JP2005243874A - Multi-pattern wiring board - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a multi-pattern wiring board which can prevent warpage in a thin and wide ceramic mother board, also can manufacture a plurality of wiring boards having excellent electrical reliability which are arranged in vertical and horizontal directions, and surely can form a wiring board resulting in no missing or crack at the time of dividing the same. <P>SOLUTION: The multi-pattern wiring board is provided with a mother board 1 where square wiring board regions 2 are arranged in the vertical and horizontal directions at the central area of the main surface, and a frame type spoil allowance region 5 is formed at the external circumferential part, a wiring conductor formed at each wiring board region 2, a groove 3 formed at the spoil allowance region 5 to surround the entire part of the wiring board region 2, and a conductive layer 4 formed at the bottom surface of the groove 3. <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

  In the present invention, a large number of wiring board regions are integrated vertically and horizontally into a central part of a main surface of a large-area mother board, each of which is a small wiring board for mounting electronic components such as semiconductor elements and crystal resonators. The present invention relates to a multi-cavity wiring board formed by arranging a plurality of wiring boards.

  Conventionally, for example, a small wiring board used for an electronic component storage package for storing an electronic component such as a semiconductor element or a crystal resonator is made of a ceramic material such as an aluminum oxide sintered body, and has a wiring conductor on the surface. In this structure, a plurality of formed rectangular flat ceramic insulating layers are stacked one above the other. An electronic device is formed by housing an electronic component on the wiring board and electrically connecting the electrode of the electronic component to an exposed portion of the wiring conductor via solder, a bonding wire, or the like.

  By the way, with the recent demand for miniaturization of electronic devices, the size of such wiring boards has become extremely small, about several millimeters square, and the thickness has become as thin as 1 mm or less. ing. In order to facilitate handling of such a small number of wiring boards and to efficiently manufacture the wiring board and the electronic device, a large number of mother boards made of a single large-area ceramic material or the like are used. The circuit board is manufactured in the form of a so-called multi-cavity wiring board in which a plurality of wiring boards are obtained simultaneously and collectively.

  This multi-cavity wiring board consists of a mother board in which a plurality of rectangular wiring board areas are formed in a matrix and a frame-shaped discard margin area is formed on the outer periphery, in order to improve productivity, The size of the mother board is increasing to about 100 mm square.

  An example of such a multi-piece wiring board is shown in FIG. The multi-cavity wiring board includes a mother board 31 in which a plurality of square-shaped wiring board areas 32 are arranged vertically and horizontally, a plurality of wiring conductors (not shown) formed in each wiring board area 32, and a mother board 31. It is the structure which comprised the frame-shaped discard margin area | region 35 formed in the outer periphery.

  A mounting portion (not shown) for mounting electronic components is formed on the upper surface of each wiring board region 32, and a part of the wiring conductor is mounted on the upper surface of the wiring substrate region 32 or its periphery. The other part of the wiring board region 32 is exposed to the lower surface and the side surface.

  An electronic component (not shown) is mounted and fixed on the mounting portion of the wiring board region 32, and the electrodes of the electronic component are exposed to the mounting portion or its periphery via an electrical connection means such as a bonding wire or solder. It is electrically connected to the wiring conductor, and a lid made of metal, glass or the like is joined to the upper surface of the wiring board region 32 so as to close the mounting portion, or an electronic component is made of a resin sealing material made of epoxy resin or the like. By covering and sealing, the electronic components are housed in the mounting portion in an airtight manner, so that a large number of electronic devices are formed in a multi-piece state in which the devices are arranged vertically and horizontally. Thereafter, the electronic device in the multi-cavity state is divided into individual wiring board regions 32 to form an electronic device as a large number of products. The electronic component may be mounted on the wiring board region 32 after the multi-piece wiring board is divided into the individual wiring board regions 32.

