EP0629869A1 - Testvorrichtung - Google Patents

Testvorrichtung Download PDF

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Publication number
EP0629869A1
EP0629869A1 EP94304098A EP94304098A EP0629869A1 EP 0629869 A1 EP0629869 A1 EP 0629869A1 EP 94304098 A EP94304098 A EP 94304098A EP 94304098 A EP94304098 A EP 94304098A EP 0629869 A1 EP0629869 A1 EP 0629869A1
Authority
EP
European Patent Office
Prior art keywords
vibration
probe head
monitoring
test apparatus
probe
Prior art date
Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
Granted
Application number
EP94304098A
Other languages
English (en)
French (fr)
Other versions
EP0629869B1 (de
Inventor
John Woodrow Shere
Neil Graham Hemingway
Current Assignee (The listed assignees may be inaccurate. Google has not performed a legal analysis and makes no representation or warranty as to the accuracy of the list.)
UH VENTURES LTD.
Matra Bae Dynamics UK Ltd
Original Assignee
UH VENTURES Ltd
British Aerospace PLC
Priority date (The priority date is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the date listed.)
Filing date
Publication date
Application filed by UH VENTURES Ltd, British Aerospace PLC filed Critical UH VENTURES Ltd
Publication of EP0629869A1 publication Critical patent/EP0629869A1/de
Application granted granted Critical
Publication of EP0629869B1 publication Critical patent/EP0629869B1/de
Anticipated expiration legal-status Critical
Expired - Lifetime legal-status Critical Current

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Classifications

    • H—ELECTRICITY
    • H04—ELECTRIC COMMUNICATION TECHNIQUE
    • H04R—LOUDSPEAKERS, MICROPHONES, GRAMOPHONE PICK-UPS OR LIKE ACOUSTIC ELECTROMECHANICAL TRANSDUCERS; DEAF-AID SETS; PUBLIC ADDRESS SYSTEMS
    • H04R29/00—Monitoring arrangements; Testing arrangements
    • H04R29/001—Monitoring arrangements; Testing arrangements for loudspeakers

Definitions

  • This invention relates to apparatus and methods suitable for the testing of electronic components which are mounted on printed circuit boards.
  • this invention aims to provide a method and apparatus for diagnosis of vibration related failures. Further more the invention aims to provide a controlled, portable, local source of vibration.
  • this invention consists of test apparatus comprising a probe head, a probe body incorporating means for vibrating the probe head, and means for monitoring the levels of vibration brought about by said probe head.
  • the invention also consists of a method for vibration diagnosis of a structure including the steps of; applying a localised source of vibration of controlled magnitude and frequency to a point on the structure, monitoring the magnitude and frequency of vibration of the structure, and monitoring the function of said structure whilst said vibration is being applied and observing any ensuing failure.
  • the means for vibrating the probe head could comprise a high-power electro-magnetic transducer.
  • the means for monitoring vibration of the structure could comprise a miniature piezo-electric accelerometer which could be fixed to the probe body. Velocity, force or displacement transducers may be preferred alternatives for some applications.
  • the vibration monitor could be incorporated in a feedback loop for controlling the operation of the vibration source.
  • a "roving" sensor moveable to various locations around a printed circuit board could be used to monitor the actual vibration levels of the board and its components. Again, this roving sensor could be used in a feedback loop to control the vibration source.
  • the sensor could be an accelerometer or velocity or displacement transducer as appropriate.
  • the output from either fixed or roving accelerometer could be integrated electronically to provide velocity and displacement levels.
  • the probe body and probe head could be incorporated into a pistol-grip, hand-held device, for example, which would allow the direct excitation of standard electronic packages such as Dual in line, TO5 and surface mount devices. This would allow typical faults occurring only during vibration to be reproduced or diagnosed outside the conventional test chamber.
  • a probe 1 receives an electrical signal generated by either a sinusoidal frequency source 2 or a noise source 3 (of variable bandwidth). The signal reaching the probe 1 is controlled by an on/off switch 4 and an amplifier 5 of variable gain.
  • the probe 1 incorporates an electro-magnetic vibrator 6 and a first miniature piezoelectric accelerometer 7 and is shown in greater detail in Figure 2.
  • the probe 1 comprises an outer casing 8 which houses a magnet 9 and a moving coil assembly 10.
  • the moving coil assembly 10 is attached to a vibration plate 11 on which is mounted a dome-shaped probe head 12 made of plastics and the miniature piezoelectric accelerometer 7.
  • the output from the first accelerometer 7 is fed to a charge amplifier 13 whose output is connected to a voltmeter 14 and, if desired, to a spectrum analyser (not shown). An output from the voltmeter 14 is used by a comparator circuit 15 to control the gain of the amplifier 5.
  • a second miniature piezoelectric accelerometer (remote from the probe 1) has its output connected to a second charge amplifier 17.
  • the output of this amplifier 17 is connected to a second voltmeter 18 and if desired to a spectrum analyser (not shown).
  • the level of vibration applied to the probe 1, its frequency and its duration are all recorded by a recorder 19 which receives inputs from a timer circuit 20 (connected to the on/off switch 4), a frequency monitor 21 (associated with the sources 3 and 4) and the voltmeter 14.
  • the probe head 12 is held either by hand or by a clamping arrangement in contact with an integrated circuit which is mounted on the printed circuit board under test.
  • the excitation frequency desired is set using the appropriate controls provided on the sources 2 and 3.
  • the second "roving" accelerometer is fixed to a point of interest on the board with a thin layer of beeswax. Closing of the switch 4 will than activate the electro-magnetic vibrator 6, the vibrations of the vibration plate 11 being coupled to the integrated circuit via the probe head 12.
  • the vibrations of the plate 11 are constantly monitored by the first accelerometer 7 which produces a charge proportional to the acceleration applied thereto.
  • the accelerometer's output is conditioned by the charge amplifier which produces a measurable voltage at its output.
  • the rms. level of this voltage, proportional to the acceleration detected by the accelerometer 7 is measured by the voltmeter which can be provided with means for converting the voltage value to units of acceleration. This latter information can be displayed to the operator and is also fed to the recorder 19.
  • An output from the voltmeter 14 is used, in a feedback loop, to control the gain of the amplifier 16 and therefore the vibration level of the probe head 12. If the measured acceleration rises above a pre-set level, for example, then the comparator circuit 15 reduces the gain of the amplifier 5 accordingly. In this way, the probe head 12 and thus the component under test can be protected from overload.
  • Typical frequencies and acceleration levels applied range from 10Hz to 2KHz and 2g(rms) to 5g (rms.) respectively.
  • the acceleration level, frequency and length of time for which excitation persists are continually recorded by the recorder 19 using the inputs from the timed circuit 20, frequency monitor 21 and voltmeter 14.
  • the roving, second accelerometer detects acceleration at the pre-chosen point of interest.
  • a 'g' level can be displayed by the second voltmeter 18.
  • the above operations can be repeated at different locations around the board under test until its design criteria have been reached or it fails electrically.
  • the amount of vibration to which the board has been subjected can be ascertained by interrogating the recorder 19. Thus the operator can ensure that the board has not exceeded its design requirements and is therefore fit for sale if no electrical faults have been found during testing.
  • the recorder 19 also tells the operator the conditions under which any failure occurred. When an electrical failure does occur, then the diagnostic equipment is removed and further solely electrical tests are carried out on each integrated circuit or each printed track if necessary, to find out which component or soldered joint, for example has actually failed.
  • Figure 1 could also be used for modal analysis of board vibrations by examining the output of the roving accelerometer with a spectrum analyser and applying an impulse to the board through the probe head.

