Method for fabricating modules comprising uniformly stacked, aligned circuit-carrying layers

• US 4,617,160 A
• Filed: 11/23/1984
• Issued: 10/14/1986
• Est. Priority Date: 11/23/1984
• Status: Expired due to Term

• Current Assignee: Irvine Sensors Corp.
• Original Assignee: Irvine Sensors Corp.
• Inventors: Belanger, Robert J., Bisignano, Alan G.
• Primary Examiner(s): Massie, Jerome
• Application Number:
  US06/674,096
• Time in Patent Office: 690 Days
• Field of Search: 156/64, 156/228, 156/245, 156/288, 156/289, 156/307.7, 156/307.3, 156/360, 156/378, 156/379, 29/572, 29/576 J, 29/577 C, 29/830, 29/834, 264/40.1, 264/263, 264/272.15, 264/272.17, 425/383, 425/352, 269/303, 269/319, 250/578
• US Class Current: 264/40.1
• CPC Class Codes: H01L 21/67121 Apparatus for making assemblies not otherwise provided for, e.g. package constructions
• CPC Class Codes: H01L 2225/06527 Special adaptation of electrical connections, e.g. rewiring, engineering changes, pressure contacts, layout
• CPC Class Codes: H01L 2225/06551 Conductive connections on the side of the device
• CPC Class Codes: H01L 2225/06555 Geometry of the stack, e.g. form of the devices, geometry to facilitate stacking
• CPC Class Codes: H01L 23/5385 Assembly of a plurality of insulating substrates
• CPC Class Codes: H01L 25/0657 Stacked arrangements of devices
• CPC Class Codes: H01L 2924/00 Indexing scheme for arrangements or methods for connecting or disconnecting semiconductor or solid-state bodies as covered by H01L24/00
• CPC Class Codes: H01L 2924/0002 Not covered by any one of groups H01L24/00, H01L24/00 and H01L2224/00
• CPC Class Codes: H05K 3/4611 by laminating two or more circuit boards H05K3/4652 takes precedence
• CPC Class Codes: Y10T 29/49126 Assembling bases
• CPC Class Codes: Y10T 29/49133 with component orienting

Abstract

A method and related fixtures are disclosed which permit formation of stacks of thin circuitry-carrying layers. The layers terminate in an access plane having a two dimensional array of closely-spaced electrical leads. The method includes the steps of measuring the thickness of separate chips, selecting groups of chips having appropriate thicknesses, applying appropriate amounts of epoxy between adjacent chips, aligning the chips (and their electrical leads) in the direction parallel to their planes (i.e., the X-axis), and closing the cavity with an end wall which (a) exerts pressure on the stacked chips and epoxy in a direction perpendicular to the chip planes, and (b) establishes a fixed height of the stack in order to align the leads in the Y-axis. The final fixture provides a fixed-size cavity for confining the layers during curing of thermo-setting adhesive which has been applied between each adjacent pair of layers. An initial fixture is provided for accurately measuring the thickness of each layer under substantial layer-flattening pressure. An intermediate fixture is provided for wet stacking the layers prior to their insertion into the final fixture.

Claims

1. In the manufacturing of an electronic-circuitry-supporting stack of layers, each of which extends in a plane perpendicular to an access plane end at one end of the stack, and each of which provides a multiplicity of spaced electrical leads at the access plane, such leads being part of a two-dimensional planar array having its X-axis parallel to the layer planes and its Y-axis perpendicular to the layer planes, the method comprising:

forming a plurality of substrate layers each having circuitry thereon providing at the access plane end a multiplicity of separate electrical leads spaced along the X-axis of the array;

measuring the thickness of each layer;

determining an order, based at least partially on the layer thickness measurements, in which to stack the layers so as to place the access plane electrical leads at their desired locations in the Y-axis of the array;

