CN106382883B - Deformation detection method and device for printed circuit board - Google Patents
Deformation detection method and device for printed circuit board Download PDFInfo
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- CN106382883B CN106382883B CN201610788420.XA CN201610788420A CN106382883B CN 106382883 B CN106382883 B CN 106382883B CN 201610788420 A CN201610788420 A CN 201610788420A CN 106382883 B CN106382883 B CN 106382883B
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- printed circuit
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- G—PHYSICS
- G01—MEASURING; TESTING
- G01B—MEASURING LENGTH, THICKNESS OR SIMILAR LINEAR DIMENSIONS; MEASURING ANGLES; MEASURING AREAS; MEASURING IRREGULARITIES OF SURFACES OR CONTOURS
- G01B7/00—Measuring arrangements characterised by the use of electric or magnetic techniques
- G01B7/16—Measuring arrangements characterised by the use of electric or magnetic techniques for measuring the deformation in a solid, e.g. by resistance strain gauge
Abstract
The invention discloses a deformation detection method and a deformation detection device for a printed circuit board, which can utilize the characteristic that power supply ripple waves change due to the change of a PDN (public data network) inductance value when a PCB (printed circuit board) deforms, and design a loop oscillator in a chip to detect frequency offset so as to determine the deformation of the PCB according to the frequency offset. Therefore, deformation detection is not required to be carried out by a mechanical trigger or a sensor, so that the design cost of PCB detection is reduced, and the available space on the PCB is saved.
Description
Technical Field
The present disclosure relates to the field of electronic technologies, and in particular, to a method and an apparatus for detecting deformation of a printed circuit board.
Background
With the progress of electronic technology, more and more electronic products tend to be portable, lightweight and intelligent, and users pay more and more attention to the functions and service life of the products. Among many factors influencing the service life of electronic products, the electronic products are frequently subjected to external force impact repeatedly due to improper use of users, and then the structure and the internal PCB are deformed, and the repeated deformation of the PCB has the effect of finally falling off or breaking device welding spots, connecting lines and the like on the PCB, so that the electronic products are finally damaged.
A common method of detecting PCB deformation is to use a mechanical structure of a small pressure trigger device in an electronic product. When the structure or the PCB is deformed, the pressure trigger device is driven by external force to generate an on-off state, the state is converted into an electric signal, and the signal is identified by a detection chip on the PCB. The method can detect whether the PCB is deformed or not, and further remind a user of taking precautions. Still other methods use pressure sensors to sense if a deformation has occurred by causing a change in pressure in the pressure sensor due to a structural deformation.
However, the current deformation detection method for the PCB requires an additional period, which not only increases the cost, but also increases the spatial structure of the PCB.
Disclosure of Invention
The embodiment of the invention provides a deformation detection method and device of a printed circuit board, which are used for solving the problems that in the prior art, the current deformation detection method of the PCB needs extra time, not only is the cost increased, but also the space structure of the PCB is increased.
The specific technical scheme is as follows:
a method of detecting deformation of a printed circuit board, the method comprising:
acquiring an inductance value on the PCB of the printed circuit; determining a corresponding working output frequency according to the inductance value;
determining whether the difference value between the working output frequency and the standard frequency is smaller than a preset threshold value;
if yes, determining that the PCB is not deformed;
if not, determining that the PCB deforms.
Optionally, determining a corresponding operating output frequency according to the inductor value includes:
obtaining an inductance value on a power distribution network PDN;
determining a voltage ripple value in the PDN loop according to the inductance value;
and determining the working output frequency corresponding to the voltage ripple value according to the voltage ripple value.
Optionally, obtaining an inductance value on the power distribution network PDN includes:
determining a difference value of inductance on the PDN based on a medium on the PCB and a circuit from two ends of a decoupling capacitor to a chip;
and taking the difference value as the inductance value.
Optionally, determining whether a difference between the working output frequency and the standard frequency is smaller than a preset threshold includes:
acquiring a first frequency output by a first register on the PCB;
comparing whether the first frequency is the same as a second frequency output by a second register on the PCB.
A deformation detecting device of a printed circuit board includes:
the acquisition module is used for acquiring the inductance value on the printed circuit PCB; determining a corresponding working output frequency according to the inductance value;
the processing module is used for determining whether the difference value between the working output frequency and the standard frequency is smaller than a preset threshold value or not; if yes, determining that the PCB is not deformed; if not, determining that the PCB deforms.
