Method for estimating the service life of a power semiconductor component

• US 5,877,419 A
• Filed: 03/04/1997
• Issued: 03/02/1999
• Est. Priority Date: 03/14/1996
• Status: Expired due to Fees

• Current Assignee: Siemens AG
• Original Assignee: Siemens AG
• Inventors: Farokhzad, Babak
• Primary Examiner(s): Biegel, Ronald L.
• Assistant Examiner(s): AMROZOWICZ, PAUL DOUGLAS
• Application Number:
  US08/811,289
• Time in Patent Office: 728 Days
• Field of Search: 73/432.1, 324/719, 324/765, 324/766, 324/768, 324/769
• US Class Current: 73/432.1
• CPC Class Codes: G01R 31/2608 for testing bipolar transistors
• CPC Class Codes: H01L 2224/4847 the connecting portion on the bonding area of the semiconductor or solid-state body being a wedge bond
• CPC Class Codes: H01L 2224/4911 the connectors being bonded to at least one common bonding area, e.g. daisy chain
• 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 2924/13055 Insulated gate bipolar transistor [IGBT]

Abstract

A method which exploits the phenomenon that an increase of the collector-emitter voltage U_CE of a semiconductor power component during a load change test can be correlated with the service life expectancy of the relevant IGBT module. A method for estimating the service life of a power semiconductor component, comprising the steps of subjecting the component to a periodic load change, measuring an electrical parameter P of the component that serves as an indicator for reliability or durability against the number N of load changes, calculating a derivative dP/dN of the electrical parameter P according to the number N of load changes; and comparing the derivative dP/dN with a target value representing a determined service life. The characteristic "longer-lived than a reference module" or, respectively, "more resistant to failure" can be allocated to a test module if the derivatives of the respective voltage U_CE satisfy the condition (dU_CE /dN)_Test <(dU_CE /dN)_Ref after the number N of load changes.

Claims

1. A method for estimating the service life of an IGBT, comprising the steps of:

subjecting the IGBT to a periodic load change;

measuring an electrical parameter P of the IGBT that serves as an indicator for reliability or durability against the number N of load changes;

calculating a derivative dP/dN of the electrical parameter P according to the number N of load changes; and

comparing the derivative dP/dN with a target value representing a determined service life.

2. The method according to claim 1, wherein the derivative dP/dN is compared with a derivative (dP/dN)_Ref, measured for a reference element under the same conditions and within the same interval of N load changes.

3. The method according to claim 2, wherein the IGBT is rated as longer-lived in relation to the reference element as long as the condition

4. The method according to claim 2, wherein at least a second derivative d² P/dN² is calculated and compared with a corresponding second derivative (d² P/dN²)_Ref of the reference element.

5. The method according to claim 2, wherein a warning signal is produced if the derivative dP/dN is larger than the target value.

6. The method according to any one of claims 1 to 5, wherein the parameter P is selected from the group consisting of a potential difference between two terminals of the IGBT, an ohmic resistance between two terminals or an ohmic resistance of an IGBT terminal.

7. The method according to claim 6, wherein the IGBT comprises an emitter terminal, an auxiliary emitter terminal and a collector terminal, a resistance (R_EH) between the emitter terminal and the auxiliary emitter terminal, a resistance of the emitter (R_E) or a resistance of the auxiliary emitter (R_H), or a collector-emitter voltage (U_CEsat) is measured against the number N of load changes.

8. A method for estimating the service life of an IGBT, comprising the steps of:

subjecting the IGBT to a periodic load change;

measuring an electrical parameter P of the IGBT that serves as an indicator for reliability or durability against the number N of load changes;

calculating a derivative dP/dN of the electrical parameter P according to the number N of load changes; and

comparing the derivative dP/dN with a target value representing a determined service life,

wherein the derivative dP/dN is compared with a derivative (dP/dN)_Ref, measured for a reference element under the same conditions and within the same interval of N load changes,

wherein at least a second derivative is calculated,

wherein the parameter P is selected from the group consisting of a potential difference between two terminals of the IGBT, an ohmic resistance between two terminals or an ohmic resistance of an IGBT terminal, and

wherein the IGBT comprises an emitter terminal, an auxiliary emitter terminal and a collector terminal, a resistance (R_EH) between the emitter terminal and the auxiliary emitter terminal, a resistance of the emitter (R_E) or a resistance of the auxiliary emitter (R_H), or a collector-emitter voltage (U_CEsat) is measured against the number N of load changes.

9. The method according to claim 8, wherein the IGBT is rated as longer-lived in relation to the reference element as long as the condition

10. The method according to claim 8 or 9, wherein a warning signal is produced if the derivative dP/dN is larger than the target value.