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CN119155890B - Circuit, system and PCB structure for improving PCB leakage performance based on FR-4 board - Google Patents

Circuit, system and PCB structure for improving PCB leakage performance based on FR-4 board Download PDF

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Publication number
CN119155890B
CN119155890B CN202411650407.9A CN202411650407A CN119155890B CN 119155890 B CN119155890 B CN 119155890B CN 202411650407 A CN202411650407 A CN 202411650407A CN 119155890 B CN119155890 B CN 119155890B
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Prior art keywords
pcb
signal
board
signal line
power supply
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CN119155890A (en
Inventor
赵建颖
李淼
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Shanghai Gulun Electronics Co ltd
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Shanghai Gulun Electronics Co ltd
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    • H—ELECTRICITY
    • H05—ELECTRIC TECHNIQUES NOT OTHERWISE PROVIDED FOR
    • H05K—PRINTED CIRCUITS; CASINGS OR CONSTRUCTIONAL DETAILS OF ELECTRIC APPARATUS; MANUFACTURE OF ASSEMBLAGES OF ELECTRICAL COMPONENTS
    • H05K1/00—Printed circuits
    • H05K1/02—Details
    • H05K1/0213—Electrical arrangements not otherwise provided for
    • H05K1/0216—Reduction of cross-talk, noise or electromagnetic interference
    • 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
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01R—ELECTRICALLY-CONDUCTIVE CONNECTIONS; STRUCTURAL ASSOCIATIONS OF A PLURALITY OF MUTUALLY-INSULATED ELECTRICAL CONNECTING ELEMENTS; COUPLING DEVICES; CURRENT COLLECTORS
    • H01R12/00—Structural associations of a plurality of mutually-insulated electrical connecting elements, specially adapted for printed circuits, e.g. printed circuit boards [PCB], flat or ribbon cables, or like generally planar structures, e.g. terminal strips, terminal blocks; Coupling devices specially adapted for printed circuits, flat or ribbon cables, or like generally planar structures; Terminals specially adapted for contact with, or insertion into, printed circuits, flat or ribbon cables, or like generally planar structures
    • H01R12/70—Coupling devices
    • H01R12/71—Coupling devices for rigid printing circuits or like structures
    • H01R12/712—Coupling devices for rigid printing circuits or like structures co-operating with the surface of the printed circuit or with a coupling device exclusively provided on the surface of the printed circuit
    • H01R12/716—Coupling device provided on the PCB
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01R—ELECTRICALLY-CONDUCTIVE CONNECTIONS; STRUCTURAL ASSOCIATIONS OF A PLURALITY OF MUTUALLY-INSULATED ELECTRICAL CONNECTING ELEMENTS; COUPLING DEVICES; CURRENT COLLECTORS
    • H01R13/00—Details of coupling devices of the kinds covered by groups H01R12/70 or H01R24/00 - H01R33/00
    • H01R13/02—Contact members
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01R—ELECTRICALLY-CONDUCTIVE CONNECTIONS; STRUCTURAL ASSOCIATIONS OF A PLURALITY OF MUTUALLY-INSULATED ELECTRICAL CONNECTING ELEMENTS; COUPLING DEVICES; CURRENT COLLECTORS
    • H01R13/00—Details of coupling devices of the kinds covered by groups H01R12/70 or H01R24/00 - H01R33/00
    • H01R13/648—Protective earth or shield arrangements on coupling devices, e.g. anti-static shielding  
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01R—ELECTRICALLY-CONDUCTIVE CONNECTIONS; STRUCTURAL ASSOCIATIONS OF A PLURALITY OF MUTUALLY-INSULATED ELECTRICAL CONNECTING ELEMENTS; COUPLING DEVICES; CURRENT COLLECTORS
    • H01R24/00—Two-part coupling devices, or either of their cooperating parts, characterised by their overall structure
    • H01R24/38—Two-part coupling devices, or either of their cooperating parts, characterised by their overall structure having concentrically or coaxially arranged contacts
    • H01R24/40—Two-part coupling devices, or either of their cooperating parts, characterised by their overall structure having concentrically or coaxially arranged contacts specially adapted for high frequency
    • H01R24/50—Two-part coupling devices, or either of their cooperating parts, characterised by their overall structure having concentrically or coaxially arranged contacts specially adapted for high frequency mounted on a PCB [Printed Circuit Board]
    • H—ELECTRICITY
    • H05—ELECTRIC TECHNIQUES NOT OTHERWISE PROVIDED FOR
    • H05K—PRINTED CIRCUITS; CASINGS OR CONSTRUCTIONAL DETAILS OF ELECTRIC APPARATUS; MANUFACTURE OF ASSEMBLAGES OF ELECTRICAL COMPONENTS
    • H05K1/00—Printed circuits
    • H05K1/02—Details
    • H05K1/0201—Thermal arrangements, e.g. for cooling, heating or preventing overheating
    • H—ELECTRICITY
    • H05—ELECTRIC TECHNIQUES NOT OTHERWISE PROVIDED FOR