Optionally, the processing module is specifically configured to obtain an inductance value on a power distribution network PDN; determining a voltage ripple value in the PDN loop according to the inductance value; and determining the working output frequency corresponding to the voltage ripple value according to the voltage ripple value.
Optionally, the obtaining module is specifically configured to determine a difference value of inductances on the PDN based on a medium on the PCB and a circuit from two ends of a decoupling capacitor to a chip; and taking the difference value as the inductance value.
Optionally, the processing module is specifically configured to obtain a first frequency output by a first register on the PCB; comparing whether the first frequency is the same as a second frequency output by a second register on the PCB.
According to the method provided by the invention, the characteristic that the power supply ripple changes due to the change of the inductance value of the PDN network when the PCB deforms can be utilized, and the loop oscillator is designed in the chip to detect the frequency offset, so that the deformation of the PCB is determined according to the frequency offset. Therefore, deformation detection is not required to be carried out by a mechanical trigger or a sensor, so that the design cost of PCB detection is reduced, and the available space on the PCB is saved.
Drawings
FIG. 1 is a flowchart illustrating a method for detecting deformation of a printed circuit board according to an embodiment of the present invention;
FIG. 2 is a schematic structural diagram of a PCB board according to an embodiment of the present invention;
FIG. 3 is a schematic structural diagram of deformation of a PCB board according to an embodiment of the present invention;
FIG. 4 is a diagram of a frequency comparison structure according to an embodiment of the present invention;
fig. 5 is a schematic structural diagram of a device for detecting deformation of a printed circuit board according to an embodiment of the present invention.
Detailed Description
The technical solutions of the present invention are described in detail with reference to the drawings and the specific embodiments, and it should be understood that the embodiments and the specific technical features in the embodiments of the present invention are merely illustrative of the technical solutions of the present invention, and are not restrictive, and the embodiments and the specific technical features in the embodiments of the present invention may be combined with each other without conflict.
Fig. 1 is a flowchart illustrating a method for detecting deformation of a printed circuit board according to an embodiment of the present invention, where the method includes:
s101, obtaining an inductance value on the PCB of the printed circuit; determining a corresponding working output frequency according to the inductance value;
s102, determining whether the difference value between the working output frequency and the standard frequency is smaller than a preset threshold value;
if yes, executing S103; if not, S104 is executed.
S103, determining that the PCB is not deformed;
and S104, determining that the PCB deforms.
Specifically, in the embodiment of the present invention, the specific structure of the PCB is as shown in fig. 2, and the PCB is generally divided into two layers, one layer is a ground layer, the other layer is a capacitor layer, and a capacitor and integrated circuit FPGA is disposed on the ground layer of the PCB.
In the PCB board, when the PCB board takes place deformation for the inductance value of PDN changes, and the inductance value again has following relation with the voltage ripple in the PDN:
Vripple＝ItransientZPDN
wherein, VrippleVoltage ripple, ZPDNIs an inductance value, ItransientIs a constant.
From the above formula, the voltage ripple is proportional to the inductance value.
And ZPDNRelated to the total inductance value in the PDN network. When the PCB is deformed, the main reasons for the change of the total inductance value are two factors:
1. the circuit connection between the thickness of the medium in the PCB and the two ends of the decoupling capacitor to the chip is deformed, so that the inductance value of the PDN network is changed;
2. when the PCB is deformed (as shown in fig. 3), the coupling mode of the PDN network and other high-frequency signals on the PCB is also changed. This varying electromagnetic field also causes variations in the voltage ripple in the PDN loop.
Based on the two points, the PCB deforms at the moment when the PCB is stressed, so that the power supply inductance value of the PDN network changes, and the difference value of the inductance on the PDN is determined based on the medium on the PCB and the circuit from the two ends of the decoupling capacitor to the chip.
Further, the loop oscillator is susceptible to voltage, which in turn causes a change in the oscillation frequency. When an FPGA device is arranged on the PCB, a closed loop consisting of delay units is designed inside the FPGA through a hardware programming language, and the closed loop is a loop oscillator. This delay cell may be instantiated by a LUT unit internal to the FPGA. The working output frequency of the power supply is influenced by the power supply ripple, and a detection circuit can be designed to judge whether the frequency changes. An example of the FPGA design of the present invention is shown in FIG. 4:
1. a LUT unit is used to serially connect a closed loop, and the total delay of the closed loop meets the requirement of the total phase delay (2 pi) of a loop oscillator. A simple accumulator a (shown in fig. 4) is driven with the output frequency of the loop oscillator.
