Method and apparatus for testing internal circuit

• US 5,818,247 A
• Filed: 07/26/1996
• Issued: 10/06/1998
• Est. Priority Date: 07/28/1995
• Status: Expired due to Fees

• Current Assignee: Daewoo Electronics (Government of South Korea)
• Original Assignee: Daewoo Electronics (Government of South Korea)
• Inventors: Pyun, Do-Sun
• Primary Examiner(s): BROWN, GLENN WARNER
• Application Number:
  US08/690,396
• Time in Patent Office: 802 Days
• Field of Search: 324/537, 324/754, 324/756, 324/757, 324/758, 324/761
• US Class Current: 324/750.19
• CPC Class Codes: G01R 31/2806 Apparatus therefor, e.g. test stations, drivers, analysers, conveyors G01R31/2805, G01R31/281, G01R31/2818 take precedence
• CPC Class Codes: G01R 31/2813 Checking the presence, location, orientation or value, e.g. resistance, of components or conductors orientation of the DUT with respect to the test fixture G01R1/06705, G01R31/281
• CPC Class Codes: G01R 31/2887 involving moving the probe head or the IC under test; docking stations moving single probes G01R1/06705; moving individual probes in multiple probes G01R1/07392

Abstract

A method and an apparatus for testing an internal circuit reduces working hours and production cost for an electronic product using a multi-fixture. A measuring pointer of a printed circuit board is decided with computer aided design data stored in the control part, and when the CAD data is not available, the measuring pointer of the printed circuit board can be programmed by sensing the pressure values for a printed circuit board with a pressure sensor. The amount of time spent when producing an electronic product using a multi-fixture is reduced and the productivity of the product by providing a product with a measuring section for measuring pointer for various models of the printed circuit board is improved. Further, the production cost of an electronic product is reduced because the test can be performed without manufacturing special fixtures. The space application is improved since the storing space of the special fixture is saved.

Claims

1. A method for testing an internal circuit, said method comprising the steps of:

a) storing in a control means reference values and set allowable values for a plurality of electronic components to be tested;

b) judging whether or not computer aided design data, including component information data and component position data for the electronic components installed in a printed circuit board, are stored in the control means;

c) when the computer aided design data is judged to be stored in the control means in said step b), positioning tester pins of a multi-fixture in an electronic component to be tested using the component position data of the computer aided design data, and judging a point where a solder pointer of the printed circuit board and a measuring pointer of the multi-fixture cross each other;

d) when the computer aided design data is not judged to be stored in the control means in said step b), calculating the pressure of each pointer in the printed circuit board, and judging which section is a solder of the printed circuit board and which section is a lead of the electronic component according to whether the calculated pressure is relatively high or low;

e) storing a first measured pointer data according to the point judged in said step c) where the solder pointer of the printed circuit board and the measured pointer of the multi-fixture cross each other, storing a second measured pointer data according to the section judged in said step d) to be the solder of the printed circuit board, and storing a third measured pointer data according to the section judged in said step d) to be the lead of the electronic component;

f) loading the first, second and third measured pointer data stored in the control means, and measuring the printed circuit board with the electronic components mounted thereon, in order to achieve a measurement result; and

g) judging whether or not a total area of the printed circuit board is measured completely, when the total area of the printed circuit board is not measured completely, moving the multi-fixture into a next area of the printed circuit board, to return said step f), and when the total area of the printed circuit board is measured completely, comparing a measured result achieved in said step f) with the reference value corresponding to the electrical component being tested stored in the control means in step a), and judging whether or not the electronic component has degraded.

2. The method for testing an internal circuit as claimed in claim 1, wherein the computer aided design data includes the component information data, the component position data, pattern data, solder mask data for the electronic components.

3. The method for testing an internal circuit as claimed in claim 1, wherein the pressure of the lead of the electronic component is higher than that of the solder of the printed circuit board.

