CN101005730A - Circuit board for reducing electromagnetic interference of electronic product - Google Patents
Circuit board for reducing electromagnetic interference of electronic product Download PDFInfo
- Publication number
- CN101005730A CN101005730A CN 200610033087 CN200610033087A CN101005730A CN 101005730 A CN101005730 A CN 101005730A CN 200610033087 CN200610033087 CN 200610033087 CN 200610033087 A CN200610033087 A CN 200610033087A CN 101005730 A CN101005730 A CN 101005730A
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- electromagnetic interference
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Abstract
The invention is used for reducing the radiation emission of circuit board caused by the signals passing through the parasitic inductance. It removes the layout of ground trace from the circuit layout, and uses metal plate and metal screw instead of the ground race. Due to removing of twist ground trace, the radiation emission is reduced.
Description
Technical field
The present invention is relevant for a kind of circuit board that reduces the electronic product electromagnetic interference.
Background technology
High speed development with communication and computer technology, make high-speed printed circuit board (printed circuitboard, abbreviation PCB) design has entered the Gigabit field, new high speed element is used and is made that so the high long Distance Transmission of speed on circuit board becomes possibility, but at the same time, the problem of the problems of Signal Integrity in the PCB design (SI), power supply integrality and electromagnetic compatibility (electro-magnetic compatibility is called for short EMC) aspect is also more outstanding.Printed circuit board (PCB) almost can appear in the middle of each electronic equipment.Electronic component in the equipment is set in according to circuit layout on the printed circuit board (PCB) of different sizes.Except fixing miscellaneous small parts, the major function of printed circuit board (PCB) provides that mutual electric current of every electronic component connects on it.Yet in high-frequency circuit and high-speed digital circuit, arbitrary cabling on the printed circuit board (PCB) will form stray inductance, will form parasitic capacitance composition and mutual inductance composition if there are two cablings to walk online.Formed capacitor and inductor numerical value is very small, therefore is a problem hardly when low frequency, still but can not ignore the influence of parasitic capacitance and stray inductance composition in the high frequency field.
Please refer to Fig. 1, it is the calcspar of common circuit at present, and printed circuit board (PCB) 10 includes: power supply unit 20, load impedance 30, transmission line 40 and stray inductance 50.Transmission line 40 is fed to the voltage or the current signal of load impedance 30 by power supply unit 20 in order to conduction between power supply unit 20 and load impedance 30.Because power supply unit 20 provides a signal that has frequency, when low frequency, transmission line 40 does not have obvious stray inductance and parasitic capacitance effect, so can ignore its influence, but under the influence of considering high frequency, then transmission line 40 must be considered as discrete elements (distributed element), will consider the influence of high-frequency effects under this situation.Signal frequency in the stray inductance is high more, the impedance of inductance is just big more, therefore, when the rising and falling edges harmonic frequency of output signal drops within the electromagnetic interference (EMI) emission band scope (rise time is 11ns or faster), give off electromagnetic wave as the stray inductance change meeting image antenna, produced electromagnetic interference (EMI).
And stray inductance 50 is under high-frequency effects, and there is stray inductance in transmission line 40 cablings in printed circuit board (PCB) 10, is known the variable quantity that has a voltage by following formula: Δ V=LdI/dt, wherein
The variable quantity of Δ V=voltage;
L=printed circuit board (PCB) cabling stray inductance resistance value;
The flow through electric current of printed circuit board (PCB) cabling of dI=changes;
The time that the dt=electric current changes.
If will begin immediately or stop to flow suddenly, tend to make cabling to produce the electric current surging when electric current.During transition each time, this a part of cabling can produce the burst current of high dI/dt.Therefore, abrupt voltage wave can utilize equation Δ V=LdI/dt to calculate.So these stray inductances not only can produce electromagnetic interference, and the abrupt voltage wave that is produced also can invade integrated control circuit, makes job insecurity.
Therefore, the stray inductance value of reduction printed circuit board (PCB) upper conductor is just very important.The size in magnetic field partly depends on the sectional area of conductor.When conductor can broaden, thickening or when shortening, magnetic field will be weakened, stray inductance will reduce.