2. 2 registers are connected in series to form a register group in a non-blocking mode, and the input of the register group is the output value of a simple accumulator A. The standard clock CLK cycles the value of the simple accumulator a to the right at fixed periods.
Based on the circuit configuration shown in fig. 4, it is possible to compare whether the first frequency is the same as the second frequency output from the second register on the PCB, while acquiring the first frequency output from the first register on the PCB.
For example, in fig. 4, under the normal PCB deformation-free state, the values of the 2 registers are all stable and equal. When the PCB is deformed suddenly, the power supply ripple supplied to the FPGA chip is changed, so that the output frequency of the loop oscillator is changed, and finally the value of the simple accumulator A is changed to a certain extent. At this point, when CLK drives 2 registers to shift cyclically, the value of register 1 is not equal to the value of register 2. Therefore, the real PCB deformation can be judged by judging the values of the 2 registers.
When a non-FPGA integrated circuit is used on the PCB, a circuit which is the same as the FPGA circuit can be designed in the chip by utilizing a CMOS process, and the function of detecting the deformation of the PCB can also be realized.
In summary, according to the method provided by the embodiment of the present invention, a loop oscillator is designed in a chip to detect a frequency offset by using a characteristic that a power supply ripple changes due to a change in an inductance value of a PDN network when a PCB deforms, so as to determine the deformation of the PCB according to the frequency offset. Therefore, deformation detection is not required to be carried out by a mechanical trigger or a sensor, so that the design cost of PCB detection is reduced, and the available space on the PCB is saved.
Corresponding to the method for detecting the deformation of the printed circuit board in the embodiment of the present invention, an apparatus for detecting the deformation of the printed circuit board is further provided in the embodiment of the present invention, and as shown in fig. 5, the apparatus for detecting the deformation of the printed circuit board in the embodiment of the present invention includes:
an obtaining module 501, configured to obtain an inductance value on the printed circuit board PCB; determining a corresponding working output frequency according to the inductance value;
a processing module 502, configured to determine whether a difference between the working output frequency and a standard frequency is smaller than a preset threshold; if yes, determining that the PCB is not deformed; if not, determining that the PCB deforms.
Further, in this embodiment of the present invention, the processing module 502 is specifically configured to obtain an inductance value on a power distribution network PDN; determining a voltage ripple value in the PDN loop according to the inductance value; and determining the working output frequency corresponding to the voltage ripple value according to the voltage ripple value.
Further, in this embodiment of the present invention, the obtaining module 501 is specifically configured to determine a difference value between inductances on the PDN based on a medium on the PCB and a circuit from two ends of a decoupling capacitor to a chip; and taking the difference value as the inductance value.
Further, in this embodiment of the present invention, the processing module 502 is specifically configured to obtain a first frequency output by a first register on the PCB; comparing whether the first frequency is the same as a second frequency output by a second register on the PCB.
While the preferred embodiments of the present application have been described, additional variations and modifications in those embodiments may occur to those skilled in the art once they learn of the basic inventive concepts. Therefore, it is intended that the appended claims be interpreted as including preferred embodiments and all alterations and modifications as fall within the scope of the application.
It will be apparent to those skilled in the art that various changes and modifications may be made in the present application without departing from the spirit and scope of the application. Thus, if such modifications and variations of the present application fall within the scope of the claims of the present application and their equivalents, the present application is intended to include such modifications and variations as well.
