JP4494714B2 - Printed wiring board - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
  The present invention suppresses external noise and unwanted radiation noise for various electronic device circuits.Applied noise shield plateThe present invention relates to a printed wiring board.
[0002]
[Prior art]
  Electromagnetic interference of electronic devices occurs when electromagnetic waves generated from noise sources are transmitted to devices that are disturbed using a conductor or space as a medium. There are various communication devices and electrical products that are used daily as sources of noise. For example, TV, CD radio cassette, VTR, microwave oven, refrigerator, washing machine, vacuum cleaner, personal computer, mobile phone, industrial robot, various medical equipmentetc,There are various types.
  In addition, the propagation of noise includes conductor conduction and space conduction, but with high frequency noise, the frequency of electromagnetic interference generated by space conduction increases. In high-function digitalized electronic devices, in order to perform work based on more functions, the frequency to be used is moving toward higher frequency.
[0003]
  In such digital devices, clock oscillators, digital ICs, switching power suppliesetcThere is a noise generation source, and noise generated in electronic and electrical devices is caused by printed circuit board patterns, power supply lines, signal lines, and I / O cables.etcFlowing through. At that time, each of these conductors becomes an antenna, and part of the noise is emitted into the air.
  If there is a place where the impedance changes suddenly in the conductor path through which the noise current flows, reflection occurs there.ForA standing wave (standing wave) is generated, and the antenna efficiency is improved in the vicinity of the frequency, and strong noise is radiated. When this standing wave is terminated with an impedance lower than the impedance of the line, it is generated near the frequency where the conductor length is an even multiple of a quarter wavelength, as in the case where the termination is open. When terminated with an impedance higher than the impedance of the line, it is generated in the vicinity of a frequency at which the conductor length is an odd multiple of a quarter wavelength.
[0004]
  A characteristic of noise radiated from a conductor on a printed wiring board is that resonance occurs with a conductor having a shorter length than that emitted from a cable or a power line. This is a conductor in a printed wiring boardofBecause it is in contact with a resin substrate with a relative dielectric constant larger than that in air, the average relative dielectric constant around the conductor is increased, so the speed of electromagnetic waves (inversely proportional to the square root of the relative dielectric constant) must be slow. by.
  That is, in the case of a conductor on a printed wiring board, the speed of electromagnetic waves is slower than in the air, so that the frequencies that resonate at ¼ wavelength and ½ wavelength are lower than in air. As a result, the printed wiring board becomes a noise antenna.
[0005]
  Therefore, as one of the measures to prevent the printed wiring board from becoming a noise antenna, a noise shielding board for covering and shielding a noise generation source with a conductor or a printed wiring board having a conductive layer on the entire surface has been conventionally used. Are known.
  For example, a printed wiring board provided with a conductive layer is usually called an undercoat so that a wiring pattern layer composed of a signal pattern, a power supply pattern, a connection portion, and the like is formed on an insulating substrate and the wiring pattern layer is covered. A first insulator layer is formed, and a conductor layer made of silver, copper paste, or the like is formed on the entire surface so as to be connected to the wiring pattern layer via a connection portion on the first insulator layer. Further, a second insulator layer usually called an overcoat is formed on the conductor layer.
[0006]
  And in such a printed wiring board, in order to reduce resistance between a conductor layer and the connection part of the wiring pattern layer from which the conductor layer is insulated, the wiring pattern and conductor layer formed on the substrate surface are reduced. The contact area with is made as large as possible.
  In addition, the connection portion between the wiring pattern layer and the conductor layer is simply provided at a connectable place, or is provided around a connection land between the electronic device and the printed wiring board. Further, a method is adopted in which the conductor layer is formed uniformly regardless of the polarity of the power supply pattern.
  For example, as seen in Patent Document 1, a wiring pattern layer and a power pattern having the same polarity as the wiring pattern layer are disposed on an insulating substrate, and a solid pattern conductor layer is connected to the power pattern through a connection portion. A printed wiring board has been proposed in which the polarity of the power supply pattern is reversed to increase the capacitance of the capacitance between the power supply pattern and the conductor layer, thereby increasing the noise suppression effect.
