Chuck

IPC 6012 (Section 3.5.1) requires the minimum conductor width to be 80%
of the pattern supplied in the procurement documentation.  You should be
getting lands that are at least 6.4 mils wide according to this.  In my
opinion this is an easily achievable specification.

One thing to be aware of is that the minimum conductor width is defined
(IPC-A-600E, Section 3.2.1) as the base of the conductor (or land), not
the top.   Of course you are interested in the top plateau width for
wire bonding.  It is possible that the conductor base is in
specification and the top is too narrow to meet your requirements.

You can increase your nominal land width to make sure the top meets you
wirebond requirements.  However, you are now adjusting your
specification to a specific manufacturer.  The when you use another
fabricator with different processes and capabilities, you'll find a
different land profile and different plateau width.

I recommend that you add a requirement that specifies the width of lands
at the top, not the bottom.  Then allow your fabricators to figure out
the best way to give you what you asked for.

> ----------
> From:         Chuck Garth[SMTP:[log in to unmask]]
> Reply To:     TechNet E-Mail Forum.;[log in to unmask]
> Sent:         Saturday, March 20, 1999 6:59 AM
> To:   [log in to unmask]
> Subject:      [TN] Aluminum wire bonding
>
> We are presently aluminum wirebonding to gold plated lands.
> Our board manufacturer has been very inconsistent in the quality.  It
> seems as
> though they are over etched by about half the amount they should be.
> Can
> anyone give me the spec's that normal board manufactures are required
> to
> provide, we are requesting .008" lands with a .010 spacing it seems as
> though
> we are getting about .005" lands and .012 spacing what should the
> requirements
> be, is there a general spec to follow.
> Any help would be appreciated.
> Chuck Garth
>
>

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