Adhesion characteristics of electroless nickel 2

[Flesh]

Can anyone comment on the typical "industry" acceptance for the adhesion characteristics for electroless nickel plating? For my application I would like to require an adhesion test (for example per ASTM B733 paragraph 9.4.1) as long as this isn't viewed as an extravagant request. I'm hoping its not, but is in fact standard practice across the industry.

 

[boo1]

From:
Elnic Elect Nickel
PP C-9 and C-27
Adhesion Strength 300 to 400 MPa (40-60 KSI)

 

[kenvlach]

Adhesion testing is pretty standard, not extravagant.
Adhesion testing is required per lot in MIL-C-26074 (usually, thin steel or Al coupons ~corresponding to workpiece composition are run concurrently with the work). Also, the test is a bit more rigorous than the ASTM test:

“3.3.3 Adhesion on metals. The coating adhesion after completion of all processing and thermal treatments shall be such that when examined at a magnification of 4X, the coating shall not show separation from the basis metal when tested in accordance with ASTM B571 as specified in 4.5.2. It also shall be impossible to detach any area of the coating with a sharp instrument on the outside radius of the bent-test specimen. Formation of cracks that do not result in loss of plating adhesion is acceptable.”

For some low-cost commercial work, the customer may waive adhesion testing to save the cost of post-plating adhesion baking (e.g., on some Al alloys), but this is not in compliance with the specification.

ASTM B733, paragraph 7.2.3 “Adhesion – The coating shall have sufficient adhesion to the basis metal to pass the specified adhesion test (see 9.4 and Test Methods B 571).”
However, the customer and producer are allowed some flexibility in the sampling.

AMS 2404 & 2405 are the most lax of the major specifications. The customer and producer have the most freedom regarding frequency of testing, and the tests are less rigorous. The article EN Specifications: Working Tools for Industry rips the AMS salt spray test requirement (48 hrs) as a waste of salt.

http://www.pfonline.com/articles/019707.html

Note: this article says MIL-C-26074 is obsolete; however, it has been reinstated by the Navy (just maybe they prefer a 100 hour salt spray test rather than 48 hours!).

Another article that may be of general interest (nil on adhesion) is Electroless Nickel: Deposit Properties, Specifications and Applications

http://www.pfonline.com/articles/pfd0024.html

 

[TVP]

Just to add to what kenvlach's excellent post, adhesion testing is routinely performed by quality platers, and is not viewed as unnecessary or extravagant. It should be a regular routine part of their control plan (QS9000, ISO9000, etc.).

 

[Flesh]

Kenvlach, TVP:
Good to hear, as I am a stickler for inspection and quality control. Thank you.

 

[JimMetalsCeramics]

Aside from the formal rsponses with ASTM and AMS cited, it is often the case that for very quick inspection the plater will rub a piece of Scotch tape over the dried plating (and the part, if it is exposed). You rip the tape off quickly. If the plating survives, this is generally indicative of a peel strength in excess of 4,000 psi. This is called the "Scotch tape" test.

Technic makes electroless nickel solutions (

http://www.technic.com).

You might want to ask them, as well.