Dynamic force measurement system

• US 4,884,223 A
• Filed: 03/22/1988
• Issued: 11/28/1989
• Est. Priority Date: 07/05/1985
• Status: Expired due to Fees

• Current Assignee: HyBond AS
• Original Assignee: HyBond AS
• Inventors: Ingle, Lloyd D., Allen, Henry V., Knutti, James W.
• Primary Examiner(s): Lall, Parshotam S.
• Assistant Examiner(s): Dixon, Joseph L.
• Application Number:
  US07/170,036
• Time in Patent Office: 616 Days
• Field of Search: 364/506, 364/508, 364/550, 364/556, 364/558, 364/567, 73/862.27, 73/862.51, 73/862.52, 73/862.53, 73/862.67, 901/33, 901/46
• US Class Current: 702/41
• CPC Class Codes: G01L 1/22 using resistance strain gauges
• CPC Class Codes: G01L 5/0038 applying a pushing force
• CPC Class Codes: G01L 5/0076 Force sensors associated with manufacturing machines G01L5/0066, G01L5/0071 and B23Q17/09 take precedence; for the specific machine or operation involved see relevant class, e.g. B21 - B42

Abstract

A dynamic force measurement system for taking a series of force measurements of a force applied against a sensor device whereby to determine, record, display and store the sequence of force measurements. The sensor device is adapted to respond to said force and provide an electronic force signal which is representative thereof. The dynamic force measurement system includes a central processing unit for operating a computer program, having data and program instruction storage means, graphic display and user interface means. A sensor interface device provides for the connecting of the sensor device to the central processing unit. The sensor interface device includes means for monitoring the force signal generated by the sensor device, converting the signal to a numerical binary format for recording in intermediate storage means within the sensor interface device for ultimate transfer to the central processing unit for display, statistical analysis and storage.

Claims

1. A dynamic bond force measurement system for taking a series of force measurements of force applied by a wire bonding tool, the system comprising:

a sensor device for positioning beneath a wire bonding tool, comprising a substrate platform, a transducer element mounted on said platform, and a pressure pedestal mounted on said transducer element for receiving the force applied by a wire bonding tool;

the transducer element comprising means for detecting forces between the pedestal and the substrate platform in the range form 0.00 to 2.00 lbs. and for producing a continuous analog output signal in the range form 0.00 to 100.00 millivolts in relation to said force;

a sensor interface device for receiving said analog output signal, the interface device comprising analog to digital converter means for converting said analog output signal, data storage means for storing discrete values of said digital output signal at a preselected sample rate, triggering means for initiating said data storage, and output means for transmitting said stored digital output signals; and

data processing means for receiving said digital output signals from said interface device, means for storing said received signals, and means for generating from said signals a graphical representation of the applied force relative to time.

2. The system as claimed in claim 1, wherein said triggering means includes control means responsive to a predetermined triggering signal to initiate said signal storage.

3. The system as claimed in claim 2, wherein said triggering signal comprises detection of a preselected force threshold value.

4. The system as claimed in claim 3, including means for manually varying said threshold value.

5. The system as claimed in claim 2, including means for providing alternative data storage triggering modes, the alternative modes including a manual triggering input mode, a force threshold value detection mode, and an automatic triggering mode.

6. The system as claimed in claim 1, including means for manually controlling the sampling rate.

7. The system as claimed in claim 6, further including means for manually controlling the sampling duration during which data is stored, said data storage means comprising means for storing said digital signals at a predetermined sampling rate until expiry of said selected sampling duration, and means for providing said stored signals to said output means for transmitting to said data processing means on completion of said selected sampling duration.

8. The system as claimed in claim 7, wherein the sampling duration comprises the time needed to collect a predetermined number of signals at a selected sample rate.

9. The system as claimed in claim 8, wherein the predetermined number of signals comprises at least 101.

10. The system as claimed in claim 1, wherein said sensor device weighs approximately 0.2 grams, said transducer element has dimensions of approximately 2×

2 mm², and said sensor device has an active sensing area of approximately 600×

600 μ

m².

11. The system as claimed in claim 10, wherein the substrate platform is of area 1/4×

1/4 inch², the pedestal area is 600×

600 μ

m², and the pedestal rises approximately 800 μ

m above the substrate surface.

12. The system as claimed in claim 11, wherein the substrate platform comprises a ceramic substrate, and a glass substrate mounted above the ceramic substrate, the transducer element is mounted on the glass substrate and binder material extends around the peripheries of the combined substrate and transducer layers to secure them together, leaving the upper surface of the transducer element exposed, the pedestal being mounted on the exposed upper surface of the transducer element and comprising means for receiving an applied force normal to its surface.

13. The system as claimed in claim 1, wherein said data processing means includes manual input means for enabling user selection of various operating parameters including a triggering mode selected from manual, external, or force threshold, a sampling rate, a sampling duration for each force measurement, and user selection of a series of data manipulation routines for manipulating previously stored data, including means for comparing the graphical representation of two different sets of force measurements, and a series of various statistical data analysis routines including mean force, force rate, percent overshoot, peak force, total energy and force duration.

14. The system as claimed in claim 1, wherein said sensor interface device includes a sample and hold register having an input for receiving said analog output signal and an output connected to said analog to digital converter, said sample and hold register comprising means for holding an analog signal for a time period required for analog to digital conversion of the previous signal and for providing said held signal at its output on expiry of said time period, and a microprocessor connected to the output of said analog to digital converter for receiving said digital output signal, said data storage means comprising a random access memory device connected to said microprocessor, said microprocessor being connected to a read only memory device containing an operating program for said microprocessor, said operating program including means for storing discrete values of said digital output signal on detection of a selected threshold digital output signal until expiry of a preselected data storage time, and means for providing said stored signals to said data processing means on expiry of said data storage time.