In order to reduce the electromagnetic field effects that produces by electric current, on printed circuit board (PCB), generally take some modes, should make power supply and ground connection as far as possible near wiring.In addition, for the area of wiring material, also should toward broaden, thickening or the direction that shortens go to improve.Particularly in the configuration of earth connection, if the circuit layout of earth connection (circuit layout) is not good, cause on it electromagnetic interference excessive, then printed circuit board (PCB) needs circuit layout (circuit layout) again, will cost of idleness and time.
Therefore, how to provide a kind of ground wire wiring method that is applied to printed circuit board (PCB) on the electronic installation, the signal that reduces printed circuit board (PCB) becomes one of researcher's problem to be solved by the electromagnetic wave effect that online stray inductance produces.
Summary of the invention
Because the shortcoming and the insurmountable problem of prior art existence, the present invention discloses a kind of circuit board of minimizing electronic product electromagnetic interference, the ground wire connecton layout that is used for printed circuit board (PCB), utilize sheet metal to follow the metal screw to replace the part of earth connection cabling originally, since remove tortuous curved around the earth connection cabling, so current signal can directly be got back to the negative pole of power supply unit by less obstruction, also can reduce the electromagnetic wave by stray inductance gave off on the circuit.
Therefore, for reaching above-mentioned purpose, the circuit board that the present invention disclosed includes sheet metal and several metal screws.Sheet metal is for replacing transmission line ground connection cabling originally, in order to the electric current between conduction power supply unit and the load impedance.Several metal screws except fixed power source supply and sheet metal and fixing metal sheet and printed circuit board (PCB), have more the function of electric current between conduction power supply unit and the load impedance.By the transmission live width on sheet metal conductor and the general printed circuit board (PCB) of metal screw conductor, stray inductance will reduce, and the electromagnetic interference of institute's radiation just reduces.
Description of drawings
Fig. 1 is for being the calcspar of common circuit at present.
Fig. 2 is the present invention's circuit block diagram.
Embodiment
Please refer to Fig. 2, it utilizes sheet metal to follow screw to replace the circuit block diagram of transmission line ground connection cabling layout originally for removing the layout of earth connection originally.
Include on the printed circuit board (PCB) 11: power supply unit 21, load impedance 31, sheet metal 41, via hole 711, via hole 712, via hole 713 and via hole 714.And hole 511, hole 512, hole 513 and hole 514 are arranged on the sheet metal 41 outside four corners of sheet metal 41, more there is a hole 52 to be positioned on the sheet metal 41.
Sheet metal 41 utilizes screw 62 that power supply unit 21 is fixed on hole 52 on the sheet metal 41 in Fig. 2.Also have hole 511, hole 512, hole 513 and hole 514 on the sheet metal 41.Hole number on the sheet metal 41 can be added to four edges of sheet metal 41 according to the mistake hole count on the printed circuit board (PCB) 11, but the arbitrary hole on the sheet metal 41 is all identical and big or small identical with the mistake hole site on the printed circuit board (PCB) 11, so that hole 511, hole 512, hole 513 and hole 514 can be locked in via hole 711, via hole 712, via hole 713 and the via hole 714 with screw 611, screw 612, screw 613, screw 614 respectively.So sheet metal 41 closely can be fixed on the printed circuit board (PCB) 11.The material of sheet metal 41 is an iron plate, on the sheet metal 41 except power supply unit 21, without any electronic component.Moreover, on the sheet metal 41 except hole 511, hole 512, hole 513 and hole 514 four corners of sheet metal 41, the smooth flat of its metal covering for stopping without any hole.Use sheet metal 41 to replace the transmission line of ground connection originally, originally the current signal of being passed back by transmission line is changed by sheet metal 41 to be passed back, since remove tortuous originally curved around transmission line ground wire cabling, so current signal can directly be got back to the negative pole of power supply unit by less obstruction.Therefore will reduce the loss (loss) of current signal in transmission, and sheet metal 41 conductors and general transmission line broad and thicker by comparison, so the stray inductance on the sheet metal 41 also can reduce.So also can reduce electromagnetic interference (EMI).