    • H05K—PRINTED CIRCUITS; CASINGS OR CONSTRUCTIONAL DETAILS OF ELECTRIC APPARATUS; MANUFACTURE OF ASSEMBLAGES OF ELECTRICAL COMPONENTS
    • H05K1/00—Printed circuits
    • H05K1/02—Details
    • H05K1/0213—Electrical arrangements not otherwise provided for
    • H—ELECTRICITY
    • H05—ELECTRIC TECHNIQUES NOT OTHERWISE PROVIDED FOR
    • H05K—PRINTED CIRCUITS; CASINGS OR CONSTRUCTIONAL DETAILS OF ELECTRIC APPARATUS; MANUFACTURE OF ASSEMBLAGES OF ELECTRICAL COMPONENTS
    • H05K1/00—Printed circuits
    • H05K1/02—Details
    • H05K1/0213—Electrical arrangements not otherwise provided for
    • H05K1/0215—Grounding of printed circuits by connection to external grounding means
    • H—ELECTRICITY
    • H05—ELECTRIC TECHNIQUES NOT OTHERWISE PROVIDED FOR
    • H05K—PRINTED CIRCUITS; CASINGS OR CONSTRUCTIONAL DETAILS OF ELECTRIC APPARATUS; MANUFACTURE OF ASSEMBLAGES OF ELECTRICAL COMPONENTS
    • H05K1/00—Printed circuits
    • H05K1/02—Details
    • H05K1/0213—Electrical arrangements not otherwise provided for
    • H05K1/0216—Reduction of cross-talk, noise or electromagnetic interference
    • H05K1/023—Reduction of cross-talk, noise or electromagnetic interference using auxiliary mounted passive components or auxiliary substances
    • H—ELECTRICITY
    • H05—ELECTRIC TECHNIQUES NOT OTHERWISE PROVIDED FOR
    • H05K—PRINTED CIRCUITS; CASINGS OR CONSTRUCTIONAL DETAILS OF ELECTRIC APPARATUS; MANUFACTURE OF ASSEMBLAGES OF ELECTRICAL COMPONENTS
    • H05K1/00—Printed circuits
    • H05K1/02—Details
    • H05K1/11—Printed elements for providing electric connections to or between printed circuits
    • H—ELECTRICITY
    • H05—ELECTRIC TECHNIQUES NOT OTHERWISE PROVIDED FOR
    • H05K—PRINTED CIRCUITS; CASINGS OR CONSTRUCTIONAL DETAILS OF ELECTRIC APPARATUS; MANUFACTURE OF ASSEMBLAGES OF ELECTRICAL COMPONENTS
    • H05K1/00—Printed circuits
    • H05K1/18—Printed circuits structurally associated with non-printed electric components
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01R—ELECTRICALLY-CONDUCTIVE CONNECTIONS; STRUCTURAL ASSOCIATIONS OF A PLURALITY OF MUTUALLY-INSULATED ELECTRICAL CONNECTING ELEMENTS; COUPLING DEVICES; CURRENT COLLECTORS
    • H01R2201/00—Connectors or connections adapted for particular applications
    • H01R2201/20—Connectors or connections adapted for particular applications for testing or measuring purposes

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  • Engineering & Computer Science (AREA)
  • Microelectronics & Electronic Packaging (AREA)
  • Physics & Mathematics (AREA)
  • Electromagnetism (AREA)
  • Computer Hardware Design (AREA)
  • General Engineering & Computer Science (AREA)
  • General Physics & Mathematics (AREA)
  • Structure Of Printed Boards (AREA)

Abstract

The invention discloses a circuit, a system and a PCB structure for improving the leakage performance of a PCB (printed Circuit Board) based on an FR-4 board, which are suitable for measuring semiconductor current lower than a Pian level, and comprise an equipotential protection layer, wherein the equipotential protection layer is connected with a signal wire and is arranged close to the signal end and used for ensuring that the potential of the equipotential protection layer is the same as that of the signal end, so that the two ends of the signal wire to be protected have no voltage difference to reduce the leakage state, and a constant temperature protection module is connected with the equipotential protection layer and comprises a heating resistance wire, a temperature detection chip, a temperature control unit, an isolation buffer unit and an isolation power supply.

Description

Circuit, system and PCB structure for improving PCB leakage performance based on FR-4 board
Technical Field
The invention relates to the technical field of semiconductors, in particular to a circuit for improving the leakage performance of a PCB (printed Circuit Board) based on an FR-4 board and a PCB structure.
Background
The printed circuit board PCB, most commonly model FR-4 epoxy board, has many factors to consider when measuring low value currents on the board, such as picoampere level or lower. For example, the PCB itself may be a source of error, affecting the accuracy of the measurement, as current leakage and medium sink current cannot be distinguished from the measured signal. It is therefore desirable to minimize the impact of these sources of error.
The test performance is generally improved by using the protection layer adding technology, however, fr-4 absorbs moisture in the air after being exposed to the air for a long time, so that the impedance of the Fr-4 is low, and under the condition that a signal wire carries a certain voltage, a signal can leak out some current from a pcb, and the test performance is affected.
