Method of forming connector structure for a ball-grid array

• US 6,199,273 B1
• Filed: 12/19/1996
• Issued: 03/13/2001
• Est. Priority Date: 12/19/1995
• Status: Expired due to Fees

• Current Assignee: Nippon Steel & Sumikin Electronics Devices Inc. (NGK Insulators Limited), Sumitomo Metal Industries Limited (Nippon Steel Corporation)
• Original Assignee: Nippon Steel & Sumikin Electronics Devices Inc. (NGK Insulators Limited), Sumitomo Metal Industries Limited (Nippon Steel Corporation)
• Inventors: Hidaka, Akihiro, Kubo, Toshihiko, Ito, Takuji, Takamichi, Hiroshi
• Primary Examiner(s): Arbes, Carl J.
• Application Number:
  US08/769,449
• Time in Patent Office: 1,545 Days
• Field of Search: 174/250, 174/260, 174/262, 174/263, 174/266, 174/259, 298/93, 298/25, 298/42
• US Class Current: 29/843
• CPC Class Codes: H01L 21/4853 Connection or disconnection of other leads to or from a metallisation, e.g. pins, wires, bumps
• CPC Class Codes: H01L 2224/11334 using preformed bumps
• CPC Class Codes: H01L 23/49816 Spherical bumps on the substrate for external connection, e.g. ball grid arrays [BGA]
• CPC Class Codes: H01L 2924/15173 in a single layer of the multilayer substrate
• CPC Class Codes: H05K 1/113 Via provided in pad; Pad over filled via
• CPC Class Codes: H05K 2201/0379 Stacked conductors
• CPC Class Codes: H05K 2201/09572 Solder filled plated through-hole in the final product soldering lead-in-hole components H05K3/3447
• CPC Class Codes: H05K 2201/0959 Plated through-holes or plated blind vias filled with insulating material
• CPC Class Codes: H05K 2201/10666 Plated through-hole for surface mounting on PCB
• CPC Class Codes: H05K 2201/10992 Using different connection materials, e.g. different solders, for the same connection
• CPC Class Codes: H05K 2203/041 Solder preforms in the shape of solder balls soldering leadless components having an array of bottom contacts H05K3/3436
• CPC Class Codes: H05K 2203/043 Reflowing of solder coated conductors, not during connection of components, e.g. reflowing solder paste
• CPC Class Codes: H05K 2203/074 Features related to the fluid pressure
• CPC Class Codes: H05K 2203/1394 Covering open PTHs, e.g. by dry film resist or by metal disc
• CPC Class Codes: H05K 3/0094 Filling or covering plated through-holes or blind plated vias, e.g. for masking or for mechanical reinforcement
• 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 3/3452 Solder masks
• CPC Class Codes: H05K 3/3478 Applying solder preforms; Transferring prefabricated solder patterns
• CPC Class Codes: Y02P 70/50 Manufacturing or production processes characterised by the final manufactured product
• CPC Class Codes: Y10T 29/49147 Assembling terminal to base
• CPC Class Codes: Y10T 29/49149 : by metal fusion bonding

Abstract

A ball-grid array connector structure for an electronic package in which the ball pitch can be reduced to increase the packaging density has a plastic substrate having at least one hollow through-hole and an electrode covering the wall of the through-hole and forming an electrode pad surrounding the through-hole on each surface of the substrate. A metallic ball is joined, either directly or through a solder or a combination of a metallic bump and a solder, to the electrode pad on at least one surface of the substrate at the position of the through-hole. The connector structure can be formed either by sealing an open end of the through-hole on the side to which the ball is not joined, or increasing the pressure within the through-hole by a pressure-control mechanism, before the through-hole is blocked by reflowing the ball itself or the metallic bump or solder used to connect the ball.

Claims

1. A method for forming a connector structure of a ball-grid array (BGA) type in an electronic package having at least one hollow through-hole, comprising at least one metallic ball joined to an electrode of the package at the position of the through-hole on at least one surface of the package, comprising joining the metallic ball to the electrode of the package at the position of the through-hole, the metallic ball being a solder ball which is joined to the electrode by reflowing the solder ball while pressure within the through-hole is controlled.

2. The method of claim 1, wherein the metallic ball is a solder ball directly joined to the electrode of the package, the method including the steps of:

sealing an open end of the through-hole on one surface of the package,

setting the solder ball on the electrode of the package on the other surface thereof at the position of the through-hole, and

subjecting the solder ball to reflowing to join the solder ball to the electrode.

3. The method of claim 1, wherein the metallic ball is a solder ball directly joined to the electrode of the package, the method including the steps of:

increasing pressure within the through-hole slightly above atmospheric pressure,

setting the solder ball on the electrode of the package on one surface thereof at the position of the through-hole, and

subjecting the solder ball to reflowing while pressure within the through-hole is kept slightly above atmospheric pressure.

