the main benefit is for SMD designs with components on both sides.
If the panel is laid out correctly (i.e. symmetrically as flipped), the
assembly process can use one set-up and run the boards through the one line
twice. During the first pass board A has it's top side components placed at
the same time as board B has it's bottom side components placed. At the end
of the line after reflow, the board is flipped and sent back through the
same line. During this pass board A has it's bottom side components placed
and Board B has it's top side components placed. One set-up, one line, one
program, two reflow cycles. This is very significant to assembly costs
because so much time is spent (read wasted) setting up lines and tying up
lines for a production run. In an example like this, they tie up only one
line, program it only once, load the parts once, but reflow twice. Got the

        There is a second benefit to this panelization as well, it comes
into play with high frequency RF designs (solid plane bottom side, all
circuits top side) like we do where absolute finest control of feature
dimensions are required (i.e. IPC class 3 at +/-20% is a mile off to us).
During fabrication, plating and etching can be grossly unequal from one side
of the board to the other due to density of plating or copper to be etched
away. Flipping each alternate board evens the distribution of copper thus
equalizing the plating and etching characteristics of the board over the
whole panel allowing for finer fabrication tolerances.

Brad Velander.

Lead PCB Designer
Norsat International Inc.
Microwave Products
Tel   (604) 292-9089 (direct line)
Fax  (604) 292-9010

See us at Booth 323 at Satellite 2002 in Washington, DC March 6-8.

-----Original Message-----
From: Dennis Saputelli [mailto:[EMAIL PROTECTED]]
Sent: Wednesday, February 27, 2002 5:16 PM
To: Protel EDA Forum
Subject: Re: [PEDA] Flipped on panel Paired Mechanical layers (ex
Inversion ...)

Ian Wilson wrote:
> real reasons why correct inversion would be useful, another would be to
> facilitate panelisation where alternate rows of boards are flipped - to
> minimise machine setup.  Leaving this to a PCB maker can be a source of
> error.  Doing it in Camtastic is my preferred option but some companies I
> work for like to have the panel in Protel for whatever reason.

i've seen those panels with some boards flipped and never understood, in
fact i still don't
can you pls explain what this offers?

Dennis Saputelli

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