Thank you to all who shared their experience/Input on my inquiry.

Great group of guys and forum.



Victor,



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

From: TechNet <[log in to unmask]> On Behalf Of Wayne Thayer

Sent: Wednesday, June 2, 2021 11:54 AM

To: [log in to unmask]

Subject: Re: [TN] ENIG plating Flex Circuit





[EXTERNAL EMAIL] 



If you look at a microsection of ANY kind of electroplating or electroless plating done on Rolled/Annealed copper, it will cure you of your curiosity as to why you should never plate over Rolled/Annealed. You have all of those nice elongated grains which are overlapped, leading to a comparatively enormous amount of bending survival. Then you plate over that with crack initiators (plating grows straight up like dense hair). And in the case of nickel, very brittle crack initiators: Not only brittle, but also very high strength, leading to even higher stress at the grain boundaries. If you do feel the need to do this, don't bother with Rolled/Annealed. Waste of money.



Wayne Thayer



On Wed, Jun 2, 2021 at 4:15 AM Nigel Burtt <[log in to unmask]> wrote:



> Interesting thread - we have an ENIG flexi and historically if we 

> specify standard ENIG then we see cracking so we have a legacy 

> exception to allow only 1-3um nickel rather than standard 3-6um per 

> IPC-4552 which has always worked for us for both solderability and mechanical reliability.

>

> However I see the most recent IPC-4552 now separately defines ENIG on 

> flexi as allowed 1.27-6um.  What is the purpose of specifying a  lower 

> thickness range level of nickel allowable in all flexi, but 3um 

> minimum required on rigid presumably for reliable solderability?

>