JP2010123832A - Printed wiring board - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a printed wiring board capable of having high reliability by preventing a plating pattern from peeling during mold clamping when a resin sealing portion is molded. <P>SOLUTION: The printed wiring board 20, wired by providing a plating pattern with a predetermined pattern made of a metal thin film on a source substrate having a copper foil layer 22a with the predetermined pattern on an insulating substrate 21, has the plating pattern formed along both a corner portion K1 that a mounting surface T1 and an end surface T2 of the source substrate form and a corner portion K2 that a reverse surface T3 on the opposite side from the mounting surface T1 and the end surface T2 form. Beveled surfaces S are formed at the corner portions K1 and K2 of the source substrate. The beveled surfaces S can be formed by rooter processing etc. <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

  The present invention relates to a printed wiring board in which a plating pattern made of a metal thin film is formed along a corner formed by one surface and an end surface of an original substrate and a corner formed by another surface and an end surface opposite to the one surface.

  In a printed wiring board, an insulating substrate serving as a base substrate is plated to form a plating pattern serving as an electrode and wiring, and power is supplied to the electronic components to be mounted and signals are transferred.

  There are various types of electronic components such as ICs, resistors, and capacitors. A conventional printed wiring board will be described in detail with reference to the drawings, taking a light emitting element as an example. FIG. 9 is a perspective view of a conventional light emitting device mounted on a mounting substrate, FIG. 10 is a perspective view of a part of a collective substrate in the manufacturing process of the conventional light emitting device, and FIG. It is sectional drawing for demonstrating.

  As shown in FIG. 9, the light emitting device 1 on which the light emitting element 30 is mounted is used for a conventional printed wiring board 2. The conventional printed wiring board 2 is cut and separated by the cut line 101 in the final process from the collective board 100 shown in FIG. The light emitting element 30 is die-bonded to one of the pair of upper surface patterns 2x and connected to the other by a bonding wire 3. The end face pattern 2y is a conductive plating pattern provided on the end face of the conventional printed wiring board 2 connected to the upper face pattern 2x. The end face pattern 2y is an inner end face of the elongated long hole-like through hole 102 provided in advance on the collective substrate 100. Is formed by electroless plating or the like. The light emitting element 30 is sealed with a resin sealing portion 40 formed of a light transmissive resin.

A light emitting device 1 configured using such a conventional printed wiring board 2 is described in Patent Document 1.
JP 2000-124344 A

  The resin sealing portion 40 of the light emitting device is molded by a transfer molding method. As shown in FIG. 11, this transfer molding method includes a conventional printed wiring board 2 on which a light emitting element 30 is mounted, an upper mold D 1 in which a cavity C is formed in the shape of a resin sealing portion 40, and a mounting surface. Molding can be performed by clamping with a lower mold D2 that holds the back side opposite to the side, filling the cavity C with molten resin, and curing.

  However, when the upper mold D1 and the lower mold D2 are clamped, in the conventional printed wiring board 2, the upper surface pattern 2x pressed by the upper mold D1 is rolled in the horizontal direction toward the outside. Since the end face pattern 2y is sandwiched between the upper mold D1 and the lower mold D2 and a vertical pressing force is applied, the end face pattern 2y breaks at a corner portion that is a connecting portion between the upper face pattern 2x and the end face pattern 2y. It may peel off from the end face pattern 2y.

  The light emitting device 1 in which the upper surface pattern 2x is peeled from the end surface pattern 2y may cause a lighting failure of the light emitting element 30 and the like, which may cause a decrease in yield.

  Therefore, the present invention provides a printed wiring board capable of preventing yield deterioration and obtaining high reliability by preventing peeling of a plating pattern in mold clamping when molding a resin sealing portion. For the purpose.

  The printed wiring board of the present invention is a printed wiring board that is wired by applying a plating pattern of a predetermined pattern with a metal thin film to the original substrate, and is opposite to the corner portion formed by one surface and an end surface of the original substrate. A plating pattern is formed along one or both of the corners formed by the other surface and the end surface, and a chamfered surface is formed at the corner of the original substrate.

  In the present invention, by providing a chamfered surface at the corner portion of the original substrate, the stress of the plating pattern rolled by the pressing force is relieved by the chamfered surface. Therefore, the plating pattern can be prevented from being peeled off when the mold is clamped, so that the yield can be prevented from deteriorating and high reliability can be obtained.

