Systems and methods for obtaining an electrical characteristics of a circuit board assembly process

• US 6,535,005 B1
• Filed: 04/26/2000
• Issued: 03/18/2003
• Est. Priority Date: 04/26/2000
• Status: Expired due to Term

• Current Assignee: Emc IP Holding Company LLC (Dell Technologies Inc.)
• Original Assignee: EMC Corporation (Dell Technologies Inc.)
• Inventors: Field, Daniel
• Primary Examiner(s): Sherry, Michael
• Assistant Examiner(s): Nguyen, Jimmy
• Application Number:
  US09/558,638
• Time in Patent Office: 1,056 Days
• Field of Search: 324/754, 324/158.1, 324/755, 324/765, 324/763, 174/260, 174/261, 174/266, 361/760, 361/777, 361/715, 361/718, 361/719, 361/200
• US Class Current: 324/763.01
• CPC Class Codes: G01R 31/281 Specific types of tests or tests for a specific type of fault, e.g. thermal mapping, shorts testing G01R31/2818 takes precedence
• CPC Class Codes: H05K 1/0268 for electrical inspection or testing
• CPC Class Codes: H05K 1/112 directly combined with via connections

Abstract

The present invention is directed to techniques for obtaining an electrical characteristic of a circuit board assembly process which involves mounting a module to an installation location of a circuit board using the circuit board assembly process, and measuring leakage current of the test structure in response to an electrical signal (e.g., a voltage) applied to the installation location. One can then determine the surface insulation resistance (SIR) of the test structure based on the electrical signal and the leakage current in order to assess the suitability of the circuit board assembly process. One arrangement of the invention is directed to a system for obtaining an electrical characteristic of a circuit board assembly process. The system includes a test structure having (i) a circuit board having a module installation location and an interface location in electrical communication with the module installation location, and (ii) a module which is mounted to the circuit board at the module installation location using the circuit board assembly process. The system further includes a signal generator that couples to the interface location of the circuit board, and that applies an electrical signal to the module installation location of the circuit board through the interface location. Additionally, the system includes a detector that that couples to the interface location, and that measures leakage current of the test structure in response to the electrical signal. The leakage current is itself an obtained electrical characteristic of the circuit board assembly process. However, the leakage current and the electrical signal enable determination of surface insulation resistance of the test structure, as another electrical characteristic of the circuit board assembly process.

Claims

1. A system for obtaining an electrical characteristic of a circuit board assembly process, the system comprising:

a test structure that includes (i) a circuit board having a module installation location and an interface location in electrical communication with the module installation location, and (ii) a module which is mounted to the circuit board at the module installation location using a circuit board assembly process;

a signal generator that couples to the interface location of the circuit board, and that applies an electrical signal to the module installation location of the circuit board through the interface location; and

a detector that couples to the interface location, and that measures leakage current of the test structure in response to the electrical signal.

2. The system of claim 1 wherein the module includes a Ball Grid Array package, and wherein the circuit board assembly process includes a Ball Grid Array component mounting process.

3. The system of claim 1 wherein the module is soldered to the circuit board at the module installation location using a soldering process.

4. The system of claim 3 wherein the circuit board and the module, which is soldered to the circuit board using the soldering process, form a first electrical pathway and a second electrical pathway which is unconnected with the first electrical pathway in order to provide a signal identifying an amount of leakage current through the test structure in response to the electrical signal.

5. The system of claim 1 wherein the detector is configured to detect a signal indicating an amount of leakage current through the test structure.

6. The system of claim 5 wherein signal generator applies, as the electrical signal, a voltage having a voltage value;

wherein the signal indicating the amount of leakage current through the test structure is a current value; and

wherein the voltage value and the current value indicate a surface insulation resistance value of the test structure.

7. The system of claim 1 wherein the detector is configured to provide, as the leakage current measured by the detector, an amperage value indicating an amount of current passing through the test structure in response to the electrical signal.

8. A test structure for providing an electrical characteristic of a circuit board assembly process, the test structure comprising:

a circuit board having a module installation location and an interface location; and

a module mounted to the circuit board at the module installation location using a circuit board assembly process, such that an electrical signal applied to the module installation location of the circuit board through the interface location of the circuit board enables measurement of leakage current of the test structure in response to the electrical signal.

