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October 2009

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Subject:
From:
Bob Willis <[log in to unmask]>
Reply To:
TechNet E-Mail Forum <[log in to unmask]>, Bob Willis <[log in to unmask]>
Date:
Fri, 23 Oct 2009 14:32:03 +0100
Content-Type:
text/plain
Parts/Attachments:
text/plain (1104 lines)
When conducting Dye and Pry on our hand on FA workshops at ITRI I normally
use a special tool or a "Wood Chisel" which is the same width as the package
or wider. The part can be easily lifted without any damage to the areas you
are trying to inspect. It makes for a simple practical demonstration. The
wood chisel or tool has an angled blade to allow a lifting force with
pressure across the width of the device.

See gif file online at www.bobwillis.co.uk/images/bobwillisD&P.gif 

When I get some time I make a video clip of the complete process for the IPC
web site. Like any process some practice allows you to develop the
technique. Kim keeps asking for defect analysis for blog content.

If anyone wants a procedure for this send me a email off line. I will
produce when I get my Productronica exhibition project out of the way

The force required is higher on standard laminates, better pad adhesion,
weaker on most high Tg laminates for the reasons everyone knows.

The correct procedure is to have a indication from your customer or test
department where the fault is located. Which edge is close to the defect
area, you then lift from the opposite side of the device. Using a wood
chisel allows you to leaver off the device, with care you don't even damage
the row of balls next to the chisel point. Trust me it works fine!

Trying to lift parts from different corners or with thin blades generally
damage the package or point you are trying to examine. When doing D&P always
wear gloves otherwise your fingers will be red or yellow for a few days!!!!!


Have a great weekend guys

Bob Willis
2 Fourth Ave, Chelmsford, Essex, CM1 4HA England
Tel: (44) 1245 351502
Fax: (44) 1245 496123
Mobile: 07860 775858
www.ASKbobwillis.com
www.SolderingStandards.com 
New Package on Package Workshops 24th November
www.ASKbobwillis.com/PoPWorkshops.pdf 
PCB Inspection & Quality Control Workshop 3rd November
www.ASKbobwillis.com/faworkshops.pdf
Book Bob's "Step by Step Failure Analysis
Workshop"4th November  www.ASKbobwillis.com/faworkshops.pdf
Package on Package Assembly & Inspection Workshops 21th January ITRI
www.ASKbobwillis.com/PoPWorkshops.pdf


-----Original Message-----
From: TechNet [mailto:[log in to unmask]] On Behalf Of Victor Hernandez
Sent: 22 October 2009 12:00
To: [log in to unmask]
Subject: Re: [TN] [spam] RE: [TN] ENIG Issue

Is anyone conducting pull test using an adhesive/epoxy for D&P.   It has
worked well for me for any size BGA, even CPU sockets.

Victor,

-----Original Message-----
From: TechNet [mailto:[log in to unmask]] On Behalf Of Werner Engelmaier
Sent: Thursday, October 22, 2009 5:47 AM
To: [log in to unmask]
Subject: Re: [TN] [spam] RE: [TN] ENIG Issue


 Hi Inge,
Yes, I have done 'Dye & Pry.'
The 'prying' part is not easy for large components. I did it starting at the
corners working piecemeal around the 4 sides.
LN2 is a god idea—I do not see how it would cause misleading results, please
explain.
Werner


-----Original Message-----
From: Hernefjord Ingemar <[log in to unmask]>
To: [log in to unmask]
Sent: Thu, Oct 22, 2009 4:44 am
Subject: [TN] [spam] RE: [TN] ENIG Issue

By the way, speaking SJ issues, has anyone of you experience from Die & Pray
technology, like the one described by some guys, who tested large game
boards, see figur 9 and 10, dye and pry testing? It's not easy to pry so
large BGAs. 
What kind of tools etc do you use? Myself, I had to dip the board under test
in
LN2 before prying off the superBGA. That's not good, the low temperature can
mislead the result. 
/Inge

http://www.celestica.com/uploadedFiles/Home/PBfree_process_paper.pdf

-----Original Message-----
From: TechNet [mailto:[log in to unmask]] On Behalf Of Werner Engelmaier
Sent: onsdag 21 oktober 2009 15:51
To: [log in to unmask]
Subject: Re: [TN] ENIG Issue

 Hi Vladimir,
Maybe we should simply drop the name 'Black Pad' entirely-too much baggage
and confusion.
Maybe we should refer to them by their failure modes and damage
mechanisms-solderability issues due to 'galvanic corrosion', brittle
fracture due to P-enrichment, brittle fracture due to 'any other cause
applicable.
Werner

-----Original Message-----
From: [log in to unmask]
To: Werner Engelmaier <[log in to unmask]>; [log in to unmask]
Sent: Wed, Oct 21, 2009 7:39 am
Subject: Re: [TN] ENIG Issue

   Werner,

Yes, I agree that there are two different phenomena BP and BF, but I can not
agree on the statement that the root cause for BF(brittle fracture) is high
P content. 