  1st invention of this application WHEREIN: In the printed wiring board wired by giving the plating pattern of a predetermined pattern by a metal thin film to an original board, the corner | angular part which the one surface and the end surface of the said original substrate comprise, and the said one surface are opposite A plating pattern is formed along one or both of the corners formed by the other surface and the end surface, and a chamfered surface is formed at the corner of the original substrate. is there.

  Since the printed wiring board of the present invention has a chamfered surface formed at a corner portion formed by one surface and an end surface of the original substrate, or a corner portion formed by the other surface and the end surface, the plating pattern is formed at the corner portion. It is formed along the chamfered surface. Therefore, a chamfered surface also appears in the plating pattern formed along this corner. When the upper mold and the lower mold are clamped, the plating pattern is rolled by the pressing force of the mold that comes into contact with one side or the other side. When the chamfered surface is not provided at the corner, stress concentrates on the boundary portion along the edge of the end surface on the one surface side or the other surface side, and the plating pattern may be broken. However, if the corner portion is provided with a chamfered surface, the stress of the plating pattern rolled by the pressing force is relieved by the chamfered surface. Therefore, it is possible to prevent the plating pattern from being peeled when the mold is clamped.

  A second invention of the present application is characterized in that, in the first invention, the chamfered surface is a single plane or a polygonal plane in which two or more planes are continuously connected.

  In 2nd invention, a chamfering surface can be easily formed by cutting processing, such as a router process, by making a chamfering surface into one plane or the polygonal surface which two or more planes connected continuously. When the chamfered surface is a single plane, the chamfered surface can be formed by a single process, so the processing time is short. Further, by making the chamfered surface a polygonal surface in which two or more planes are continuously connected, the stress can be further relaxed, so that the plating pattern can be prevented from peeling even when the degree of clamping is high.

  According to a third invention of the present application, in the first invention, the chamfered surface is formed in a substantially arc shape.

  In the third invention, since the chamfered surface is formed in a substantially arc shape, the stress can be further reduced as compared with the polygonal surface, so that the plating pattern is prevented from being peeled even when the degree of clamping is higher. be able to.

  According to a fourth invention of the present application, in the first to third inventions, the plating pattern is continuously formed from one surface side of the original substrate to the other surface side through the end surface. It is a feature.

  In the fourth invention, when the plating pattern is continuously formed from one surface side of the original substrate to the other surface side through the end surface, the plating pattern of the end surface portion is viewed from above and below when the mold is clamped. Although a large pressing force is applied, the stress at each corner can be relieved because the plating pattern has a chamfered surface. Therefore, even if the plating pattern is continuously formed from one surface side of the original substrate to the other surface side through the end surface, peeling of the plating patterns at both corners can be prevented.

  According to a fifth invention of the present application, in any one of the first to fourth inventions, the plating pattern is formed of a multilayer plating layer.

  In the fifth invention, since the chamfered surface formed at the corner of the original substrate appears in the outermost plating pattern even if the plating pattern is formed of a multilayer plating layer, a copper plating layer, a nickel plating layer, It can be formed by laminating a plating pattern such as a gold plating layer.

(Embodiment)
A printed wiring board according to an embodiment of the present invention will be described with reference to the drawings. In this embodiment, a light-emitting device in which a light-emitting element is mounted on the printed wiring board will be described as an example. 1A and 1B are diagrams for explaining a light emitting device using a printed wiring board according to an embodiment of the present invention. FIG. 1A is a perspective view seen from the back side, FIG. 1B is a front view, and FIG. Is a plan view, and (D) is a rear view.

  As shown in FIG. 1A to FIG. 1D, the light emitting device 10 is a side view type LED, and includes a printed wiring board 20, a light emitting element 30, and a resin sealing portion 40. The light emitting device 10 is formed by dicing a collective substrate on which a light emitting element 30 is mounted and a resin sealing portion 40 for sealing the light emitting element 30 is formed into individual pieces.

  The printed wiring board 20 has a wiring pattern 22 formed on an insulating substrate 21 made of BT resin (bismaleimide triazine resin thermosetting resin). The wiring pattern 22 includes a cathode electrode 221 and an anode electrode 222 as connection electrodes formed by dicing as described above.

  The cathode electrode 221 is integrally formed with an upper surface cathode electrode part 221x on which the light emitting element 30 is conductively mounted, an end surface cathode electrode part 221y, and a lower surface cathode electrode part 221z. The anode electrode 222 includes an upper surface anode electrode part 222x having a bonding pad electrically connected to the light emitting element 30 by a wire 31, an end surface anode electrode part 222y, and a lower surface anode electrode part 222z from the mounting surface side via the end surface. Further, it is integrally formed up to the back surface side opposite to the mounting surface. A resist film 23 that functions as a polarity display is provided on the back side of the printed wiring board 20.