[0007]
[Patent Document 1]
          Japanese Patent Laid-Open No. 7-283580
[0008]
[Problems to be solved by the invention]
  However, in such a conventional printed wiring board and noise shield board, in addition to the shielding effect due to the conductivity of the entire surface (solid pattern) conductor layer, the conductor layer and the power supply pattern having the opposite polarity to the conductor layer Since the external noise and the unnecessary radiation noise are suppressed only by the stray capacitance between them, there is a problem that the noise suppressing effect is not sufficient.
  This is because external noise and unnecessary radiation noise having a higher frequency are generated with the recent high-functional digitalization of electronic / electrical devices.
[0009]
  Therefore, for example, as shown in FIG. 15A with a plan view, and FIG. 15B with a cross-sectional view along the line XX, a solid pattern conductor on the entire surface of one surface of the insulating substrate 110. In the noise shield plate 100 provided with the layer 120, when a high frequency signal is applied between the points p and q of the conductor layer 120, the current flowing in the conductor layer 120 is near the end of the conductor layer 120 near the surface. Therefore, a large loop current path is formed near the surface as indicated by a thick broken line 130.
  Therefore, although the conductor layer 120 of the noise shield plate has a sufficient area and thickness (d0), it cannot fully exhibit a shielding effect for suppressing noise, but also by its loop-shaped current path. An antenna is formed and noise is emitted from the antenna.
  The same applies to the case of shielding with a solid conductor layer of a printed wiring board as disclosed in the above-mentioned Patent Document 1.
[0010]
  The present invention has been made in order to solve such problems, and is sufficiently shielded against electromagnetic interference caused by high frequency external noise and unnecessary radiation noise associated with high-function digitalization of electronic / electrical devices. The purpose is to obtain an effect.
[0011]
[Means for Solving the Problems]
  According to this inventionPrinted wiring boardIn order to achieve the above object, a flat insulatorOne ofOn the surfaceMore than oneThe opening ofWith uniform distribution densityOverlay the formed conductor layerA printed wiring pattern made of a conductive material is formed on the other surface, and the plurality of openings open the surface opposite to the insulator..
  Then, the inside of the opening formed in the conductor layer on one surface of the insulator is used as a mounting space for an electronic / electrical device, and the insulator is used for wiring penetrating between both surfaces in the opening and / Or through hole (through hole or via hole) for lead terminal insertion of the electronic / electrical deviceShiThe electronic / electrical device mounted in the opening and the printed wiring pattern can be electrically connected through the through hole.
[0012]
  Also,To this printed wiring boardAboveThe plurality of apertures in the conductor layer may have the same shape and size at least in a predetermined region.
  furtherThe shape of the opening may be a circle, an ellipse, or a regular polygon, or may be other shapes.
[0013]
  FurthermoreThese two printed wiring boards may be configured such that one printed wiring board is formed by facing each other with the printed wiring pattern side facing each other and sandwiching an insulating layer therebetween to bond them.
[0014]
DETAILED DESCRIPTION OF THE INVENTION
  Less than,After explaining the noise shield plate and the printed wiring board that are the basis of this invention,Embodiments of the present invention will be specifically described with reference to the drawings.
  [Noise shield plate]
  First, this inventionNoise shield plate that is the basis ofexplain about.
  FIG.ThatThe first of the noise shield plateExample(A) is the top view, (b) is sectional drawing which follows the AA line. This noise shield plate 1 is provided with a conductor layer 12 having a uniform thickness and a plurality of apertures 12a on one surface of a flat insulator 11 having a uniform thickness. It is a thing.
  Each of the plurality of apertures 12a is a circular aperture having a diameter of D1, and is formed with a substantially uniform density distributed over the entire surface of one surface of the conductor layer 12, and is insulated as illustrated. The surface opposite to the body 11 is open. In the example shown in the figure, the apertures 12a are aligned in the vertical and horizontal directions, but the present invention is not limited to this.
[0015]
  thisNoise shield plate 1In the insulator 11, for example, an aluminum oxide sintered body, an aluminum nitride sintered body, a silicon carbide sintered body, an inorganic insulating material such as glass ceramics, an organic insulating material such as an epoxy resin or a fluororesin, or It is formed using a composite insulating material formed by bonding inorganic insulating powder such as ceramic powder with a thermosetting resin such as epoxy resin.
