TechNetters:
I want to thank everyone that shared their knowledge and/or experience with my inquiry.
Great forum to be a member of...... Abundance of wealth info.....
Victor,
-----Original Message-----
From: TechNet <[log in to unmask]> On Behalf Of Wayne Thayer
Sent: Monday, May 31, 2021 5:08 PM
To: [log in to unmask]
Subject: Re: [TN] ENIG plating Flex Circuit
[EXTERNAL EMAIL]
Richard brings up a key question.
Nickel IS very brittle. If you have exposed traces on flex, and cover them with ENIG, then the traces will definitely crack if stretched/bent. On the other hand, if you are simply using it on solder pads, I don't think that after soldering you would have an issue.
But you don't have to ENIG the trace to make it very susceptible to stretch-cracks. Just plate copper on top of rolled-annealed in a bend area.
On proper flex designs vias are pattern plated and kept away from bend areas.
It is kind of neat that trace failures in flex due to bending are on the inside of the bend for properly built flex, but if you plate, the first failure happens on the outside of the bend.
Wayne Thayer
On Thu, May 27, 2021 at 8:30 AM [log in to unmask] < [log in to unmask]> wrote:
> Why would you want that portion of the flex, where is exits from the
> rigid board, to have nickel plating? That is typically under the
> polyimide layer and is also typically covered with a bead of epoxy along the edge.
>
> -----Original Message-----
> From: Hernandez, Victor G <[log in to unmask]>
> Sent: Thursday, May 27, 2021 9:33 AM
> To: TechNet E-Mail Forum <[log in to unmask]>; Stadem, Richard D <
> [log in to unmask]>
> Cc: Hernandez, Victor G <[log in to unmask]>
> Subject: RE: [TN] ENIG plating Flex Circuit
>
> ----
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> Folks,
>
> I want to be clear that my main concern at this time is the FLEX
> Circuit portion as it exits the Rigid Flex termination region of the
> Rigid Flex Board.
> I was not aware that nickel could withstand flexing/bending. Nickel is
> brittle. A 90 degree bend on a flex circuit with a distance of 0.122 inch.
> I will conduct x-sec to see if I find any copper/ENIG conductor anomalies.
>
> Victor,
>
> -----Original Message-----
> From: TechNet <[log in to unmask]> On Behalf Of [log in to unmask]
> Sent: Thursday, May 27, 2021 9:18 AM
> To: [log in to unmask]
> Subject: Re: [TN] ENIG plating Flex Circuit
>
>
> [EXTERNAL EMAIL]
>
> Me neither. It takes a very sharp bend in the flex to affect most
> ENIG-finished individual component pads, and most larger ground
> planes/traces are typically not finished (covered with polyimide).
> And (again, typically) once the components are soldered in place it is
> pretty darn hard to bend the flex sharply enough to do any damage. You
> would have to try really hard. The components would crack before any
> damage was done to the soldered pads.
> ENIG is one of the most common flex circuit finishes.
> Odin
> -----Original Message-----
> From: TechNet <[log in to unmask]> On Behalf Of Larry Brophy
> Sent: Thursday, May 27, 2021 8:04 AM
> To: [log in to unmask]
> Subject: Re: [TN] ENIG plating Flex Circuit
>
> ----
> External E-mail --- CAUTION: This email originated from outside GDMS.
> Do not click links or open attachments unless you recognize the sender
> and know the content is safe.
>
> Never had a problem with it Victor.
>
> Regards,
>
> Larry
>
> -----Original Message-----
> From: TechNet <[log in to unmask]> On Behalf Of Hernandez, Victor G
> Sent: Thursday 27 May 2021 14:03
> To: [log in to unmask]
> Subject: [TN] ENIG plating Flex Circuit
>
> Fellow TechNetters:
>
> Is ENIG surface plating finish suitable for a flexible circuit in a
> Rigid
> Flex application? Nickel is brittle.
>
> Victor,
>
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