  In the light emitting element 30, an n electrode is provided on the lower surface of a conductive substrate, an n layer, a light emitting layer, and a p layer are sequentially stacked on the upper surface of the substrate, and a p electrode is provided on the p layer (not shown). .

  The resin sealing portion 40 is formed by forming an epoxy resin by a transfer molding method or the like in order to seal the light emitting element 30 and the wire 31.

  Here, the wiring pattern 22 will be described in detail with reference to FIG. FIG. 2 is an enlarged cross-sectional view of an end portion of the printed wiring board shown in FIG. In FIG. 2, only the anode electrode 222 is shown, but the same applies to the cathode electrode 221 located on the opposite side of the anode electrode 222.

  As shown in FIG. 2, the upper surface anode electrode portion 222x and the lower surface anode electrode portion 222z of the wiring pattern 22 include a copper foil layer 22a that is a metal layer as a base, a copper plating layer 22b, an electroless nickel plating layer 22c, And a surface gold plating layer 22d.

  The copper foil layer 22a is a metal layer having a predetermined pattern by forming a copper foil layer having a thickness of 12 μm on the entire insulating substrate 21 and then removing unnecessary portions by etching.

  The copper plating layer 22b is a metal layer having a thickness of 10 μm to 15 μm formed on the copper foil layer 22a by electrolytic plating.

  The electroless nickel plating layer 22c is an electroless plating layer formed on the upper surface of the copper plating layer 22b to a thickness of 10 μm to 15 μm by an electroless plating process. Since the electroless nickel plating layer 22c is formed by an electroless plating process, the thickness can be formed almost uniformly, so that the copper plating layer 22b can be protected from corrosion due to oxidation.

  The surface gold plating layer 22d is an electrolytic plating layer formed to a thickness of 0.3 μm to 0.8 μm by an electrolytic plating process.

  The end surface anode electrode portion 222y of the wiring pattern 22 is obtained by omitting the copper foil layer 22a from the upper surface anode electrode portion 222x or the lower surface anode electrode portion 222z. That is, after the copper foil layer 22a is formed on the upper surface and the lower surface of the insulating substrate 21, the copper plating layer 22b is formed to connect the copper foil layer 22a to the upper surface and the lower surface, respectively. Becomes the base metal layer. Then, an electroless nickel plating layer 22c and a surface gold plating layer 22d are sequentially formed on the upper surface of the copper plating layer 22b, thereby forming an end face anode electrode portion 222y, and an anode electrode 222 having a substantially U-shaped cross section. Can be formed.

  Thus, in the present embodiment, a plating pattern is formed by the copper plating layer 22b, the electroless nickel plating layer 22c, and the surface gold plating layer 22d.

  A method of manufacturing the light emitting device according to the embodiment of the present invention configured as described above will be described with reference to FIGS. FIG. 3A to FIG. 3C are diagrams showing respective steps for explaining a method for manufacturing a printed wiring board. 4A and 4B are enlarged views of an end portion of the printed wiring board in each manufacturing process. FIG. 5 is a diagram illustrating a modified example of the chamfered surface. FIG. 6 is a diagram illustrating a state in which the light emitting elements are mounted on the collective substrate. FIG. 7 is a cross-sectional view showing a clamped state. FIG. 8 is a partially enlarged cross-sectional view showing an end portion in a clamped state.

  First, after forming a copper foil layer having a thickness of 12 μm on the entire insulating substrate 21, unnecessary portions are removed by etching to prepare an original substrate on which a copper foil layer 22a having a predetermined pattern is formed (FIG. 3A). ), FIG. 4 (A)). This original substrate is a collective substrate that is diced later to obtain a large number of printed wiring boards 20.

  Next, a chamfering process for forming a chamfered surface S at a corner portion K1 formed by the mounting surface T1 and the end surface T2 or a corner portion K2 formed by the back surface T3 and the end surface T2 opposite to the mounting surface T1 is performed.

  The chamfered surface S can be formed by chamfering along the corners K1 and K2 by router processing (see FIGS. 3B and 4B). If the chamfering is performed once, the corners K1 and K2 are formed with a single chamfered surface S1 as shown in FIG. Further, by chamfering the corners, the corner portions K1 and K2 can be formed in which the chamfered surface S2 in which two or more planes are continuously connected is formed. FIG. 5B shows the case of three planes.

  By increasing the number of chamfers, it is possible to obtain a substantially arc-shaped chamfered surface. However, if the number of chamfers is increased, it takes time for router processing. Polishing with a liquid is desirable.

