So many women with that profession, very unusual, very unusual. I'm glad to
hear you stopped there...
Inge
----- Original Message -----
From: "Whittaker, Dewey (EHCOE)" <[log in to unmask]>
To: <[log in to unmask]>
Sent: Tuesday, September 08, 2009 5:06 PM
Subject: Re: [TN] Need clever comments
If you keep pressing the issues to the finish, we should change the name
of this forum to compliancenet.
We have built many assemblies for Aerospace using compliant pin
technology. Granted the majority has been with HASL, but many with a
hassle free ENIG.
Also it was from a time that I was allowed to have my hands firmly
around the neck of the Designer, PB Fabricator, Plating/Final Finish
Process Engineer, Compliant Pin MFG./Designer and the Assembly House
personnel.
Dewey
-----Original Message-----
From: TechNet [mailto:[log in to unmask]] On Behalf Of Bev Christian
Sent: Monday, September 07, 2009 2:09 PM
To: [log in to unmask]
Subject: Re: [TN] Need clever comments
Ha! Speaking or old Nortelers...
Subject: Re: Press-fit terminations
From: Anslow, Phillip
Reply-To: (Leadfree Electronics Assembly Forum)
Date: Wed, 3 Aug 2005 15:59:21 +0100
Content-Type: text/plain
Back in my old Nortel days w.r.t press-fit connectors, there was a big
question mark over their use with ENIG due to possible exposure of
subcutaneous nickel and possible corrosion after assembly - particularly
on
backplanes/midplanes. But, they were still used on PIUs with ENIG finish
-
so... from memory it came down to the style of compliant pin collapse
employed and as you say hole size (but this is a few years ago and the
memory dims...).
I expect there will be many expert opinions in the Technet forum
archives
w.r.t. press-fit and ENIG issue specifically.
Regards,
Phil.
And I also found the following:
IPC-4552 (July 2002 version)
1.2 Description
ENIG is an electroless nickel layer capped with a thin layer of
immersion
gold. It is a multifunctional surface finish, applicable to soldering,
aluminum wire bonding, press fit connections, and as a contact surface.
The
immersion gold protects the underlying nickel from oxidation/passivation
over its intended life. However, this layer is not totally impervious
and it
will not pass the requirements of a 'classic' porosity test.
1.4.5.1 Press Fit
Press fit requirements shall meet Telcordia GR-1217-CORE. Excessive
nickel
thickness can lead to concerns with press fit insertion forces.
Regards,
Bev
-----Original Message-----
From: Inge [mailto:[log in to unmask]]
Sent: Monday, September 07, 2009 4:15 PM
To: TechNet E-Mail Forum; Bev Christian
Subject: Re: [TN] Need clever comments
Bev,
I'm glad that TN got so many experienced members. Read what our brother
net
SMT wrote:
from a SMT mail conversation
' No offense to some of the people here, but this forum's getting
frustrating in terms of the lack of expertise. Too many rookies from
foreign
countries new to SMT, some of them asking really dumb questions, and
when an
advanced inquiry like Hussman's does come up, there's only one response,
from good ol' reliable DaveF an industry consultant who's been here
since
the '90s.'
Be proud, brethren
Inge
----- Original Message -----
From: "Bev Christian" <[log in to unmask]>
To: <[log in to unmask]>
Sent: Monday, September 07, 2009 9:47 PM
Subject: Re: [TN] Need clever comments
> Inge,
> Well you will just have to wait until I can try and roust out an old
> Nortel
> process engineer and get back to you.
> Bev
>
> -----Original Message-----
> From: Inge [mailto:[log in to unmask]]
> Sent: Monday, September 07, 2009 11:06 AM
> To: TechNet E-Mail Forum; Bev Christian
> Subject: Re: [TN] Need clever comments
>
> Observation 1: I don't make that coincidence, I ask you all about a
> possible
>
> connection. Why? Because my experience is that one anomaly is often
> followed
>
> by more. Like lack of vitamins can cause many diseases. But my main
worry
> is
>
> the anomalous solder pad look and also the presence of copper on the
> solder
> mask surface.
>
> Observation 2: in fact, if you study the conductor lines under strong
> light,
>
> there seems to be more copper colour than tin.
>
> Q2: Well, is pressfit positive or negative with nickel plating.
Ericsson,
> one of the biggest telecom companies, have forbidden pressfit + nickel
> plating. And you say that Nortel have done it for years. Who is
poppycock?
>
> Inge
>
> ----- Original Message -----
> From: "Bev Christian" <[log in to unmask]>
> To: <[log in to unmask]>
> Sent: Monday, September 07, 2009 3:14 PM
> Subject: Re: [TN] Need clever comments
>
>
>> Inge,
>> Observation 1: How in the world can you make a connection between tin
>> whiskers and CAF?!!
>>
>> Observation 2: If copper is "penetrating" the solder mask, it makes
me
>> wonder what it is doing to the tin overlayer! I would be concerned
about
>> tin/copper intermetallic growing to the surface and oxidizing.
>>
>> Q2 Popppycock! Companies like Nortel and other put press fit
connectors
>> into ENIG boards for years. Of course it is always a good idea not
to
>> try
>> and put an elephant in a mouse hole. Make sure the pin and hole are
>> dimensional matched, the pin is put in straight and the proper force,
>> speed
>> and assembly apparatus are used to do it and that the end results are
>> cross-sectioned initially to make sure that it is right.
>>
>> Bev
>> RIM
>>
>>
>> -----Original Message-----
>> From: TechNet [mailto:[log in to unmask]] On Behalf Of Hernefjord
Ingemar
>> Sent: Monday, September 07, 2009 7:22 AM
>> To: [log in to unmask]
>> Subject: [TN] Need clever comments
>>
>>
>> Hi all, need some professional backup regarding MIL quality boards.
>>
>> Objects: FR-4 Class III double-sided multi-layer boards, populated
with
>> SOICS, BGAs,and a lot of passive components.
>>
>> Observation 1 : the non soldered board have lots of Tin whiskers on
>> inside
>> of the PTH barrel. My thought is this: if whiskers can grow long
before
>> the
>> board is assembled, then ain't it likely that even CAF can be
generated?
>> See photo 1.
>>
>> Observation 2: Copper has somehow penetrated the solder mask. This
can
>> be
>> found everywhere along the conductor traces. You need a very good
light
>> microscope and a SEM to see it. See photo 2.
>>
>> Board data: Copper with 0.8 micrometer Immersion Tin. No nickel
barrier.
>> Solder mask thickness not specified.
>>
>> Application: Typical MIL-883 environment
>>
>> Q1: What is your opinion about that thin Tin directly on copper? I
>> dislike
>> the concept. Copper is very mobile at high temperatures, and combined
>> with
>> humidity, there can be leakage currents and corrosion issues. Even if
the
>> boards are CCd, there is a risk with copper .
>>
>> Q2: I gave the advice to introduce a nickel barrier, but our
customer
>> claimed, that they can't because of pressfit connectors and pressfit
test
>> pins on the board. Furthermore, they had heard that one cannot have
>> nickel
>> platings when pressfitting, because the nickel will crack and oxidize
and
>> cause electrical disfunction. Is this your opinion too? Are there any
>> relevant testing behind such statements?
>>
>> Thanks in advance
>>
>> Inge
>>
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