Regards,

Vladimir
SENTEC
11 Canadian Road, Unit 7.
Scarborough, ON M1R 5G1
Tel: (416) 899-1882
Fax: (905) 882-8812
www.sentec.ca


From:  Werner Engelmaier <[log in to unmask]>

Date: Tue, 20 Oct 2009 23:59:34 -0400
To: <[log in to unmask]>; <[log in to unmask]>
Subject: Re: [TN] ENIG Issue
 Vladimir,

Indeed you sent me that ATOTECH paper, but I have several references that
disagree with their definition, as well as others that agree with the
Atotech paper.

There seem to be (at least) 2 different 'defects' at work-one with
hyper-galvanic corrosion of the Ni during Au-plating causing soldering
problems, and another causing brittle separation due to a weakened interface
cause by too much P.

Are we in agreement on this?

I do not really care what you call either of them-clearly the root cause is
different in these cases and so is what needs to be done.

Clearly, what we need is for the IPC to form a committee to provide proper
definitions and 'names.'

Werner

-----Original Message-----

From: [log in to unmask]

To: TechNet E-Mail Forum <[log in to unmask]>; Werner Engelmaier
<[log in to unmask]>

Sent: Tue, Oct 20, 2009 11:23 pm

Subject: Re: [TN] ENIG Issue

Werner,
We've been through it several times already. As far as I know, BP was
defined as 
a case of poor Ni-P plating with cavitation present in the layer. I think I
sent 
you an old ATOTECH paper on the topic a while ago.
Regards,
Vladimir

SENTEC

11 Canadian Road, Unit 7.

Scarborough, ON M1R 5G1

Tel: (416) 899-1882

Fax: (905) 882-8812

www.sentec.ca

-----Original Message-----

From: Werner Engelmaier <[log in to unmask]>

Date:         Tue, 20 Oct 2009 22:57:21 

To: <[log in to unmask]>

Subject: Re: [TN] ENIG Issue
 Hi Vladimir,
Then we are not communicating.

Please explain to me what YOU mean by 'BP failure'.

When I say 'BP failure', I mean it is because too much P between the Ni and
the 

IMC layers has weakened the bond leading to brittle separation on sufficient


loading. I do not differentiate as to the cause(s) for too much P. For me
they 

describe a damage mechanism.

You can similar appearance with too much and too little P.
Werner

-----Original Message-----

From: [log in to unmask]

To: Werner Engelmaier <[log in to unmask]>; [log in to unmask]
Sent: Tue, Oct 20, 2009 10:44 pm

Subject: Re: [TN] ENIG Issue

   Werner,
You just confirmed what I said in my previous e-mail. You customer got
failure 

with black appeared pads, but it wasn't BP failure. Similar appearance
doesn't 

mean the same mechanism.

Regards,

Vladimir



SENTEC
11 Canadian Road, Unit 7.
Scarborough, ON M1R 5G1
Tel: (416) 899-1882
Fax: (905) 882-8812

www.sentec.ca

From:  Werner Engelmaier <[log in to unmask]>

Date: Tue, 20 Oct 2009 22:16:40 -0400

To: <[log in to unmask]>; <[log in to unmask]>

Subject: Re: [TN] ENIG Issue
 Hi Vladimir,

I have one client who experienced 'Black Pad' after 9(!) soldering
operations. 

The P-content got progressively worse; it peaked with the EDS spikes for P
being 


as high as those for Sn.

Werner

-----Original Message-----

From: [log in to unmask]

To: TechNet E-Mail Forum <[log in to unmask]>; Werner Engelmaier 

<[log in to unmask]>

Sent: Tue, Oct 20, 2009 10:07 pm

Subject: Re: [TN] ENIG Issue


Werner,


With all due respect, I don't think you are right.


Regards,

Vladimir

SENTEC


11 Canadian Road, Unit 7.

Scarborough, ON M1R 5G1

Tel: (416) 899-1882

Fax: (905) 882-8812

www.sentec.ca


-----Original Message-----

From: Werner Engelmaier <[log in to unmask]>

Date:         Tue, 20 Oct 2009 22:01:35 

To: <[log in to unmask]>

Subject: Re: [TN] ENIG Issue

 Hi George,

\While what you say in the first paragraph is correct, the second paragraph
is 

not.
'Black Pad' is not an all-or-nothing proposition. The seeds are sown at the 
Ni-plating (not the Au-plating) with the P-codeposition. However, multiple
or 







lengthy expositions to high soldering temperatures result in more Ni being 







dissolved to form IMCs leaving ever more P behind. This can create 'Black
Pad' 







where none existed before.







Werner























 























 















-----Original Message-----







From: George Milad <[log in to unmask]>







To: [log in to unmask]







Sent: Tue, Oct 20, 2009 9:52 pm







Subject: Re: [TN] ENIG Issue























































































As always as soon as there is a solderability issue with ENIG, "Black pad"  







comes up. This is a problem because it does not allow for further 







investigation.  Everyone accepts since this is ENIG then it must be black
pad.







 







If this was a black pad issue the back side should have exhibited the same  







problem. BP occurs during the plating of the gold on top of the Ni. BP 







cannot  differentiate one side from the other.







 







Do not accept BP as the answer and keep investigating.







 







 







Regards







George Milad







George Milad







National Accounts  Manager for Technology







Uyemura International Corp (UIC)







249 Town Line Rd  







Southington CT 06489







[log in to unmask]







Cell: (516) 901  3874















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