Disclosure of Invention
The invention aims to provide a circuit, a system and a PCB structure for improving the leakage performance of a PCB based on an FR-4 board, which can be realized by using the FR-4 board of a common PCB without increasing excessive cost.
The invention provides a circuit for improving the leakage performance of a PCB (printed Circuit Board) based on an FR-4 board, which is suitable for measuring semiconductor current lower than the Pian level, and comprises the following steps:
The equipotential protection layer is connected with the signal line and is arranged close to the signal end, and is used for ensuring that the potential of the equipotential protection layer is the same as that of the signal end, so that the two ends of the signal line to be protected have no voltage difference to reduce the occurrence of a leakage state;
The constant temperature protection module is connected with the equipotential protection layer, and comprises:
the heating resistance wire is used for heating the PCB board through heat generated by the electric heating element by heat conduction to maintain the constant temperature environment on the PCB board;
the temperature detection chip is used for monitoring the potential state of the heating resistance wire in real time and transmitting the potential state to the temperature control unit;
The temperature control unit is used for sending a real-time level adjustment instruction to the heating resistance wire according to the current monitored potential state change, so that the voltage on the equipotential protection layer is consistent with the voltage of the signal end;
The isolation buffer unit is used for acquiring the voltage of the signal end and transmitting the voltage to the temperature control unit through an isolation power supply;
The isolating power supply is used for supplying power to the constant temperature protection module and converting an input power supply into an isolated output power supply, and the output power supply is floating and can meet any change of the level of the heating resistance wire;
Under test mode, PCB based on FR-4 panel appears absorbing the moisture in the air in the exposure of presetting time and leads to PCB impedance to become low and signal line carries the condition that the voltage appears leaking, through constant temperature protection module provides constant temperature environment for the signal line, under the circumstances of guaranteeing the constant temperature, guarantees the equipotential protective layer's electric potential is the same with the electric potential of signal terminal on the signal line, avoids signal to spill from PCB when the signal line carries the voltage.
Preferably, the signal end of the signal wire is used as an output and measurement port of the whole circuit, the signal end of the signal wire is connected with an external element to be measured through a center contact of a triaxial connector, the signal end of the signal wire is connected with one end of an equipotential protection layer through a triaxial connector, the other end of the equipotential protection layer is connected with one end of a heating resistance wire, the other end of the heating resistance wire is connected with a negative electrode port of an isolation power supply, meanwhile, one end of the heating resistance wire is connected with an input end of a temperature control unit, an output end of the temperature control unit is connected with a positive electrode port of the isolation power supply, a power supply negative electrode port of the isolation power supply is grounded, the power supply positive electrode port of the isolation power supply is externally supplied with power, the signal end of the signal wire is connected with a positive electrode input port of the isolation buffer unit, and the negative electrode input port of the isolation buffer unit and the output port of the isolation buffer unit are connected to a negative electrode port of the isolation power supply.
Preferably, the input end of the temperature control unit is connected with the output end of the temperature detection chip.
Preferably, one end of the triaxial connector except for the center contact is connected with the PCB main board ground through an output high-potential port arranged on the PCB, and the other end of the triaxial connector except for the center contact is connected with the PCB main board ground through an output low-potential port arranged on the PCB.
Preferably, the heating resistance wire is disposed close to the signal line to be protected, and is used for providing an effective heating effect for surrounding PCB boards, and simultaneously performing equipotential protection on the equipotential protection layer connected with the heating resistance wire.
The invention also provides a circuit system for improving the leakage performance of the PCB based on the FR-4 board, which comprises the circuit for improving the leakage performance of the PCB based on the FR-4 board.
The invention also provides a PCB structure for improving the PCB leakage performance based on the FR-4 board, which is applied to the circuit for improving the PCB leakage performance based on the FR-4 board, wherein the upper surface of the PCB structure at least comprises signal wires distributed in the middle, one or more heating resistance wires are arranged along the length direction of the signal wires, and the heating resistance wires are tightly surrounded on two sides of the signal wires to form a detection area.
Preferably, a groove structure is arranged around the detection area, the groove structure isolates the detection area from the PCB area outside the detection area to form an air isolation area, the impedance of the intermediate signal is improved through the air isolation area, and meanwhile, the temperature isolation is carried out on the signal line and the PCB area through the air isolation area, so that the ambient temperature of the signal line is ensured to be constant.
Preferably, a temperature detection chip is arranged in the detection area, the temperature detection chip is arranged close to the signal end of the signal wire, and the signal end of the signal wire is connected with the triaxial connector.
Preferably, the PCB structure at least comprises a signal wire, an FR-4 structure layer and a PCB copper skin layer which are distributed and arranged in sequence from top to bottom.