fabricating a stack-confining structure which includes (a) lower and upper wall members having surfaces which will engage the lower and upper layers of the stack to determine the Y-axis dimension, and (b) a plurality of position reference elements perpendicular to said wall members adapted to determine the X-axis alignment of at least two sides of each of the layers;

wet stacking the layers in the predetermined order after applying substantially the same amount of a liquid adhesive material between each pair of adjacent layers;

placing the layers in the stack-confining structure supported on the lower wall member;

aligning the layers along the X-axis by engaging them against the position reference elements of the stack-confining structure;

using the upper and lower wall members of the stack-confining structure to exert pressure along the Y-axis causing the Y-axis dimension of the stack to correspond to the desired final dimension; and

subjecting the confined stack to heat in order to cause the liquid adhesive to secure the layers in an integrated stack.

2. The method of claim 1 which also comprises:

adding a plurality of additional position reference elements to the stack-confining structure after aligning the layers, thereby completely confining the stack in a fixed volume space during the heating step.

3. The method of claim 1 wherein the Y-axis dimension of the stack-confining structure is controlled by members having a thermal expansion coefficient approximating that of the layer material.

4. The method of claim 2 wherein the Y-axis dimension of the stack-confining structure is controlled by members having a thermal expansion coefficient approximating that of the layer material.

5. The method of claim 1 wherein:

three sides of the stack-confining structure are first assembled, leaving the structure unconfined on three sides;

the layers are then inserted in the structure with their access plane ends visible for alignment inspection;

the layers are pushed along their X-axis into engagement against the reference element on one side; and

X-axis alignment is checked by microscopic inspection of the access plane.

6. The method of claim 2, wherein:

three sides of the stack-confining structure are first assembled, leaving the structure unconfined on three sides;

the layers are then inserted in the structure with their access plane ends visible for alignment inspection;

the layers are pushed along their X-axis into engagement against the reference element on one side; and

X-axis alignment is checked by microscopic inspection of the access plane.

7. The method of claim 6 wherein:

after X-axis alignment, the remaining three sides of the stack-confining structure are assembled; and

one of the final three sides is caused to exert pressure on the stack along the Y-axis.

8. The method of claim 1 wherein:

an excess amount of liquid adhesive material is used in order to prevent void areas between layers; and

the excess liquid adhesive material is permitted to escape from the stack.

9. The method of claim 2 wherein:

an excess amount of liquid adhesive material is used to order to prevent void areas between layers; and

the excess liquid adhesive material is permitted to escape from the stack.

10. The method of claim 7 wherein:

an excess amount of liquid adhesive material is used in order to prevent void areas between layers; and

the excess liquid adhesive material is permitted to escape from the stack.

11. The method of claim 1 which also comprises:

stacking a plurality of the multi-layer integrated stacks in a multi-stack combination;

applying liquid adhesive material between adjacent stacks;

supporting the multi-stack combination in a stack-confining structure;

aligning the stacks in the X-axis;

exerting pressure along the Y-axis to cause the Y-axis dimension to correspond to the desired final dimension; and

subjecting the confined multi-stack combination to heat in order to cause the liquid adhesive to secure the stacks in an integrated combination of multi-layer stacks.

12. The method of claim 2 which also comprises:

stacking a plurality of the multi-layer integrated stacks in a multi-stack combination;

applying liquid adhesive material between adjacent stacks;

supporting the multi-stack combination in a stack-confining structure;

aligning the stacks in the X-axis;

exerting pressure along the Y-axis to cause the X-axis dimension to correspond to the desired final dimension; and

subjecting the confined multi-stack combination to heat in order to cause the liquid adhesive to secure the stacks in an integrated combination of multi-layer stacks.

13. The method of claim 1 which also comprises:

applying mold release material to the layer-engaging surfaces of the stack-confining structure before the layers are placed in the structure.

14. The method of claim 2 which also comprises:

applying mold release material to the layer-engaging surfaces of the stack-confining structure before the layers are placed in the structure.