Method of mounting electronic component on substrate without generation of voids in bonding material

• US 7,159,309 B2
• Filed: 02/12/2002
• Issued: 01/09/2007
• Est. Priority Date: 09/19/2001
• Status: Active Grant

• Current Assignee: Fujitsu Limited
• Original Assignee: Fujitsu Limited
• Inventors: Yamada, Hiroshi, Yamamoto, Tsuyoshi, Suehiro, Mitsuo
• Primary Examiner(s): Kim; Paul D.
• Application Number:
  US10/073,106
• Publication Number:
  US 20030051905A1
• Time in Patent Office: 1,792 Days
• Field of Search: 298/31, 298/32, 298/40, 298/41, 298/44, 298/46, 298/51, 298/54, 156/64, 156/356, 156/357, 156/358, 228/175, 228/227, 228/180.22, 174/259, 174/260, 361/770, 361/804, 257/686, 257/778, 438/103, 438/106, 438/112, 438/118, 438/119, 438/127
• US Class Current: 29/832
• CPC Class Codes: H01L 2224/29035 covering only the peripheral area of the surface to be connected
• CPC Class Codes: H01L 2224/29036 covering only the central area of the surface to be connected
• CPC Class Codes: H01L 2224/73103 Bump and layer connectors
• CPC Class Codes: H01L 2224/73204 the bump connector being embedded into the layer connector
• CPC Class Codes: H01L 2924/00012 Relevant to the scope of the group, the symbol of which is combined with the symbol of this group
• CPC Class Codes: H05K 2201/0129 Thermoplastic polymer, e.g. auto-adhesive layer; Shaping of thermoplastic polymer
• CPC Class Codes: H05K 2201/10734 Ball grid array [BGA]; Bump grid array
• CPC Class Codes: H05K 2201/10977 Encapsulated connections applying non-metallic protective coatings for encapsulating mounted components H05K3/284
• CPC Class Codes: H05K 2203/0182 Using a temporary spacer element or stand-off during processing
• CPC Class Codes: H05K 2203/0475 Molten solder just before placing the component
• CPC Class Codes: H05K 2203/1105 Heating or thermal processing not related to soldering, firing, curing or laminating, e.g. for shaping the substrate or during finish plating
• 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 3/3494 Heating methods for reflowing of solder using integral heating means H05K1/0212
• CPC Class Codes: Y02P 70/50 Manufacturing or production processes characterised by the final manufactured product
• CPC Class Codes: Y10T 29/4913 Assembling to base an electrical component, e.g., capacitor, etc.
• CPC Class Codes: Y10T 29/49144 by metal fusion
• CPC Class Codes: Y10T 29/49146 with encapsulating, e.g., potting, etc.
• CPC Class Codes: Y10T 29/49151 by deforming or shaping
• CPC Class Codes: Y10T 29/49155 Manufacturing circuit on or in base
• CPC Class Codes: Y10T 29/49163 : with sintering of base
• CPC Class Codes: Y10T 29/49169 : Assembling electrical component directly to terminal or elongated conductor

Abstract

When an electronic component is mounted on a substrate, the electronic component is first placed on the substrate with a solid support interposed between the electronic component and the substrate. The solid support serves to space a terminal conductor of the electronic component from a corresponding terminal pad on the substrate. A conductive bonding material is then melted on the terminal pad. The melted conductive bonding material gets exposed to the peripheral atmosphere over a larger area. Even if a bubble is generated within the melted conductive bonding material, the bubble is allowed to easily get out of the melted conductive bonding material. Removal of the gas is promoted in the melted conductive bonding material. The solid support is subsequently melted. The electronic component is moved down toward the substrate, thereby contacting the terminal conductor with the melted conductive bonding material on the corresponding terminal pad. Removal of the gas in this manner leads to improvement in the strength of bonding between the substrate and the electronic component.

Claims

1. A method of mounting an electronic component on a substrate, comprising:

placing the electronic component on the substrate with a solid support interposed between the electronic component and the substrate so as to space a terminal conductor of the electronic component from a corresponding terminal pad on the substrate;

melting a conductive bonding material on the terminal pad; and

thereafter

melting the solid support so as to move down the electronic component toward the substrate, thereby contacting the terminal conductor with the conductive bonding material melting on the corresponding terminal pad, wherein the electronic component drops toward the substrate based on its own weight in response to melting of the solid support.

2. The method according to claim 1, wherein said solid support is made of a thermoplastic resin material having a melting point higher than that of the conductive bonding material.

3. The method according to claim 1, wherein said conductive bonding material comprises solder particles dispersed in a flux including an organic solvent.

4. The method according to claim 1, wherein said solid support has an adherent property on its surface.