Method for screening early failure of ceramic capacitor

• US 5,510,719 A
• Filed: 08/16/1994
• Issued: 04/23/1996
• Est. Priority Date: 08/20/1993
• Status: Expired due to Term

• Current Assignee: Murata Manufacturing Co Limited
• Original Assignee: Murata Manufacturing Co Limited
• Inventors: Yamamoto, Shigekatsu
• Primary Examiner(s): Wieder, Kenneth A.
• Assistant Examiner(s): BROWN, GLENN WARNER
• Application Number:
  US08/291,158
• Time in Patent Office: 616 Days
• Field of Search: 324/548, 324/555, 324/658, 324/678, 324/679, 324/684, 324/685, 324/690, 324/501, 209/574, 320/1
• US Class Current: 324/548
• CPC Class Codes: G01R 31/64 Testing of capacitors
• CPC Class Codes: Y10S 320/13 Fault detection

Abstract

A method of screening ceramic capacitors. The method includes the steps of: charging the ceramic capacitors by applying a constant d.c. voltage which is larger than the rated voltage and smaller than the breakdown voltage; and leaving the charged ceramic capacitor in a temperature around the maximum working temperature for a specific period of time with both terminals of each ceramic capacitor opened electrically; and eliminating defective capacitors whose residual voltage values are smaller than a specific voltage value.

Claims

1. A method of screening early failure of ceramic capacitors comprising the steps of:

charging each ceramic capacitor by applying a d.c. voltage which is larger than a rated voltage of the ceramic capacitor and smaller than a breakdown voltage of the ceramic capacitor;

opening both terminals of each of the charged ceramic capacitors electrically, and leaving the capacitors for a predetermined period of time at a temperature around a predetermined maximum working temperature;

measuring residual voltage values of the ceramic capacitors after said predetermined period of time, identifying capacitors whose residual voltage values are smaller than a predetermined voltage value as being defective, and eliminating such defective capacitors.

2. A screening method as claimed in claim 1, further comprising the step of connecting a high input impedance buffer in series between the capacitor and a measuring apparatus while the residual voltage value of each ceramic capacitor is measured.

3. A screening method as claimed in claim 1, wherein the ceramic capacitors are charged at room temperature.

4. A screening method as claimed in claim 1, wherein the ceramic capacitors are charged at a temperature around the maximum working temperature.

5. A screening method as claimed in claim 1, wherein the residual voltage values of the ceramic capacitors are measured at room temperature.

6. A screening method as claimed in claim 1, wherein the residual voltage values of the ceramic capacitors are measured at a temperature around the maximum working temperature.