Resistor having moisture resistant layer

• US 6,201,290 B1
• Filed: 01/08/1999
• Issued: 03/13/2001
• Est. Priority Date: 01/08/1998
• Status: Expired due to Fees

• Current Assignee: Matsushita Electric Industrial Company Limited (Panasonic Holdings Corporation)
• Original Assignee: Matsushita Electric Industrial Company Limited (Panasonic Holdings Corporation)
• Inventors: Nakatani, Mitsunari, Yamada, Hiroyuki
• Primary Examiner(s): Abraham, Fetsum
• Application Number:
  US09/228,025
• Time in Patent Office: 795 Days
• Field of Search: 257/358, 257/359, 257/363, 257/489
• US Class Current: 257/536
• CPC Class Codes: H01C 1/032 plural layers surrounding the resistive element H01C1/028 takes precedence
• CPC Class Codes: H01C 17/006 adapted for manufacturing resistor chips
• CPC Class Codes: H01C 7/003 Thick film resistors

Abstract

A resistor comprising a substrate typically made of aluminum, a pair of top electrode layers made of a thin noble metal film disposed on both ends of the top face of the substrate, and a resistance layer of a thin metal film made of Ni system or Cr system disposed on the top face of the substrate so as to electrically connect with the top electrode layer. The moisture absorbency of a protective layer is reduced to upgrade sealing of the resistance layer by covering the resistance layer with two resin layers: a first protective layer made of polyimide resin and a second protective layer made of epoxy resin, which have different water vapor permeability, to improve the reliability, particularly the moisture resistance characteristics, of the resistor.

Claims

1. A resistor comprising:

a substrate having a top face;

a pair of top electrode layers disposed on sides of the top face of said substrate;

a resistance layer disposed on the top face of said substrate so as to electrically connect with said top electrode layers;

a first resin protective layer disposed to cover at least an exposed area of said resistance layer on the top face of said substrate; and

a second resin protective layer disposed to cover at least said first protective layer

wherein said first protective layer has a first water vapor permeability which is greater than a second water vapor permeability of said second protective layer.

2. The resistor as defined in claim 1, wherein said first protective layer comprises a polyimide resin and said second protective layer comprises an epoxy resin.

3. The resistor as defined in claim 1, wherein said first protective layer and said second protective layer are both comprised of epoxy resin.

4. The resistor as defined in claim 1, wherein said resistance layer is a thin metal film comprising at least one of Ni, Cr, and Ta.

5. The resistor as defined in claim 1, wherein said top electrode layers are thin metal films comprising at least one of Ni, Au, and Cu.

6. A resistor comprising:

a substrate having a top face;

a pair of top electrode layers disposed on sides of the top face of said substrate;

a resistance layer disposed on the top face of said substrate so as to electrically connect with said top electrode layers;

a first resin protective layer disposed to cover at least an exposed area of said resistance layer on the top face of said substrate; and

a second resin protective layer disposed to cover at least said first protective layer,

wherein said first protective layer comprises a polyimide resin and said second protective layer comprises an epoxy resin.