  The thickness of the insulator 11 is appropriately set according to the characteristics of the material to be used and so as to satisfy the conditions such as mechanical strength and electrical characteristics corresponding to the required use conditions.
[0016]
  The conductor layer 12 is formed of, for example, a metallized metal powder such as copper, silver, silver / palladium, or a thin film of a metal material such as copper, silver, nickel, chromium, titanium, or an alloy thereof.
  The conductor layer 12 is formed by forming a metal layer on the entire surface of the insulator 11 by, for example, a printing method, a sputtering method, a vacuum deposition method, a plating method, or the like. It is formed in a pattern shape (circular in this example) and size.
  Note that the materials and forming methods of these insulators and conductor layers are common to the insulators and conductor layers in the embodiments of the noise shield plate and the printed wiring boards described below.
[0017]
  In the noise shield plate 1 shown in FIG. 1, when a high-frequency signal is applied between one circle point and two circle points shown in (a), a current flows through the conductor layer 12 through a path shown by a broken line. The portion indicated by the thick broken line shows a path in which the current density of this current is large, and it becomes a loop-shaped path connecting between one circle and two circles along the circumference of the opening 12a having a diameter D1. Form an antenna of this loop size.
  At this time, the circumference L of the opening 12a is L = π × D1, and the area S of the circular opening 12a is S = π × (D1 / 2).²It becomes.
  Also, the radiated electric field intensity E is given by E = K · S · In · f²/ D1.
  Here, K: constant, S: area in the loop, In: noise current, f: frequency,
d1: the thickness of the conductor layer 12.
[0018]
  From the above formula, the smaller the area S in the loop, the smaller the radiated electric field strength E, and the spatial conduction (spatial radiation), that is, unnecessary radiation noise is reduced. The size of the area S in the loop is determined by the circumference L which is the length of the loop or the diameter D1 of the circle. Then, the circumference L and the size of the circle (diameter D1) can be determined from the wavelength λ at the frequency to be particularly reduced. In this case, it is desirable that λ >> L / 4. However, in practice, the average relative dielectric constant εr of the insulator 11 in the circular portion of the opening 12a varies depending on the material, but is about 3 to 6, which is larger than that in the air. It is preferable to determine the size of the opening 12a, that is, the size of the diameter D1 of the circle so as to be 12 · λ.
[0019]
  Next, the distribution of current flowing in the thickness direction of the conductor layer 12 only flows to the surface side as the current becomes higher in frequency (the current in this case is referred to as the skin current). When the skin current of the noise current In becomes 1 / e (e: natural number), if the skin current flows through the skin depth (skin depth) ds, it is expressed by the following equation.
        ds = √ (2 / ω ・ μ ・ α)
  Here, ω: angular frequency, μ: magnetic permeability, α: conductivity.
[0020]
  Copper is mainly used for the conductor layer 12. The skin depth ds at each frequency when this copper is used is 100 MHz: 6.61 μm and 1 GHz: 2.09 μm. If the thickness of the conductor layer 12 is about four times the skin depth ds, about 90% of the noise current at that frequency can be passed. However, considering that the skin current flows in the vicinity of both surfaces of the conductor layer 12, it is necessary to allow some margin when determining the thickness of the conductor layer 12.
  Since unnecessary radiation noise is subject to legal regulations of 30 MHz to 1 GHz, it can be said that the unnecessary radiation noise is within an appropriate range when the thickness of the conductor layer 12 of the noise shield plate 1 is 35 μm. Note that noise in a frequency band of 200 MHz or more is likely to be radiated from a control board on which a CPU or the like is mounted, and the thickness d1 of the conductor layer 12 of the noise shield plate 1 is a general thickness. It is possible to make the thickness thinner than this because it is too much compared with a certain 35 μm.
[0021]
  In addition, since high-frequency current has a strong tendency to flow through the skin and edges of the conductor, resistance loss increases as the current density increases in such a portion, but the resistance value itself is sufficiently small. The influence of noise on radiation is small, and most of it is released as heat. Furthermore, since the shape of the opening 12a of the conductor layer 12 is uniform as shown in FIG. 1 (a), the current flowing through the conductor layer 12 is dispersed and close to a parallel electric field, which is ideal. Noise shield plate can be provided.