In the selection of via hole 711, via hole 712, via hole 713 and via hole 714, when high speed, highdensity PCB design, the via hole of printed circuit board (PCB) is the smaller the better, because a via hole mainly is made up of two parts, the one, middle boring (drill hole), the 2nd, the pad area around the boring (not indicating), this two-part size has determined the size of via hole.Obviously, when high speed, highdensity PCB design, via hole is the smaller the better, can leave more wiring space on this model, and in addition, via hole is more little, and the parasitic capacitance of himself is also more little, is more suitable for being used for high speed circuit.And on printed circuit board (PCB) 11, via hole 711, via hole 712, via hole 713 and via hole 714 need be fixed through screw 611, screw 612, screw 613, screw 614 with hole 511, hole 512, hole 513 and hole 514 on the metallic plate 41, so the hole on sheet metal 41 also meets the hole size of crossing of printed circuit board (PCB) 11.
In this structure, no matter be that metal screw or sheet metal are all broad and thicker conductor and general transmission line by comparison, so when sheet metal 41 replaces generally the transmission line ground wire that forms with the printed circuit mode, stray inductance on it will reduce, because stray inductance reduces, the electromagnetic interference of institute's radiation just reduces.And because sheet metal 41 is the conductor on a wide plane, electric current does not need according to cabling in the past, and can be walked by shortest path, can determine that minimum obstruction gets back to the negative pole of power supply unit, reduces the loss of current signal when transmitting.
Claims (12)
1. circuit board that reduces the electronic product electromagnetic interference, this circuit board comprises a power supply unit and several electronic components at least, it is characterized in that: described circuit board also includes one in order to connect the sheet metal of this power supply unit and these several electronic components, as the ground connection of this circuit board, thereby make electric current get back to this power supply unit by this sheet metal.
2. according to the circuit board of claim 1 described minimizing electronic product electromagnetic interference, it is characterized in that: described circuit board is a printed circuit board (PCB) (PCB).
3. according to the circuit board of claim 1 described minimizing electronic product electromagnetic interference, it is characterized in that: described sheet metal is the conductor on a wide plane.
4. according to the circuit board of claim 1 described minimizing electronic product electromagnetic interference, it is characterized in that: described sheet metal material is an iron.
5. according to the circuit board of claim 1 described minimizing electronic product electromagnetic interference, it is characterized in that: only there is this power supply unit described sheet metal top.
6. according to the circuit board of claim 1 described minimizing electronic product electromagnetic interference, it is characterized in that: only there are several holes that are connected with this printed circuit board (PCB) with this power supply unit described sheet metal top.
7. according to the circuit board of claim 1 described minimizing electronic product electromagnetic interference, it is characterized in that: described power supply unit utilizes a screw to be fixed on this sheet metal by a hole.
8. according to the circuit board of claim 1 described minimizing electronic product electromagnetic interference, it is characterized in that: described several load impedances are passive device, this passive device be selected from electric capacity, inductance and group that resistance is formed one of them.
9. according to the circuit board of claim 1 described minimizing electronic product electromagnetic interference, it is characterized in that: described several load impedances are active member, this active member by diode, transistor formed group one of them.
10. according to the circuit board of claim 1 described minimizing electronic product electromagnetic interference, it is characterized in that: described sheet metal utilizes several screws to be fixed on this printed circuit board (PCB) by several holes.
11. the circuit board according to claim 7 described minimizing electronic product electromagnetic interference is characterized in that: described screw is a metal material.
