U.S. patent application number 09/837643 was filed with the patent office on 2002-04-18 for low-cost high-density gang-punch.
This patent application is currently assigned to International Business Machines Corporation. Invention is credited to Balz, James G., DiMaria, Ferdinand D., Knickerbocker, John U., LaPlante, Mark J., Long, David C., Weiss, Thomas, Westerfield, Robert P. JR..
Application Number | 20020043556 09/837643 |
Document ID | / |
Family ID | 22435440 |
Filed Date | 2002-04-18 |
United States Patent
Application |
20020043556 |
Kind Code |
A1 |
LaPlante, Mark J. ; et
al. |
April 18, 2002 |
Low-cost high-density gang-punch
Abstract
A gang-punch pin apparatus for punching selected hole patterns
in thin sheet materials such as greensheets is provided. The
gang-punch pin apparatus uses program plates in the punch apparatus
which plates are positioned intermediate the non-punching end of
the punch pins and a clearance plate wherein punch pins not used
for punching a particular layer of the MLC are retracted into
during punching. At the other punch pin locations, the punch pins,
upon activation of the punch apparatus by compressing an expandable
chamber, usually by application of a force on the punch apparatus,
are extended through the lower portion of the punch apparatus to
form vias in a greensheet. A die apparatus is also provided for use
with the punch assembly to form the vias and to remove the punched
material (slugs) from the die apparatus. The gang punch-pin may be
shorter than conventional pins and be made at a low cost because of
the thin sheet metal plates preferably used to make the component
parts of the punch and die apparatus.
Inventors: |
LaPlante, Mark J.; (Walden,
NY) ; Balz, James G.; (Walden, NY) ; DiMaria,
Ferdinand D.; (Wappingers Falls, NY) ; Knickerbocker,
John U.; (Hopewell Junction, NY) ; Long, David
C.; (Wappingers Falls, NY) ; Weiss, Thomas;
(Poughquag, NY) ; Westerfield, Robert P. JR.;
(Montgomery, NY) |
Correspondence
Address: |
DELIO & PETERSON, LLC
121 WHITNEY AVENUE
NEW HAVEN
CT
06510
US
|
Assignee: |
International Business Machines
Corporation
Armonk
NY
|
Family ID: |
22435440 |
Appl. No.: |
09/837643 |
Filed: |
April 18, 2001 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
|
|
09837643 |
Apr 18, 2001 |
|
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|
09128448 |
Aug 3, 1998 |
|
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|
Current U.S.
Class: |
234/1 ; 234/111;
83/687 |
Current CPC
Class: |
Y10T 83/8727 20150401;
B26F 2210/08 20130101; B26F 1/04 20130101; H05K 3/005 20130101;
Y10T 83/883 20150401; H05K 1/0306 20130101; Y10T 83/04 20150401;
Y10T 83/943 20150401 |
Class at
Publication: |
234/1 ; 234/111;
83/687 |
International
Class: |
B26F 001/14 |
Claims
1. A programmable gang-punch apparatus using punch pins for
punching selected hole patterns in thin sheet material wherein,
depending on the hole pattern to be punched, some of the punch pins
are used for punching and the remaining punch pins are
non-punching, the apparatus comprising a pair of opposed plates
containing vertical through-holes which are separated by a pressure
chamber and in which punch pins having an enlarged upper end are
positioned, a program plate overlying the upper opposed plated
containing a plurality of vertical through-holes for punch pins
where punching is not desired, a clearance plate overlying the
program plate having vertical through-holes in all punch pin
locations and into which holes non-punching punch pins are
retracted during punching of the thin sheet material.
2. A gang-punch apparatus for punching selected hole patterns in
thin sheet material comprises: a lower stripper plate formed with a
plurality of vertical through-holes; a guide plate formed with a
plurality of corresponding vertical through-holes wherein the
through-holes; a pressure chamber or other expandable/contracting
means between the guide and lower stripper plates, the plates when
the chamber is not compressed being in an extended non-punching
position and, when compressed, the plates being in a contracted
punching position; a plurality of elongated punch pins axially
slideably disposed in the vertical through-holes of the guide and
stripper plates with the upper ends of the pins being larger so
that the pins rest on the guide plate shoulder, the pins being of a
length when the guide and stripper plates are in a contracted
punching position, the lower ends of the pins extend below the
lower surface of the stripper plate and through a thin sheet
material and die; a program plate disposed on the upper surface of
the guide plate formed with a plurality of vertical through-holes
overlying non-punching punch pins; a clearance plate disposed on
the surface of the program plate formed with a plurality of
vertical through-holes corresponding to the vertical through-holes
of the guide and stripper plates, the clearance plate being of a
thickness sufficient to contain in the through-holes the
non-punching punch pins when the guide and stripper plates are in a
contracted punching position; and means to exert a force on the
clearance plate to force the guide and stripper plates closer
together thereby extending the punching punch pins below the lower
surface of the stripper plate and forming a hole pattern in the
thin sheet material with the non-punching punch pins extending into
the vertical through-holes of the clearance plate so that there is
no punching of the thin sheet material at the non-punching punch
pin locations.