  Like thisNoise shield plateAccording to the above, even in the case of high-frequency noise, the area of the loop that emits noise is small, and the distribution of high-frequency current tends to be uniform, so it relies on stray capacitance like a shield with a solid pattern conductor. Therefore, unnecessary radiation noise having a high frequency can be effectively reduced.
[0022]
  FIG. 2 shows the present invention.The basis ofThe second of the noise shield plateExampleFIG.
  The noise shield plate 2 has a first conductor layer 12 in which a large number of apertures 12a are formed with a uniform distribution density on one surface of a flat insulator 11 and a thickness d2 on the other surface. The second conductor layer 13 in which a large number of apertures 13a are formed with a uniform distribution density is provided in an overlapping manner. As is apparent from FIG. 2, each of the openings 12 a and 13 a opens a surface opposite to the insulator 11.
  According to the noise shield plate 2, since the insulator 11 is sandwiched between the two conductor layers 12 and 13, the shield effect can be further exhibited. In each of the other embodiments described below, the shielding effect can be further increased by providing a conductor layer having a plurality of openings formed on both surfaces of the insulator as described above.
  The conductor layer 12 and the conductor layer 13 on both sides of the insulator 11 are made of the material, the thicknesses d1 and d2, the sizes of the openings 12a and 13a, and the distribution state thereof.etcThey may be the same or different, but in this example they are the same.
[0023]
  Next, this inventionThe basis ofThe third of the noise shield plateExampleWill be described with reference to FIG. FIG. 3A is a plan view of the noise shield plate, and FIG. 3B is a sectional view taken along the line BB.
  The noise shield plate 3 is formed on one surface of a flat insulator 11 by arranging a plurality of square-shaped openings 14a each having a side length D2 aligned vertically and horizontally at a uniform density. The conductor layer 14 is provided so as to overlap. The thickness of the conductor layer 14 is d3, and the opening 14a opens the surface opposite to the insulator 11.
  In the conductive layer 14 of the noise shield plate 3, the path of the high-frequency current flowing between the three circle points and the four circle points shown in FIG. 3A is the inner edge of the square opening 14a as shown by the thick broken line. It is formed in a loop shape close to.
  As described above, when the shape of the opening 14a is square, the high-frequency current between the three circles and the four circles is less likely to flow than in the case of a circle or an ellipse. There is no change in the effect of reducing unnecessary radiation noise.
[0024]
  here,theseThe example from which the shape and distribution of the opening formed in the conductor layer of a noise shield board differ is shown. The following figure shows only the conductor layer.
  FIG. 4 shows an example in which the shape of the opening 15a of the conductor layer 15 is an ellipse. FIG. 5 shows an example in which openings 16 a and 16 b having different diameters are alternately arranged in the conductor layer 16.
  6 and 7 show examples of the conductor layer in the case where the noise shield plate has a plurality of regions for shielding noise of different frequencies.
[0025]
  In the example shown in FIG. 6, the conductor layer 17 is composed of a first region 17A and a second region 17B, and a number of circular openings 17a are formed in the first region 17A.ButA large number of square holes 17b are formed in the second region 17B.
  The plurality of apertures 17a and 17b in each of the regions 17A and 17B have the same shape and size and uniform distribution in each region. This is because when a noise source exists in a plurality of regions, in order to exert a shielding effect according to noise of different frequencies near the source, the shape and size according to each frequency Openings are formed in each region with a uniform distribution.
  In the example shown in FIG. 7, circular holes 18a and 18b are formed in the first region 18A and the second region 18B of the conductor layer 18, but the size and distribution of the circles are the first. This shows a case in which the area 18A and the second area 18B are different. Also in this case, the shielding effect corresponding to the noise generation sources having different frequencies can be exhibited in each of the regions 18A and 18B.
[0026]
  By using a noise shield plate having a plurality of regions provided with such a conductor layer, it effectively shields noise of different frequencies generated by each noise source near the plurality of noise sources. be able to.
