CN107861046A - Circuit board short circuit point measuring equipment and method based on TDR technology - Google Patents
Circuit board short circuit point measuring equipment and method based on TDR technology Download PDFInfo
- Publication number
- CN107861046A CN107861046A CN201710952135.1A CN201710952135A CN107861046A CN 107861046 A CN107861046 A CN 107861046A CN 201710952135 A CN201710952135 A CN 201710952135A CN 107861046 A CN107861046 A CN 107861046A
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- China
- Prior art keywords
- circuit board
- signal
- short dot
- point
- tdr
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Classifications
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- G—PHYSICS
- G01—MEASURING; TESTING
- G01R—MEASURING ELECTRIC VARIABLES; MEASURING MAGNETIC VARIABLES
- G01R31/00—Arrangements for testing electric properties; Arrangements for locating electric faults; Arrangements for electrical testing characterised by what is being tested not provided for elsewhere
- G01R31/28—Testing of electronic circuits, e.g. by signal tracer
- G01R31/2801—Testing of printed circuits, backplanes, motherboards, hybrid circuits or carriers for multichip packages [MCP]
- G01R31/281—Specific types of tests or tests for a specific type of fault, e.g. thermal mapping, shorts testing
- G01R31/2812—Checking for open circuits or shorts, e.g. solder bridges; Testing conductivity, resistivity or impedance
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- Engineering & Computer Science (AREA)
- Computer Hardware Design (AREA)
- Microelectronics & Electronic Packaging (AREA)
- General Engineering & Computer Science (AREA)
- Physics & Mathematics (AREA)
- General Physics & Mathematics (AREA)
- Tests Of Electronic Circuits (AREA)
- Testing Of Short-Circuits, Discontinuities, Leakage, Or Incorrect Line Connections (AREA)
Abstract
A circuit board short circuit point measuring device based on TDR technology comprises an arithmetic unit, a step signal generator, a reflection signal collector, a probe and a display; the measuring method comprises the steps of measuring by a probe, reading the distance between a short circuit point and a measuring point, moving the measuring point, reading the distance and judging; the device integrates a step signal emitter and a reflected signal collector; determining a welding short-circuit point by using a TDR model technology; the position of the short-circuit point is determined through multi-point measurement without cutting or powering up the circuit board, and the method is simple to operate, high in efficiency and reliable in result.
Description
Technical field
The present invention relates to a kind of short dot measuring apparatus for having assembled printed circuit board (PCB), it is mainly used in electronic circuit board test
Field, it is especially a kind of to be based on TDR（Time Domain Reflectometry-domain reflectometer）The circuit board short circuit of technology
Point measuring apparatus and method.
Background technology
With the development of science and technology, PCB（Printed Circuit Board-printed circuit board）Placement-and-routing is more next
More intensive, component package is less and less, the easy shape of leg of two adjacent nearer interelements in the welding process of pcb board
Into bridging type short circuit phenomenon, multiway element, particularly close pin element is easy to short circuit problem occur in welding.Nowadays it is more normal
The investigation method for the PCB solder shorts seen is secant method, but the risk that secant method can not recover to use to circuit board presence, and
And the investigation time is longer, success rate is relatively low.
The content of the invention
It is an object of the invention to provide a kind of circuit board short dot measuring apparatus and method based on TDR technologies, for
The deficiencies in the prior art, be a kind of simple efficient circuit board short dot measuring apparatus and method, by measure reflected signal come
Judge the position of short dot, realize the judgement of the short dot to solder shorts PCB.
The technical solution of the present invention：A kind of circuit board short dot measuring apparatus based on TDR technologies, it is characterised in that
It includes arithmetic element, step generator, reflected signal collector, probe and display；Wherein, the probe and PCB
Plate is in be bi-directionally connected；The input of the probe receives the signal that step generator is sent, and its output end is by reflected signal
It is sent to reflected signal collector；The arithmetic element is in respectively two-way company with step generator and reflected signal collector
Connect；The input of the display is connected with arithmetic element.