3. The gang-punch apparatus of claim 2 wherein the expandable
contacting means is a pressure chamber.
4. The gang-punch apparatus of claim 3 wherein a head plate having
corresponding vertical through-holes is disposed intermediate the
guide plate and the program plate to form a shoulder on the guide
plate to secure the punch pins in the guide and stripper
plates.
5. The gang-punch apparatus of claim 4 wherein at least one of the
plates is made of a thin material fabricated by laser,
photoetching, mechanical drilling or electro-discharge
machining.
6. The gang punch apparatus of claim 2 wherein the guide plate,
stripper plate, program plate or clearance plate comprise a
composite of multiple plates with the outer plates having uniform,
accurately placed holes and the inner plate or plates having larger
holes.
7. The gang punch apparatus of claim 6 wherein the outer holes are
formed by laser or photoetching.
8. The gang punch apparatus of claim 7 wherein the outer holes are
tapered.
9. The gang punch apparatus of claim 2 wherein all the possible
punch locations are incorporated on a closely spaced grid.
10. A die apparatus for use with a punch apparatus for punching
hole patterns in thin sheet material comprising: a die plate formed
with vertical through-holes corresponding to the punch pins of the
punch apparatus; a window plate on which the die plate is disposed,
the window plate comprising a plurality of vertical through-holes
each through-hole corresponding to at least one of the vertical
through-holes of the die plate and larger than the vertical
through-holes of the die plate to support the die plate and to
facilitate punched material removal after punching; and a groove
plate on which the window plate is disposed, the groove plate
having a plurality of channels preferably less than the number of
vertical through-holes in the window plate, each channel
corresponding to at least one of the vertical through holes in the
window plate and connected to a vacuum and/or pressure source to
remove punched material from the die apparatus.
11. The die apparatus of claim 10 wherein the window plate
comprises a plurality of interconnecting webs which support the die
plate and which provides an open area for the removal of punched
material.
12. A method of gang-punching selective hole patterns in thin sheet
material comprises the steps of: providing a gang-punch pin
apparatus of claim 2; positioning the punch apparatus on top of a
greensheet which is disposed on top of a die apparatus; exerting a
force on the punch apparatus collapsing the pressure chamber and
moving the desired punch pins through the greensheet and into the
die apparatus with the non-punching pins retracting into the
clearance plate; and removing the force on the punch assembly and
expanding the pressure chamber to retract the punch pins from the
die plate and greensheet into the guide and stripper plates.
13. The method of claim 12 wherein the gang-punch pin apparatus is
the apparatus of claim 4.
14. The method of claim 12 wherein the gang-punch pin apparatus is
the apparatus of claim 5.
15. A thin sheet material having hole patterns therein made by the
method of claim 12.
16. A thin sheet material having hole patterns therein made by the
method of claim 13.
17. A thin sheet material having hole patterns therein made by the
method of claim 14.
18. The thin sheet material of claim 15 wherein the thin sheet
material is a greensheet.
Description
CROSS-REFERENCE TO RELATED APPLICATIONS
[0001] Aspects of the present invention are related to subject
matter disclosed in co-pending applications entitled Apparatus and
Method for Producing Punch Pin with Spherical Head and Gang Punch
Tool Assembly both co-pending applications filed on even date
herewith and both assigned to the same assignee as the present
invention.
BACKGROUND OF THE INVENTION
[0002] 1. Field of the Invention
[0003] This invention relates to a punch apparatus and method for
punching holes in thin sheet material and, more particularly, to a
method and gang-punch apparatus containing a plurality of punches
in a fixed pattern and which apparatus is programmable to activate
certain punches to form holes in a desired hole pattern in the thin
sheet material, such as a greensheet.
[0004] 2. Description of Related Art
[0005] In the manufacture of multilayer ceramic (MLC) substrates
for integrated circuit semiconductor package structures, a
plurality of green ceramic sheets (commonly termed greensheets) are
formed by doctor blading a slurry containing a resin binder, a
particulate ceramic material, solvents and a plasticizer, drying
the doctor bladed sheet and cutting it into appropriate size
sheets. Through-holes, commonly termed vias, are then punched in
the greensheets to facilitate forming electrical interconnections
through the sheet. Electrically conductive paste is deposited in
the holes and in appropriate patterns on the surface of the
greensheets, the sheets stacked and laminated, and the assembly
subsequently fired at a sintering temperature.