  In each of the embodiments described above, examples of the shape of the opening of the conductor layer are a circle, an ellipse, and a square, but a polygon other than a square, a rectangle, and other shapes may be used. However, in order to reduce the antenna effect by minimizing the path through which the noise current flows, it is most preferable to use a circular opening, and then to a polygon or ellipse close to it.
[0027]
  Noise shield plateStill another example of the conductor layer is shown in FIGS. The conductor layer 19 shown in FIG. 8 is made of a lattice-like conductive material that forms a large number of square openings 19a.
  9 is made of a net-like conductive material forming a large number of hexagonal openings 20a.
  The lattice-like or net-like pattern of these conductor layers 19 and 20 may be formed by forming a conductor film on the entire surface of the flat insulator and then performing etching or the like. One knitted in a lattice shape or a net shape can also be used.
  If such a conductor layer is provided, the path through which the noise current flows becomes a loop along the opening 19a or 20a by the lattice or mesh, and the loop area can be further reduced. The shield effect can be further exhibited by becoming smaller. In particular, a braided wire with fine grids and meshes can more uniformly disperse the current distribution, thereby enhancing the shielding effect.
[0028]
    Next, this inventionThe basis of4th of noise shield plateExampleWill be described with reference to FIG.
  thisNoise shield plate 4According to FIG.Noise shield plate 1 explained(First noise shield plate) and Fig. 2Noise shield plate 2 explainedThe (second noise shield plate) is laminated and laminated on the lower surface side of the insulator 1 of the noise shield plate 1 shown in FIG. 1 to constitute one noise shield plate.
  As clearly shown in FIG. 10, the opening 12 a of the conductor layer 12 sandwiched between the insulator 11 of the noise shield plate 1 and the insulator 11 of the noise shield plate 2 is provided between the insulators 11 and 11. The openings 12a of the outer conductive layers 12 and 12 other than the conductor layer 12 are open on the surface opposite to the insulators 11.
  Therefore, the two insulators 11 and the three conductor layers 12, 12, and 13 are formed, and the openings 12a and 13a formed in the respective conductor layers are circular with the same diameter and at the same position. Is provided. However, the present invention is not limited to this, and the shape and size of the opening of each conductor layer and its formation positionetcMay be different.
[0029]
  Also mentioned aboveNoise shield plateCan be combined in any combination of the same or different, and multiple sheets (two or more) stacked togetherWowOne noise shield plate can be configured.
  As a result, it is possible to more reliably shield high frequency noise of the same frequency, or to enable shielding of a plurality of high frequency noises of different frequencies.
[0030]
  [Printed wiring board]
  Next, this inventionThe basis ofPrinted circuit boardExampleWill be described.
  Figure 11 shows thePrinted wiring boardFIG. The printed wiring board 5 is formed with a plurality of apertures 52a with a uniform distribution density on one surface of a planar insulator 51 having a uniform thickness similar to that of the noise shield plate 1 shown in FIG. The conductive layer 52 is provided in an overlapping manner, and a printed wiring pattern 53 made of a conductive material is formed on the other surface. The plurality of apertures 52a open the surface opposite to the insulator 51.
  The printed wiring pattern 53 is shown by cross hatching for the sake of illustration, but in actuality, it is an active element such as an IC, LSI, or transistor, and a passive element such as a capacitor or a resistor.etcIn order to configure various electronic circuits by mounting the circuit elements, a complicated wiring pattern such as a signal line for transmitting a signal on the circuit, a power line for supplying power, a ground line, or a terminal is used. It is formed by etching a film or the like.
[0031]
  The insulator 11 of the printed wiring board 5 and the conductor layer 52 provided on one surface thereof and the opening 52a thereof are described above.With each noise shield plateIt can be configured similarly.
  Therefore, it is preferable that the plurality of openings 52a of the conductor layer 52 have the same shape and size at least in a predetermined region and have a uniform distribution density. Further, the shape of the opening 52a may be a circle, an ellipse, or a regular polygon, or may be other shapes. Alternatively, a mesh-like or grid-like conductor may be used.
