Compound resistor manufacturing method

• US 4,907,341 A
• Filed: 12/31/1987
• Issued: 03/13/1990
• Est. Priority Date: 02/27/1987
• Status: Expired due to Fees

• Current Assignee: John Fluke Mfg. Co., Inc.
• Original Assignee: John Fluke Mfg. Co., Inc.
• Inventors: Duperon, David N., Chapel, Roy W. Jr.
• Primary Examiner(s): ECHOLS, PERCY W
• Application Number:
  US07/140,294
• Time in Patent Office: 803 Days
• Field of Search: 29/610.1, 29/612, 219/121.69, 219/121.85, 335/195, 335/3, 335/9, 335/13, 335/25, 335/308
• US Class Current: 29/612
• CPC Class Codes: H01C 17/232 Adjusting the temperature coefficient; Adjusting value of resistance by adjusting temperature coefficient of resistance
• CPC Class Codes: Y10T 29/49082 Resistor making
• CPC Class Codes: Y10T 29/49085 Thermally variable

Abstract

This invention relates to a proces of manufacturing and adjusting a compound resistor. The compound resistor is formed of a resistive material forming a predominant portion of the resistance and having a small negative temperature coefficient of resistance coupled with an adjustment material having an extremely low resistance and a very high positive temperature coefficient of resistance. After forming the resistive and adjustment portions, a portion of the adjustment material is removed to adjust the composite TCR of the compound resistor substantially to zero without significantly affecting resistance.

Claims

1. A method for making a compound resistor, comprising the steps of:

forming a first portion of said compound resistor with a first resistance and a first temperature coefficient of resistance;

forming a second portion of said compound resistor with a second resistance and a second temperature coefficient of resistance, said second resistance different in magnitude from said first resistance and said second temperature coefficient of resistance different from and opposite in direction from said first temperature coefficient of resistance; and

removing portions of one of said first and second portions until the composite temperature coefficient of resistance of said first and second portions is substantially zero.

2. The method of claim 1, wherein said first and second portions are connected in series with each other.

3. A method of making a compound resistor, comprising the steps of:

(a) depositing a higher resistivity thin film material on a substrate;

(b) depositing a lower resistivity thin film material on said higher resistivity material;

(c) removing a portion of said lower resistivity material to form a portion having a first resistance and a positive temperature coefficient of resistance;

(d) removing a portion of said higher resistivity material to form a resistive portion connected to and at least partially underlying said lower resistivity material having a second resistance substantially larger than said first resistance and a negative temperature coefficient of resistance substantially smaller than said positive temperature coefficient of resistance;

(e) measuring a composite temperature coefficient of resistance of the resulting total resistance portions;

(f) removing portions of said lower resistivity material; and

(g) repeating said measuring and removing steps and until the temperature coefficient of resistance measures in the range of plus or minus 0.5 ppm/°

C.

4. The method as related in claim 3 wherein:

said repeating said measuring and removing steps are repeated until the temperature coefficient of resistance measures absolute zero.

5. The method as recited in claim 3 including:

hermetically sealing said adjustment and resistive portions under a laser transparent cover before the step of measuring; and

laser removing portions without effecting said hermetic sealing after the step of measuring.

6. The method of claim 3, wherein said first and second portions are connected in series with each other.

7. A method for making a compound resistor, comprising the steps of:

depositing a first resistance material having a first resistivity on a substrate;

depositing a second resistance material having a second resistivity less than said first resistivity on said first resistance material;

removing a portion of said second resistance material to form an adjustment portion having a first resistance and first positive temperature coefficient of resistance;

removing a portion of said first resistance material to form a resistive portion connected to said adjustment portion and having a second resistance substantially larger in magnitude than said first resistance and a negative temperature coefficient of resistance substantially smaller in magnitude than said first positive temperature coefficient of resistance;

measuring the temperature coefficient of resistance of said compound resistor; and

removing portions of one of said first and second resistance materials until the temperature coefficient of resistance of said compound resistor measures substantially zero.

8. The method as recited in claim 7 including:

hermetically sealing said adjustment and resistive portions before the step of measuring the temperature coefficient of resistances; and

laser removing portions after the step of measuring the temperature coefficient of resistances.

9. A method for making a compound resistor, comprising the steps of:

depositing on a substrate a first resistance material having a first resistivity;

depositing on said substrate a second resistance material having a second resistivity lower than the first resistivity of said first resistance material;

removing a portion of said second resistance material to form an adjustment portion having a first value of resistance and a positive temperature coefficient of resistance, said first resistance material having a value of resistance that is substantially larger than that of said first value of resistance and a negative temperature coefficient of resistance that is substantially smaller in magnitude than that of said positive temperature coefficient of resistance;

removing a portion of said first resistance material to form first and second resistive portions, at least one of said first and second resistive portions connected to said adjustment portion;

measuring a ratio of the temperature coefficient of resistances between (a) one of said first and second resistive portions and said adjustment portion and (b) the other of said first and second resistive portions;

removing a portion of said second resistance material; and

repeating the measuring and removing steps until the ratio of the temperature coefficient of resistances is substantially zero.