The step generator is used to produce the step signal that voltage magnitude is 3.3V；The jump signal generator
Output impedance is 50 Ω.
The reflected signal collector is the reflected signal collector for including sample-hold circuit, passes through spy for gathering
The step signal transmitting that head returns involves back wave, by using high speed FPGA（Field-Programmable Gate
Array-field programmable gate array）Back wave is involved to transmitting and carries out discrete conversion.
The display shows step waveform caused by step generator, the ripple by the back wave collected of popping one's head in
Shape and the distance between the short dot by being calculated to the quantifier of back wave reflection interval and measurement point.
The step generator is derailing switch of the BUZ50A type VMOS FETs of Siemens Company as pulse
Part, using the switch of 74HC123 monostable flipflop driving FETs, by FPGA to 74HC123 pulsewidths and time delay
Control, it is achieved thereby that the controllable output of step signal.
The reflected signal collector is made up of fpga chip and analog acquisition chip；Wherein, the fpga chip
It is core devices, is the Kintex-7 Series FPGA chip XC7K325T-3 of Xilinx companies production, its flank speed is reachable
741MHz；There is timer inside the high speed fpga chip XC7K325T-3, for measuring between step signal and reflected signal
Time difference, so as to which the position of short dot be calculated；The analog acquisition chip is the ADS5400-SP of 1GSPS sample rates
Analog acquisition chip, you can discrete acquisitions are carried out to waveform, so as to realize the detection to reflected signal.
The display is the liquid crystal display with LVDS interface；The liquid crystal display is connected with fpga chip by LVDS interface,
Liquid crystal display is driven, the waveform collected shown, and indicate metrical information.
A kind of circuit board short dot measuring method based on TDR technologies, it is characterised in that it comprises the following steps：
1. first by the power supply signal point of probe measurement short circuit current plate edges of boards, by equipment read short dot and measurement point it
Between distance；
2. according to the distance value of reading, it is close to the less point of measurement distance that measurement distance is worth larger point；Again read off and set
The measurement distance of standby middle short dot and measurement point；
3. measuring method as above is iteratively repeated, until the measurement distance that equipment obtains can not reduce again；
4. short-circuiting range delimited according to final measurement point, in the range of component be short circuit fault.
The operation principle of the present invention：Using the principle that signal can be launched during impedance mismatch under high frequency, pass through measurement
The back wave of measured object judges the position of impedance discontinuity point.When pcb board solder shorts, the TDR moulds of its equiva lent impedance
Type is as shown in figure 3, incoming signal and reflected signal can produce superposition at signal source.In Short-way model, reflected signal is with entering
Signal waveform contrast is penetrated, therefore the voltage magnitude after two Signal averagings is 0V.Therefore reflected signal collector is passed through
Gather the time of step signal foundation and the time difference of blackout, you can measure signal source and the distance of short dot.This equipment
Use process it is fairly simple, by equipment probe access short circuit signal wire in, the diverse location of click signal line, pass through sight
The short dot distance in device display is examined to judge location of short circuit, i.e., at short dot distance minimum.
The superiority of the present invention：1. being integrated with step signal transmitter with reflected signal collector in one, step is used
Step signal is loaded on short-circuit signal line by signal projector by cable, and reflection letter is gathered using reflected signal collector
Number, by measuring the reflection interval of reflected signal, to judge the distance of short dot and measurement point；It is final true by multi-point sampler
Determine the position of short dot；2. TDR modelling techniques are used, reflection letter during by measuring equivalent impedance mismatch under step signal
Number, to determine that welding is completed and and the solder shorts point of circuit board that is not powered on；3. without carrying out secant to circuit board, without
Circuit board is powered up, it is that can determine that the position of short dot, simple to operate, efficiency that multimetering need to be only carried out to circuit board
Height, reliable results.
Brief description of the drawings
Fig. 1 is a kind of overall structure block diagram of the circuit board short dot measuring apparatus based on TDR technologies involved by the present invention.