  In such a multi-cavity wiring board, nickel is usually applied to the surface of the wiring conductor in advance to prevent oxidation corrosion, improve the wettability of the solder, and improve the bonding property of the bonding wire. Metal plating is applied.

  In order to plate the wiring conductor, a multi-piece wiring board is immersed in a plating solution such as nickel or gold, and a predetermined plating current is supplied to the wiring conductor. A plating conduction pattern 37 is formed on a pair of sides of the mother board 31 so as to be electrically connected to the wiring conductor, and a conduction terminal (see FIG. (Not shown) is brought into contact with the plating conduction pattern 37, and the plating conduction pattern 37 is sandwiched from above and below by a pair of ends of the conduction terminal, whereby the conduction terminal and the plating conduction pattern 37 are connected from the power source. A current for plating is supplied to the wiring conductor.

  As shown in FIG. 2, the plating conduction pattern 37 is formed by depositing a conductor layer such as a metallized layer on the inner surfaces of the elliptical arc-shaped or arc-shaped cutout portions 38 formed on the pair of end surfaces of the mother substrate 31. It is formed by doing.

  In this case, in general, in the electroplating method, the current density tends to increase as the portion to be plated (the exposed surface of the wiring conductor) near the outer peripheral portion of the mother substrate 31 increases, and the plating solution is circulated and supplied. It is known that the plating rate is high and the plating thickness is thick because it is easily applied.

  Therefore, in order to make the thickness of the plating such as nickel or gold deposited on the wiring conductor in the wiring board region 32 uniform, a frame-like conductor layer is formed on the main surface of the disposal margin region 35 of the mother board 31. 34 is formed in electrical connection with the plating conduction pattern 37 and the wiring conductor.

  The frame-like conductor layer 34 draws a plating metal, such as nickel or gold, to be deposited on the inner portion to be plated, and deposits it on the conductor layer 34 itself, so that the plating thickness of the portion to be plated is increased. It functions as a so-called auxiliary cathode that suppresses variations, and prevents the plating thickness deposited on the wiring conductor in the inner wiring board region 32 from increasing.

  A through conductor is formed on the boundary between the adjacent wiring board regions 32, and the through conductors electrically connect between the wiring conductors of the adjacent wiring board regions 32 and the upper and lower wiring conductors. It is formed, and when it is divided into individual wiring board regions 32, it is divided vertically so that it becomes a side conductor (castellation conductor) located on the side face of the wiring board.

For example, if the mother board 31 is made of a ceramic material, such a multi-piece wiring board is prepared with a plurality of ceramic green sheets (hereinafter also simply referred to as green sheets) and becomes a wiring board region 32. A through hole is formed at a predetermined position of the region and the boundary of the region, and then a pair of end faces of the green sheet are punched out into a semicircular shape, a semi-elliptical shape, etc. to form a notch 38, The metal paste is printed and applied to the surface of the green sheet, the entire inner surface of the cutout portion 38, and the through-holes, and then the metal paste is applied to a predetermined wiring conductor, frame-shaped conductor layer 34, and plating conduction pattern 37. The green sheet is printed and applied in a pattern such as the above, and finally, the green sheet is laminated to form a laminate and fired.
JP 2000-340898 A

  However, in recent years, small-sized wiring boards used for electronic component storage packages and the like have been required to be further reduced in size, in particular, to be thinner due to the demand for low-profile electronic devices. For example, the mother board 31 has become very thin, for example, with a thickness of 1 mm or less.

  When the mother board 31 is thinned in this way, the outer peripheral portion of the main surface of the mother board is caused by the difference in shrinkage rate during firing between the metal paste that becomes the frame-like conductor layer 34 and the green sheet that becomes the mother board 31. In each side, a large stress over the entire length of each side acts in one direction, and this stress causes the base substrate 31 to be warped in a concave shape or a convex shape, and each wiring board region 32 is divided into individual pieces. The boundary lines between the wiring board regions 32 and between the wiring board region 32 and the disposal margin region 35 are distorted, so that there is a problem that cracks and burrs are generated in the individual wiring boards. Further, when mounting electronic parts such as semiconductor elements without dividing the mother board 31, the mounting portion is deformed, mounting accuracy is deteriorated, and mounting defects frequently occur.

