Re: Dark deposit on pins near leaking SMD electrolytic caps


Jim Ford
 

OK. I will change my story to I've never seen 3-layer boards.

Usually when I see something that doesn't make sense, I attribute it to "It must have been less expensive to do it that way."

Thanks, Harvey.

Jim

------ Original Message ------
From: "Harvey White" <madyn@dragonworks.info>
To: TekScopes@groups.io
Sent: 2/9/2021 8:53:30 PM
Subject: Re: [TekScopes] Dark deposit on pins near leaking SMD electrolytic caps

Physically, one layer, copper on top.

inner layer (* see note)

outer layer, copper on bottom.

That inner layer can be single sided or two sided, depending. I don't think that anything in the manufacturing process keeps it from being so. I've actually made 3 layer boards, although they're quite awkward without plated through holes.

One side of that inner layer can be missing, so yes, a 3 layer board. I guess it was cheaper to make for some reason, but that was then, long ago (in electron lives) then...

Harvey


On 2/9/2021 11:33 PM, Jim Ford wrote:
3-layer boards? Never heard of them. Maybe you mean 3 dielectric layers and 4 metal layers? PCBs are built up from the inside out, starting with a core (fully cured dielectric sheet plated on both sides with copper foil) and adding more cores and/or prepregs (partially cured dielectric sheet plated on one side with copper) symmetrically on both sides until the stackup is done. Hence there is always an even number of (metal) layers. Always!

Jim Ford

------ Original Message ------
From: "greenboxmaven via groups.io" <ka2ivy=verizon.net@groups.io>
To: TekScopes@groups.io
Sent: 2/9/2021 6:02:16 PM
Subject: Re: [TekScopes] Dark deposit on pins near leaking SMD electrolytic caps

The Sonys have three layer boards, I didn't have any problems. However, I can imagine some very bad problems if the electrolyte got into a connection that connects with one of the inner layers. How would you deal with that?

Bruce Gentry, KA2IVY


On 2/9/21 20:44, Raymond Domp Frank wrote:
On Wed, Feb 10, 2021 at 02:38 AM, greenboxmaven wrote:

I have restored some Sony video recorders that were loaded with the bad
condensers.
The affected Tek 'scopes use multilayer boards, making a slightly more intricate procedure advisable.

Raymond

















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