Fig. 2 is a kind of concrete structure block diagram of the circuit board short dot measuring apparatus based on TDR technologies involved by the present invention.
Fig. 3 is a kind of operation principle schematic diagram of the circuit board short dot measuring method based on TDR technologies involved by the present invention.
Embodiment
Embodiment：A kind of circuit board short dot measuring apparatus based on TDR technologies（See Fig. 1）, it is characterised in that it includes
Arithmetic element, step generator, reflected signal collector, probe and display；Wherein, the probe is in double with pcb board
To connection；The input of the probe receives the signal that step generator is sent, and reflected signal is sent to by its output end
Reflected signal collector；The arithmetic element is in respectively to be bi-directionally connected with step generator and reflected signal collector；Institute
The input for stating display is connected with arithmetic element.
The step generator is used to produce the step signal that voltage magnitude is 3.3V；The jump signal generator
Output impedance is 50 Ω.
The reflected signal collector is the reflected signal collector for including sample-hold circuit, passes through spy for gathering
The step signal transmitting that head returns involves back wave, and involving back wave to transmitting by using high speed FPGA carries out discrete conversion
（See Fig. 1）.
The display shows step waveform caused by step generator, the ripple by the back wave collected of popping one's head in
Shape and the distance between the short dot by being calculated to the quantifier of back wave reflection interval and measurement point（See Fig. 1）.
The step generator（See Fig. 2）It is the BUZ50A type VMOS FETs of Siemens Company as pulse
Switching device, using the switch of 74HC123 monostable flipflop driving FETs, to 74HC123 pulsewidths and prolonged by FPGA
The control of slow time, it is achieved thereby that the controllable output of step signal.
The reflected signal collector（See Fig. 2）It is to be made up of fpga chip and analog acquisition chip；Wherein, it is described
Fpga chip is core devices, be Xilinx companies production Kintex-7 Series FPGA chip XC7K325T-3, its most high speed
Rate is up to 741MHz；There is timer inside the high speed fpga chip XC7K325T-3, believe for measuring step signal with reflection
Time difference between number, so as to which the position of short dot be calculated；The analog acquisition chip is 1GSPS sample rates
ADS5400-SP analog acquisition chips, you can discrete acquisitions are carried out to waveform, so as to realize the detection to reflected signal.
The display（See Fig. 2）It is the liquid crystal display with LVDS interface；The liquid crystal display is connect with fpga chip by LVDS
Mouth connection, is driven to liquid crystal display, the waveform collected is shown, and indicate metrical information.
A kind of circuit board short dot measuring method based on TDR technologies, it is characterised in that it comprises the following steps：
1. first by the power supply signal point of probe measurement short circuit current plate edges of boards, by equipment read short dot and measurement point it
Between distance；
2. according to the distance value of reading, it is close to the less point of measurement distance that measurement distance is worth larger point；Again read off and set
The measurement distance of standby middle short dot and measurement point；
3. measuring method as above is iteratively repeated, until the measurement distance that equipment obtains can not reduce again；
4. short-circuiting range delimited according to final measurement point, in the range of component be short circuit fault.
With reference to embodiment and its accompanying drawing, the present invention is described in more detail.
The structured flowchart for the circuit board short dot measuring apparatus based on TDR technologies that the present invention designs is as shown in figure 1, it is led
It is most of to include step generator, reflected signal collector, arithmetic element and display etc. four.
Step generator in structured flowchart of the present invention is used for the step signal for producing certain voltage amplitude, and passes through
Probe spreads out of signal, and according to nowadays common equivalent impedance, the output impedance of this step generator is 50 Ω.
Reflected signal collector in structured flowchart of the present invention is used to gather the step signal transmitted wave returned by popping one's head in
And back wave, this collector include sample-hold circuit, back wave is involved to transmitting by using high speed FPGA and carries out discrete turn
Change.
