Substrate for mounting electronic part and electronic part

• US 20060237231A1
• Filed: 03/20/2006
• Published: 10/26/2006
• Est. Priority Date: 04/25/2005
• Status: Active Grant

• Current Assignee: Hitachi Kyowa Engineering Company Limited (Hitachi, Ltd.)
• Original Assignee: Hitachi Kyowa Engineering Company Limited (Hitachi, Ltd.)
• Inventors: Matsushima, Naoki, Hata, Shohei, Fujinaga, Takeru
• Granted Patent: US 7,511,232 B2
• Time in Patent Office: Days
• US Class Current: 174/521
• CPC Class Codes: H01L 2224/0554 External layer
• CPC Class Codes: H01L 2224/0555 Shape
• CPC Class Codes: H01L 2224/0556 Disposition
• CPC Class Codes: H01L 2224/05568 the whole external layer protruding from the surface
• CPC Class Codes: H01L 2224/05573 Single external layer
• CPC Class Codes: H01L 2224/05599 Material
• CPC Class Codes: H01L 2224/05647 Copper [Cu] as principal constituent
• CPC Class Codes: H01L 2224/13 of an individual bump connector
• CPC Class Codes: H01L 2224/13099 Material
• CPC Class Codes: H01L 2224/131 with a principal constituent of the material being a metal or a metalloid, e.g. boron [B], silicon [Si], germanium [Ge], arsenic [As], antimony [Sb], tellurium [Te] and polonium [Po], and alloys thereof
• CPC Class Codes: H01L 2224/13111 Tin [Sn] as principal constituent
• CPC Class Codes: H01L 2224/45099 Material
• CPC Class Codes: H01L 2224/451 with a principal constituent of the material being a metal or a metalloid, e.g. boron (B), silicon (Si), germanium (Ge), arsenic (As), antimony (Sb), tellurium (Te) and polonium (Po), and alloys thereof
• CPC Class Codes: H01L 2224/48091 Arched
• CPC Class Codes: H01L 2224/48247 connecting the wire to a bond pad of the item
• CPC Class Codes: H01L 2224/81801 Soldering or alloying
• CPC Class Codes: H01L 23/49582 Metallic layers on lead frames
• CPC Class Codes: H01L 23/49811 Additional leads joined to the metallisation on the insulating substrate, e.g. pins, bumps, wires, flat leads H01L23/49827 takes precedence
• CPC Class Codes: H01L 23/4985 Flexible insulating substrates H01L23/49572 and H01L23/49855 take precedence
• CPC Class Codes: H01L 23/49866 characterised by the materials materials of the substrates H01L23/14, of the lead-frames H01L23/49579
• CPC Class Codes: H01L 24/10 : Bump connectors bumps on insulating substrates, e.g. chip carriers, H01L23/49816; Manufacturing methods related thereto
• CPC Class Codes: H01L 24/13 : of an individual bump connector
• CPC Class Codes: H01L 24/48 : of an individual wire connector
• CPC Class Codes: H01L 24/81 : using a bump connector
• 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 2924/01006 : Carbon [C]
• CPC Class Codes: H01L 2924/01019 : Potassium [K]
• CPC Class Codes: H01L 2924/01022 : Titanium [Ti]
• CPC Class Codes: H01L 2924/01024 : Chromium [Cr]
• CPC Class Codes: H01L 2924/01029 : Copper [Cu]
• CPC Class Codes: H01L 2924/0103 : Zinc [Zn]
• CPC Class Codes: H01L 2924/01033 : Arsenic [As]
• CPC Class Codes: H01L 2924/01047 : Silver [Ag]
• CPC Class Codes: H01L 2924/0105 : Tin [Sn]
• CPC Class Codes: H01L 2924/01068 : Erbium [Er]
• 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 2924/01084 : Polonium [Po]
• 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 2924/10253 : Silicon [Si]
• CPC Class Codes: H01L 2924/10329 : Gallium arsenide [GaAs]
• CPC Class Codes: H01L 2924/15787 : Ceramics, e.g. crystalline carbides, nitrides or oxides
• CPC Class Codes: H01L 2924/15788 : Glasses, e.g. amorphous oxides, nitrides or fluorides
• CPC Class Codes: H01L 2924/181 : Encapsulation
• CPC Class Codes: H01L 2924/19041 : being a capacitor
• CPC Class Codes: H01L 2924/19043 : being a resistor
• CPC Class Codes: H05K 3/3426 : characterised by the leads
• CPC Class Codes: H05K 3/3463 : Solder compositions in relation to features of the printed circuit board or the mounting process

Abstract

The present invention is characterized by a structure having a substrate 1, and metallization layers 2 formed on the substrate 1, on which a Sn solder film 3 and an Ag film 4 are formed. The Ag film 4 is a metal free from oxidization at room temperature in the atmosphere. In a wet process, since only an exposed side of the Sn solder film 3 is oxidized by the cell reaction of Ag and Sn, an upper surface of the Ag film 4 on the solder film, which would otherwise affect the connection, is not oxidized. Since the Ag film 4 melts into the Sn solder simultaneously with melting of the Sn solder film 3, the Ag film 4 does not hinder the connection.

Claims

1. A substrate for mounting an electronic part, comprising:

a base material;

metallization layers formed on the base material; and

a Sn solder portion formed on a part of a surface of said metallization layers;

wherein the substrate further comprises an Ag film formed on a surface of the Sn solder portion, the surface being used for mounting the electronic part.

2. The substrate for mounting an electronic part as claimed in claim 1, wherein the Sn solder portion is composed of an alloy solder containing Sn as a main component.

3. The substrate for mounting an electronic part as claimed in claim 1, wherein the Ag film is composed of an alloy containing Ag as a main component.

4. The substrate for mounting an electronic part as claimed in claim 1, wherein the Ag film is formed so that a ratio of Ag is 73 wt % or less based on a total amount of the Sn solder portion and the Ag film.

5. The substrate for mounting an electronic part as claimed in claim 1, wherein the substrate further comprises an Au film formed on the Ag film.

6. An electronic part comprising:

a base material;

metallization layers formed on the base material; and

a Sn solder portion formed on a part of a surface of said metallization layers;

wherein the electronic part further comprises an Ag film formed on a surface of the Sn solder portion.

8. The electronic part as claimed in claim 6, wherein the Sn solder portion is composed of an alloy solder containing Sn as a main component.

10. The electronic part as claimed in claim 6, wherein the Ag film is composed of an alloy containing Ag as a main component.

12. The electronic part as claimed in claim 6, wherein the Ag film is formed so that a ratio of Ag is 73 wt % or less based on a total amount of the Sn solder portion and the Ag film.

14. The electronic part as claimed in claim 6, wherein an Au film is formed on the Ag film.

7. An electronic part comprising:

a lead frame;

a function element mounted on the lead frame;

a plurality of bonding wires which connect terminals said function element and leads of the lead frame; and

a resin part molding the function element, the plurality of bonding wires and a part of the lead frame;

wherein leads extending outward from the resin part are subjected to Sn plating, and Ag film are formed on connecting portions of the leads which are subjected to Sn plating.

9. The electronic part as claimed in claim 7, wherein the Sn solder portion is composed of an alloy solder containing Sn as a main component.

11. The electronic part as claimed in claim 7, wherein the Ag film is composed of an alloy containing Ag as a main component.

13. The electronic part as claimed in claim 7, wherein the Ag film is formed so that a ratio of Ag is 73 wt % or less based on a total amount of the Sn solder portion and the Ag film.

15. The electronic part as claimed in claim 7, wherein an Au film is formed on the Ag film.