Multi-strand substrate for ball-grid array assemblies and method

• US 6,465,743 B1
• Filed: 12/05/1994
• Issued: 10/15/2002
• Est. Priority Date: 12/05/1994
• Status: Expired due to Term

• Current Assignee: North Star Innovations Inc. (Wi-LAN Inc.)
• Original Assignee: Motorola, Inc. (Motorola Solutions, Inc.)
• Inventors: Owens, Norman Lee
• Primary Examiner(s): PALADINI, ALBERT WILLIAM
• Application Number:
  US08/349,281
• Time in Patent Office: 2,871 Days
• Field of Search: 174/261, 174/266, 174/262, 174/260, 298/46, 298/30, 361/760, 361/765, 361/767, 361/810, 257/684, 257/687, 257/737
• US Class Current: 174/260
• CPC Class Codes: H01L 21/481 Insulating layers on insulating parts, with or without metallisation
• CPC Class Codes: H01L 21/4846 Leads on or in insulating or insulated substrates, e.g. metallisation H01L21/4821 takes precedence; metallisation of ceramics in general C04B41/51; printed circuits H05K3/00
• CPC Class Codes: H01L 2224/05599 Material
• CPC Class Codes: H01L 2224/32225 the item being non-metallic, e.g. insulating substrate with or without metallisation
• CPC Class Codes: H01L 2224/45015 being circular
• CPC Class Codes: H01L 2224/45099 Material
• CPC Class Codes: H01L 2224/48091 Arched
• CPC Class Codes: H01L 2224/48227 connecting the wire to a bond pad of the item
• CPC Class Codes: H01L 2224/48465 the other connecting portion not on the bonding area being a wedge bond, i.e. ball-to-wedge, regular stitch
• CPC Class Codes: H01L 2224/73265 Layer and wire connectors
• CPC Class Codes: H01L 2224/83 using a layer connector
• CPC Class Codes: H01L 2224/85 using a wire connector
• CPC Class Codes: H01L 2224/85399 Material
• CPC Class Codes: H01L 2224/97 the devices being connected to a common substrate, e.g. interposer, said common substrate being separable into individual assemblies after connecting
• CPC Class Codes: H01L 23/13 characterised by the shape
• CPC Class Codes: H01L 23/49816 Spherical bumps on the substrate for external connection, e.g. ball grid arrays [BGA]
• CPC Class Codes: H01L 24/48 of an individual wire connector
• CPC Class Codes: H01L 24/73 Means for bonding being of different types provided for in two or more of groups H01L24/10, H01L24/18, H01L24/26, H01L24/34, H01L24/42, H01L24/50, H01L24/63, H01L24/71
• CPC Class Codes: H01L 24/97 the devices being connected to a common substrate, e.g. interposer, said common substrate being separable into individual assemblies after connecting
• 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 2924/00012 : Relevant to the scope of the group, the symbol of which is combined with the symbol of this group
• CPC Class Codes: H01L 2924/00014 : the subject-matter covered by the group, the symbol of which is combined with the symbol of this group, being disclosed without further technical details
• CPC Class Codes: H01L 2924/01006 : Carbon [C]
• CPC Class Codes: H01L 2924/01029 : Copper [Cu]
• CPC Class Codes: H01L 2924/01033 : Arsenic [As]
• CPC Class Codes: H01L 2924/01078 : Platinum [Pt]
• CPC Class Codes: H01L 2924/01079 : Gold [Au]
• CPC Class Codes: H01L 2924/01082 : Lead [Pb]
• CPC Class Codes: H01L 2924/01087 : Francium [Fr]
• CPC Class Codes: H01L 2924/12042 : LASER
• CPC Class Codes: H01L 2924/12044 : OLED
• CPC Class Codes: H01L 2924/14 : Integrated circuits
• CPC Class Codes: H01L 2924/15311 : being a ball array, e.g. BGA
• CPC Class Codes: H01L 2924/181 : Encapsulation
• CPC Class Codes: H01L 2924/207 : Diameter ranges
• CPC Class Codes: H01L 2924/3025 : Electromagnetic shielding
• CPC Class Codes: H05K 2201/09063 : Holes or slots in insulating substrate not used for electrical connections
• CPC Class Codes: H05K 3/0052 : Depaneling, i.e. dividing a panel into circuit boards; Working of the edges of circuit boards
• CPC Class Codes: H05K 3/0097 : Processing two or more printed circuits simultaneously, e.g. made from a common substrate, or temporarily stacked circuit boards H05K3/0052 takes precedence
• CPC Class Codes: Y10T 29/49126 : Assembling bases
• CPC Class Codes: Y10T 29/4913 : Assembling to base an electrical component, e.g., capacitor, etc.
• CPC Class Codes: Y10T 29/49222 : forming array of contacts or terminals