9. The test structure of claim 8 wherein the module includes a Ball Grid Array package, and wherein the circuit board assembly process includes a Ball Grid Array component mounting process.

10. The test structure of claim 8 wherein the module installation location of the circuit board includes (i) a set of first circuit board contacts which are electrically connected together, and (ii) a set of second circuit board contacts which are electrically connected together;

and wherein the module includes (i) a set of first module contacts which connects with the set of first circuit board contacts, and (ii) a set of second module contacts which connects with the set of second circuit board contacts and which is electrically isolated from the set of first module contacts.

11. The test structure of claim 8 wherein the module and the circuit board form a set of cells when the electrical signal is applied to the module installation location of the circuit board, each cell having voltage gradient lines which radially extend between solder joints connecting the module to the circuit board.

12. The test structure of claim 8 wherein the module installation location of the circuit board includes an array of contacts and a set of electrical connections, wherein each contact of an inner portion of the array has four immediately adjacent neighboring contacts, and wherein the set of electrical connections connects each contact of the inner portion to a contact other than one of the four immediately adjacent neighboring contacts of that contact.

13. The test structure of claim 8 wherein the module is soldered to the circuit board at the module installation location using a soldering process.

14. The test structure of claim 13 wherein the circuit board and the module, which is soldered to the circuit board using the soldering process, form a first electrical pathway and a second electrical pathway which is unconnected with the first electrical pathway in order to provide a signal identifying an amount of leakage current through the test structure in response to the electrical signal.

15. A test structure for providing an electrical characteristic of a circuit board assembly process, the test structure comprising:

a circuit board having a module installation location and an interface location; and

a module mounted to the circuit board at the module installation location using a circuit board assembly process, such that an electrical signal applied to the module installation location of the circuit board through the interface location of the circuit board enables measurement of leakage current of the test structure in response to the electrical signal, wherein the module installation location of the circuit board includes a set of first contacts and a set of second contacts, and wherein the electrical signal is a voltage applied between the set of first contacts and the set of second contacts in order to determine, as the electrical characteristic, a surface insulation resistance of the test structure based on the voltage and the leakage current.

16. A method for forming a test structure for obtaining an electrical characteristic of a circuit board assembly process, the method comprising the steps of:

providing a circuit board having a module installation location and an interface location in electrical communication with the module installation location; and

mounting a module to the module installation location of the circuit board using a circuit board assembly process in order to form a test structure, such that an electrical signal applied to the module installation location of the circuit board through the interface location enables measurement of leakage current of the test structure in response to the electrical signal.

17. The method of claim 16 wherein the module includes a Ball Grid Array package, and wherein the step of mounting includes the step of:

soldering the Ball Grid Array package to the module installation location of the circuit board using a Ball Grid Array component mounting process, as a portion of the circuit board assembly process.

18. The method of claim 16 wherein the module installation location of the circuit board includes (i) a set of first circuit board contacts which are electrically connected together, and (ii) a set of second circuit board contacts which are electrically connected together;

wherein the module includes (i) a set of first module contacts, and (ii) a set of second module contacts which is electrically isolated from the set of first module contacts; and

wherein the step of mounting includes the step of;

connecting the set of first module contacts to set of first circuit board contacts, and connecting the set of second module contacts to the set of second circuit board contacts.

19. The method of claim 16 wherein the step of mounting includes the step of:

forming solder joints between the module and the circuit board in order to form a set of cells when the electrical signal is applied to the module installation location of the circuit board, each cell having voltage gradient lines which radially extend between the solder joints connecting the module to the circuit board.

20. The method of claim 16 wherein the module installation location of the circuit board includes an array of contacts and a set of electrical connections, wherein each contact of an inner portion of the array has four immediately adjacent neighboring contacts, and wherein the set of electrical connections connects each contact of the inner portion to a contact other than one of the four immediately adjacent neighboring contacts of that contact.

21. The method of claim 16 wherein the step of mounting includes the step of:

soldering the module to the circuit board using a soldering process such that a first electrical pathway and a second electrical pathway which is unconnected with the first electrical pathway are formed in order to provide a signal identifying an amount of leakage current through the test structure in response to the electrical signal.

22. The method of claim 16, further comprising the step of:

detecting a signal indicating an amount of leakage current through the test structure.

23. The method of claim 22, further comprising the step of:

applying, as the electrical signal, a voltage having a voltage value such that the signal indicating the amount of leakage current through the test structure is a current value, and wherein the voltage value and the current value indicate a surface insulation resistance value of the test structure.

