Hi Michael,

I'd follow Phil's advice and talk to your suppliers to show you the
panelization of your parts.

1. The laminate manufacturers have big sheets of laminate that are cut down
for us PCB guys.  Sheet sizes vary depending on the equipment they use to
make the laminate.  For example my 18" x 24" panels come from a sheet that
was laminated at 38" x 50" and then trimmed to a "full sheet" size of 36" x
48".  We always go with the laminate grain in the long axis.

PCB Manufacturers will use various sizes of panels depending on their
individual process variations.  For example, our largest panel size (for
now) is 20" x 28".   My last shop ran everything on a 16" x 18" panel
because we did manual plating.  I've seen shops running huge 30" x 40"
panels but that was because the boards were about that big. Bigger is not
always better - a larger area panel requires greater process uniformity
(that ought to be there - yes?) and an increased chance of handling damage.
As Phil mentioned, it is common to discuss panelization options with the PCB
manufacturer to best match their process capability and any cost savings,
shorter lead times they might realize.  You might include whether you accept
bad ("x-out") parts on a panel in the procurement documentation.

2. Pretty standard to leave 125 mils between panels and use a 93 mil bit
with a double pass.  If it is a tighter tolerance you might use a different
smaller bit.  If this was a multilayer foil lamination I'd suggest adding
theft copper in the route lines to avoid possible wrinkles.

3. The boarder area also depends on how their processes run.  A generic
figure would be no less than 0.25" all around.  It depends on the process:
tooling holes, registration locations, plating connections, etc.  This is a
single sided board so you might be able to get closer to the edge.  A deeper
question is what pattern (starburst, solid, offset dots or none) to use on
multilayers and when.

Looking forward to IPC up in the pond - guys and gals.

Hans

~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
Hans M. Hinners
Process Engineer
Toppan Electronics, Inc.
770 Miramar Road
San Diego, CA 92126
(858) 695 - 2222 ext. 241
(858) 695 - 6823 fax
[log in to unmask]



-----Original Message-----
From: Hiteshew, Michael [mailto:[log in to unmask]]
Sent: Wednesday, March 28, 2001 12:22 PM
To: [log in to unmask]
Subject: [TN] Laminated FR4 Standard Sheet Size?


Hi TechNetters,

        I'm trying to determine how many PCB's will fit comfortably on a
standard sheet of laminated FR4. This is for a single sided rectangular
board 2.5" x 3.5". Here's what I need to know:

1. How big is a standard sheet of FR4?

2. How much room do I allow between each PCB for routing bits?

3. How much material do I need to allow for around the edge of the sheet as
unusable?

Thanks in advance,

  -Michael Hiteshew

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