[0032]
  If this printed wiring board 5 is used, the effect of high frequency noise from the opposite side of the insulator 51 to the electronic circuit on the printed wiring pattern 53 side can be greatly reduced by the shielding effect of the conductor layer 52. In addition, radiation of high frequency noise from the electronic circuit can be greatly reduced.
  Further, a single printed wiring board may be configured by stacking a plurality of such printed wiring boards with an insulating layer interposed therebetween. In that case, a conductor layer having a plurality of apertures may be provided on both outermost surfaces.
[0033]
  Next, the printed wiring board of the present inventionFirstThe embodiment will be described with reference to FIGS. FIG. 12 is a plan view showing a state where an electronic / electrical device is mounted on the printed wiring board, and FIG. 13 is a partial sectional view of the printed wiring board.
  This printed wiring board 6 has an electronic / electrical device (IC in the illustrated example) such as an IC, LSI, transistor, etc. in a plurality of openings 62a formed in the conductor layer 62 on one surface of the insulator 61. As shown in FIG. 13, a printed wiring pattern 63 made of a conductive material is formed on the other surface of the insulator 61. In FIG. 13, the printed wiring pattern 63 is schematically shown by cross-hatching.
[0034]
  Further, as shown in FIG. 13, a plurality of through holes 61 a are formed in the insulator 61 as through holes for wiring passing through both surfaces in the opening 62 a and / or for lead terminal insertion of the electronic / electrical device 10. is doing.
  The configuration of this printed wiring board 6 is basically shown in FIG.Print shownAlthough it is the same as that of the wiring board 5, the size and shape of the opening 62 a of the conductor layer 62 may be formed corresponding to the electronic / electric device mounted thereon. In the example shown in FIG. 12, all the apertures 62 are circular with the same diameter and the same electronic / electric device 10 is mounted. However, the present invention is not limited to this. A hole having a shape may be formed.
[0035]
  Further, the through hole 61a shown in FIG. 13 is provided between the electronic / electric device 10 mounted in the opening 62a of the conductor layer 62 on one surface of the insulator 61 and the printed wiring pattern 63 formed on the other surface. It is provided to electrically connect to a predetermined wiring. In order to omit the wiring inserted into the through hole 61a, a thin film is formed on the inner wall of the through hole 61a with a metal material such as copper, silver, nickel, chromium, titanium, gold, niobium and alloys thereof. And may be made into a conductor.
In the example shown in FIG. 13, lead terminals (legs) of ICs that are the electronic / electrical devices 10 are inserted into the through-holes 61 a formed as conductors so as to be connected to the printed wiring pattern 63. The size, number and arrangement of the through holes 61a can be changed as appropriate according to the application.
[0036]
  According to this embodiment, a short ring S for the electronic / electrical device 10 is formed by a portion along the inner periphery of the opening 62a of the conductor layer 62 as shown by a thick broken line in FIG. Since the short ring S cancels out the magnetic field of noise radiated into the air, a shielding effect can be exhibited.
  By selecting the shape and size of the opening 62a so as to generate a short ring S that matches the frequency of noise generated by the electronic / electrical device 10 mounted on the opening 62a, It becomes possible to effectively cancel the radiation to the air, and the shield effect can be further exhibited.
[0037]
  Next, the printed wiring board of the present inventionSecondThe embodiment will be described with reference to FIG. thisSecondThe embodiment isAs shown in FIG.Printed wiring board 5 orFirstA single printed wiring board is configured by stacking a plurality of the same or different types of printed wiring boards, such as the printed wiring board 6 of the embodiment, with an insulating layer interposed therebetween.
[0038]
  In the example shown in FIG. 14, the printed wiring board 6 as shown in FIG. 12 and FIG. 13 and the printed wiring board 7 having a similar structure are arranged on the side of the conductor layers 62 and 72 of the insulators 61 and 71. On the outside, the printed wiring patterns 63 and 73 are opposed to each other, and an insulating layer 81 is sandwiched therebetween and bonded together to form a new printed wiring board 8.
  Although illustration is abbreviate | omitted to each of the insulators 61 and 71,FirstA large number of through-holes (through-holes penetrating between the upper and lower surfaces of two layers) and via-holes (through-holes penetrating only one layer) as described in the embodiment are formed, and electronic components and circuit patterns on both sides are formed. Enables electrical connection.