[0006] The formation of the vias in the ceramic material is
accomplished in its green state. Prior to being fired, the
greensheets are easily deformed and the precision with which the
via holes are formed is greatly dependent upon the use of an
apparatus which minimizes distortion or disruption to the
structural integrity of the greensheet other than forming the via
hole. With the size of electrical components constantly being
reduced through technical improvement, the positioning of the vias
in ceramic greensheets is becoming ever more restrictive. Further,
with the increase in the quantity of the electronic circuits that
may be positioned and packaged on a small area of the ceramic
substrate, a requirement for a larger number of via holes in the
greensheet is evident.
[0007] Large numbers of holes must be punched into a greensheet
with a high degree of precision in order to properly position the
holes. At the same time, this punching operation must occur very
rapidly in order to produce the large numbers of greensheets that
are necessary in the mass production of electronic components.
[0008] A significant portion of the costs associated in
manufacturing ceramic packages can be attributed to punching vias
in greensheets. A number of factors play a major role in accounting
for these costs such as: 1) the high cost for punch die sets
customized to a specific product; 2) the long lead-time associated
with punch die set fabrication precludes early introduction of a
new product; 3) non-customized automated punch die sets have very
low through put for a non-grid product; and 4) automated punch/die
sets punches step repeat numerous times to punch a single sheet
resulting in low throughput.
[0009] One method for punching greensheets is using a gang-punching
apparatus. A gang-punch is a punch/die set where all the punches
for a particular ceramic greensheet layer are rigidly and
permanently mounted in a fixed plate. The gang-punch is used to
punch the entire sheet (layer) with a single stroke. A gang-punch
has very high throughput and is cost effective for very high volume
products.
[0010] Unfortunately, the use of a gang-punch apparatus has
drawbacks since the fabrication of dedicated gang-punches with
fixed patterns of via holes are not practical for engineering
changes (E.C.'s) or multiple patterns because the same apparatus
cannot be easily modified to form different via hole patterns in
ceramic greensheets having a different via pattern thereby
requiring separate gang-punch apparatus for each E.C. or pattern
desired. Additionally, the turn-around time for a new
gang-punch/die set is lengthy and high via density is unattainable
with single punch heads and usually require multiple punch heads
with staggered punches to punch tight grids. The cost is also
prohibitive for the punches since for a typical pattern (up) that
is specified nine (9) times on each greensheet (9-up) and with each
pattern having 2000 (or more) vias, such a 9-up layer would require
a gang punch apparatus with a total of 18,000 punches. For a
multilayer ceramic substrate composed of ten (10) layers, with each
layer requiring a separate gang punch apparatus with 18,000
punches, 180,000 punches would be required to populate these
apparatus. At a typical cost of $1 per punch, it would cost
$180,000 for the punches alone. Current technology limits for
single stroke gang-punching is a minimum punch spacing of about 16
mils.
[0011] A number of attempts have been made to provide a gang-punch
apparatus which will economically and efficiently provide the means
to make via openings in greensheets. One type apparatus utilizes an
interposer mask which contains hole openings where holes are
desired to be punched. In these apparatus, a plurality of punch
elements arranged in a grid are positioned over the greensheet
which is covered by the interposer mask. When the punch elements
contact the interposer mask as the punch heads are moved
downwardly, the holes will be punched where the openings occur
since the punch element would pass through the openings in the
interposer mask and through the ceramic greensheet. In other areas
covered by the interposer mask, i.e., where holes are not desired,
the interposer mask will cause the punch element to be retracted
into the punch head. Such apparatus are shown in IBM Technical
Disclosure Bulletins, Vol. 16, No. 12, May 1974; Vol. 19, No. 4,
Sep. 1976 and Vol. 26, No. 10A, Mar. 1984. Other punch apparatus
are shown in U.S. Pat. Nos. 4,872,381; 4,425,829; 5,024,127;
5,090,284; and 5,233,895. In U.S. Pat. No. 4,872,381, supra, for
example, a programmable magnetic repulsion punching apparatus is
shown. A progressive gang-punch is shown in IBM Technical
Disclosure Bulletin Vol. 15, No. 2, Jul. 1972 wherein a gang-punch
is shown utilizing steel balls on the surface of the punch head at
locations of punches to be punched which when a roller traverse the
top of the punch head only vias are punched where steel balls are
located. The disclosures of the above references and patents are
hereby incorporated by reference.
[0012] Bearing in mind the problems and deficiencies of the prior
art, it is therefore an object of the present invention to provide
a programmable gang-punch apparatus for punching selected hole
patterns in thin sheet material such as greensheets.
