Semiconductor device leadframe die attach pad having a raised bond pad

• US 5,859,387 A
• Filed: 11/29/1996
• Issued: 01/12/1999
• Est. Priority Date: 11/29/1996
• Status: Expired due to Term

• Current Assignee: Allegro Microsystems Incorporated (Sanken Electric Company Limited)
• Original Assignee: Allegro Microsystems Incorporated (Sanken Electric Company Limited)
• Inventors: Gagnon, Jay J
• Primary Examiner(s): Ledynh, Bot L.
• Assistant Examiner(s): Ngo, Hung V.
• Application Number:
  US08/758,403
• Time in Patent Office: 774 Days
• Field of Search: 174/52.4, 257/666, 257/670, 257/672, 257/674, 257/676, 257/678, 257/692, 257/693, 361/723, 361/820
• US Class Current: 174/531
• CPC Class Codes: H01L 2224/05599 Material
• CPC Class Codes: H01L 2224/45144 Gold (Au) as principal constituent
• 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 2224/48247 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 2224/48599 Principal constituent of the connecting portion of the wire connector being Gold (Au)
• CPC Class Codes: H01L 2224/49171 Fan-out arrangements
• CPC Class Codes: H01L 2224/85399 Material
• CPC Class Codes: H01L 23/49503 characterised by the die pad
• CPC Class Codes: H01L 23/49562 for devices being provided for in H01L29/00
• CPC Class Codes: H01L 24/45 of an individual wire connector
• CPC Class Codes: H01L 24/48 of an individual wire connector
• CPC Class Codes: H01L 24/49 of a plurality of wire connectors
• 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 2924/01005 Boron [B]
• CPC Class Codes: H01L 2924/0105 Tin [Sn]
• CPC Class Codes: H01L 2924/01079 Gold [Au]
• CPC Class Codes: H01L 2924/01322 : Eutectic Alloys, i.e. obtained by a liquid transforming into two solid phases
• CPC Class Codes: H01L 2924/014 : Solder alloys
• CPC Class Codes: H01L 2924/14 : Integrated circuits
• CPC Class Codes: H01L 2924/181 : Encapsulation
• CPC Class Codes: H01L 2924/351 : Thermal stress

Abstract

A semiconductor device includes a lead frame assembly having a die attach pad with a die secured by a die bonding material. A portion of the die bonding material may flow out from between the die and the die attach pad to form a squash out layer. A raised bond pad is at least partially in the squash out layer area and extends upward from said die attach pad sufficient to be above the squash out layer. A bond wire has one end secured to a ground terminal on the die and the other end to the raised bond pad. The whole structure is encapsulated in a plastic package.

Claims

1. A semiconductor device lead frame assembly adapted to be encapsulated by a plastic package, comprising:

a die attach pad,

inner bond fingers spaced apart from a die attach pad,

said lead frame having dual gauge metal portions, said die attach pad being in a portion with reduced thickness,

said die attach pad having its thickness so dimensioned that the bottom of said die attach pad does not extend through said plastic package,

said die attach pad adapted to allow a die to be secured to said die attach pad by a die bonding material, a portion of said die bonding material which flows out from between said die and said die attach pad to form a squash out layer covering a first area of said die attach pad, and

a raised bond pad, at least partially in said first area, extending upward from said die attach pad sufficient to be above said squash out layer.

2. The semiconductor device lead frame assembly of claim 1, adapted to allow a bond wire to have one end secured to said die and the other end to said raised bond pad, wherein said raised bond pad is so dimensioned upward to reduce the angle at which said bond wire attaches to the raised bond pad so as to create a secure bond attachment resistant to thermal cycling stresses and not contacting the edge of the die.

3. The semiconductor device lead frame assembly of claim 1, wherein said raised bond pad is formed upward from a portion of said die attach pad.

4. The semiconductor device lead frame assembly of claim 3, wherein said portion of said die attach pad is slit and formed upward from said die attach pad.

5. The semiconductor device lead frame assembly of claim 4, wherein two sides of said raised bond pad are secured to said die attach pad and so dimensioned so as to be self supporting and able to be wire bonded without support fixtures.

6. A semiconductor device, comprising:

a plastic package,

a lead frame having a die attach pad and inner bond fingers spaced apart from said die attach pad,

said lead frame having dual gauge metal portions, said die attach pad being in a portion with reduced thickness,

said die attach pad having its thickness so dimensioned that the bottom of said die attach pad does not extend through said plastic package,

a die secured to said die attach pad by a die bonding material, a portion of said die bonding material which flows out from between said die and said die attach pad to form a squash out layer covering a first area of said die attach pad,

a raised bond pad at least partially in said first area extending upward from said die attach pad sufficient to be above said squash out layer,

a bond wire having one end secured to said die and the other end to said raised bond pad, and

said plastic package encapsulating said die, die attach pad, raised bond pad and bond wire.

7. The semiconductor device of claim 6, wherein said raised bond pad is so dimensioned upward to reduce the angle at which said bond wire attaches to the raised bond pad so as to create a secure bond attachment resistant to thermal cycling stresses and not contacting the edge of the die.

8. The semiconductor device of claim 7, wherein said raised bond pad is formed upward from a portion of said die attach pad.

9. The semiconductor device of claim 8, wherein said portion is slit and formed upward from said die attach pad.

10. The semiconductor device of claim 9, wherein said raised bond pad is secured to said die attach pad on two sides of said raised bond pad and is so dimensioned to be self supporting and able to be wire bonded without support fixtures.