Aiming at the prior art, the invention has the following beneficial effects:
1. The circuit for improving the leakage performance of the PCB based on the FR-4 board comprises an equipotential protection layer, wherein the equipotential protection layer is connected with a signal wire and is arranged close to the signal end, so that the same potential of the equipotential protection layer and the signal end is ensured, and the voltage difference between two ends of the signal wire to be protected is reduced, thereby reducing the leakage risk. The constant temperature protection module comprises a heating resistance wire, a temperature detection chip and a temperature control unit, and is used for maintaining a constant temperature environment on a PCB, ensuring the stable potential state of the heating resistance wire and further keeping the voltage on the equipotential protection layer consistent with the voltage of the signal end. And the isolation buffer unit is used for acquiring the voltage of the signal end and transmitting the voltage to the temperature control unit through the isolation power supply, so that the stability and reliability of signal transmission are enhanced. And the isolating power supply is used for supplying power to the constant temperature protection module, converting the input power supply into an isolated output power supply and meeting the random change requirement of the level of the heating resistance wire.
2. The signal end of the signal wire is connected with an external element to be tested through the center contact of the triaxial connector and is connected with the equipotential protection layer, so that the stability and the accuracy of signal transmission are ensured.
One end of the coaxial connector except the center contact is connected with an output high-potential port on the PCB, and the other end of the coaxial connector except the center contact is connected with an output low-potential port and is connected to the ground of the PCB main board, so that a complete signal transmission and grounding loop is formed, and the anti-interference capability is improved.
3. The temperature control unit is connected with the temperature detection chip, wherein the input end of the temperature control unit is connected with the output end of the temperature detection chip, the potential state of the heating resistance wire is monitored in real time, and an adjusting instruction is sent out, so that the voltage on the equipotential protection layer is ensured to be consistent with the voltage of the signal end. The heating resistance wire is arranged close to the signal wire to be protected, so that an effective heating effect is provided for surrounding PCB (printed circuit board), and meanwhile, the equipotential protection layer performs equipotential protection, so that the leakage risk is further reduced.
4. The PCB structure for improving the electric leakage performance of the PCB based on the FR-4 board material is characterized in that the upper surface of the PCB structure at least comprises signal wires distributed in the middle and one or more heating resistance wires arranged along the length direction of the signal wires by applying the circuit scheme, so that a detection area is formed. The groove structure is arranged around the detection area, the detection area is isolated from the external PCB area to form an air isolation area, the impedance of the intermediate signal is improved, and the leakage risk is reduced. The temperature detection chip is arranged in the detection area, is arranged close to the signal end of the signal wire, and is connected with the triaxial connector, so that the stability and the accuracy of signal transmission are ensured. The PCB structure at least comprises a signal wire, an FR-4 structure layer and a PCB copper skin layer which are distributed and arranged in sequence from top to bottom to form a complete PCB structure system.
In summary, the circuit realizes the Pian-class current test of the common PCB board by the self-grinding circuit and PCB board-level structural design, and improves the PCB leakage performance based on the FR-4 board. Through the designs of the equipotential protection layer, the constant temperature protection module, the isolation buffer unit, the isolation power supply and the like, the stability and the accuracy of signal transmission are ensured, and the electromagnetic interference and the signal loss are reduced. The anti-interference capability and the safety of the system are enhanced, the problems caused by electromagnetic interference or potential difference can be effectively prevented, and the normal operation of equipment and the safety of personnel are ensured.
Drawings
FIG. 1 is a schematic block diagram of a circuit for improving the leakage performance of a PCB based on FR-4 board according to a first embodiment of the invention;
FIG. 2 is a top view of a PCB structure for improving leakage performance of a PCB based on FR-4 board according to a first embodiment of the invention;
Fig. 3 is a side view of a signal line in a PCB structure for improving leakage performance of a PCB based on an FR-4 board according to the first embodiment of the invention.
Detailed Description
For the purpose of making the objects, technical solutions and advantages of the embodiments of the present invention more apparent, the technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings in the embodiments of the present invention, and it is apparent that the described embodiments are some embodiments of the present invention, but not all embodiments of the present invention. All other embodiments, which can be made by those skilled in the art based on the embodiments of the invention without making any inventive effort, are intended to be within the scope of the invention.
As shown in fig. 1, the present invention provides a circuit for improving leakage performance of a PCB based on FR-4 board, suitable for semiconductor current measurement below the picoampere level, comprising:
The equipotential protection layer 2 is connected with the signal line 1 and is arranged close to the signal end, and is used for ensuring that the potential of the equipotential protection layer 2 is the same as the potential of the signal end, so that the two ends of the signal line 1 to be protected have no voltage difference to reduce the occurrence of a leakage state, and the equipotential protection layer which is the same as the potential of the signal end is added and is close to the signal end, so that the leakage phenomenon can be reduced, and the requirement of isolation impedance is reduced because the two sections have no voltage difference;
because the common PCB board has the moisture absorption characteristic, a set of constant temperature protection system, namely constant temperature protection module 3 is added to the circuit, is connected with equipotential protection layer 2, includes:
the heating resistance wire is used for heating the PCB board through heat generated by the electric heating element by heat conduction to maintain the constant temperature environment on the PCB board;
the temperature detection chip is used for monitoring the potential state of the heating resistance wire in real time and transmitting the potential state to the temperature control unit;
The temperature control unit is used for sending a real-time level adjustment instruction to the heating resistance wire according to the current monitored potential state change, so that the voltage on the equipotential protection layer is consistent with the voltage of the signal end;
The isolation buffer unit is used for acquiring the voltage of the signal end, transmitting the voltage to the temperature control unit through the isolation power supply, and adding an isolation buffer chip into the circuit for acquiring the voltage of the signal end. Through isolating the power supply, the potential of the heating resistance wire is ensured to be consistent with the signal end all the time, so that the equipotential protection effect is realized;
The isolating power supply is used for supplying power to the constant temperature protection module and converting an input power supply into an isolated output power supply, the output power supply is floating and can meet the requirement of random change of the level of the heating resistance wire, and the isolating power supply not only provides power for the constant temperature system, but also can allow the level of the resistance wire to be changed randomly due to the fact that the output end of the isolating power supply is floating so as to meet the requirement of keeping consistent with the signal end. The circuit ensures stable operation of the system, reduces the influence of environmental factors (such as humidity) on circuit performance, and simultaneously ensures the integrity and reliability of the signal line.