[0039]
  Then, four conductive layers (conductor layers 62 and 72 and printed wiring patterns 63 and 73) are provided for the three insulator layers (insulators 61 and 71 and insulating layer 81). By using the outer conductor layers 62 and 72 as power supply layers (reference potential layers of + potential layer and −potential layer) and the inner printed wiring patterns 63 and 73 as patterns of other signal lines, etc. The effect of stray capacitance can be added as in the case of patterns, and further noise countermeasures are taken.be able to.
[0040]
【The invention's effect】
  As described above, the present inventionPrinted wiring boardWith the use of high-performance digitalization of electronic and electrical devices, the antenna area is attenuated by reducing the loop area that emits noise against electromagnetic interference caused by external noise and unnecessary radiation noise that have been increased in frequency. A sufficient shielding effect can be obtained by making the distribution of the high-frequency current uniform. To create a short ring in the vicinity of electronic and electrical devicesTherefore,A shielding effect against noise radiation can be obtained.
[Brief description of the drawings]
FIG. 1 This inventionThe basis ofThe first of the noise shield plateExample(A) is a top view, (b) is sectional drawing which follows the AA line.
FIG. 2 This inventionThe basis ofThe second of the noise shield plateExampleFIG.
FIG. 3 shows a third noise shield plate according to the present invention.Example(A) is a top view, (b) is sectional drawing which follows the BB line.
FIG. 4The basis ofIt is a top view which shows the other example of the conductor layer of a noise shield board.
FIG. 5 is a plan view showing still another example of the conductor layer.
[Fig. 6]pluralIt is a top view which shows the example of the conductor layer of the noise shield board which has an area | region.
FIG. 7 is a plan view showing another example of the conductor layer.
FIG. 8 is a plan view showing an example of a grid-like conductor layer.
FIG. 9 is a plan view showing a part of a net-like conductor layer.
FIG. 10 shows the present invention.The basis of4th of noise shield plateExampleFIG.
FIG. 11The basis ofPrinted circuit boardExampleIt is sectional drawing which shows this typically.
FIG. 12 shows a printed wiring board according to the present invention.FirstIt is a top view which shows the state which mounted the electronic / electrical device in the opening of the conductor layer in embodiment.
FIG. 13 is also a partial cross-sectional view of the printed wiring board.
FIG. 14 shows a printed wiring board according to the present invention.SecondIt is a typical sectional view showing an embodiment.
15A and 15B are views showing an example of a conventional noise shield plate, where FIG. 15A is a plan view, and FIG. 15B is a cross-sectional view taken along line XX.
[Explanation of symbols]
1, 2, 3, 4: Noise shield plate
5, 6, 7, 8: Printed wiring board
10: Electric / electronic device 10a: Lead terminal
11, 51, 61, 71: Insulator
12-20, 52, 62, 72: Conductor layer
12a-20a, 52a, 62a, 72a: Opening
17A, 17B, 18A, 18B: Area

Claims (4)

A conductor layer in which a plurality of openings are formed with a uniform distribution density is provided on one surface of a flat insulator, and a printed wiring pattern is formed on the other surface with a conductive material. In the printed wiring board in which the hole opens the surface opposite to the conductor layer ,
Wherein said conductor is formed in layer within said opening on one surface of the insulator and mounting space for electronic and electric devices, wiring and / or penetrating between both sides in the opening in the insulator Forming a through hole for inserting the lead terminal of the electronic / electrical device;
An electronic / electrical device mounted in the opening and the printed wiring pattern can be electrically connected through the through hole. The printed wiring board according to claim 1 ,
The printed wiring board, wherein the plurality of openings formed in the conductor layer have the same shape and size at least in a predetermined region. In the printed wiring board according to claim 1 or 2 ,
The printed wiring board, wherein the shape of the opening formed in the conductor layer is any one of a circle, an ellipse, and a regular polygon. The two printed wiring boards according to any one of claims 1 to 3 , wherein the printed wiring pattern sides face each other, and an insulating layer is sandwiched between them to be bonded to each other. Printed wiring board.

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