Surface mount type package unit and method for manufacturing the same

• US 5,901,046 A
• Filed: 12/10/1997
• Issued: 05/04/1999
• Est. Priority Date: 12/10/1996
• Status: Expired due to Term

• Current Assignee: DENSO Corporation
• Original Assignee: DENSO Corporation
• Inventors: Ohta, Tameharu, Yamasaki, Takashi, Gohara, Kenichi
• Primary Examiner(s): Picard, Leo P.
• Assistant Examiner(s): FOSTER, DAVID A
• Application Number:
  US08/988,402
• Time in Patent Office: 510 Days
• Field of Search: 361/728, 361/736, 361/737, 361/743, 361/748, 361/763, 361/767, 361/772, 361/764, 361/783, 257/723, 257/724, 174/260, 174/250, 174/255, 174/52.5, 438/53
• US Class Current: 361/760
• CPC Class Codes: H01L 2224/05554 being square
• CPC Class Codes: H01L 2224/32225 the item being non-metallic, e.g. insulating substrate with or without metallisation
• CPC Class Codes: H01L 2224/48137 the bodies being arranged next to each other, e.g. on a common substrate
• CPC Class Codes: H01L 2224/48227 connecting the wire to a bond pad of the item
• CPC Class Codes: H01L 2224/49175 Parallel arrangements
• CPC Class Codes: H01L 2224/73265 Layer and wire connectors
• 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 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 2924/10156 at the periphery
• CPC Class Codes: H01L 2924/16195 Flat cap [not enclosing an internal cavity]
• CPC Class Codes: H01L 2924/351 Thermal stress
• CPC Class Codes: H05K 1/111 Pads for surface mounting, e.g. lay-out
• CPC Class Codes: H05K 2201/09154 Bevelled, chamferred or tapered edge
• CPC Class Codes: H05K 2201/09781 Dummy conductors, i.e. not used for normal transport of current; Dummy electrodes of components
• CPC Class Codes: H05K 2201/10727 Leadless chip carrier [LCC], e.g. chip-modules for cards
• CPC Class Codes: H05K 2203/306 Lifting the component during or after mounting; Increasing the gap between component and PCB
• CPC Class Codes: H05K 3/3442 having edge contacts, e.g. leadless chip capacitors, chip carriers
• CPC Class Codes: Y02P 70/50 Manufacturing or production processes characterised by the final manufactured product

Abstract

A package body holding an acceleration sensor circuit therein has signal electrodes and four dummy electrodes insulated from the signal electrode on a mounted surface thereof. The signal electrodes are electrically connected to the sensor circuit element. The mounted surface of the package body has chamfered portions on verge portions thereof, and auxiliary electrodes are formed on the chamfered portions to be integrally connected to the signal electrodes. The thus constructed package body is mounted on a circuit board by a reflow method using a solder paste so that the signal, dummy, and auxiliary electrodes are connected to a wiring pattern on the circuit board through solder portions. In this process, the solder paste on the dummy electrodes in a fused state generate an internal pressure to retain a clearance between the package body and the circuit board. As a result, the thickness of the solder portions between the package body and the circuit board can be secured, and reliability at a mounted state is improved.

Claims

1. A surface mount type package unit comprising:

a circuit board;

a conductive member provided on the circuit board;

a package body having a mounted surface and mounted on the circuit board with the mounted surface facing the circuit board through the conductive member;

a circuit element held on the package body;

a signal electrode provided on the mounted surface of the package body adjacently to an end portion of the mounted surface and electrically connected to the circuit element, the signal electrode directly connected to the conductive member of the circuit board through solder; and

a dummy electrode provided on the mounted surface of the package body and connected to the conductive member of the circuit board through solder;

wherein the solder between the signal electrode and the conductive member is exposed to an outside of the mounted surface of the package body when the signal electrode is joined to the conductive member through the solder; and

wherein a clearance between the package body and the circuit board is held by an internal pressure generated in the solder between the dummy electrode and the conductive member in a fused state of the solder.

2. The surface mount type package unit according to claim 1, wherein the signal electrode has a shape extending from a center portion of the mounted surface to an end portion of the mounted surface.