4. The method of claim 1, wherein the method includes the steps of:

increasing pressure within the through-hole slightly above atmospheric pressure,

forming a solder-containing layer on the electrode of the package on one surface thereof at the position of the through-hole,

setting the metallic ball on the solder-containing layer, and

subjecting the solder-containing layer to reflowing to join the metallic ball to the electrode through the solder while the pressure within the through-hole is kept slightly above atmospheric pressure.

5. The method of claim 1, wherein the electronic package has a substrate in which said at least one through-hole is formed, and wherein the substrate has an electrically insulating film overlaid on both surfaces thereof except for the area on at least one surface thereof to which the metallic ball is attached, the method including the steps of:

applying a photoresist film to both surfaces of the substrate,

forming an opening in the photoresist film on one surface of the substrate at the position of the through-hole by exposure of a selected area of the photoresist film followed by development,

setting the metallic ball in the opening of the photoresist film so as to sit it on an electrode of the substrate on said one surface thereof, and

subjecting the metallic ball to reflowing to join it to the substrate.

6. A method for forming a connector structure of a ball-grid array (BGA) type in an electronic package having at least one hollow through-hole, comprising at least one metallic ball joined to an electrode of the package at the position of the through-hole on at least one surface of the package, comprising joining the metallic ball to the electrode of the package at the position of the through-hole, the metallic ball being joined to the electrode of the package through solder, the method including melting the solder to join the metallic ball to the electrode through the solder at the position of the through-hole while pressure within the through-hole is controlled.

7. The method of claim 6, wherein the metallic ball has a surface coating of solder and is joined to the electrode of the package through the solder, the method including the steps of:

sealing an open end of the through-hole on one surface of the package,

setting the metallic ball on the electrode of the package on the other surface thereof at the position of the through-hole, and

subjecting the coating of solder to reflowing to join the metallic ball to the electrode through the solder.

8. The method of claim 6, wherein the metallic ball has a surface coating of solder and is joined to the electrode of the package through the solder, the method including the steps of:

increasing pressure within the through-hole slightly above atmospheric pressure,

setting the metallic ball on the electrode of the package on one surface thereof at the position of the through-hole, and

subjecting the coating of solder to reflowing to join the metallic ball to the package through the solder while the pressure within the through hole is kept slightly above atmospheric pressure.

9. The method of claim 6, wherein the method includes the steps of:

sealing an open end of the through-hole on one surface of the package,

forming a solder-containing layer on the electrode of the package on the other surface thereof at the position of the through-hole,

setting the metallic ball on the solder-containing layer, and

subjecting the solder-containing layer to reflowing to join the metallic ball to the electrode through the solder.

10. The method of claim 6, wherein the electronic package has a substrate in which said at least one through-hole is formed, and wherein the substrate has an electrically insulating film overlaid on both surfaces thereof except for the area on at least one surface thereof to which the metallic ball is attached, comprising the steps of:

applying a photoresist film to both surfaces of the substrate,

forming an opening in the photoresist film on one surface of the substrate at the position of the through-hole by exposure of a selected area of the photoresist film followed by development,

setting the metallic ball having a surface coating of solder in the opening of the photoresist film so as to sit it on an electrode of the substrate on said one surface thereof, and

subjecting the solder coating to reflowing to join the metallic ball to the substrate through the solder.

11. The method of claim 6, wherein the electronic package has a substrate in which said at least one through-hole is formed, and wherein the substrate has an electrically insulating film overlaid on both surfaces thereof except for the area on at least one surface thereof to which the metallic ball is attached, the method including the steps of:

applying a photoresist film to both surfaces of the substrate,

forming an opening in the photoresist film on one surface of the substrate at the position of the through-hole by exposure of a selected area of the photoresist film followed by development,

setting the metallic ball in the opening of the photoresist film so as to sit it on an electrode of the substrate on said one surface thereof, and

subjecting the metallic ball to reflowing to join it to the substrate.

12. A method for forming a connector structure of a ball-grid array (BGA) type in an electronic package having at least one hollow through-hole, comprising at least one metallic ball joined to an electrode of the package at the position of the through-hole on at least one surface of the package, comprising joining the metallic ball to the electrode of the package at the position of the through-hole, the metallic ball being joined to the electrode of the package through a metallic bump and solder, the method including melt-forming the metallic bump on the electrode of the package at the position of the through-hole while pressure within the through-hole is controlled.

13. The method of claim 12, wherein the method includes the steps of:

sealing an open end of the through-hole on one surface of the package,

melt-forming the metallic bump on the electrode of the package on the other surface thereof at the position of the through-hole,

forming a solder-containing layer on the metallic bump,

setting the metallic ball on the solder-containing layer, and

subjecting the solder-containing layer to reflowing to join the metallic ball to the metallic bump through the solder.

14. The method of claim 12, wherein the method includes the steps of:

increasing pressure within the through-hole slightly above atmospheric pressure,

melt-forming the metallic bump on the electrode of the package on one surface thereof at the position of the through-hole while the pressure within the through-hole is kept slightly above atmospheric pressure,

forming a solder-containing layer on the metallic bump,

setting the metallic ball on the solder-containing layer, and

subjecting the solder-containing layer to reflowing to join the metallic ball to the metallic bump through the solder.