24. A method for forming a test structure for obtaining an electrical characteristic of a circuit board assembly process, the method comprising the steps of:

providing a circuit board having a module installation location and an interface location in electrical communication with the module installation location; and

mounting a module to the module installation location of the circuit board using a circuit board assembly process in order to form a test structure, such that an electrical signal applied to the module installation location of the circuit board through the interface location enables measurement of leakage current of the test structure in response to the electrical signal, wherein the module installation location of the circuit board includes a set of first contacts and a set of second contacts, and wherein the electrical signal is a voltage applied between the set of first contacts and the set of second contacts in order to determine, as the electrical characteristic, a surface insulation resistance of the test structure based on the voltage and the leakage current.

25. A method for obtaining an electrical characteristic of a circuit board assembly process, the method comprising the steps of:

providing a test structure that includes (i) a circuit board having a module installation location and an interface location in electrical communication with the module installation location, and (ii) a module which is mounted to the circuit board at the installation location;

applying an electrical signal to the module installation location of the circuit board through the interface location of the circuit board; and

measuring leakage current of the test structure in response to the electrical signal.

26. The method of claim 25 wherein the module includes a Ball Grid Array package, and wherein the step of providing includes the step of:

mounting the Ball Grid Array package to the module installation location of the circuit board using a Ball Grid Array component mounting process, as a portion of the circuit board assembly process.

27. The method of claim 25 wherein the module installation location of the circuit board includes (i) a set of first circuit board contacts which are electrically connected together, and (ii) a set of second circuit board contacts which are electrically connected together;

wherein the module includes (i) a set of first module contacts, and (ii) a set of second module contacts which is electrically isolated from the set of first module contacts; and

wherein the step of providing includes the step of;

mounting the module to the module installation location of the circuit board such that the set of first module contacts connect to set of first circuit board contacts, and the set of second module contacts connect to the set of second circuit board contacts.

28. The method of claim 25 wherein the step of providing includes the step of:

mounting the module to the module installation location of the circuit board such that solder joints form between the module and the circuit board in order to form a set of cells when the electrical signal is applied to the module installation location of the circuit board, each cell having voltage gradient lines which radially extend between the solder joints connecting the module to the circuit board.

29. The method of claim 25 wherein the module installation location of the circuit board includes an array of contacts and a set of electrical connections, wherein each contact of an inner portion of the array has four immediately adjacent neighboring contacts, and wherein the set of electrical connections connects each contact of the inner portion to a contact other than one of the four immediately adjacent neighboring contacts of that contact.

30. The method of claim 25, further comprising the step of:

exposing the test structure to an extreme environmental condition for a period of time in order to stress the test structure prior to the steps of applying and measuring.

31. The method of claim 25 wherein the step of providing the test structure includes the step of:

soldering the module to the circuit board using a soldering process such that a first electrical pathway and a second electrical pathway which is unconnected with the first electrical pathway are formed in order to provide a signal identifying an amount of leakage current through the test structure in response to the electrical signal.

32. The method of claim 25 wherein the step of measuring includes the step of:

detecting a signal indicating an amount of leakage current through the test structure.

33. The method of claim 32 wherein the step of applying the electrical signal includes the step of:

providing, as the electrical signal, a voltage having a voltage value such that the signal indicating the amount of leakage current through the test structure is a current value, and wherein the voltage value and the current value indicate a surface insulation resistance value of the test structure.

34. The method of claim 25 wherein the step of measuring leakage current includes the step of:

obtaining, as the leakage current, an amperage value indicating an amount of current passing through the test structure in response to the electrical signal.

35. A method for obtaining an electrical characteristic of a circuit board assembly process, the method comprising the steps of:

providing a test structure that includes (i) a circuit board having a module installation location and an interface location in electrical communication with the module installation location, and (ii) a module which is mounted to the circuit board at the installation location;

applying an electrical signal to the module installation location of the circuit board through the interface location of the circuit board;

measuring leakage current of the test structure in response to the electrical signal, wherein the module installation location of the circuit board includes a set of first contacts and a set of second contacts, and wherein the electrical signal is a voltage applied between the set of first contacts and the set of second contacts; and

determining, as the electrical characteristic, a surface insulation resistance of the test structure based on the voltage and the leakage