I think it would be more accurate to say if you have ISOLATED
thin tracks they tend to get etched away, so you place extra
copper near them to protect them.
I don't think you can cause etching problems by adding copper.
unless your clearances are too small.

I have had bare-board vendors suggest that their life would be
easier if everyone would pour copper around every layer! That
would be less etching and balanced construction, what could be
nicer?

Anyway, if you are hatching a plane to avoid warping it may not
work... you would probably be better off just adding a corres-
ponding fill to the opposite layer for balance.

I have never heard of any real advantage to hatching except for
the warning that I've read (but never seen in real life) that a
large solid area of copper won't bond well with the soldermask
and it could delaminate, but I suspect this is a hold-over from
old-time chemistries that have since improved.

take all that with a grain of salt, and best wishes,
Jack






Matthew Lamkin <[log in to unmask]>@IPC.ORG>
12Aug2002 06:38 AM

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Subject:  [DC] Copper areas, To hatch or not to hatch?
Retain Until: 09/11/2002 Retention Category: G90 - Information and Reports
Caterpillar Confidential:  Green


Hello, I am having a small discussion with one of the engineers at the
moment about groundplane
and whether or not it should be hatched or solid?

AFAIKR if you have large areas of copper on a board with lots of thin
tracks
it can cause etching problems because the
board is not even, so some of the thinner tracks can get etched away.

Also, when it is sent through the hot processes (Reflow/wave etc) it can
cause the board to warp, if one side has more large areas
of copper on than the other.

Hatched copper is supposed to prevent both these from happening.

For a small digital board that does not have high currents going through it
solid groundplane is not required and hatched will suffice.
I have seen many modern PC cards that use hatched grounding on.

Now the big question is "am I talking codswallop here" or what?

I'd appreciate some comments from you more experienced engineers.
P.S. I'm referring to single/double sided boards only not Multilayer.
(although I'd appreciate comments regarding those as well to cope with my
current 4L board).


Thankyou,
Matthew Lamkin.

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