In this embodiment, in the test mode, when the PCB based on the FR-4 board is exposed to air for a preset time, the PCB impedance becomes low and the signal line 1 carries voltage to generate leakage, the constant temperature protection module 3 provides a constant temperature environment for the signal line, under the condition of ensuring constant temperature, the potential of the equipotential protection layer 2 is ensured to be the same as the potential of the signal end on the signal line 1, so that the signal is prevented from leaking from the PCB when the signal line 1 carries voltage, the test performance is improved by adding the protection layer technology, the problem that the signal leaks from the PCB when the signal line 1 carries voltage is solved, and the defect that the signal leaks some current from the PCB when the signal line 1 carries a certain voltage to influence the test performance is solved, so that the leakage is prevented and the test performance is improved when the constant temperature is maintained.
Specifically, the signal end of the signal wire 1 is used as an output and measurement port of the whole circuit, the signal end of the signal wire is connected with an external element to be measured through a center contact of a triaxial connector, the signal end of the signal wire is connected with one end of an equipotential protection layer through a triaxial connector, the other end of the equipotential protection layer is connected with one end of a heating resistance wire, the other end of the heating resistance wire is connected with a negative electrode port of an isolation power supply, meanwhile, one end of the heating resistance wire is connected with an input end of a temperature control unit, an output end of the temperature control unit is connected with a positive electrode port of the isolation power supply, a power supply negative electrode port of the isolation power supply is grounded, the external power supply of the power supply positive electrode port of the isolation power supply is supplied, the signal end of the signal wire 1 is connected with a positive electrode input port of the isolation buffer unit, and the negative electrode input port of the isolation buffer unit and the output port of the isolation buffer unit are connected to a negative electrode port of the isolation power supply. The design enables the signal wire 1 to directly reflect the state of an external element to be tested, provides accurate input information for a subsequent signal processing, data analysis or control system, reduces intermediate links and improves the efficiency and accuracy of signal transmission. The signal end of the signal wire is connected with the external element to be tested and the equipotential protection layer through the triaxial connector, so that the stability and the reliability of signal transmission are ensured by using the triaxial connector, meanwhile, the connection with the equipotential protection layer is beneficial to eliminating electromagnetic interference and improving the signal quality, and the connection mode is beneficial to simplifying the circuit layout, so that the whole system is more compact and easier to maintain. The introduction of the equipotential protection layer plays a vital role in the circuit, and the equipotential protection of the circuit is realized by connecting the heating resistance wire with the negative electrode port of the isolation power supply, so that the protection mechanism can effectively prevent the problems of arc discharge and the like caused by potential difference, and the safety and the stability of the circuit are improved. The heating resistance wire and the temperature control unit work cooperatively, wherein one end of the heating resistance wire is connected with the input end of the temperature control unit, and the other end of the heating resistance wire is connected with the positive electrode port of the isolation power supply, so that the temperature control unit can monitor the temperature change of the heating resistance wire in real time and adjust the output power according to the requirement so as to realize accurate temperature control. The isolation buffer unit plays a role in supporting up and down in the whole circuit, the signal end of the signal wire 1 is connected with the negative electrode port of the isolation power supply, and meanwhile, the negative electrode input port and the output port of the isolation buffer unit are also respectively connected with the negative electrode port of the isolation power supply, so that the isolation buffer unit is beneficial to further isolating external interference and improving the stability and reliability of signal transmission. The design realizes efficient signal transmission, accurate temperature control and reliable equipotential protection through reasonable circuit layout and element selection.
Specifically, the input end of the temperature control unit is connected with the output end of the temperature detection chip. This design enables the temperature control unit to directly receive the temperature signal from the temperature detection chip. The temperature detection chip is responsible for monitoring the temperature of the heating resistance wire or the element to be detected in real time and converting the temperature into an electric signal to be output. By directly connecting this output signal to the input of the temperature control unit, it is ensured that the temperature control unit can accurately and quickly obtain the current temperature information. Meanwhile, the accuracy and the response speed of temperature control are improved, namely, the temperature detection chip can monitor temperature changes in real time and rapidly transmit the changes to the temperature control unit, so that the temperature control accuracy of the whole system is remarkably improved, and the response speed of the system is improved due to reduction of delay and interference in the signal transmission process, so that the system can control the temperature of the heating resistance wire more accurately to meet different application requirements.