[0013] It is an additional object of the invention to provide a
programmable gang-punch apparatus which may be fabricated using
laser or photoetch techniques.
[0014] It is further object of the present invention to provide a
method for punching via holes in greensheets using the gang-punch
pin apparatus of the invention.
[0015] It is another object of the invention to provide greensheets
and other substrates punched with through holes using the apparatus
and method of the invention.
[0016] Other objects and advantages of the present invention will
be readily apparent from the following description.
SUMMARY OF THE INVENTION
[0017] The above and other objects and advantages, which will be
apparent to one of skill in the art, are achieved in the present
invention which is directed to, in a first aspect, a programmable
gang-punch apparatus using punch pins for punching selected hole
patterns in thin sheet material such as a greensheet wherein,
depending on the hole pattern to be punched, some of the punch pins
are used for punching and the remaining punch pins are
non-punching, the apparatus broadly stated comprising a pair of
opposed plates containing vertical through-holes forming an
expandable/contractible chamber, e.g., a pressure chamber and in
which punch pins having an enlarged upper end are positioned, a
program plate overlying the upper opposed plate containing a
plurality of vertical through-holes for punch pins where punching
is not desired, a clearance plate overlying the program plate
having vertical through-holes in all punch pin locations and into
which holes punch pins not punching during punching are retracted
and preferably an overlying pusher plate to exert a force on the
apparatus for punching.
[0018] In another aspect of the invention, a preferred gang-punch
apparatus comprises:
[0019] a lower stripper plate formed with a plurality of vertical
through-holes;
[0020] a guide plate formed with a plurality of corresponding
vertical through-holes;
[0021] a pressure chamber or other expandable/contracting means
between the guide and lower stripper plates, the plates when the
chamber is not compressed being in an extended non-punching
position and, when compressed, the plates being in a contracted
punching position;
[0022] a plurality of elongated punch pins axially slideably
disposed in the vertical through-holes of the guide and stripper
plates with the upper ends of the pins being larger so that the
pins rest on the guide plate shoulder, the pins being of a length
when the guide and stripper plates are in a contracted punching
position, the lower ends of the pins extend below the lower surface
of the lower stripper plate and through a thin sheet material being
punched and die;
[0023] a program plate disposed on the upper surface of the guide
plate formed with a plurality of vertical through-holes overlying
non-punching punch pins;
[0024] a clearance plate disposed on the upper surface of the
program plate formed with a plurality of vertical through-holes
corresponding to the vertical through-holes of the guide and
stripper plates, the clearance plate being of a thickness
sufficient to contain in the through-holes the non-punching punch
pins when the guide and stripper plates are in a contracted
punching position; and means to exert a force on the clearance
plate to force the guide and stripper plates together thereby
extending the punching punch pins below the lower surface of the
stripper plate and forming a hole pattern in the thin sheet
material with the non-punching punch pins extending into the
vertical through-holes of the clearance plate so that there is no
punching of the thin sheet material at the non-punching punch pin
locations.
[0025] It is a preferred feature of the invention that a pressure
chamber be used between the guide and stripper plates to enable the
plates to be in an extended non-punching position or contracted
punching position. The chamber may be expanded with the application
of air or other pressure within the chamber. The apparatus in the
non-punching position will have air or other gas within the chamber
under pressure so that the punch pins are disposed within the guide
and stripper plates. When the apparatus is to be used, the air
pressure within the chamber will be vented or reduced so that a
force exerted on the pusher plate will force the guide plate toward
the stripper plate extending the desired punch pins below the lower
surface of the stripper plate and the non-punch pins into the
through-holes of the clearance plate. After the punching operation,
air will be forced into the chamber, extending the chamber and,
once again, positioning all the punch pins within the guide and
stripper plates.
[0026] In another aspect of the invention, a head plate having
corresponding vertical through-holes is used intermediate the guide
plate and the program plate to form the shoulder on the guide plate
to secure the punch pins in the guide and stripper plates.
[0027] It is an additional aspect of the invention to provide a die
apparatus for use with the programmable gang-punch apparatus for
punching selected hole patterns in thin sheet material. The die
apparatus comprises:
[0028] a die plate formed with vertical through-holes corresponding
to the vertical through-holes of the guide and stripper plates;
[0029] a window plate on which the die plate is disposed, the
window plate comprising a plurality of vertical through-holes each
through-hole corresponding to at least one of the vertical
through-holes of the die plate and larger than the vertical
through-holes of the die plate to support the die plate and to
facilitate punched material removal after punching; and
[0030] a groove plate on which the window plate is disposed, the
groove plate having a plurality of channels preferably less than
the number of vertical through-holes in the window plate and
connected to a vacuum or pressure source to remove punched material
from the die apparatus. Additionally, the groove plate provides
support for the window plate, preventing the window and die plates
from bending under the load imposed on them by the punching
forces.