Abstract

A multi-strand printed circuit board substrate for ball-grid array (BGA) assemblies includes a printed wiring board (11) having a plurality of BGA substrates (12) arranged in N rows (14) and M columns (16) to form an N by M array. N and M are greater than or equal to 2 and the size of the N by M array is selected such that each of the plurality of BGA substrates (12) maintains a planarity variation less than approximately 0.15 mm (approximately 6 mils). The printed wiring board (11) has a thickness (26) sufficient to minimize planarity variation and to allow a manufacturer to use automated assembly equipment without having to use support pallets or trays.

Claims

1. A method for assembling ball-grid array (BGA) packages, comprising the steps of:

providing a plurality of BGA substrates arranged in an N by M array within a printed circuit board having a thickness, wherein N and M are greater than or equal to 2, each of the plurality of BGA substrates having a plurality of bond posts on one side and a plurality of contact pads on an opposite side;

attaching a semiconductor die to each of the plurality of BGA substrates, the semiconductor die having a plurality of bond pads;

encapsulating the semiconductor die with an encapsulant;

curing the encapsulant;

attaching conductive solder balls to each of the plurality of contact pads; and

dividing the N by M array into separate BGA packages, and wherein each of the separate BGA packages is substantially planar.

2. The method of claim 1 wherein the step of encapsulating the semiconductor die includes encapsulating with an encapsulant having a thermal coefficient of expansion close to that of the semiconductor die and the printed circuit board, and wherein size of the N by M array and the thickness are such that each of the plurality of BGA substrates maintains a planarity variation less than approximately 0.15 mm after assembly.

3. The method of claim 1 wherein the step of providing the plurality of BGA substrates arranged in the N by M array within the printed circuit board includes providing the plurality of BGA substrates within a printed circuit board having a plurality of stress-relief slots at various locations within the printed circuit board.

4. The method of claim 1 wherein the step of providing the plurality of BGA substrates arranged in the N by M array within the printed circuit board includes providing the plurality of BGA substrates within a printed circuit board having a thickness in a range from approximately 0.5 mm to approximately 0.8 mm.

5. The method of claim 1 wherein the step of providing the plurality of BGA substrates arranged in the N by M array within the printed circuit board includes providing the plurality of BGA substrates within a printed circuit board having a width on an order of 63 mm.

6. The method of claim 1 wherein the step of providing the plurality of BGA substrates arranged in the N by M array within the printed circuit board includes providing the plurality of BGA substrates within a printed circuit board having a length in a range from approximately 187 mm to 212 mm.

7. The method of claim 1 further comprising the steps of:

bonding conductive wires to the plurality of bond pads and the plurality of bond posts after the step of attaching the semiconductor die; and

marking the BGA packages after the step of encapsulating the semiconductor die.

8. The method of claim 1 wherein the step of providing the plurality of BGA substrates arranged in the N by M array within the printed circuit board includes providing the plurality of BGA substrates within a printed circuit board comprises of an organic resin.