Specifically, one end of the triaxial connector except for the center contact is connected with the PCB main board ground through an output high-potential port arranged on the PCB, and the other end of the triaxial connector except for the center contact is connected with the PCB main board ground through an output low-potential port arranged on the PCB. A triaxial connector is a connector having three mutually insulated conductor layers, commonly used for high frequency signal transmission, and consists of a center contact for transmitting signals, an inner conductor for shielding and grounding, an insulating layer and an outer conductor. The two ends of the triaxial connector, except the center contact, are respectively connected with an output high-potential port and an output low-potential port on the PCB, and are finally connected to the ground of the PCB main board. This connection forms a complete signal transmission and ground loop. By connecting the two ends of the triaxial connector, except the center contact, to the high-potential and low-potential ports on the PCB board, respectively, and ensuring that they are both grounded, the stability and reliability of signal transmission can be significantly improved. The triaxial connector has excellent shielding performance, so that the anti-interference capability of the system can be effectively enhanced when the triaxial connector is applied to a signal transmission system. By grounding the outer conductor of the connector, a faraday cage effect is created that minimizes the effects of external electromagnetic fields, thereby protecting the internal signals from interference.
Specifically, the heating resistance wire is close to the signal wire to be protected and is used for providing an effective heating effect for surrounding PCB boards, and meanwhile, equipotential protection is carried out on the equipotential protection layer connected with the heating resistance wire, so that the resistance wire can be as close to the signal wire as possible, and therefore the PCB area near the signal wire can be heated more directly, and the heating efficiency is improved.
The circuit principle in the embodiment is as follows, referring to fig. 1, in the block diagram, a source end and a signal end are system output and measurement ports, and a picoampere-level small current needs to be tested, namely a signal wire which needs to be protected by the system. The system is added with an equipotential protection layer, the potential of the equipotential protection layer is the same as that of the signal end, and the equipotential protection layer is close to the signal end, so that the two sections have no voltage difference, leakage can be reduced, and the isolation impedance requirement is lowered. Because of the moisture absorption characteristic of the common PCB, a set of constant temperature protection module is added, and the constant temperature protection module comprises a heating resistance wire, a temperature detection chip, a temperature control unit, an isolation power supply and an isolation buffer unit. The circuit is provided with an isolation buffer chip, the voltage of the signal terminal is taken, and the potential of the heat-resistant wire is always consistent with that of the signal terminal by adding an isolation power supply, so that the equipotential protection effect is realized. Secondly, the design can enable the resistance wire to be as close to the signal wire as possible, so that the resistance wire can heat the PCB near the signal wire more fully and directly. The addition of the isolation power supply not only provides power for the constant temperature system, but also enables the level of the resistance wire to be changed randomly because the output end of the isolation power supply floats, thereby meeting the requirement of keeping the same with the signal end. Based on the same inventive concept, the invention also provides a circuit system for improving the PCB leakage performance based on the FR-4 board, comprising the circuit for improving the PCB leakage performance based on the FR-4 board.
Referring to fig. 2, the invention further provides a PCB structure for improving the leakage performance of a PCB based on an FR-4 board, and the circuit for improving the leakage performance of a PCB based on an FR-4 board according to the above embodiment is applied, the upper surface of the PCB structure at least includes a signal wire 1 distributed in the middle, one or more heating resistance wires 4 are arranged along the length direction of the signal wire 1, the heating resistance wires 4 are tightly enclosed on two sides of the signal wire 1 to form a detection area 5, the signal wire 1 is in the middle, and the heating resistance wires 4 tightly enclose the detection area, thereby not only playing a role of heating surrounding FR-4 and drying, but also playing a role of an equipotential unique structural design protection layer.
Referring to fig. 3, a groove structure 6 is disposed around the detection area 5, the groove structure 6 isolates the detection area 5 from the PCB area 7 outside the detection area to form an air isolation area, the impedance of the intermediate signal is improved through the air isolation area, meanwhile, the temperature of the signal line 1 and the PCB area 7 is isolated through the air isolation area, the constant temperature around the signal line 1 is ensured, and the PCB area 7 is completely hollowed out outside the heating resistance wire.
Specifically, a temperature detection chip 8 is disposed in the detection area 5, and the temperature detection chip 8 is disposed near the signal end of the signal line 1, and the signal end of the signal line 1 is connected with a triaxial connector 9.
Specifically, the PCB structure at least includes a signal line 1, an FR-4 structural layer 10 and a PCB copper layer 11 which are distributed from top to bottom in sequence, and as seen from a side view, a layer of PCB copper layer 11 is added below the signal line, which plays a role in equipotential surrounding signals and also plays a role in transferring temperature, so that a temperature detection chip in the top view can completely detect the temperature condition of the whole detection area 5.