[0031] In an additional aspect of the invention, a method of
gang-punching selective hole patterns in thin sheet material
comprises the steps of:
[0032] providing a gang-punch pin apparatus and die apparatus as
described above;
[0033] positioning the punch apparatus on top of a greensheet which
is disposed on top of the die apparatus;
[0034] exerting a force on the punch apparatus collapsing the
pressure chamber and moving the desired punch pins through the thin
sheet material and into the die plate with the non-punching pins
retracting into the clearance plate;
[0035] removing the punched material from the die apparatus;
and
[0036] removing the force on the punch assembly and expanding the
pressure chamber to retract the punch pins from the die plate and
greensheet into the guide and stripper plates.
[0037] In another preferred aspect of the invention, at least one
and preferably all the plates of the punch apparatus and/or die
apparatus are made of a thin material which can be fabricated by
using lasers or other such hole forming techniques such as
photoetching, mechanical drilling and electro-discharge machining.
Multiple plates, such as the clearance plates, may be necessary to
provide the necessary plate thickness for punch pin retraction
clearance. The techniques available for fabricating these thin
plates are of a much lower cost than those for thicker plates.
Another feature of the invention is that the thin plates enable
usage of short punches having a length up to about 0.250 inch,
preferably about 0.025 to 0.100 inch. The benefit of short length
provides an increase in buckling strength by an amount inversely
proportional to the square of the length.
[0038] The programmable gang punch apparatus of the invention is
preferably used with an assembly as described in a patent
application entitled "Gang Punch Tool Assembly" filed on even date
herewith and assigned to the assignee of the subject application.
Punch pins for use in the apparatus are preferably made as
described in a patent application entitled "Apparatus and Method
for Providing Punch Pins with Spherical Head" filed on even date
herewith and assigned to the assignee of the subject invention.
BRIEF DESCRIPTION OF THE DRAWINGS
[0039] The features of the invention believed to be novel and the
elements characteristic of the invention are set forth with
particularity in the appended claims. The figures are for
illustration purposes only and are not drawn to scale. The
invention itself, however, both as to organization and method of
operation, may best be understood by reference to the detailed
description which follows taken in conjunction with the
accompanying drawings in which:
[0040] FIGS. 1A-1D shows the gang-punch apparatus and die apparatus
of the invention being used in a series of steps to form selected
via holes in a greensheet.
[0041] FIGS. 2A-2E show a 4 layer package containing multilayer
ceramic substrate with the required via holes in each layer and a
data layer FIG. 2E showing the total number of via holes and
positions thereof needed for the gang-punch apparatus.
[0042] FIGS. 3A-3D show the program plates used to form respective
layers of FIGS. 2A-2D using the apparatus of the invention.
[0043] FIG. 4 shows various plates of the apparatus formed as a
composite of multiple plates rather than one single plate.
[0044] FIG. 5A and 5B shows a pressure chamber of an apparatus of
the invention.
[0045] FIG. 6 shows a cut-away plan view of a universal groove
plate of a die of the invention.
DESCRIPTION OF THE PREFERRED EMBODIMENT(S)
[0046] In describing the preferred embodiment of the present
invention, reference will be made herein to FIGS. 1-6 of the
drawings in which like numerals refer to like features of the
invention. Features of the invention are not necessarily shown to
scale in the drawings.
[0047] Referring now to the figures in detail, the present
invention of a method of using the punch apparatus and die
apparatus of the invention to make via openings in greensheets can
be demonstrated. In FIG. 1A, a gang-punch assembly shown generally
as 10 is shown positioned above and apart from die assembly 11
which has a greensheet 29 thereon. As will be shown in the
following figures, in operation, gang punch assembly 10 with
stripper plate 12 is placed on top of greensheet 29 in registration
with the vertical through-holes 24a-24k of die plate 24. The punch
assembly will then be activated by exerting a force on the
gang-punch assembly and the via holes punched.
[0048] Referring to FIG. 1A, punch assembly 10 comprises a stripper
plate 12 having vertical through-hole openings 12a-12k therein.
