
>
>
>
>
> ---------------------------------------------------
>
>
>
>
>
>
>
> Technet Mail List provided as a service by IPC using LISTSERV 15.0
>
>
>
>
>
>
>
> To unsubscribe, send a message to
> [log in to unmask]<mailto:[log in to unmask]> with following text in
>
>
>
>
>
>
>
> the BODY (NOT the subject field): SIGNOFF Technet
>
>
>
>
>
>
>
> To temporarily halt or (re-start) delivery of Technet send e-mail to
>
>
>
>
>
>
>
> [log in to unmask]<mailto:[log in to unmask]>: SET Technet NOMAIL or (MAIL)
>
>
>
>
>
>
>
> To receive ONE mailing per day of all the posts: send e-mail to
>
>
>
>
>
>
>
> [log in to unmask]<mailto:[log in to unmask]>: SET Technet Digest
>
>
>
>
>
>
>
> Search the archives of previous posts at: http://listserv.ipc.org/archives
>
>
>
>
>
>
>
> Please visit IPC web site http://www.ipc.org/contentpage.asp?Pageid=4.3.16
>
>
>
>
>
>
>
> for additional information, or contact Keach Sasamori at
> [log in to unmask]<mailto:[log in to unmask]> or
>
>
>
>
>
>
>
> 847-615-7100 ext.2815
>
>
>
>
>
>
>
> -----------------------------------------------------
>
>
>
>
>
>
>
>
>
>
>
>
>
>
>
>
>
>
>
>
>
> ______________________________________________________________________
>
>
>
>
>
>
>
> This email has been scanned by the MessageLabs Email Security System.
>
>
>
>
>
>
>
> For more information please contact helpdesk at x2960 or
> [log in to unmask]<mailto:[log in to unmask]>
>
>
>
>
>
>
>
> ______________________________________________________________________
>
>
>
>
>
>
>
>
>
>
>
>
>
>
> ---------------------------------------------------
>
>
>
>
>
>
>
> Technet Mail List provided as a service by IPC using LISTSERV 15.0
>
>
>
>
>
>
>
> To unsubscribe, send a message to
> [log in to unmask]<mailto:[log in to unmask]> with following text in
>
>
>
>
>
>
>
> the BODY (NOT the subject field): SIGNOFF Technet
>
>
>
>
>
>
>
> To temporarily halt or (re-start) delivery of Technet send e-mail to
>
>
>
>
>
>
>
> [log in to unmask]<mailto:[log in to unmask]>: SET Technet NOMAIL or (MAIL)
>
>
>
>
>
>
>
> To receive ONE mailing per day of all the posts: send e-mail to
>
>
>
>
>
>
>
> [log in to unmask]<mailto:[log in to unmask]>: SET Technet Digest
>
>
>
>
>
>
>
> Search the archives of previous posts at: http://listserv.ipc.org/archives
>
>
>
>
>
>
>
> Please visit IPC web site http://www.ipc.org/contentpage.asp?Pageid=4.3.16
>
>
>
>
>
>
>
> for additional information, or contact Keach Sasamori at
> [log in to unmask]<mailto:[log in to unmask]> or
>
>
>
>
>
>
>
> 847-615-7100 ext.2815
>
>
>
>
>
>
>
> -----------------------------------------------------
>
>
>
>
>
>
>
>
>
>
>
>
>
>
>
>
>
>
>
>
>
> ______________________________________________________________________
>
>
>
>
>
>
>
> This email has been scanned by the MessageLabs Email Security System.
>
>
>
>
>
>
>
> For more information please contact helpdesk at x2960 or
> [log in to unmask]<mailto:[log in to unmask]>
>
>
>
>
>
>
>
> ______________________________________________________________________
>
>
>
>
>
>
>
>
>
>
>
>
>
>
> ---------------------------------------------------
>
>
>
>
>
>
>
> Technet Mail List provided as a service by IPC using LISTSERV 15.0
>
>
>
>
>
>
>
> To unsubscribe, send a message to
> [log in to unmask]<mailto:[log in to unmask]> with following text in
>
>
>
>
>
>
>
> the BODY (NOT the subject field): SIGNOFF Technet
>
>
>
>
>
>
>
> To temporarily halt or (re-start) delivery of Technet send e-mail to
>
>
>
>
>
>
>
> [log in to unmask]<mailto:[log in to unmask]>: SET Technet NOMAIL or (MAIL)
>
>
>
>
>
>
>
> To receive ONE mailing per day of all the posts: send e-mail to
>
>
>
>
>
>
>
> [log in to unmask]<mailto:[log in to unmask]>: SET Technet Digest
>
>
>
>
>
>
>
> Search the archives of previous posts at: http://listserv.ipc.org/archives
>
>
>
>
>
>
>
> Please visit IPC web site http://www.ipc.org/contentpage.asp?Pageid=4.3.16
> for
>
>
>
>
>
>
>
> additional information, or contact Keach Sasamori at
> [log in to unmask]<mailto:[log in to unmask]> or
>
>
>
>
>
>
>
> 847-615-7100 ext.2815
>
>
>
>
>
>
>
> -----------------------------------------------------
>
>
>
>
>
>
>
>
>
>
>
>
>
>
> ______________________________________________________________________
>
>
>
>
>
>
>
> This email has been scanned by the MessageLabs Email Security System.