4. The method for testing an internal circuit as claimed in claim 1, wherein the step of measuring the printed circuit board with the electronic component mounted thereon in said step f), comprises the substeps of:

applying a measured reference voltage to the electronic component;

feedbacking the voltage passing through the electronic component; and

comparing the feedbacked voltage with the corresponding reference value stored in the control means, and displaying whether or not the electronic component is good based on whether or not the feed backed voltage is at or above the permitted set value corresponding to the electric component being tested stored in the control means.

5. The method for testing an internal circuit as claimed in claim 4, wherein the measuring reference voltage is 2.5 volts and the feedbacked voltage is lower than the measuring reference voltage.

6. The method for testing an internal circuit as claimed in claim 4, wherein said step g) further comprises the substep of displaying a result of whether or not the electronic component has degraded after judging whether or not the electronic component has degraded.

7. A method of testing an internal circuit, said method comprising the steps of:

i) storing in a control means reference values and set allowable values for a plurality of electronic components to be tested;

ii) judging whether or not computer aided design data for the electronic components installed in a printed circuit board, including component information data, component position data indicating distances of the electronic components from a reference point on the printed circuit board in X and Y axial directions, pattern data, and solder mask data, are stored in the control means;

iii) when the computer aided design data are stored in the control means, positioning tester pins of a multi-fixture in an electronic component to be tested using the component position data of the computer aided design data, and judging a point where the solder pointer of the printed circuit board and a measuring pointer of the multi-fixture cross each other;

iv) when the computer aided design data is not stored in the control means, calculating first and second pressures of first and second measuring pointers respectively of a solder of the printed circuit board and a lead of the electronic component;

v) comparing the first pressure with the second pressure calculated in said step iv), and judging based on whether the first or the second pressure is relatively higher or lower, which section is the solder of the printed circuit board and which section is the lead of the electronic component;

vi) storing in the control means a first measuring pointer data according to the point judged in said step iii) where the solder pointer of the printed circuit board and the measuring pointer of the multi-fixture cross each other, a second measuring pointer data according to the solder of the printed circuit board, and a third measuring pointer data according to the section judged in said step iv) to be the lead of the electronic component;

vii) loading the first, second, and third measuring pointer data stored in the control means, and measuring the printed circuit board with the electronic components mounted thereon, in order to achieve a measurement result; and

viii) judging whether or not a total area of the printed circuit board is measured completely, so that when the total area of the printed circuit board is not measured completely, moving the multi-fixture into a next area of the printed circuit board, to return to said step vii), and when the total area of the printed circuit board, to return to said step vii), and when the total area of the printed circuit board is measured completely, comparing a measured result achieved in said step vii) with the reference value of the corresponding electrical component being tested stored in the control means in said step i), and judging whether or not the electronic component has degraded and displaying information about a degraded state.

8. An apparatus for testing an internal circuit, said apparatus comprising:

a multi-fixture having a plurality of tester pins of the same size, uniformly spaced apart from each other, and movable along at least one printed circuit board on which at least one electronic component is mounted;

a motor for controlling the position of said multi-fixture relative to said circuit board and for moving said multi-fixture along said circuit board;

a first means for selecting a plurality of measuring modes, respectively relating to resistance, capacitance, inductance, and reactance for the electronic component, for applying a measuring reference voltage to the electronic component, and for outputting a voltage feedbacked from the at least one electronic component;

a second means, including at least one switch connected to the tester pins of said multi-fixture, for switching to apply the measuring reference voltage from said first means to the electronic component, and to apply a feedbacked voltage of the applied measuring reference voltage from the electronic component to said first means;

a pressure sensor for calculating which section is a solder of the printed circuit and which section is a lead of the electronic component;

a third means for storing reference values and set allowable values for a plurality of electronic components to be tested, for selectively storing computer aided design data having component information data and component position data of the electronic components, for controlling said first means so that said first means selects the measuring modes of the electronic components, for judging which section is the solder of the printed circuit board and which section is the lead of the electronic component according to whether the sensed pressure from said pressure sensor is relatively high or low, for using the judged measured pointers and controlling said first means so that said first means measures the electronic component, for comparing the resulting voltage values measured by said first means with the stored reference values to judge whether or not the electronic component has degraded based on whether the value is at or above the stored set allowable value, and for controlling a switching operation of said second means and an operation of said motor; and

a displaying device for displaying the resulting measured data judged by said third means.