Overlying stripper plate 12 is guide plate 13 having vertical
through holes 13a-13k in registration with vertical through-hole
openings 12a-12k of stripper plate 12. Between guide plate 13 and
stripper plate 12 is a pressure chamber shown generally as 14
bounded by stripper plate 12 and guide plate 13. This chamber 14 as
shown in FIGS. 5A and 5B, comprising guide plate 13 above and
stripper plate 12 below, allows stripper plate 12 to move up and
down with respect to guide plate 13. This is achieved as shown in
FIGS. 5A and 5B by enclosing plates 12 and 13 with a surrounding
pressure containment assembly consisting of outer rings 61a and
61b, rigidly fixed to guide plate 13, and moveable inner rings 62a
and 62b rigidly attached to stripper plate 12. A flexible rubber
diaphragm 60 allows inner rings 62a and 62b to move in relation to
outer rings 61a and 61b while maintaining pressure within the
pressure chamber 14. Pressure in pressure chamber 14 can be
controlled by utilizing gas ports 63. FIG. 5A shows the pressure
chamber 14 in an expanded, non-punching portion with low pressure
(10 psi) applied through ports 63. FIG. 5B shows the pressurized
chamber 14 in a contracted, punching position. At this point after
punching, high gas pressure can be applied through ports 63 to the
pressure chamber 14, to apply a holding force to the stripper plate
12, firmly holding the greensheet 29 against the die plate 24 while
retracting (stripping) the punch pins from the die assembly 11 and
greensheet 24.
[0049] Following this stripping operation, high pressure is
exhausted and low pressure is again applied to the pressurized
chamber 14 so that the gang punch assembly 10 may be lifted to gain
access for removal of the greensheet 29. This prevents
over-extension (bowing) of the stripper plate 12 which may cause
the punch pins 15 to be retracted past the upper surface of the
stripper plate 12 causing possible damage to the punch pins 15 upon
re-entry into the stripper plate 12.
[0050] Although a pressure containment ring assembly 61a and 61b
and 62a and 62b are shown, alternate methods of sealing pressure
chamber 14 can be used. These may consist of O-ring seals or others
to prevent the pressurized air from escaping the pressure
chamber.
[0051] Referring back to FIG. 1A, the punch pins 15a-15k have a
spherical head 16a-16k at the upper end of each punch pin with said
spherical heads slightly larger than the diameter of the punch pin.
The punch pins may be made of any suitable material with tungsten
being preferred. A head plate 17 is positioned on the upper surface
of guide plate 13 and has a plurality of corresponding vertical
through-holes 17a-17k corresponding to the vertical through-holes
of guide plate 13. The pins 15a-15k are shown disposed in the guide
and stripper plates and the head plate 17. The vertical through
openings of head plate 17 are slightly larger than the vertical
through-hole openings of stripper plate 12 and guide plate 13 to
accommodate the larger punch pin head. The heads 16a-16k of punch
pins 15a-15k, therefore, rest on the upper surface of guide plate
13 and are restricted when the punch assembly is at rest from
moving downwardly through the guide and stripper plates by the
heads 16a-16k of the punch pins.
[0052] A program plate 18 is shown on top of head plate 17 and
comprises a plurality of vertical through-hole openings 18a, 18b,
18e, 18g, 18h, 18i, 18j and 18k. The size of the vertical
through-hole openings are approximately the same size as the
vertical through-hole openings of head plate 17 to accommodate
movement of the punch pins 15a-15k therethrough. The program plate
18 has openings only where punching of the greensheet is not
desired. Where punching of the greensheet is desired as, for
example, punch pins 15c, 15d and 15f, there are no vertical
through-hole openings in the program plate 18.
[0053] On top of program plate 18 is a clearance plate assembly
shown generally as 19. The clearance plate assembly comprises a
lower clearance plate 20, an intermediate clearance plate 21 and an
upper clearance plate 22. A force plate 23 is disposed on top of
upper clearance plate 22. Each clearance plate has vertical
through-hole openings therein corresponding to the vertical
through-hole openings of stripper plate 12, guide plate 13 and head
plate 17. Thus, clearance plate 20 has vertical through openings
20a-20k, clearance plate 21 has vertical through-hole openings
21a-21k and upper clearance plate 22 has vertical through-hole
openings 22a-22k. As will be more fully described hereinbelow, for
punch pin 15a, which is a non-punching pin for the particular
greensheet to be punched, during the punching operation, punch pin
15a will be forced upward through vertical through-hole openings
18a, 20a, 21a and 22a. This is to be contrasted with punch pin 15c,
which is a punching pin, which during the punching operation will
be forced downward through the lower surface of stripper plate 12
forming a via in greensheet 29.
[0054] Referring now to the die assembly 11 of FIG. 1A, a groove
plate 28 has a series of channels 28a, 28b and 28c extending to an
opening (not shown) for removing punched material (commonly termed
slugs). Disposed on the surface of groove plate 28 is a window
plate assembly shown generally as 25. The window plate assembly 25
comprises a lower window plate 26 and an upper window plate 27.
