Method of manufacturing a printed circuit assembly

• US 5,839,188 A
• Filed: 01/05/1996
• Issued: 11/24/1998
• Est. Priority Date: 01/05/1996
• Status: Expired due to Fees

• Current Assignee: Honeywell International Inc.
• Original Assignee: Alliedsignal Inc.
• Inventors: Pommer, Richard J.
• Primary Examiner(s): Arbes, Carl J.
• Application Number:
  US08/583,645
• Time in Patent Office: 1,054 Days
• Field of Search: 29/830, 29/846, 29/874, 29/825, 156/310
• US Class Current: 29/830
• CPC Class Codes: H01L 2224/83138 the guiding structures being at least partially left in the finished device
• 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 2924/01079 Gold [Au]
• CPC Class Codes: H01L 2924/01327 Intermediate phases, i.e. intermetallics compounds
• CPC Class Codes: H01L 2924/09701 Low temperature co-fired ceramic [LTCC]
• CPC Class Codes: H05K 1/141 One or more single auxiliary printed circuits mounted on a main printed circuit, e.g. modules, adapters H05K1/142 and H05K1/147 take precedence
• CPC Class Codes: H05K 2201/0195 Dielectric or adhesive layers comprising a plurality of layers, e.g. in a multilayer structure
• CPC Class Codes: H05K 2201/10378 Interposers
• CPC Class Codes: H05K 2201/10666 Plated through-hole for surface mounting on PCB
• CPC Class Codes: H05K 2201/10977 Encapsulated connections applying non-metallic protective coatings for encapsulating mounted components H05K3/284
• CPC Class Codes: H05K 2203/063 of preperforated insulating layer
• CPC Class Codes: H05K 2203/1189 Pressing leads, bumps or a die through an insulating layer
• CPC Class Codes: H05K 3/305 Affixing by adhesive
• CPC Class Codes: H05K 3/3436 having an array of bottom contacts, e.g. pad grid array or ball grid array components
• CPC Class Codes: H05K 3/368 parallel to each other H05K3/361 takes precedence
• CPC Class Codes: H05K 3/4069 for via connections in organic insulating substrates
• CPC Class Codes: H05K 3/462 characterized by laminating only or mainly similar double-sided circuit boards
• CPC Class Codes: H05K 3/4623 the circuit boards having internal via connections between two or more circuit layers before lamination, e.g. double-sided circuit boards H05K3/462 takes precedence
• CPC Class Codes: H05K 3/4647 by applying an insulating layer around previously made via studs
• CPC Class Codes: Y10T 29/49117 Conductor or circuit manufacturing
• CPC Class Codes: Y10T 29/49126 : Assembling bases

Abstract

A printed circuit assembly and method of making the same utilize in one embodiment an adhesive layer including a plurality of non-conductive "gauge particles" disposed within a non-conductive adhesive. When the adhesive layer is disposed between opposing printed circuit layers (be they insulating substrates, conductive layers, or other layers), individual gauge particles are interposed or sandwiched at various points between the layers such that the diameters of the particles control the layer separation throughout overlapping areas of thereof, thereby permitting careful control over layer separation. A printed circuit assembly and method of making the same utilize in another embodiment an interlayer interconnecting technology incorporating conductive posts that are deposited on one of a pair of contact pads formed on opposing printed circuit boards and thereafter bonded to the other in the pair of contact pads during lamination. Fusible material may be utilized in the conductive posts to facilitate mechanical bonding to a contact pad, and the posts project through a dielectric layer disposed between the printed circuit boards, thereby forming the electrical connections between the boards at discrete locations.

Claims

1. A method of manufacturing a printed circuit assembly, comprising:

(a) forming a conductive post on a first printed circuit board, the printed circuit board including an insulating substrate with a conductive layer disposed thereon, wherein the conductive post is disposed on a first contact pad disposed in the conductive layer of the first printed circuit board;

(b) placing a second printed circuit board over the first printed circuit board with a second contact pad aligned with the conductive post and with a dielectric layer disposed there between, the second printed circuit board including an insulating substrate with a conductive layer disposed thereon, wherein the second contact pad is disposed in the conductive layer of the second printed circuit board, and wherein at least one of the first and second printed circuit boards includes a second conductive layer formed on the opposite surface of the insulating substrate; and

(c) compressing the first and second printed circuit boards together until the conductive post extends across the dielectric layer and abuts the second contact pad, thereby electrically connecting the first and second contact pads, and providing a predetermined separation between the conductive layer of the first printed circuit board and the conductive layer of the second printed circuit board.

2. The method of claim 1, wherein the dielectric layer comprises an adhesive, and wherein compressing the first and second printed circuit boards includes mechanically bonding the first and second printed circuit boards to one another with the adhesive.

3. The method of claim 2, wherein the dielectric layer further includes a dielectric film coated on both sides with the adhesive and including an aperture through which extends the conductive post.

4. The method of claim 2, wherein the dielectric layer further includes a prepreg sheet filled with the adhesive and including an aperture through which extends the conductive post.

5. The method of claim 2, wherein the dielectric layer includes a grid of apertures, and wherein the conductive post is aligned with one of the apertures in the grid of apertures.

6. The method of claim 1, wherein the conductive post has a width which is smaller than the widths of the first and second contact pads.

7. The method of claim 1, wherein forming a conductive post includes depositing a first metal layer on the first contact pad, and depositing a second, fusible metal layer over the first metal layer, and wherein compressing the first and second printed circuit boards includes applying heat to fuse the second metal layer to the second contact pad.

8. The method of claim 7, wherein forming a conductive post includes photoimaging a resist mask, and wherein the first and second metal layers are deposited via electroplating through the resist mask.

9. The method of claim 7, further comprising depositing an adhesion promoting layer on the second contact pad, and wherein compressing the first and second printed circuit boards fuses the adhesion promoting layer with the second metal layer on the conductive post.

10. The method of claim 1, wherein the forming step includes the steps of depositing a first layer on the first contact pad, and depositing a second, fusible layer over the first layer, and wherein compressing the first and second printed circuit boards includes applying heat to fuse the second layer to the second contact pad.

11. The method of claim 10, wherein the second, fusible layer comprises a conductive ink.

12. The method of claim 10, wherein the second fusible layer comprises a fusible material.