Claims (2)
1. A deformation detection method of a printed circuit board is characterized by comprising the following steps:
obtaining an inductance value on a power distribution network PDN;
determining a voltage ripple value in the PDN loop according to the inductance value;
determining the working output frequency corresponding to the voltage ripple value through a ring oscillator according to the voltage ripple value;
determining whether the difference value between the working output frequency and the standard frequency is smaller than a preset threshold value;
if yes, determining that the printed circuit board is not deformed;
if not, determining that the printed circuit board deforms;
wherein obtaining an inductance value on the power distribution network PDN comprises: determining a difference value of inductance on the PDN based on a medium on the printed circuit board and a circuit from two ends of a decoupling capacitor to a chip, and taking the difference value as the inductance value;
wherein determining whether a difference between the operating output frequency and a standard frequency is less than a preset threshold comprises: acquiring a first frequency output by a first register on the printed circuit board, and comparing whether the first frequency is the same as a second frequency output by a second register on the printed circuit board;
the circuit comprises a printed circuit board, a capacitor, an integrated circuit FPGA, a delay unit and an LUT unit, wherein the capacitor and the integrated circuit FPGA are arranged on a ground layer of the printed circuit board, a closed loop consisting of the delay unit is designed in the FPGA, and the delay unit is generated by instantiating the LUT unit in the FPGA.
2. A deformation detection device of a printed circuit board is characterized by comprising:
the acquisition module is used for acquiring the inductance value on the power distribution network PDN; determining a voltage ripple value in the PDN loop according to the inductance value; determining the working output frequency corresponding to the voltage ripple value through a ring oscillator according to the voltage ripple value;
the processing module is used for determining whether the difference value between the working output frequency and the standard frequency is smaller than a preset threshold value or not; if yes, determining that the printed circuit board is not deformed; if not, determining that the printed circuit board deforms;
the obtaining module is specifically configured to determine a difference value of inductances on the PDN based on a medium on the printed circuit board and a circuit from two ends of a decoupling capacitor to a chip; taking the difference value as the inductance value;
the processing module is specifically configured to acquire a first frequency output by a first register on the printed circuit board; comparing the first frequency to a second frequency output by a second register on the printed circuit board to determine if the first frequency is the same,
the circuit comprises a printed circuit board, a capacitor, an integrated circuit FPGA, a delay unit and an LUT unit, wherein the capacitor and the integrated circuit FPGA are arranged on a ground layer of the printed circuit board, a closed loop consisting of the delay unit is designed in the FPGA, and the delay unit is generated by instantiating the LUT unit in the FPGA.
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| Application Number | Priority Date | Filing Date | Title |
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| CN201610788420.XA CN106382883B (en) | 2016-08-31 | 2016-08-31 | Deformation detection method and device for printed circuit board |
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| CN201610788420.XA CN106382883B (en) | 2016-08-31 | 2016-08-31 | Deformation detection method and device for printed circuit board |
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| CN106382883A CN106382883A (en) | 2017-02-08 |
| CN106382883B true CN106382883B (en) | 2020-09-18 |
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| CN107809882B (en) * | 2017-09-21 | 2019-10-15 | 维沃移动通信有限公司 | A kind of method and mobile terminal for repairing pcb board deformation |
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| US4114428A (en) * | 1976-09-24 | 1978-09-19 | Popenoe Charles H | Radio-frequency tuned-circuit microdisplacement transducer |
| US20020158840A1 (en) * | 2001-04-27 | 2002-10-31 | Alps Electric Co., Ltd. | Coordinate input device having reduced number of components, being easy to assemble, and including deformation detecting elements |
| CN104076235A (en) * | 2013-03-27 | 2014-10-01 | 深圳市海洋王照明工程有限公司 | Method of detecting open circuit of printed line of PCB |
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|---|---|---|---|---|
| FR2653197B1 (en) * | 1989-10-12 | 1991-12-27 | Vulcanic | METHOD FOR WATERPROOFING AN END OF AN ELECTRIC HEATING ELEMENT AND WATERPROOFING ELEMENT THROUGH THIS METHOD. |
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2016
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| US4114428A (en) * | 1976-09-24 | 1978-09-19 | Popenoe Charles H | Radio-frequency tuned-circuit microdisplacement transducer |
| US20020158840A1 (en) * | 2001-04-27 | 2002-10-31 | Alps Electric Co., Ltd. | Coordinate input device having reduced number of components, being easy to assemble, and including deformation detecting elements |
| CN104076235A (en) * | 2013-03-27 | 2014-10-01 | 深圳市海洋王照明工程有限公司 | Method of detecting open circuit of printed line of PCB |
| CN204258753U (en) * | 2014-10-31 | 2015-04-08 | 中国兵器工业集团第二一四研究所苏州研发中心 | A kind of high accuracy clock circuit of resistance to high overload based on thick-film resistor |
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