  The present invention has been devised in view of such a problem, and the object thereof is to provide a main part of the discard margin area 35 on the outer periphery of the mother board 31 in the wiring board area 32 which has been further reduced in size, particularly reduced in thickness. Even if a frame-like conductor layer 34 for preventing variation in plating thickness is provided on the surface, the difference in shrinkage ratio during firing between the metal paste that becomes the frame-like conductor layer 34 and the green sheet that becomes the mother substrate 31 It is possible to prevent the occurrence of defects in the warp of the mother board 31 by mitigating the above, and as a result, it is possible to prevent the occurrence of cracks and burrs when dividing each wiring board region 32 into individual pieces. An object of the present invention is to provide a multi-piece wiring board that can be applied with good plating layers without causing a large thickness variation on the surface of the wiring conductor.

  A multi-cavity wiring board according to the present invention includes a mother board in which a plurality of rectangular wiring board regions are formed in a central portion of a main surface in a vertical and horizontal manner, and a frame-shaped discard margin region is formed in an outer peripheral portion; A wiring conductor formed in each wiring board region; a groove formed in the discard margin region so as to surround the entire wiring board region; and a conductor layer formed in a bottom surface of the groove. It is characterized by.

  In the multi-cavity wiring board of the present invention, it is preferable that the mother board is divided into grooves along the boundary between the wiring board areas on the main surface and the boundary between the wiring board area and the margin area. The groove has a depth that is less than ½ of the thickness of the mother substrate and is deeper than the dividing groove.

  In the multi-cavity wiring board of the present invention, the conductor layer is electrically connected to the wiring conductor in each wiring board region, and the wiring conductor and the conductor layer have a plating layer on the exposed surface. It is characterized by being deposited.

  According to the multi-cavity wiring board of the present invention, a plurality of quadrangular wiring board regions are formed in the center portion of the main surface in the vertical and horizontal directions, and a mother board in which a frame-shaped discard margin region is formed in the outer peripheral portion; A wiring conductor formed in each wiring board region, a groove formed so as to surround the entire wiring board region in the disposal margin area, and a conductor layer formed on the bottom surface of the groove. Even if stress is generated due to the difference in shrinkage rate during firing between the conductor layer formed on the bottom surface of the groove and the mother substrate, the stress is separated from the main surface of the mother substrate, the center of the thickness Stress that acts on the bottom surface of the groove located in the vicinity, and is more likely to generate a relatively large stress due to surface contraction. Can reduce the warpage of the mother board. It is possible to stop.

  Even when the conductor layer is deposited on the bottom surface of the groove, the conductor layer is formed on the outer periphery of the mother substrate, so that the current for plating is most likely to flow, and as an auxiliary cathode It functions effectively and can effectively prevent variations in the thickness of the plating layer deposited on the wiring conductor.

  Thereby, cracks and burrs can be prevented from occurring when each wiring board region is divided into individual pieces, and a plating layer can be deposited without causing a large thickness variation in the wiring conductor. As a result, it is possible to prevent the occurrence of cracks and burrs when dividing each wiring board region into individual pieces, and to deposit the plating layer well without causing a large thickness variation on the surface of the wiring conductor Thus, it is possible to provide a multi-piece wiring board that can be made to operate.

  According to the multi-cavity wiring board of the present invention, it is preferable that the mother board has dividing grooves formed along the boundary between the wiring board areas on the main surface and the boundary between the wiring board area and the disposal margin area. In addition, since the groove formed in the disposal margin region has a depth less than ½ of the thickness of the mother board and is formed deeper than the divided groove, each mother board can be easily formed along the divided groove. In addition to being divided into regions, it is possible to prevent the mechanical strength of the mother board from being lowered at the portion where the groove is formed, and mechanical damage such as cracking to occur on the mother board.