It should be noted that the above-mentioned embodiments are merely for illustrating the technical solution of the present invention, and not for limiting the same, and although the present invention has been described in detail with reference to the above-mentioned embodiments, it should be understood by those skilled in the art that the technical solution described in the above-mentioned embodiments may be modified or some technical features may be equivalently replaced, and these modifications or substitutions do not make the essence of the corresponding technical solution deviate from the spirit and scope of the technical solution of the embodiments of the present invention.

Claims (10)

1.一种提高基于FR-4板材的PCB漏电性能的电路，其特征在于，适用于低于皮安级的半导体电流测量，包括：1. A circuit for improving the leakage performance of a PCB based on FR-4 board, characterized in that it is suitable for measuring semiconductor currents below the picoampere level, comprising: 等电位保护层，所述等电位保护层与信号线连接，且紧邻信号端设置，用于确保所述等电位保护层的电位与信号端的电位相同，使得待保护信号线两端无电压差以减少出现漏电状态；An equipotential protection layer, which is connected to the signal line and is arranged close to the signal end, and is used to ensure that the potential of the equipotential protection layer is the same as the potential of the signal end, so that there is no voltage difference between the two ends of the signal line to be protected to reduce the occurrence of leakage; 恒温保护模块，与所述等电位保护层连接，包括：The constant temperature protection module is connected to the equipotential protection layer and includes: 加热电阻丝，用于通过电热元件本身产生的热量以热传导加热PCB板来维持PCB板上的恒温环境；The heating resistor wire is used to heat the PCB board by heat conduction through the heat generated by the electric heating element itself to maintain a constant temperature environment on the PCB board; 温度检测芯片，用于实时监测所述加热电阻丝的电位状态并传输至温度控制单元；A temperature detection chip is used to monitor the potential state of the heating resistance wire in real time and transmit it to the temperature control unit; 温度控制单元，用于根据当前监测到的电位状态变化向所述加热电阻丝发出实时电平调节指令，使得等电位保护层上的电压与信号端的电压保持一致；A temperature control unit, used for sending a real-time level adjustment instruction to the heating resistance wire according to the currently monitored potential state change, so that the voltage on the equipotential protection layer is consistent with the voltage at the signal end; 隔离缓冲单元，用于获取信号端的电压通过隔离电源传输至所述温度控制单元；An isolation buffer unit, used for acquiring the voltage of the signal end and transmitting it to the temperature control unit through an isolation power supply; 隔离电源，用于向所述恒温保护模块供电，并将输入电源转换为隔离的输出电源，该输出电源是浮动的，能够满足所述加热电阻丝电平的任意变化；An isolated power supply, used to supply power to the constant temperature protection module and convert the input power into an isolated output power supply, the output power supply is floating and can meet any change in the level of the heating resistance wire; 在测试模式下，基于FR-4板材的PCB在预设时间暴露在空气中出现吸收空气中的水分导致PCB阻抗变低且信号线携带电压出现漏电的情况，通过所述恒温保护模块向所述信号线提供恒温环境，在确保恒温的情况下，确保所述等电位保护层的电位与信号线上信号端的电位相同，避免在信号线携带电压时信号从PCB漏出。In the test mode, when a PCB based on FR-4 board material is exposed to the air for a preset period of time, it absorbs moisture in the air, causing the PCB impedance to become low and the voltage carried by the signal line to leak. The constant temperature protection module provides a constant temperature environment for the signal line. While ensuring the constant temperature, the potential of the equipotential protection layer is ensured to be the same as the potential of the signal end of the signal line, thereby preventing the signal from leaking from the PCB when the signal line carries voltage. 2.如权利要求1所述的提高基于FR-4板材的PCB漏电性能的电路，其特征在于，所述信号线的信号端作为整个电路的输出和测量端口，所述信号线的信号端通过三同轴连接器的中心触点与外部待测元件连接，且所述信号线的信号端通过三同轴连接器与所述等电位保护层的一端连接，所述等电位保护层的另一端与加热电阻丝的一端连接，所述加热电阻丝的另一端与所述隔离电源的负极端口连接，同时所述加热电阻丝的一端与所述温度控制单元的输入端连接，所述温度控制单元的输出端与所述隔离电源的正极端口连接，所述隔离电源的电源负极端口接地，所述隔离电源的电源正极端口外部供电，且所述信号线的信号端与所述隔离缓冲单元的正极输入端口连接，所述隔离缓冲单元的负极输入端口与所述隔离缓冲单元的输出端口连接至所述隔离电源的负极端口。2. The circuit for improving the leakage performance of a PCB based on an FR-4 sheet material as described in claim 1 is characterized in that the signal end of the signal line serves as the output and measurement port of the entire circuit, the signal end of the signal line is connected to an external component to be measured through a central contact of a three-coaxial connector, and the signal end of the signal line is connected to one end of the equipotential protection layer through a three-coaxial connector, the other end of the equipotential protection layer is connected to one end of a heating resistor, the other end of the heating resistor is connected to the negative port of the isolation power supply, and at the same time, one end of the heating resistor is connected to the input end of the temperature control unit, the output end of the temperature control unit is connected to the positive port of the isolation power supply, the negative power supply port of the isolation power supply is grounded, the positive power supply port of the isolation power supply is externally powered, and the signal end of the signal line is connected to the positive input port of the isolation buffer unit, the negative input port of the isolation buffer unit and the output port of the isolation buffer unit are connected to the negative port of the isolation power supply. 