Electronic component

• US 6,259,593 B1
• Filed: 12/14/1999
• Issued: 07/10/2001
• Est. Priority Date: 12/18/1998
• Status: Expired due to Term

• Current Assignee: Murata Manufacturing Co Limited
• Original Assignee: Murata Manufacturing Co Limited
• Inventors: Nishiyama, Shigeki, Moriwaki, Nobushige
• Primary Examiner(s): Dinkins, Anthony
• Application Number:
  US09/460,049
• Time in Patent Office: 574 Days
• Field of Search: 361/306.1, 361/306.3, 361/307, 361/368.1, 361/309, 361/310, 361/321.2, 361/321.3, 361/321.5
• US Class Current: 361/303
• CPC Class Codes: B23K 35/262 Sn as the principal constituent
• CPC Class Codes: H01G 4/008 Selection of materials
• CPC Class Codes: H05K 3/3442 having edge contacts, e.g. leadless chip capacitors, chip carriers
• CPC Class Codes: H05K 3/3463 Solder compositions in relation to features of the printed circuit board or the mounting process

Abstract

A coating layer composed of a solder containing tin as the major component and a metal such as copper or silver which is the same as that contained in a external electrode in an amount greater than the eutectic concentration, is formed on the external electrode. The solder can suppress the solid-phase diffusion without formation of the barrier layer.

Claims

1. An electronic component comprising an electronic component body, an external electrode comprising a metal on the electronic component body, and a coating on the external electrode, wherein the coating comprises a tin solder containing the same metal as contained in the external electrode in an amount greater than the eutectic concentration thereof.

2. An electronic component according to claim 1, wherein the external electrodes contain copper and the solder contains in an amount of at least 0.7 percent by weight.

3. An electronic component according to claim 2, wherein the solder contains more than about 1 percent by weight of copper.

4. An electronic component according to claim 3, wherein the solder contains about 5 percent by weight or less of copper.

5. An electronic component according to claim 2, wherein the solder contains about 5 percent by weight or less of copper.

6. An electronic component according to claim 1, wherein the external electrodes contain silver and the solder contains silver in an amount of at least 3.5 percent by weight.

7. An electronic component according to claim 6, wherein the solder contains more than about 5 percent by weight of silver.

8. An electronic component according to claim 7, wherein the solder contains about 15 percent by weight or less of silver.

9. An electronic component according to claim 6, wherein the solder contains about 15 percent by weight or less of silver.

10. An electronic component according to claim 1, wherein the solder contains about 1 percent by weight or less of zinc.

11. An electronic component according to claim 1, wherein the external electrode has a thickness greater than the thickness of a solid-phase layer of the solder diffused therein under the temperature conditions in use for which the electronic component is designed to be subjected.

12. An electronic component according to claim 1, wherein the coating layer is a melted solder dipping layer or a solder reflow layer.

13. An electronic component according to claim 1, wherein the electronic component body comprises ceramic.

14. An electronic component according to claim 13 having at least one internal electrode electrically in the interior of the electronic component body and connected to the external electrode.

15. An electronic component according to claim 14, wherein the electronic component is a monolithic ceramic capacitor.

16. An electronic component according to claim 1, further comprising a terminal coupled to the external electrode via the coating.

17. An electronic component according to claim 1, having a pair of external electrodes on the body, each of which has said coating thereon.

18. An electronic component according to claim 1, wherein the coating covers the entire external electrode surface.

19. An electronic component according to claim 1, wherein the coating covers less than the entire external electrode surface.