David;
Most any drill machine with depth control (Z axis micrometer scale) can be
used for this type of rework. Even a drill machine without depth control can
be used, by properly setting the down limit. I have done rework of this
nature in the past. However, there are a few things that must be considered.
First, are there components on both sides of the board? If there are
components on the bottom side of the board - opposite side of the board that
needs drilling, then a special fixture may need to be fabbed in order to
support the board on the drill table. (To prevent the board from 'rocking'
around, and to prevent damage to the components) Next, if there are
components that are very close to the drill location, these components may
need to be removed. The reason for this is to allow enough room for the
pressure foot of the spindle. If the pressure foot of the spindle contacts
the components during the actual drill cycle, then the depth control will
not be accurate, and may even crush the components.
A Uv laser can also be employed to rework these boards. Using a laser will
negate the pressure foot clearance requirements, but may still need a
fixture to hold and support the board. Most lasers do have limitations as to
how far the z axis can be operated, so if the components are very tall, plus
the height of the fixture, may violate the z axis height limitations. Using
a laser to do this will be difficult, and the rework house may need to cross
section a few boards in order to be sure the laser parameters are drilling
to proper depth. I have attempted through holes with a laser through very
thick panels, and have found that beyond .050" depth, the laser beam is now
out of focus, and no matter how many repetitions are applied, the beam has
'diverged' to the point where the centroidal energy of a Gaussian beam has
completely dissipated, and all the beam is doing at that depth is heating up
the laminate.
Dave Simonik
Laser Process Tech.
Sanmina SCI Corp.
Owego NY Division
-----Original Message-----
From: David Tremmel [mailto:[log in to unmask]]
Sent: Monday, January 26, 2004 6:00 PM
To: [log in to unmask]
Subject: Board rework
Hello everyone,
There are some populated boards which have an inner trace which needs to be
opened.
I need information on either leasing or purchasing the machinery or a
company (in North America or Mexico) that can drill thru an inner trace
which needs to be opened, but not entirely through the board.
Each boards needs 2 drillings. I have approx. 15,000 boards.
Thank you in advance for the help.
Thank you,
David Tremmel
Belmont Trading Company
3160 MacArthur Boulevard
Northbrook, Il 60062
(847) 412-9690 - Ext. 346
(847) 858-5540 - Cell
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