>
>
>
>
>
>
>
> For more information please contact helpdesk at x2960 or
> [log in to unmask]<mailto:[log in to unmask]>
>
>
>
>
>
>
>
> ______________________________________________________________________
>
>
>
>
>
>
>
>
>
>
>
>
>
>
> ---------------------------------------------------
>
>
>
>
>
>
>
> Technet Mail List provided as a service by IPC using LISTSERV 15.0
>
>
>
>
>
>
>
> To unsubscribe, send a message to
> [log in to unmask]<mailto:[log in to unmask]> with following text in
>
>
>
>
>
>
>
> the BODY (NOT the subject field): SIGNOFF Technet
>
>
>
>
>
>
>
> To temporarily halt or (re-start) delivery of Technet send e-mail to
>
>
>
>
>
>
>
> [log in to unmask]<mailto:[log in to unmask]>: SET Technet NOMAIL or (MAIL)
>
>
>
>
>
>
>
> To receive ONE mailing per day of all the posts: send e-mail to
>
>
>
>
>
>
>
> [log in to unmask]<mailto:[log in to unmask]>: SET Technet Digest
>
>
>
>
>
>
>
> Search the archives of previous posts at: http://listserv.ipc.org/archives
>
>
>
>
>
>
>
> Please visit IPC web site http://www.ipc.org/contentpage.asp?Pageid=4.3.16
> for
>
>
>
>
>
>
>
> additional information, or contact Keach Sasamori at
> [log in to unmask]<mailto:[log in to unmask]> or
>
>
>
>
>
>
>
> 847-615-7100 ext.2815
>
>
>
>
>
>
>
> -----------------------------------------------------
>
>
>
>
>
>
>
>
>
>
>
>
>
>
> ______________________________________________________________________
>
>
>
>
>
>
>
> This email has been scanned by the MessageLabs Email Security System.
>
>
>
>
>
>
>
> For more information please contact helpdesk at x2960 or
> [log in to unmask]<mailto:[log in to unmask]>
>
>
>
>
>
>
>
> ______________________________________________________________________
>
>
>
>
>
>
>
>
>
>
>
>
>
>
> ---------------------------------------------------
>
>
>
>
>
>
>
> Technet Mail List provided as a service by IPC using LISTSERV 15.0
>
>
>
>
>
>
>
> To unsubscribe, send a message to
> [log in to unmask]<mailto:[log in to unmask]> with following text in
>
>
>
>
>
>
>
> the BODY (NOT the subject field): SIGNOFF Technet
>
>
>
>
>
>
>
> To temporarily halt or (re-start) delivery of Technet send e-mail to
>
>
>
>
>
>
>
> [log in to unmask]<mailto:[log in to unmask]>: SET Technet NOMAIL or (MAIL)
>
>
>
>
>
>
>
> To receive ONE mailing per day of all the posts: send e-mail to
>
>
>
>
>
>
>
> [log in to unmask]<mailto:[log in to unmask]>: SET Technet Digest
>
>
>
>
>
>
>
> Search the archives of previous posts at: http://listserv.ipc.org/archives
>
>
>
>
>
>
>
> Please visit IPC web site http://www.ipc.org/contentpage.asp?Pageid=4.3.16
> for
>
>
>
>
>
>
>
> additional information, or contact Keach Sasamori at
> [log in to unmask]<mailto:[log in to unmask]> or
>
>
>
>
>
>
>
> 847-615-7100 ext.2815
>
>
>
>
>
>
>
> -----------------------------------------------------
>
>
>
>
>
>
>
> ______________________________________________________________________
> This email has been scanned by the MessageLabs Email Security System.
> For more information please contact helpdesk at x2960 or [log in to unmask]
> ______________________________________________________________________
>
______________________________________________________________________
This email has been scanned by the MessageLabs Email Security System.
For more information please contact helpdesk at x2960 or [log in to unmask]
______________________________________________________________________
---------------------------------------------------
Technet Mail List provided as a service by IPC using LISTSERV 15.0
To unsubscribe, send a message to [log in to unmask] with following text in
the BODY (NOT the subject field): SIGNOFF Technet
To temporarily halt or (re-start) delivery of Technet send e-mail to [log in to unmask]: SET Technet NOMAIL or (MAIL)
To receive ONE mailing per day of all the posts: send e-mail to [log in to unmask]: SET Technet Digest
Search the archives of previous posts at: http://listserv.ipc.org/archives
Please visit IPC web site http://www.ipc.org/contentpage.asp?Pageid=4.3.16 for additional information, or contact Keach Sasamori at [log in to unmask] or 847-615-7100 ext.2815
-----------------------------------------------------
|