Arithmetic element in structured flowchart of the present invention is measured by high speed FPGA to the reflection interval of back wave, and control is aobvious
Show that device shows step waveform caused by step generator, and the waveform of the back wave collected by popping one's head in.By to anti-
The metering of ejected wave reflection interval, calculate the distance between short dot and measurement point.
A kind of circuit structure block diagram such as Fig. 2 for circuit board short dot measuring apparatus based on TDR technologies that the present invention designs
It is shown.
Step generator need to produce a kind of zooming pulse signal, therefore the switching speed in signal generator
It is one of key index, equipment is made using switching device of the BUZ50A type VMOS FETs of Siemens Company as pulse
With the switch of 74HC123 monostable flipflop driving FETs, pass through controls of the FPGA to 74HC123 pulsewidths and time delay
System, it is achieved thereby that the controllable output of step signal.
The core devices of reflected signal collector are high speed FPGA, and in order to improve sampling rate, equipment employs Xilinx
The Kintex-7 Series FPGA chip XC7K325T-3 of company's production, its flank speed are arranged in pairs or groups and adopted using 1GSPS up to 741MHz
The ADS5400-SP analog acquisition chips of sample rate, you can discrete acquisitions are carried out to waveform, so as to realize the inspection to reflected signal
Survey.A timer is included inside high speed FPGA, for measuring the time difference between step signal and reflected signal, so as to calculate
Obtain the position of short dot.
Device, as waveform display unit, is carried out from LVDS interface liquid crystal display using FPGA LVDS interface to liquid crystal display
Driving, the waveform collected is shown, and indicate metrical information.
Operation principle and process of the present invention are：The original that signal can be launched when the present invention utilizes impedance mismatch under high frequency
Reason, the position of impedance discontinuity point is judged by the back wave for measuring measured object.When pcb board solder shorts, its is equivalent
The TDR models of impedance are as shown in figure 3, incoming signal and reflected signal can produce superposition at signal source.In Short-way model, instead
Signal and incoming signal waveform contrast are penetrated, therefore the voltage magnitude after two Signal averagings is 0V.Therefore reflection is passed through
Signal picker gathers the time difference between step signal and reflected signal, you can measures signal source and the distance of short dot.This
The use process of equipment is fairly simple, and the probe of equipment is accessed in the signal wire of short circuit, the diverse location of click signal line, led to
The short dot distance crossed in facilities for observation display judges location of short circuit, i.e., at short dot distance minimum.
In Fig. 3, V is the step voltage of step signal；0 represents the 0V voltages of step signal output；Tp be measurement point with it is short
Time between waypoint needed for signal transmission；Z0 is the impedance value on non-short-circuit signal line；Z=0 represents the signal wire after short dot
Impedance value, as 0.
Above example is only the concrete application example to circuit board short dot measuring apparatus of the present invention based on TDR technologies
Son, it is not intended to limit the application claim.Every modification carried out in the application claim technical scheme and non-intrinsically safe change
Enter, within the application claims.
The present invention does not address part and is applied to prior art.
Claims (8)
1. a kind of circuit board short dot measuring apparatus based on TDR technologies, it is characterised in that it includes arithmetic element, step signal
Generator, reflected signal collector, probe and display；Wherein, the probe is in be bi-directionally connected with pcb board；The probe
Input receives the signal that step generator is sent, and reflected signal is sent to reflected signal collector by its output end；Institute
It is in respectively to be bi-directionally connected with step generator and reflected signal collector to state arithmetic element；The input of the display with
Arithmetic element connects.
A kind of 2. circuit board short dot measuring apparatus based on TDR technologies according to claim 1, it is characterised in that the rank
Jump signal generator is used to produce the step signal that voltage magnitude is 3.3V；The output impedance of the jump signal generator is 50
Ω。
A kind of 3. circuit board short dot measuring apparatus based on TDR technologies according to claim 2, it is characterised in that the rank
Jump signal generator is made up of switching device and driver；The switching device is the BUZ50A type VMOS fields effect of Siemens Company
Should switching device of the pipe as pulse；The driver is the switch of 74HC123 monostable flipflop driving FETs.