3. The surface mount type package unit according to claim 1, wherein:

the mounted surface of the package body has a chamfered portion on a verge portion thereof;

an auxiliary electrode is provided on the chamfered portion to be connected to the signal electrode; and

the auxiliary electrode is joined to the conductive member of the circuit board by the solder when the signal electrode is joined to the conductive member by the solder.

4. The surface mount type package unit according to claim 1, wherein the circuit board has a main surface on which the package body is mounted, and the main surface of the circuit board is substantially parallel to the mounted surface of the package body.

5. The surface mount type package unit according to claim 1, wherein an area of the mounted surface of the package body is the largest of all surfaces of the package body.

6. The surface mount type package unit according to claim 1, wherein the dummy electrode has a circular shape.

7. The surface mount type package unit according to claim 1, wherein the dummy electrode includes a plurality of dummy electrode members, and the dummy electrode members are arranged on the mounted surface symmetrically with respect to a center of the mounted surface.

8. The surface mount type package unit according to claim 1, wherein the auxiliary electrode is partially provided on the chamfered portion at a position adjacent to the mounted surface of the package body.

9. The surface mount type package unit according to claim 1, wherein the circuit element includes a circuit for processing an electrical signal of a sensor.

10. The surface mount type package unit according to claim 9, wherein the circuit element includes an element for converting a dynamic amount into an electrical signal.

11. The surface mount type package unit according to claim 10, wherein the dynamic amount is an amount of acceleration.

12. A method for manufacturing a surface mount type package unit including a package body directly mounted on a circuit board through solder, the method comprising steps of:

forming a signal electrode on a mounted surface of the package body;

forming a dummy electrode on the mounted surface of the package body to be in a non-contacting state with respect to the signal electrode;

chamfering a verge portion of the mounted surface to form a chamfered portion;

forming an auxiliary electrode on the chamfered portion to contact the signal electrode;

preparing the circuit board having a conductive member on a surface thereof; and

bonding the signal electrode, the dummy electrode and the auxiliary electrode of the package body to the conductive member of the circuit board by fused solder.

13. The method for manufacturing a surface mount type package unit according to claim 12, the signal electrode and the dummy electrode are formed in the same process.

14. The method for manufacturing a surface mount type package unit according to claim 12, wherein the dummy electrode is formed into a circular shape.

15. The method for manufacturing a surface mount type package unit according to claim 12, wherein the dummy electrode is composed of a plurality of dummy electrode members, and the plurality of dummy electrode members are formed on the mounted surface of the package body with a symmetrical arrangement with respect to a center of the mounted surface.

16. The method for manufacturing a surface mount type package unit according to claim 12, wherein the auxiliary electrode is partially formed on the chamfered portion at a position adjacent to the mounted surface.

17. A surface mount type package unit comprising:

a circuit board;

first and second conductive members provided on the circuit board;

a package body mounted on the circuit board via the first and second conductive members, the package body having a mounted surface facing the circuit board and a secondary surface adjacent to the mounted surface, the secondary surface being non-parallel to the mounted surface;

a circuit element held on the package body;

a signal electrode provided on the mounted surface of the package body to face the first conductive member of the circuit board, and electrically connected to the circuit element;

a first solder portion provided between the signal electrode and the first conductive member to make contact between the signal electrode and the first conductive member;

an auxiliary electrode provided on the secondary surface of the package body to face the first conductive member, and integrally connected to the signal electrode;

a auxiliary solder portion provided between the auxiliary electrode and the first conductive member, and integrally connected to the first solder portion;

a dummy electrode provided on the mounted surface of the package body to face the second conductive member of the circuit board, and electrically insulated from the signal electrode and the first conductive member; and

a second solder portion provided between the dummy electrode and the second conductive member.

18. The surface mount type package unit according to claim 17, wherein the secondary surface is a chamfered portion of the mounted surface.

19. The surface mount type package unit according to claim 17, wherein the auxiliary solder portion is exposed to the outside of the package unit.

20. The surface mount type package unit according to claim 17, wherein the dummy electrode has a circular shape.

21. The surface mount type package unit according to claim 20, wherein the second solder portion has a barrel-like shape.