  In addition, the stress due to the difference in shrinkage between the metal paste as the conductor layer on the bottom surface of the groove and the green sheet as the mother substrate is caused by the stress of the groove located near the center of the thickness away from the main surface of the mother substrate. Since it acts on the bottom surface portion, it is possible to more effectively prevent the mother substrate from warping due to the difference in shrinkage rate during firing between the conductor layer and the mother substrate.

  Further, even if the dividing groove for dividing this multi-piece wiring board into individual wiring board regions is formed longer than the conductor layer formed on the bottom surface of the groove in the discarding area on the outer periphery of the mother board, the conductor Does not break the layers. As described above, by forming the dividing groove long in the longitudinal direction and the width direction of the mother substrate up to the end of the mother substrate, the dividing property of the mother substrate can be further improved.

  Further, according to the multi-cavity wiring board of the present invention, preferably, the conductor layer is electrically connected to the wiring conductor in each wiring board region, and the wiring conductor and the conductor layer are plated on the exposed surface. Since the layer is deposited, the oxidative corrosion of the wiring conductor can be prevented, and the wettability of the solder and the bondability of the bonding wire can be improved. Also, the wiring conductor (not shown) formed in all the wiring board regions, the conductor layer on the bottom surface of the groove formed on the main surface of the mother board, and the plating conduction pattern should be integrated. Thus, the thickness of the plating layer deposited on the wiring conductor in each wiring board region can be made uniform and stable.

  Next, a multi-piece wiring board according to the present invention will be described with reference to the accompanying drawings.

  FIG. 1A is a plan view showing an example of an embodiment of a multi-piece wiring board according to the present invention, and FIG. 1B is a cross-sectional view. In the figure, 1 is a mother board, 2 is a wiring board area, 3 is a groove, 4 is a conductor layer formed on the bottom surface of the groove 3, and 5 is a margin area. In addition, although the wiring conductor is formed in each wiring board area | region 2, the wiring conductor is abbreviate | omitted in order to make drawing easy to see.

  The mother board 1, the wiring board area 2, the groove 3, the conductor layer 4, and the disposal margin area 5 constitute the multi-cavity wiring board of the present invention.

  Here, the mother substrate 1 is formed by laminating ceramic layers made of a ceramic material such as an aluminum oxide sintered body, an aluminum nitride sintered body, a mullite sintered body, or a glass ceramic. Moreover, each wiring board area | region 2 is a square shape whose length of one side is about 2-20 mm and thickness is about 0.5-2 mm, for example. A mounting portion (not shown) for storing and mounting electronic components is provided at the center of the upper surface of each wiring board region 2.

  If such a mother substrate 1 is made of, for example, an aluminum oxide sintered body, a plurality of green sheets obtained by forming a raw material powder such as aluminum oxide into a sheet shape are prepared, and the substrate is partitioned vertically and horizontally. Next, a part of the green sheet is subjected to an appropriate punching process, and then laminated and fired.

  A wiring conductor (not shown) is formed in each wiring board region 2. The wiring conductor is electrically connected to an electrode of an electronic component mounted on the mounting portion via a bonding wire, solder, or the like, and functions as a conductive path leading to the lower surface or side surface of the wiring board region 2.

  The wiring conductor is made of a metal material such as tungsten, molybdenum, copper, or silver. For example, when the wiring conductor is made of tungsten, a metal paste of tungsten is printed on a green sheet as the mother substrate 1 in a predetermined wiring conductor pattern. It is formed by keeping.

  On the surface of the wiring conductor, a plating layer (such as nickel or gold) is used to prevent oxidative corrosion and to improve characteristics such as solder wettability when bonding solder and bonding wires and bonding wire bonding properties. (Not shown) is attached.