Each window plate has corresponding openings 26a-26f and 27a-27f
forming vertical through-hole openings in the window plate. It will
be noticed that the diameter of the window plate openings are
larger than the via openings 24a-24k of die plate 24. The die plate
24 is disposed on top of the window plate assembly 25 and comprises
a series of via openings 24a-24k which correspond to vertical
through-hole openings 12a-12k of stripper plate 12. A greensheet 29
is disposed on the top of die plate 24.
[0055] Referring now to FIG. 1B, the punch assembly 10 has been
placed on the surface of greensheet 29 and has been activated for
the punching operation. Thus, a force as shown by arrow A is
applied to force plate 23 to force pressure chamber 14 to contract.
The chamber 14 will typically be vented allowing gas in the chamber
to be expelled. As chamber 14 contracts, punch pins 15c, 15d and
15f will be forced through the lower surface of stripper plate 12
and into greensheet 29 at corresponding die plate openings 24c, 24d
and 24f. The non-punching punch pins 15a, 15b, 15e and 15g-15k are
forced upward through the vertical through-holes in the program
plate and the clearance plates and do not punch the greensheet.
[0056] Referring now to FIG. 1C, the punching operation has been
completed and the pressure chamber 14 is completely contracted so
that the punch pins 15c, 15d and 15f extend completely through the
respective die openings and window plate openings forming slugs
30c, 30d and 30f which are shown falling toward the bottom of
channel 28b. As shown in FIG. 1D, after the punching operation,
high pressure air is supplied to chamber 14 expanding the chamber
and retracting guide plate 13 from stripper plate 12 and retracting
punch pins 15c, 15d and 15f from the die assembly 11 and greensheet
29. In its final position, the punch pins 15c, 15d and 15f will be
completely removed from greensheet 29 and the apparatus ready for
the punching of another greensheet. The slugs 30c, 30d and 30f may
be removed by vacuum or air pressure in the channel. An important
feature of the invention is that pressure chamber 14 acts to
maintain lower stripper plate 12 in contact with the greensheet 29
surface thus holding the greensheet firmly in place against the die
plate 24 during both punching and stripping to ensure positional
accuracy while minimizing tearing or other deformation of the
formed via.
[0057] Another important feature of the current invention is the
utilization of a Universal Groove plate. FIG. 6 shows a cut-away
plan view of the die portion of the present invention. A portion of
a die plate 24 with closely spaced holes 24x depicting a typical
punch pin density of 0.004" diameter on a 0.008" grid. A cut-away
view of the window plate 25 is shown below the die plate 24 with
open cells 25x providing clearance for the punch pins 15 and slugs
30 as they penetrate the die 24.
[0058] Webs 25y in the window plate 25 span the grooves 28a, 28b,
and 28c in the groove plate 28 and rest on the top surface of webs
70 of the groove plate 28 shown as webs 70a, 70b, 70c and 70d to
transfer the punching force on the die plate 24 caused by the punch
pins 15, to the groove plate 28. The webs 25y of the window plate
are sufficiently narrow (approximately 0.002") as to enable their
placement between the holes 24x in the die 24 so as not to
interfere with the punch pins 15 and slugs 30 as they pass through
the die plate 24.
[0059] Placement of the groove plate webs 70a-70d is not dependent
on the location of the holes 24b in the die plate 24 because the
window webs 25y provide sufficient rigidity to span any open area
(i.e., 28a, 28b or 28c) in the channel plate 28. This allows for a
universal groove plate design independent upon the location of
punch locations in the plates above, allowing the groove plate to
be re-used for any pattern, reducing cost.
[0060] For areas where punch pin density does not dictate the use
of the open window area 25x such as single isolated punches, or
small clusters of punches, small clearance areas can be used that
are centered on the localized areas. A single punch area 71 is
indicated by die location 24a with corresponding window plate
clearance hole 25z. A cluster of punches 72 is shown with die
locations 24e and 24f with corresponding window plate clearance
holes 25s and 25t. The clearance holes form a continuous area
surrounding the die holes without substantially decreasing the load
transfer capability of the window plate to the groove plate 28.
[0061] With reference to the punch assembly 10 as shown in FIG. 1A
for example, clearance plates 20, 21 and 22, program plate 18, head
plate 17, guide plate 13 and stripper plate 12 may be formed from
thin sheet material using, e.g., lasers, photoetching, mechanical
drilling, electro-discharge machining, etc. Materials such as
stainless steel, steel alloys, tungsten carbide and molybdenum may
be used with stainless steel and molybdenum being preferred. This
significantly reduces the cost of the assembly and the time needed
for fabrication of the punch assembly. Likewise, die plate 24 and
window plates 26 and 27 of die assembly 11 may also be made from
thin sheet material. The thin sheet material may likewise be any
suitable material such as stainless steel, steel alloys, tungsten
carbide and molybdenum, preferably stainless steel and molybdenum.