12. the circuit board according to claim 10 described minimizing electronic product electromagnetic interference is characterized in that: described several screws are metal material.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN 200610033087 CN101005730A (en) | 2006-01-20 | 2006-01-20 | Circuit board for reducing electromagnetic interference of electronic product |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN 200610033087 CN101005730A (en) | 2006-01-20 | 2006-01-20 | Circuit board for reducing electromagnetic interference of electronic product |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| CN101005730A true CN101005730A (en) | 2007-07-25 |
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Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CN 200610033087 Pending CN101005730A (en) | 2006-01-20 | 2006-01-20 | Circuit board for reducing electromagnetic interference of electronic product |
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| CN (1) | CN101005730A (en) |
Cited By (10)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN102487575A (en) * | 2010-12-02 | 2012-06-06 | 鸿富锦精密工业（深圳）有限公司 | A printed circuit board |
| CN102695361A (en) * | 2011-03-23 | 2012-09-26 | 鸿富锦精密工业（深圳）有限公司 | Printed circuit board |
| CN102802339A (en) * | 2011-05-23 | 2012-11-28 | 鸿富锦精密工业（深圳）有限公司 | Printed circuit board (PCB) |
| CN102833939A (en) * | 2011-06-13 | 2012-12-19 | 鸿富锦精密工业（深圳）有限公司 | Capacitor performance optimization method and circuit board designed by applying same |
| CN105340133A (en) * | 2013-03-15 | 2016-02-17 | 伟创力有限责任公司 | Method and apparatus for creating perfect microwave absorbing printed circuit boards |
| CN106163245A (en) * | 2016-06-28 | 2016-11-23 | 广东欧珀移动通信有限公司 | PCB board assembly and mobile terminal with it |
| WO2019128310A1 (en) * | 2017-12-26 | 2019-07-04 | 杭州三花研究院有限公司 | Electric pump |
| CN111224317A (en) * | 2020-04-20 | 2020-06-02 | 深圳市汇顶科技股份有限公司 | Laser emitting device |
| WO2021128551A1 (en) * | 2019-12-28 | 2021-07-01 | 惠州Tcl移动通信有限公司 | Pcb and terminal device using same |
| CN116171509A (en) * | 2020-09-03 | 2023-05-26 | 三菱电机株式会社 | connection structure |
-
2006
- 2006-01-20 CN CN 200610033087 patent/CN101005730A/en active Pending
Cited By (15)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN102487575A (en) * | 2010-12-02 | 2012-06-06 | 鸿富锦精密工业（深圳）有限公司 | A printed circuit board |
| CN102695361A (en) * | 2011-03-23 | 2012-09-26 | 鸿富锦精密工业（深圳）有限公司 | Printed circuit board |
| CN102802339A (en) * | 2011-05-23 | 2012-11-28 | 鸿富锦精密工业（深圳）有限公司 | Printed circuit board (PCB) |
| CN102833939A (en) * | 2011-06-13 | 2012-12-19 | 鸿富锦精密工业（深圳）有限公司 | Capacitor performance optimization method and circuit board designed by applying same |
| US9961812B2 (en) | 2013-03-15 | 2018-05-01 | Flextronics Ap, Llc | Method and apparatus for creating perfect microwave absorbing skins |
| CN105340133A (en) * | 2013-03-15 | 2016-02-17 | 伟创力有限责任公司 | Method and apparatus for creating perfect microwave absorbing printed circuit boards |
| US10085370B2 (en) | 2013-03-15 | 2018-09-25 | Flextronics Ap, Llc. | Powder coating method and apparatus for absorbing electromagnetic interference (EMI) |
| US10285312B2 (en) | 2013-03-15 | 2019-05-07 | Flextronics Ap, Llc | Method and apparatus for creating perfect microwave absorbing printed circuit boards |
| CN106163245A (en) * | 2016-06-28 | 2016-11-23 | 广东欧珀移动通信有限公司 | PCB board assembly and mobile terminal with it |
| CN106163245B (en) * | 2016-06-28 | 2019-05-10 | Oppo广东移动通信有限公司 | PCB assembly and mobile terminal with same |
| WO2019128310A1 (en) * | 2017-12-26 | 2019-07-04 | 杭州三花研究院有限公司 | Electric pump |
| US11742728B2 (en) | 2017-12-26 | 2023-08-29 | Zhejiang Sanhua Intelligent Controls Co., Ltd. | Electric pump |
| WO2021128551A1 (en) * | 2019-12-28 | 2021-07-01 | 惠州Tcl移动通信有限公司 | Pcb and terminal device using same |
| CN111224317A (en) * | 2020-04-20 | 2020-06-02 | 深圳市汇顶科技股份有限公司 | Laser emitting device |
| CN116171509A (en) * | 2020-09-03 | 2023-05-26 | 三菱电机株式会社 | connection structure |
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