  This plating layer is formed by supplying a plating current to the portion to be plated (surface of the wiring conductor) in the plating solution and performing electrolytic plating.

  The conductor layer 4 formed on the bottom surface of the groove 3 is for reducing and making uniform the plating layer deposited at this time. That is, the conductor layer 4 functions as a so-called auxiliary cathode, thereby preventing the plating layer deposited on the wiring conductor in the inner wiring board region 2 from becoming thick and causing variations in the plating layer thickness. ing.

  The conductor layer 4 is made of the same metal material as that of the wiring conductor. For example, if the conductor layer 4 is made of tungsten, a metal paste of tungsten is printed in a frame-like pattern on the discard margin region 5 of the mother board 1. Is formed. The conductor layer 4 is preferably formed of the same material as the wiring conductor in consideration of productivity and the like.

  In the multi-piece wiring board of the present invention, the groove 3 is formed in the discard margin area 5 so as to surround the entire wiring board area 2, and the conductor layer 4 is formed on the bottom surface of the groove 3.

  As a result, even if stress is generated between the conductor layer 4 formed on the bottom surface of the groove 3 and the mother substrate 1 due to a difference in shrinkage rate during firing, the stress is generated from the main surface of the mother substrate 1. The conductor layer 4 is formed on the main surface of the abandon margin region 5 of the mother substrate 1 which acts on the bottom surface of the groove 3 located near the center of the separated thickness, and relatively large stress is likely to occur due to surface shrinkage. Since the stress acting on the mother board 1 can be made smaller than that in the case where it is done, the warp of the mother board 1 can be prevented.

  Further, even when the conductor layer 4 is deposited on the bottom surface of the groove 3, since the conductor layer 4 is formed on the outer peripheral portion of the mother substrate 1, the current for plating is most likely to flow. It effectively functions as an auxiliary cathode and can effectively prevent variations in the thickness of the plating layer deposited on the wiring conductor.

  Therefore, cracks and burrs can be prevented from occurring when each wiring board region 2 is divided into individual pieces, and a plating layer can be deposited without causing a large thickness variation in the wiring conductor. As a result, it is possible to prevent the occurrence of cracks and burrs when dividing each wiring board region 2 into individual pieces, and to cover the plating layer satisfactorily without causing a large thickness variation on the surface of the wiring conductor. A multi-piece wiring board that can be attached can be provided.

  The groove 3 is formed by forming a frame-shaped punched portion corresponding to the groove 3 over a plurality of layers from the uppermost layer to the lower layer among the green sheets to be the mother substrate 1. It is formed. In addition, when the frame-shaped punching part is formed on the outer periphery of the green sheet, it is separated into an outer part (outer peripheral part) and an inner part (center part) than the punching part. Laminate on green sheet. Further, instead of completely punching into a frame shape, a column portion (non-punched portion) may be provided in a part, and the outer peripheral portion and the center portion may be connected via the column portion.

  The conductor layer 4 is preferably formed with a width of 2 mm or more in order to prevent variations in the plating thickness of the wiring conductor. In this case, it is not necessary to form the groove 3 so as to be continuous over the entire circumference of the mother substrate 1. For example, the main surfaces of the wiring substrate region 2 and the discard margin region 5 are approximately equal to the length of the side of the wiring substrate region 2. May be formed so that they are connected at the same height, and the continuous conductor layer 4 may be formed in the pillar portion via the inner layer of the mother board. As will be described later, when forming the dividing groove 6 for facilitating the division of the mother board 1, in order to ensure the mechanical strength of the mother board 1, the column part is formed avoiding the dividing groove 6. It is desirable to do.

  Moreover, it is preferable that the conductor layer 4 has a thickness of 10 to 30 μm in view of electrical characteristics, productivity of a multi-piece wiring board, effective prevention of warpage during firing, and the like.