Landscapes

  • Health & Medical Sciences (AREA)
  • General Health & Medical Sciences (AREA)
  • Otolaryngology (AREA)
  • Physics & Mathematics (AREA)
  • Engineering & Computer Science (AREA)
  • Acoustics & Sound (AREA)
  • Signal Processing (AREA)
  • Testing Electric Properties And Detecting Electric Faults (AREA)
EP19940304098 1993-06-12 1994-06-07 Testvorrichtung Expired - Lifetime EP0629869B1 (de)

Applications Claiming Priority (2)

Application Number Priority Date Filing Date Title
GB9312162A GB2278975A (en) 1993-06-12 1993-06-12 Test apparatus
GB9312162 1993-06-12

Publications (2)

Publication Number Publication Date
EP0629869A1 true EP0629869A1 (de) 1994-12-21
EP0629869B1 EP0629869B1 (de) 1999-03-03

Family

ID=10737076

Family Applications (1)

Application Number Title Priority Date Filing Date
EP19940304098 Expired - Lifetime EP0629869B1 (de) 1993-06-12 1994-06-07 Testvorrichtung

Country Status (3)

Country Link
EP (1) EP0629869B1 (de)
DE (1) DE69416728T2 (de)
GB (1) GB2278975A (de)

Cited By (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
EP0806589A1 (de) * 1996-05-11 1997-11-12 Gec-Marconi Limited Schwingungsregelung

Citations (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
WO1989012379A1 (fr) * 1988-06-03 1989-12-14 Thomson-Csf Systeme de detection de particules libres dans un boitier de composant et procede de detection

Family Cites Families (6)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
GB1082874A (en) * 1965-02-22 1967-09-13 M E L Equipment Co Ltd Processes wherein a mound of liquid is raised by acoustic vibrations
CH446783A (de) * 1965-06-10 1967-11-15 Vyzk Ustav Mech Ultraschallgenerator mit einem Ultraschall-Resonanz-Schwingungssystem
US3924335A (en) * 1971-02-26 1975-12-09 Ultrasonic Systems Ultrasonic dental and other instrument means and methods
US3889166A (en) * 1974-01-15 1975-06-10 Quintron Inc Automatic frequency control for a sandwich transducer using voltage feedback
US4687962A (en) * 1986-12-15 1987-08-18 Baxter Travenol Laboratories, Inc. Ultrasonic horn driving apparatus and method with active frequency tracking
GB2260875B (en) * 1991-10-23 1995-06-28 Anthony Best Dynamics Ltd Noise source

Patent Citations (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
WO1989012379A1 (fr) * 1988-06-03 1989-12-14 Thomson-Csf Systeme de detection de particules libres dans un boitier de composant et procede de detection

Cited By (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
EP0806589A1 (de) * 1996-05-11 1997-11-12 Gec-Marconi Limited Schwingungsregelung

Also Published As

Publication number Publication date
GB2278975A (en) 1994-12-14
DE69416728T2 (de) 1999-07-01
GB9312162D0 (en) 1993-07-28
EP0629869B1 (de) 1999-03-03
DE69416728D1 (de) 1999-04-08

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