9. The apparatus for testing an internal circuit as claimed in claim 8, wherein said multi-fixture moves in X and Y axial directions so that said first means measures at least the dimension of the printed circuit board.

10. The apparatus for testing an internal circuit as claimed in claim 8, wherein said multi-fixture includes a plurality of springs positioned around the tester pins to absorb shocks when the tester pins contact the printed circuit board.

11. The apparatus for testing an internal circuit as claimed in claim 8, wherein the tester pins in said multi-fixture are comprised of a conductor.

12. The apparatus for testing an internal circuit as claimed in claim 8, wherein said motor includes a stepping motor that rotates at an angle in proportion to pulse numbers by applying a pulse signal as a pressure.

13. The apparatus for testing an internal circuit as claimed in claim 8, wherein said first means includes an analog-digital converter for converting the received feedbacked voltage from the electronic component into a digital value.

14. The apparatus for testing an internal circuit as claimed in claim 8, wherein said second means includes a relay.

15. The apparatus for testing an internal circuit as claimed in claim 8, wherein said second means is comprised of a complementary metal-oxide semiconductor transistor.

16. The apparatus for testing an internal circuit as claimed in claim 8, wherein said third means further includes a motor controlling section for controlling a speed of said motor using a motor controlling program.

17. The apparatus for testing an internal circuit as claimed in claim 8, wherein said displaying device includes a monitor.

18. An apparatus for testing an internal circuit, said apparatus comprises:

a multi-fixture having a plurality of tester pins of the same size, uniformly spaced apart from each other, a plurality of springs positioned around said tester pins to absorb a shock when the tester pins contact the printed circuit board, and movable along at least one printed circuit board, on which at least one electronic component is mounted;

a stepping motor for controlling the position of said multi-fixture for moving said multi-fixture along at least one printed circuit board;

a first means, including an analog-digital converter, for converting a received feedbacked voltage from the electronic component into a digital value, for selecting a plurality of measuring modes, respectively relating to resistance, capacitance, inductance, and reactance for the electronic component, for applying a measuring reference voltage to the electronic component, and for outputting a voltage feedbacked from the electronic component;

a second means having at least one switch connected to the tester pins of said multi-fixture for switching to apply the measuring reference voltage from said first means to the electronic component and to apply a feedbacked voltage of the applied measuring reference voltage from the electronic component to said first means;

a pressure sensor for calculating which section is a solder of the printed circuit and which section is a lead of the electronic component;

a third means for storing reference values and set allowable values for a plurality of electronic components to be tested, for selectively storing computer aided design data having component information data and component position data of the electronic components, for controlling said first means so that said first means selects the measuring modes of the electronic components, for judging which section is the solder of the printed circuit board and which section is the lead of the electronic component based on whether the sensed pressure from said pressure sensor is relatively high or low, for using the judged measured pointers and controlling said first means so that said first means measures the electronic component, for comparing the resulting voltage values measured by said first means with the stored reference values to judge whether or not the electronic component has degraded based on whether the value is at or above the stored set allowable value, said third means including a motor controlling section for operating said stepping motor, and for controlling a switching operation of said second means and the operation of said motor; and

a monitor for displaying the resulting measured data judged by said third means.

19. The apparatus for testing an internal circuit as claimed in claim 18, wherein said multi-fixture moves in X and Y axial directions so that said first means measures at least the dimension of the printed circuit board, and wherein the tester pins in said multi-fixture are comprised of a conductor.

20. The apparatus for testing an internal circuit as claimed in claim 18, wherein said second means is comprised of a complementary metal-oxide semiconductor transistor.