Residual material detection in backdrilled stubs

Patent metadata

Field	Value
Publication number	US-9739825-B2
Application number	US-201615205617-A
Country	US
Kind code	B2
Filing date	Jul 8, 2016
Priority date	May 20, 2014
Publication date	Aug 22, 2017
Grant date	Aug 22, 2017

Abstract

A stub of a via formed in a printed circuit board is backdrilled to a predetermined depth. A capacitance probe is positioned within the via. Then the capacitance probe is used to obtain a test capacitance measurement. The test capacitance measurement is compared to a predetermined baseline capacitance measurement. Residual conductive plating material in the backdrilled stub causes the test capacitance measurement to exceed the predetermined baseline capacitance measurement. An indication is made that the predetermined baseline capacitance measurement has been exceeded.

First claim

What is claimed is:

1. A method for measuring and assessing the adequacy of a backdrilling operation, the method comprising:
obtaining a test capacitance measurement of a backdrilled stub of a via formed in a printed circuit board;
comparing the test capacitance measurement to a baseline capacitance measurement, residual conductive plating material in the backdrilled stub causing the test capacitance measurement to exceed the baseline capacitance measurement; and
indicating that the test capacitance measurement exceeds the baseline capacitance measurement.

2. The method of claim 1 , wherein the obtaining the test capacitance measurement is performed using a capacitance probe.

3. The method of claim 2 further comprising:
prior to the using the capacitance probe to obtain the test capacitance measurement, positioning the capacitance probe within the via.

4. The method of claim 1 , wherein the baseline capacitance measurement is a predetermined baseline capacitance measurement.

5. The method of claim 1 , further comprising:
in response to the indicating that the test capacitance measurement exceeds the baseline capacitance measurement, re-drilling the stub.

6. The method of claim 1 , further comprising:
adjusting the baseline capacitance measurement based on the sensitivity of an interface with which the via is intended to be associated.

7. A system for measuring and assessing the adequacy of a backdrilling operation, the system comprising:
a capacitance probe deployment device; and
a computer operatively coupled to the capacitance probe deployment device, the computer configured to:
instruct the capacitance probe deployment device to use a capacitance probe to obtain a test capacitance measurement of a backdrilled stub of a via formed in a printed circuit board;
compare the test capacitance measurement to a baseline capacitance measurement, the residual conductive plating material in the backdrilled stub causing the test capacitance measurement to exceed the baseline capacitance measurement; and
indicate that the test capacitance measurement exceeds the baseline capacitance measurement.

8. The system of claim 7 , wherein the computer is further configured to:
prior to the capacitance probe obtaining the test capacitance measurement, instruct the capacitance probe deployment device to position the capacitance probe with the via.

9. The system of claim 8 , wherein the baseline capacitance measurement is a predetermined baseline capacitance measurement.

10. The system of claim 7 , wherein the indicating that the test capacitance measurement exceeds the baseline capacitance measurement includes instructing a drill device to re-drill the stub.

11. The system of claim 7 , wherein the computer is further configured to:
adjust the baseline capacitance measurement based on the sensitivity of an interface with which the via is intended to be associated.

12. A computer program product for measuring and assessing the adequacy of a backdrilling operation, the computer program product comprising a computer readable storage medium having instructions embodied therewith, the instructions executable by a computer to cause the computer to:
instruct a capacitance probe deployment device to use a capacitance probe to obtain a test capacitance measurement of a backdrilled stub of a via formed in a printed circuit board;
compare the test capacitance measurement to a baseline capacitance measurement, the residual conductive plating material in the backdrilled stub causing the test capacitance measurement to exceed the baseline capacitance measurement; and
indicate that the test capacitance measurement exceeds the baseline capacitance measurement.

13. The computer program product of claim 12 , wherein the instructions are further executable by the computer to cause the computer to:
prior to the capacitance probe obtaining the test capacitance measurement, instruct the capacitance probe deployment device to position the capacitance probe within the via.

14. The computer program product of claim 13 , wherein the baseline capacitance measurement is a predetermined baseline capacitance measurement.

15. The computer program product of claim 12 , wherein the indicating that the test capacitance measurement exceeds the baseline capacitance measurement includes instructing a drill device to re-drill the stub.

16. The computer program product of claim 12 , wherein the instructions are further executable by the computer to cause the computer to:
adjust the baseline capacitance measurement based on the sensitivity of an interface with which the via is intended to be associated.

Assignees

• IBM

Inventors

• Bartley Gerald K
• Becker Darryl J
• Doyle Matthew S
• Germann Philip R
• Maxson Mark O

Classifications

• G01R27/2605

  Measuring capacitance (capacitive sensors G01D5/24) · CPC title

• G01R31/28

  Testing of electronic circuits, e.g. by signal tracer ({EMC, EMP or similar testing of electronic circuits G01R31/002;} testing for short-circuits, discontinuities, leakage or incorrect line connection G01R31/50; checking computers {or computer components} G06F11/00; checking static stores for correct operation G11C29/00 {; testing receivers or transmitters of transmission systems H04B17/00}) · CPC title

• H05K3/0047 Primary

  Drilling of holes · CPC title

• G01R31/2801 Primary

  Testing of printed circuits, backplanes, motherboards, hybrid circuits or carriers for multichip packages [MCP] (G01R31/318508 takes precedence; contactless testing G01R31/302; testing contacts or connections G01R31/66) · CPC title

• H05K1/0251

  related to vias or transitions between vias and transmission lines · CPC title