  Further, the groove 3 in which the conductor layer 4 is formed on the bottom surface does not need to have the same width over the entire circumference of the mother board 1. For example, the width on the outer side of each corner portion of the wiring substrate region 2 where the current density for plating is particularly high is made wider than the width at other portions, so that variations in plating thickness can be prevented more reliably. Also good.

  In order to effectively prevent the plating solution from staying in the groove 3 and reducing the effect of preventing the thickness variation of the wiring conductor due to the decrease in the plating formation efficiency of the plating conductor layer 4, the groove 3 is formed. It may be formed so that the width becomes wider toward the upper side, and the flow of the plating solution into the groove 3 may be improved.

  Here, considering the balance of the porcelain shrinkage during firing of the upper surface and the lower surface of the mother substrate 1, it is desirable to form the grooves formed at the same depth on both surfaces of the discard margin region 5 on the outer periphery of the mother substrate 1. . In this case, it is desirable to form the conductor layer 4 on the bottom surfaces of the grooves on both sides in order to more reliably prevent the mother substrate 1 from warping. Further, it is desirable that the thickness of the mother substrate 1 in the groove 3 is 0.2 mm or more as the thinnest portion. When the thickness is less than 0.2 mm, there is a high possibility that the mother substrate 1 will be accidentally cracked due to a slight mechanical impact when the mother substrate 1 after firing is handled.

  Further, the mother board 1 has divided grooves 6 formed along the boundary between the wiring board areas 2 on the main surface and the boundary between the wiring board area 2 and the discard margin area 5, respectively. As shown, the depth d is preferably less than ½ of the thickness t of the mother substrate 1 and deeper than the dividing groove 6. 2 is an enlarged cross-sectional view of the main part of the multi-piece wiring board shown in FIG. 1. In FIG. 2, the same parts as those in FIGS. 1 (a) and 1 (b) are denoted by the same reference numerals.

  As a result, the mother board 1 can be easily divided into the respective wiring board regions 2 along the dividing grooves 6, and the mechanical strength of the mother board 1 is lowered at the portion where the grooves 3 are formed. It is possible to prevent the substrate 1 from being mechanically broken such as a crack.

  Further, the stress due to the difference in shrinkage between the metal paste as the conductor layer 4 on the bottom surface of the groove 3 and the green sheet as the mother substrate 1 is near the center of the thickness t away from the main surface of the mother substrate 1. Therefore, it is possible to more effectively prevent the warp of the mother substrate 1 due to the difference in shrinkage rate during firing between the conductor layer 4 and the mother substrate 1. Become.

  Further, the dividing groove 6 for dividing the multi-piece wiring board into individual wiring board areas 2 is disposed in the discard margin area 5 on the outer periphery of the mother board 1 and exceeds the conductor layer 4 formed on the bottom surface of the groove 3. Even if it is formed long, the conductor layer 4 will not be disconnected. In this way, by forming the dividing grooves long in the longitudinal direction and the width direction of the mother substrate up to the end of the mother substrate, the division property of the mother substrate 1 can be further improved.

  Further, in the multi-piece wiring board of the present invention, the conductor layer 4 is electrically connected to the wiring conductor of each wiring board region 2, and the wiring conductor and the conductor layer 4 have a plating layer on the exposed surface. It is preferred that it be deposited.

  Thereby, the oxidative corrosion of the wiring conductor can be prevented, and the wettability of the solder and the bondability of the bonding wire can be improved. Also, the wiring conductor (not shown) formed in all the wiring board regions and the conductor layer 4 on the bottom surface of the groove 3 formed in the main surface of the mother board 1 are integrated with each other through the plating conduction pattern 7. Conductivity is obtained from a plating jig or the like, and the thickness of the plating layer deposited on the wiring conductor in each wiring board region 2 can be made uniform and stable.