4. a kind of circuit board short dot measuring apparatus based on TDR technologies according to claim 1, it is characterised in that described anti-
It is the reflected signal collector for including sample-hold circuit to penetrate signal picker.
5. a kind of circuit board short dot measuring apparatus based on TDR technologies according to claim 4, it is characterised in that described anti-
Penetrating signal picker is made up of fpga chip and analog acquisition chip；Wherein, the fpga chip is core devices, is
The Kintex-7 Series FPGA chip XC7K325T-3 of Xilinx companies production, its flank speed is up to 741MHz；The high speed
There is timer inside fpga chip XC7K325T-3；The analog acquisition chip is the ADS5400-SP moulds of 1GSPS sample rates
Analog quantity acquisition chip.
6. a kind of circuit board short dot measuring apparatus based on TDR technologies according to claim 1, it is characterised in that described aobvious
Show that device shows step waveform caused by step generator, by the waveform for the back wave collected of popping one's head in and by anti-
The distance between short dot that the quantifier of ejected wave reflection interval calculates and measurement point.
7. a kind of circuit board short dot measuring apparatus based on TDR technologies according to claim 6, it is characterised in that described aobvious
It is the liquid crystal display with LVDS interface to show device；The liquid crystal display is connected with fpga chip by LVDS interface, and liquid crystal display is driven
It is dynamic.
8. a kind of circuit board short dot measuring method based on TDR technologies, it is characterised in that it comprises the following steps：
1. first by the power supply signal point of probe measurement short circuit current plate edges of boards, by equipment read short dot and measurement point it
Between distance；
2. according to the distance value of reading, it is close to the less point of measurement distance that measurement distance is worth larger point；Again read off and set
The measurement distance of standby middle short dot and measurement point；
3. measuring method as above is iteratively repeated, until the measurement distance that equipment obtains can not reduce again；
4. short-circuiting range delimited according to final measurement point, in the range of component be short circuit fault.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN201710952135.1A CN107861046A (en) | 2017-10-13 | 2017-10-13 | Circuit board short circuit point measuring equipment and method based on TDR technology |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN201710952135.1A CN107861046A (en) | 2017-10-13 | 2017-10-13 | Circuit board short circuit point measuring equipment and method based on TDR technology |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| CN107861046A true CN107861046A (en) | 2018-03-30 |
Family
ID=61699763
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| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CN201710952135.1A Withdrawn CN107861046A (en) | 2017-10-13 | 2017-10-13 | Circuit board short circuit point measuring equipment and method based on TDR technology |
Country Status (1)
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|---|---|
| CN (1) | CN107861046A (en) |
Cited By (2)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN110554273A (en) * | 2019-09-02 | 2019-12-10 | 昆山纬亚智能科技有限公司 | Detection method of PCBA short circuit point |
| CN112578264A (en) * | 2020-11-25 | 2021-03-30 | 海鹰企业集团有限责任公司 | Positioning device for various short circuit points of circuit board card |
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2017
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| DE4130051A1 (en) * | 1991-09-10 | 1993-03-11 | Siemens Ag | Short circuit fault locator for multilayer circuit board assembly - passes current through one conductor and measures voltage between internal point in this conductor and a connection to the second conductor |
| CN2368042Y (en) * | 1999-02-12 | 2000-03-08 | 大众电脑股份有限公司 | Electric characteristics testing mechanism of printed circuit board |
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Cited By (2)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN110554273A (en) * | 2019-09-02 | 2019-12-10 | 昆山纬亚智能科技有限公司 | Detection method of PCBA short circuit point |
| CN112578264A (en) * | 2020-11-25 | 2021-03-30 | 海鹰企业集团有限责任公司 | Positioning device for various short circuit points of circuit board card |
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Application publication date: 20180330 |
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