Method employing an elevating of atmospheric pressure during the heating and/or cooling phases of ball grid array (BGA) soldering of an IC device to a PCB

• US 5,385,291 A
• Filed: 01/10/1994
• Issued: 01/31/1995
• Est. Priority Date: 01/10/1994
• Status: Expired due to Fees

• Current Assignee: Plexus Services Corporation (Plexus Corporation)
• Original Assignee: Micron Custom Manufacturing Services, Inc. (Plexus Corporation)
• Inventors: Latta, Richard W.
• Primary Examiner(s): Heinrich, Samuel M.
• Application Number:
  US08/179,396
• Time in Patent Office: 386 Days
• Field of Search: 228/180.22, 228/219, 228/246, 228/256, 228/262.9
• US Class Current: 228/180.22
• CPC Class Codes: H01L 2224/81801 Soldering or alloying
• CPC Class Codes: H01L 24/81 using a bump connector
• CPC Class Codes: H01L 2924/01005 Boron [B]
• CPC Class Codes: H01L 2924/01006 Carbon [C]
• CPC Class Codes: H01L 2924/01033 Arsenic [As]
• CPC Class Codes: H01L 2924/01082 Lead [Pb]
• CPC Class Codes: H01L 2924/014 Solder alloys
• CPC Class Codes: H01L 2924/14 Integrated circuits
• CPC Class Codes: H05K 2201/10734 Ball grid array [BGA]; Bump grid array
• CPC Class Codes: H05K 2203/074 Features related to the fluid pressure
• CPC Class Codes: H05K 2203/306 Lifting the component during or after mounting; Increasing the gap between component and PCB
• 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: Y02P 70/50 Manufacturing or production processes characterised by the final manufactured product

Abstract

There is a method for increasing the life of the mechanical bonding between the PCB and the surface mount IC. Specifically, the invention elevates the atmospheric pressure during the heating and cooling phases of Ball Grid Array (BGA) soldering of an IC device to a PCB. This accomplishes a decreasing of the curvature of the solder ball wall inherent in the typical BGA technique. Uniquely, by increasing the atmospheric pressure around the solder ball during the cooling phases, specifically, the outer pressure will decrease the outer curvature of the walls. This allows the PCB and IC to increase the stand off distance, and increase the strength of the mechanical properties of the weld. With stronger bonding, the ICs will stay bonded longer to the PCB before deteriorating and thereby needing replacement.

Claims

1. A method of bonding Ball Grid Array (BGA) soldered ICs, comprising the steps of:

a) providing a BGA soldered IC;

b) providing an appropriate PCB;

c) pressing the IC, at an appropriate location, onto the PCB;

d) heating the PCB and IC arrangement;

e) applying an atmospheric pressure above standard atmospheric pressure;

f) pulling the IC away from the PCB a distance greater than 0.025 inches; and

g) solidifying the solder bond between the IC and PCB.

2. A method of bonding ICs to a PCB, comprising:

providing an IC that has been BGA soldered;

pressing the IC onto the PCB at an appropriate location;

heating the solder until it is softened and adheres to both the IC and PCB;

increasing atmospheric pressure around the solder;

causing the stand off distance to be greater than 0.025 inches; and

solidifying the solder.

3. A method of bonding ICs to PCB, comprising the steps of:

a) providing a soldered IC;

b) providing an appropriate PCB;

c) pressing the IC, at an appropriate location, onto the PCB;

d) heating the PCB and IC arrangement;

e) applying an atmospheric pressure above standard atmospheric pressure;

f) pulling the IC away from the PCB a distance greater than what can be achieved under standard atmospheric pressure conditions; and

g) solidifying the solder bond between the IC and PCB.

4. A method of bonding ICs to a PCB, comprising:

providing an IC that has been soldered;

pressing the IC onto the PCB at an appropriate location;

heating the solder until it is softened and adheres to both the IC and PCB;

increasing atmospheric pressure around the solder;

causing the stand off distance to be greater than what can be achieved under standard atmospheric pressure conditions; and

solidifying the solder.