Implementing micro BGA assembly techniques for small die

• US 6,655,022 B1
• Filed: 09/24/1998
• Issued: 12/02/2003
• Est. Priority Date: 09/24/1998
• Status: Expired due to Term

• Current Assignee: Micron Technology, Inc.
• Original Assignee: Intel Corporation
• Inventors: Foehringer, Richard B., Kaller, Deborah S., Eskildsen, Steven R.
• Primary Examiner(s): Tugbang, A. Dexter
• Application Number:
  US09/160,535
• Time in Patent Office: 1,895 Days
• Field of Search: 298/27, 298/25, 298/30, 298/31, 298/32, 298/41, 257/791, 257/777, 257/778, 257/779, 438/126, 438/127, 438/111, 438/112, 427/96
• US Class Current: 29/841
• CPC Class Codes: H01L 23/16 Fillings or auxiliary members in containers or encapsulations, e.g. centering rings H01L23/42, H01L23/552 take precedence
• CPC Class Codes: H01L 23/4985 Flexible insulating substrates H01L23/49572 and H01L23/49855 take precedence
• 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 2924/0002 Not covered by any one of groups H01L24/00, H01L24/00 and H01L2224/00
• CPC Class Codes: H01R 4/024 comprising preapplied solder
• CPC Class Codes: Y10T 29/49121 Beam lead frame or beam lead device
• CPC Class Codes: Y10T 29/4913 Assembling to base an electrical component, e.g., capacitor, etc.
• CPC Class Codes: Y10T 29/49146 with encapsulating, e.g., potting, etc.

Abstract

A method of implementing a micro BGA is introduced. More specifically, the method discloses packaging an integrated circuit into an integrated circuit assembly. The method first mounts polyimide tape to a lead frame. The polyimide tape serves as a substrate for the integrated circuit package. Next, a piece of elastomer is coupled to said polyimide tape. Then an integrated circuit die is attached to said elastomer. Lead beams are then bonded from bond pads on said die to said lead frame. Solder balls are attached to said lead frame. The attached solder balls may be located beyond the area of said die.

Claims

1. A method of packaging an integrated circuit into an integrated circuit assembly, said method comprising:

mounting flexible polyimide tape to a lead frame, wherein said flexible polyimide tape serves as a substrate of a micro BGA package;

coupling elastomer to said flexible polyimide tape;

attaching a die to said elastomer;

bonding lead beams from bond pads on said die to said lead frame;

attaching a solder mask to said lead frame, said solder mask having a plurality of solder mask openings to expose solder landings on said lead frame, said solder mask having a larger size than said die wherein length and width dimensions of said solder mask extend beyond length and width dimensions of said die;

encapsulating a periphery of said die, said lead beams, and said solder mask with an encapsulation material, wherein a plurality of stiffener piece parts are added to said encapsulation material beyond said periphery of said die, said stiffener piece parts to provide a stiffening function for said micro BGA package; and

attaching solder balls to solder landings coupled on said lead frame, said solder balls arranged in a ball grid array wherein at least one of said attached solder balls is located beyond surface area of said die in a horizontal direction such that said attached solder balls overhang area of said die.

2. The method of claim 1 further comprising covering said integrated circuit assembly with the encapsulation material.

3. The method of claim 2 wherein said assembly comprises of lead beams, die attach, and edges of said die.

4. The method of claim 1 further comprising:

reflowing said integrated circuit assembly; and

cleaning said integrated circuit assembly.

5. The method of claim 1 further comprising singulating said integrated circuit assembly from said substrate.

6. The method of claim 2 further comprising curing the encapsulated integrated circuit assembly.

7. The method of claim 1 wherein said attaching solder balls to said lead frame further comprises of fluxing attachment sites on said lead frame.

8. The method of claim 1 wherein said solder balls in said ball grid array have a 0.75 millimeter pitch.

9. The method of claim 1 further comprising the step of covering said integrated circuit assembly with epoxy, said epoxy functioning as a stiffener.

10. The method the claim 9 wherein said assembly comprises of lead beams, die attach, and edges of said die.

11. The method of claim 1 wherein said die is a flash memory.