Method of making an electronic assembly

• US 7,510,108 B2
• Filed: 07/26/2005
• Issued: 03/31/2009
• Est. Priority Date: 07/26/2005
• Status: Expired due to Fees

• Current Assignee: Apple Inc.
• Original Assignee: Delphi Technologies, Inc. (BorgWarner Incorporated)
• Inventors: Lawlyes, Daniel A., Laudick, David A.
• Primary Examiner(s): Stoner; Kiley
• Assistant Examiner(s): SAAD, ERIN BARRY
• Application Number:
  US11/190,130
• Publication Number:
  US 20070023488A1
• Time in Patent Office: 1,344 Days
• Field of Search: 228/180.22, 228/179.1, 228/222, 257/704, 257/706, 257/778, 361/783, 361/760, 438/106, 438/108
• US Class Current: 228/179.1
• CPC Class Codes: H01L 21/563 Encapsulation of active face of flip-chip device, e.g. underfilling or underencapsulation of flip-chip, encapsulation preform on chip or mounting substrate
• CPC Class Codes: H01L 21/565 Moulds
• CPC Class Codes: H01L 2224/16225 the item being non-metallic, e.g. insulating substrate with or without metallisation
• CPC Class Codes: H01L 2224/32225 the item being non-metallic, e.g. insulating substrate with or without metallisation
• CPC Class Codes: H01L 2224/73203 Bump and layer connectors
• CPC Class Codes: H01L 2224/73204 the bump connector being embedded into the layer connector
• CPC Class Codes: H01L 2224/73253 Bump and layer connectors
• CPC Class Codes: H01L 2224/83102 using surface energy, e.g. capillary forces
• CPC Class Codes: H01L 2224/92125 the second connecting process involving a layer connector
• CPC Class Codes: H01L 24/28 Structure, shape, material or disposition of the layer connectors prior to the connecting process
• 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 2924/01029 Copper [Cu]
• CPC Class Codes: H01L 2924/01082 Lead [Pb]
• CPC Class Codes: H01L 2924/14 Integrated circuits

Abstract

A method of making an electronic assembly comprising an electronic component that is attached to a circuit board by protruding solder bumps of the electronic component places the electronic component on a surface of the circuit board so that solder bumps on the bottom of the electronic component engage contact pads on the top of the circuit board. The solder bumps are then reflowed to attach the electronic component to the circuit board after which the electronic component is underfilled by providing a mold die having a mold cavity, a gate leading into the mold cavity and a vent leading out of the mold cavity. The mold die is placed over the electronic component and onto the surface of the circuit board so that the electronic component is inside the mold cavity and the mold cavity is sealed. An encapsulating material, preferably an epoxy material, is transferred or injected into the mold cavity to fill space between the respective surfaces of the electronic component and the circuit board and then cured to encapsulate the solder bumps that have been reflowed. An optional integrated heat sink for the electronic component may be used when practicing the method of the invention to make an electronic assembly.

Claims

1. A method of making an electronic assembly having a laminated circuit board with contact pads on a surface and a flip chip having protruding solder bump on a surface comprising the steps of:

placing the flip chip on the surface of the laminated circuit board so that the solder bumps of the flip chip engage the contact pads of the laminated circuit device,

providing a heat sink shell having a window, placing the heat sink shell over the flip chip and onto the surface of the laminated circuit board,

providing a mold die having a mold cavity, a gate leading into the mold cavity and a vent leading out of the mold cavity,

placing the mold die over the heat sink shell and onto the surface of the laminated circuit device outwardly of the flip chip so that the flip chip and the heat sink are in the mold cavity and the mold cavity is sealed, and

injecting an epoxy material through the gate into the mold cavity and through the window into space between the flip chip and the laminated circuit board, such that the epoxy material encapsulates the solder bumps and contacts.

2. The method of making the electronic assembly of claim 1 wherein the heat sink shell has a peripheral wall engaging the laminated circuit board and wherein the window is disposed in the peripheral wall of the heat sink shell for epoxy to pass through and into the space between the respective surfaces of the flip chip and the laminated circuit board.

3. The method of making the electronic assembly of claim 1 wherein the mold die is removed and the electronic assembly is trimmed to remove any epoxy runners from the gate and the vent.