ENIG is defined in IPC-4552, in Table 3-1 "Requirements of Electroless
Nickel Immersion Gold Plating". Electroless nickel thickness is 3 to 6
uM [118.1 to 236.2 uINCHES]. The Immersion Gold Thickness is .05 uM
[1.97 uINCHES] MINIMUM. The standard goes on to say that the typical
gold thickness will be 3 to 5 uINCHES.
If a board vendor goes below 50 uINCHES, it is NOT ENIG as specified per
the IPC.
-----Original Message-----
From: TechNet [mailto:[log in to unmask]] On Behalf Of Victor Hernandez
Sent: Wednesday, October 21, 2009 6:01 AM
To: [log in to unmask]
Subject: Re: [TN] ENIG Issue
Where are the recommended thickness values for Au/Ni on ENIG processes?
Some vendors go below 50 micro inches in the nickel.
Victor,
-----Original Message-----
From: TechNet [mailto:[log in to unmask]] On Behalf Of Rex Waygood
Sent: Wednesday, October 21, 2009 3:35 AM
To: [log in to unmask]
Subject: Re: [TN] ENIG Issue
Dear Bill
These are the causes that I have seen for the problem you describe.
Porous/thin gold permitting passivation of the Ni which the first reflow
makes much worse.
Thin Ni causing copper to migrate through and produce a non-solderable
surface under the gold, again the first reflow accelerates this.
I have also seen passivated Ni under gold but that just makes all the
components fall off in shear test or shock test, so it is reasonably
apparent.
I went through a period of wanting ENIG to disappear off the face of the
earth. However over the years the process window for ENIG seems to have
improved and our problems diminished.
Perhaps I should not have said that.........................
Rex
Rex Waygood
Technical Manager
Hansatech EMS provides value manufacturing through engineering and
quality
Hansatech EMS Limited
Benson Road
Nuffield Industrial Estate
Poole
01202 338200
-----Original Message-----
From: TechNet [mailto:[log in to unmask]] On Behalf Of [log in to unmask]
Sent: 21 October 2009 00:21
To: [log in to unmask]
Subject: [TN] ENIG Issue
Fellow TechNetters: I ran into a problem and I am looking for more
information. We had some PCB made with ENIG for SMT applications. We
populated the backside, ran them through the convection oven, the solder
fillets were fine. Populated the first five (5) PCBs on the topside,
ran them through the convection oven, and the solder fillets were quite
bad, actually dewetted. Could not even be touched up. Tried two (2)
more random PCBs and got the same results. Never have run into this
before but have been told it is NOT a unique problem. Has anybody had
this happen? Have to tell our customer that they are not going to be
getting their PCBs on time and would rather not look like the north end
of a southbound mule.
Thanks in advance for your assistance.
Bill Black
1 631 667 9699 X13
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