3.如权利要求1所述的提高基于FR-4板材的PCB漏电性能的电路，其特征在于，所述温度控制单元的输入端与所述温度检测芯片的输出端连接。3. The circuit for improving the leakage performance of a PCB based on FR-4 board material as claimed in claim 1, characterized in that the input end of the temperature control unit is connected to the output end of the temperature detection chip. 4.如权利要求2所述的提高基于FR-4板材的PCB漏电性能的电路，其特征在于，所述三同轴连接器上除中心触点的一端与PCB板上设置的输出高电位端口连接PCB主板大地，所述三同轴连接器上除中心触点的另一端与PCB板上设置的输出低电位端口连接PCB主板大地。4. The circuit for improving the leakage performance of a PCB based on an FR-4 board as described in claim 2 is characterized in that one end of the three-coaxial connector except the center contact is connected to the output high potential port set on the PCB board to the PCB main board ground, and the other end of the three-coaxial connector except the center contact is connected to the output low potential port set on the PCB board to the PCB main board ground. 5.如权利要求1所述的提高基于FR-4板材的PCB漏电性能的电路，其特征在于，所述加热电阻丝靠近所述待保护信号线设置，用于对周围的PCB板提供有效的加热效果，同时对与所述加热电阻丝连接的所述等电位保护层进行等电位保护。5. The circuit for improving the leakage performance of a PCB based on an FR-4 board as described in claim 1 is characterized in that the heating resistor is arranged close to the signal line to be protected, so as to provide an effective heating effect to the surrounding PCB board, and at the same time, perform equipotential protection on the equipotential protection layer connected to the heating resistor. 6.一种提高基于FR-4板材的PCB漏电性能的电路系统，其特征在于，包括如权利要求1至5中任意一项所述的提高基于FR-4板材的PCB漏电性能的电路。6. A circuit system for improving the leakage performance of a PCB based on an FR-4 board, characterized in that it comprises a circuit for improving the leakage performance of a PCB based on an FR-4 board as claimed in any one of claims 1 to 5. 7.一种提高基于FR-4板材的PCB漏电性能的PCB结构，其特征在于，应用如权利要求1至5中任意一项所述的提高基于FR-4板材的PCB漏电性能的电路，所述PCB结构上表面至少包括中间分布的信号线，沿所述信号线的长度方向设有一个或多个加热电阻丝，所述加热电阻丝紧密包围在所述信号线两侧形成检测区。7. A PCB structure for improving the leakage performance of a PCB based on an FR-4 board, characterized in that a circuit for improving the leakage performance of a PCB based on an FR-4 board as described in any one of claims 1 to 5 is applied, the upper surface of the PCB structure includes at least a signal line distributed in the middle, one or more heating resistors are provided along the length direction of the signal line, and the heating resistors are tightly surrounded on both sides of the signal line to form a detection area. 8.如权利要求7所述的提高基于FR-4板材的PCB漏电性能的PCB结构，其特征在于，所述检测区周围设有凹槽结构，所述凹槽结构将所述检测区与所述检测区外的PCB区域隔离形成一空气隔绝区，通过所述空气隔绝区提高中间信号的阻抗，同时通过所述空气隔绝区对信号线与PCB区域进行温度隔绝，确保信号线周围温度恒定。8. The PCB structure for improving the leakage performance of a PCB based on an FR-4 board material as described in claim 7 is characterized in that a groove structure is provided around the detection area, and the groove structure isolates the detection area from the PCB area outside the detection area to form an air isolation area, and the impedance of the intermediate signal is increased by the air isolation area. At the same time, the signal line and the PCB area are temperature-isolated by the air isolation area to ensure that the temperature around the signal line is constant. 9.如权利要求7所述的提高基于FR-4板材的PCB漏电性能的PCB结构，其特征在于，所述检测区内设有温度检测芯片，且所述温度检测芯片靠近所述信号线的信号端设置，所述信号线的信号端与三同轴连接器连接。9. The PCB structure for improving the leakage performance of a PCB based on FR-4 board material as described in claim 7, characterized in that a temperature detection chip is provided in the detection area, and the temperature detection chip is arranged close to the signal end of the signal line, and the signal end of the signal line is connected to a three-coaxial connector. 10.如权利要求7所述的提高基于FR-4板材的PCB漏电性能的PCB结构，其特征在于，所述PCB结构至少包括从上到下依次分布设置的信号线、FR-4结构层和PCB铜皮层。10. The PCB structure for improving leakage performance of a PCB based on FR-4 board material as claimed in claim 7, characterized in that the PCB structure at least comprises a signal line, a FR-4 structure layer and a PCB copper layer which are sequentially arranged from top to bottom.
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CN115494276A (en) * 2022-09-01 2022-12-20 苏州金燧光电科技有限公司 Current accurate measurement method based on simulation conditioning technology

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