  The plating conduction pattern 7 is formed on, for example, two opposing sides of the mother substrate 1 and serves as a terminal for receiving a current from a plating jig or the like. The plating conduction pattern 7 can be formed by the same method using the same metal material as the wiring conductor 2 and the conductor layer 4.

  As described above, it is possible to prevent the occurrence of cracks and burrs when the wiring board regions 2 are divided into individual pieces. In addition, when mounting electronic components such as semiconductor elements without dividing the mother board 1, mounting accuracy can be prevented from being deteriorated and mounting defects can be prevented.

  In addition, a plating conduction pattern 7 is formed on each of a pair of opposing sides of the mother substrate 1, and each plating conduction pattern formed on each of a pair of opposing sides of the mother substrate 1 by this configuration. 7 is sandwiched from above and below by a conduction terminal provided on a plating jig (rack), whereby the electrical connection between the plating conduction pattern 7 and the conduction terminal can be made easy and reliable. Thus, a plating current can be supplied to the wiring conductor more reliably, and a plating layer having a uniform thickness can be more reliably formed on the wiring conductor.

  A metal pin of a rack conduction terminal is fitted and brought into contact with the plating conduction pattern 7, and plating is applied to the wiring conductor of each wiring board region 2 from the conduction terminal via the plating conduction pattern 7 in the plating solution. By supplying an electric current, metal components (nickel, gold, etc.) in the plating solution are deposited, and the wiring conductor is plated.

  In addition, it is preferable that the plating conduction pattern 7 has a thickness of, for example, 10 to 30 μm in view of electrical characteristics, productivity of a multi-piece wiring board, effective prevention of warpage during firing, and the like.

  Alternatively, the groove-shaped notch 8 may be formed in the vertical direction on the outer surface of the mother substrate 1, and the plating conduction pattern 7 may be formed on the inner surface of the notch 8. In this case, since the terminal of the plating jig is easily fitted and fixed in the notch 8, the workability is improved and the current for plating can be more reliably supplied.

  As a result, according to the present invention, it is possible to provide a multi-piece wiring board capable of producing a wiring board excellent in electrical connection reliability.

  It should be noted that the present invention is not limited to the above embodiments, and various modifications may be made without departing from the gist of the present invention. For example, in this example, the mother board is composed of 28 wiring board regions of 7 rows × 4 columns, but it is needless to say that the mother board may be composed of other arrangement numbers.

(A) is a top view which shows an example of embodiment of the multi-cavity wiring board of this invention, (b) is sectional drawing of the multi-cavity wiring board of (a). It is a principal part expanded sectional view of the multi-piece wiring board shown in FIG. (A) is a plan view of a conventional multi-cavity wiring board, (b) is a cross-sectional view of the multi-cavity wiring board of (a), and (c) is an enlarged main part of the multi-cavity wiring board of (a). It is sectional drawing.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 ... Mother board 2 ... Wiring board area | region 3 ... Groove 4 ... Conductor layer 5 ... Discard allowance area 6 ... Dividing groove

Claims (3)

A plurality of quadrangular wiring board regions are arranged in the center of the main surface in the vertical and horizontal directions, and a mother board in which a frame-shaped discarding area is formed in the outer periphery, and wiring conductors formed in the respective wiring board regions A multi-piece wiring board comprising: a groove formed so as to surround the entire wiring board area in the abandon margin area; and a conductor layer formed on a bottom surface of the groove. The mother board is formed with dividing grooves along the boundary between the wiring board regions on the main surface and the boundary between the wiring board region and the abandonment region, and the groove has a depth of the mother substrate. 2. The multi-piece wiring board according to claim 1, wherein the multi-cavity wiring board is less than ½ of the thickness of the substrate and deeper than the dividing groove. The conductive layer is electrically connected to the wiring conductor in each wiring board region, and the wiring conductor and the conductive layer are coated with a plating layer on the exposed surface. The multi-piece wiring board according to claim 1 or 2.

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