The thickness of the material is generally about 0.002 to 0.040
inch.
[0062] In yet another aspect of the invention, stripper plate 12,
grid plate 13, and die plate 24, for example, as shown in FIG. 4,
can be composed of an assembly of separate plates bonded together
to form a single unit. This allows the outer plates such as 13a and
13c to be formed by photoetch processes well-known in the art to
produce extremely uniform, accurately placed holes 72 compared to
larger holes 73 in plates 12b, 13b and 24b, while the entire
assembly overcomes the limitations of a one-to-one aspect ratio
limit for such etching processes.
[0063] Spacer plates 12b, 13b and 24b as shown in FIG. 4 can be
fabricated using alternate and less accurate means such as laser
drilling, mechanical drilling, EDM machining, as well as photoetch
techniques. This allows a looser tolerance on the hole locations
and diameter. The holes in plates 12b, 13b and 24b may be oversized
as it serves only to separate the plates 13a and 13c, 12a and 12c
and 24a, and provides the necessary clearance for the punch shank
as well as providing increased rigidity to the assemblies 12, 13
and 24.
[0064] For die plate 24, plate 24b provides the necessary rigidity
without the requirement of having another thin plate on the
opposite side from plate 24a.
[0065] Additionally, the photoetch process allows the generation of
tapered holes as shown as 72a in FIG. 4 to facilitate punch
loading, proper punch to hole clearance, slug removal, etc. Bonding
of the assemblies 12, 13, and 24 can be accomplished by using
adhesives including epoxies, urethanes, silicon rubbers, etc. The
assemblies can also be soldered, welded, riveted or otherwise
fastened.
[0066] Referring now to FIGS. 2A-2E and 3A-3D, it can be seen how a
gang-punch apparatus of the invention is constructed depending on
the via-layout of the multilayer ceramic substrate to be built and
also how the program plates are designed for use in the apparatus
to make the multilayer ceramic substrate electronic component
product. The layers of the multilayer ceramic are shown as 31, 32,
33 and 34. Each layer has via holes therein. Thus, layer 31 has via
holes 35a, 35c, 35e, 35g and 35i. Layer 32 has via holes 35a, 35b,
35d, 35e, 35f and 35h. Layer 33 has via holes 35d and 35h. Layer 34
has via hole 35i. Based on the via holes of the MLC, gang apparatus
data plate 35 shows the location of all the via holes which have to
be punched to form the MLC comprising substrate layers 31-34. Using
this data, a gang-punch apparatus is formed having a 3.times.3
array of via holes 35a-35i. Thus, there would be a total of 9 punch
pins in the gang-punch apparatus with some of the punch pins being
non-punch pins depending on the layer being punched.
[0067] As shown in FIGS. 3A-3D, to form program plate 31a for use
in the apparatus of the invention to make MLC greensheet substrate
layer 31, program plate 31a would have through hole openings 35b,
35d, 35f and 35h therein. As discussed hereinabove, these openings
in program plate 31a would be non-punch pin locations which would
not be punched in the greensheet since the respective punch pins
15b, 15d, 15f and 15h would be retracted into the clearance plate
through-holes. Similarly, program plate 32a has through-hole
openings 35c, 35g and 35i. When program plate 32a is used in the
apparatus of the invention, via holes will be formed in via
locations 35a, 35b, 35d, 35e, 35f and 35h. With regard to program
plate 33a, via openings would only be formed in MLC layer 33 at via
locations 35d and 35h. Likewise, using program plate 34a to make
MLC layer 34, a via will only be punched in layer 34 at via
location 35i.
[0068] It is apparent that this program feature enables this single
gang-punch apparatus to manufacture up to all of the layers in a
MLC ceramic substrate.
[0069] Additionally, it is possible to create a gang-punch
apparatus which has incorporated therein all the possible punch
locations on a closely spaced grid (i.e. 0.004 inch diameter on
0.008 inch centers). This gang-punch could therefore punch any
pattern, utilizing only different program plates so long as said
pattern was designed so that the punches fall on the closely spaced
grid.
[0070] While the present invention has been particularly described,
in conjunction with a specific preferred embodiment, it is evident
that many alternatives, modifications and variations will be
apparent to those skilled in the art in light of the foregoing
description. It is therefore contemplated that the appended claims
will embrace any such alternatives, modifications and variations as
falling within the true scope and spirit of the present
invention.
[0071] Thus, having described the invention, what is claimed
is:
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