Hi Victor,
I actually tried twice to reply to you, but the message didn't post. (Maybe because I sent HTML format instead of plain text?) I'll try again.
The sample was etched. I asked our lab about their etch process, and here is their reply.
"We use ammonia hydroxide 10 parts to 1 part hydrogen peroxide. It is only applied for 3 seconds and washed off and dried."
I am sorry, but I no longer have this sample. The lab report has good old fashioned Polaroid photographs. I rescanned the originals to IPC groupsite. They are the same photos, but perhaps they will be a little clearer.
http://ipc-technet.groupsite.com/uploads/files/x/000/06a/2ef/SmearVert.jpg?1314122607
http://ipc-technet.groupsite.com/uploads/files/x/000/06a/2ed/SmearHoriz.jpg?1314122565
Best regards,
Raye Rivera
-----Original Message-----
From: [log in to unmask] [mailto:[log in to unmask]]
Sent: Friday, August 26, 2011 4:43 AM
To: [log in to unmask]; Rivera, Raye
Cc: [log in to unmask]
Subject: RE: [TN] Is Desmear or Etchback Optional?
Raye,
I saw the additional photos you posted. Again, I ask if the sample were chemically etched. When searching for IP sep or drill smear I don't etch the sample so as not to jeopardized the interface. Once the sample has been etched the area of interest is exemplified by the chemistry. Even Ray Charles can see the anomaly.
Victor,
-----Original Message-----
From: TechNet [mailto:[log in to unmask]] On Behalf Of Rivera, Raye
Sent: Monday, August 22, 2011 11:11 AM
To: [log in to unmask]
Subject: Re: [TN] Is Desmear or Etchback Optional?
Hi Victor,
I agree the root cause is probably a drilling issue. Re-reading my earlier post, I see I used the term "insufficient desmear" rather casually. What I meant to say was that the desmear process did not remove all the resin the drill left behind. I cannot tell from the photos whether this was caused by excessive smearing due to a dull drill or some deficiency of the actual desmear process.
Best regards,
Raye Rivera
QA Manager * Canoga Perkins * 818-678-3872 * [log in to unmask]
-----Original Message-----
From: TechNet [mailto:[log in to unmask]] On Behalf Of Victor Hernandez
Sent: Monday, August 22, 2011 5:00 AM
To: [log in to unmask]
Subject: Re: [TN] Is Desmear or Etchback Optional?
Raye,
I finally got to see the 2 photos that you shared. I would like more clues as to which this is a desmear process anomaly. At first glance I see what appears to be rough drilling.
Victor, Cell: 512.736.6817
-----Original Message-----
From: TechNet [mailto:[log in to unmask]] On Behalf Of Rivera, Raye
Sent: Friday, August 19, 2011 2:46 PM
To: [log in to unmask]
Subject: Re: [TN] Is Desmear or Etchback Optional?
Hi Victor,
Certainly! I uploaded a copy of the lab report to groupsite. Here is the link.
http://ipc-technet.groupsite.com/uploads/files/x/000/069/daa/SmearRept.pdf?1313782786
Best regards,
Raye Rivera
-----Original Message-----
From: TechNet [mailto:[log in to unmask]] On Behalf Of Victor Hernandez
Sent: Friday, August 19, 2011 10:31 AM
To: [log in to unmask]
Subject: Re: [TN] Is Desmear or Etchback Optional?
Can you so kindly share the above stated desmear artifact on a cross section. A picture is worth 1000 words.
Victor,
-----Original Message-----
From: TechNet [mailto:[log in to unmask]] On Behalf Of Rivera, Raye
Sent: Friday, August 19, 2011 11:29 AM
To: [log in to unmask]
Subject: Re: [TN] Is Desmear or Etchback Optional?
Hi Bob,
We have seen insufficient desmear here and it does create an unreliable connection. A properly prepared microsection will show the defect clearly, which is how we (or rather, the lab we contract) caught it.
I suppose it is possible that some shop might entirely skip desmear to save money, but any shop with that attitude would not last long. It is a key part of the process and skipping it would absolutely result in defective and rejectable boards.
Best regards,
Raye Rivera
-----Original Message-----
From: TechNet [mailto:[log in to unmask]] On Behalf Of Robert Kondner
Sent: Friday, August 19, 2011 6:59 AM
To: [log in to unmask]
Subject: Re: [TN] Is Desmear or Etchback Optional?
Would NO DESMEAR result in connection of barrels to planes (perhaps un-reliable connections) or would many internal connections be open?
Is it the case that some low cost shops would NOT DESMEAR to reduce costs and get away with it?
Thanks,
Bob K.
-----Original Message-----
From: TechNet [mailto:[log in to unmask]] On Behalf Of Pete
Sent: Friday, August 19, 2011 9:37 AM
To: [log in to unmask]
Subject: Re: [TN] Is Desmear or Etchback Optional?
It's not actually "kissing away 2 mils"
When you start adding up tolerances for drill hole size, location, layer registration, process allowance.... you can easily come up with 2 mils difference from one shop to another. 10 mils hole to copper shouldn't be difficult at all for a good fab shop.
Not that it's really possible, but any shop so particular with their drilling that they wouldn't require some sort of desmear would be particular enough to desmear anyway.
Pete
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