  That is, when the chamfer is formed by router processing, the chamfered surface S can be formed in a short time when the chamfered surface S is a single plane (the chamfered surface S1), but the corners K1 and K2 are polygonal surfaces. The degree of dispersion of the pressing force at the time of clamping is smaller than the surface S2. When the chamfered surface S is a polygonal surface (chamfered surface S2), the degree of dispersion of the pressing force increases, but it takes time to chamfer. Therefore, it is desirable to determine the number of chamfering times by router processing according to the pressing force at the time of clamping, or to select the chamfered surface S to be an arc surface by polishing with a polishing liquid.

  In FIG. 4B, the chamfered surface S is formed only on the copper foil layer 22a, but the copper foil layer 22a and the insulating substrate 21 may be chamfered together.

  Next, a plating process for forming a plating pattern on the copper foil layer 22a is performed.

  First, the copper foil layer 22a and the end face T2 on the mounting surface T1 and the back surface T3 are formed on the insulating substrate 21 on which the copper foil layer 22a is formed by forming a plating pattern having a thickness of 10 μm to 15 μm by electrolytic plating. A copper plating layer 22b is formed to connect the two. At this time, since the copper plating layer 22b on the chamfered surface S is formed with a predetermined thickness along the chamfered surface S, the corners of the copper plated layer 22b are not perpendicular.

  Further, an electroless nickel plating layer 22c is formed on the copper plating layer 22b by electroless plating, and a surface gold plating layer 22d is formed on the electroless nickel plating layer 22c by electrolytic plating (FIGS. 3C and 2). reference). These plating layers also have somewhat different thicknesses on the mounting surface T1, the back surface T3, and the end surface T2, but are formed almost uniformly on the copper plating layer 22b. The chamfered surface S of the foil layer 22a is substantially maintained.

  In this way, a plating pattern comprising the copper plating layer 22b, the electroless nickel plating layer 22c, and the surface gold plating layer 22d is formed on the copper foil layer 22a, and the chamfered surfaces S are provided at the corners K1 and K2. As a result, the wiring pattern 22 can be formed on the collective substrate.

  Next, a mounting process for mounting the light emitting element 30 on the printed wiring board 20 is performed. As shown in FIG. 6, in the mounting step, after the light emitting element 30 is conductively mounted on the bonding pad provided on the upper surface cathode electrode part 221x, the light emitting element 30 and the bonding pad provided on the upper surface anode electrode part 222x are connected to the wire. Conductive connection is made by 31.

  Next, a sealing process for sealing the light emitting element 30 is performed. In the sealing process, the printed wiring board 20 in the state of the collective board on which the wiring pattern 22 is formed and the light emitting element 30 is mounted is mounted on the upper mold D1 in which the cavity C is formed, as shown in FIG. In order to hold the back surface side opposite to the surface, the mold is clamped with a lower mold D2 provided with a recess P for accommodating the printed wiring board 20, and the cavity C is filled with a molten resin and cured. This is a step of forming the resin sealing portion 40.

  When the upper mold D1 and the lower mold D2 are clamped, the end portion of the printed wiring board 20 is sandwiched with a pressing force of about 30 to 60 t. The ends of the printed wiring board 20 are crushed by this clamping, and the upper surface anode electrode part 222x and the lower surface anode electrode part 222z are rolled in the horizontal direction toward the outside of the printed wiring board 20, as shown in FIG. . Further, a vertical pressing force is applied to the end face anode electrode portion 222y.

  However, by chamfering the corners K1 and K2 of the insulating substrate 21 provided with the copper foil layer 22a, the copper plating layer 22b, the electroless nickel plating layer 22c, and the surface gold plating layer 22d, which are plating patterns, are also chamfered. Since S appears, the stress in the plating pattern portions of the upper surface anode electrode part 222x and the lower surface anode electrode part 222z rolled in the horizontal direction is relieved by the chamfered surface.

  Therefore, the plating pattern can be prevented from being peeled off when the mold is clamped, so that the occurrence of light emission failure due to the peeling of the plating pattern can be suppressed. Therefore, deterioration of yield can be prevented and high reliability can be obtained.

  Moreover, even if the chamfered surface S provided on the copper foil layer 22a of the cathode electrode 221 or the anode electrode 222 has a plating pattern formed of a multilayer plating layer, each plating pattern is formed of a metal thin film. A chamfered surface S also appears on the surface gold plating layer 22d which is the outermost plating pattern. Therefore, corrosion resistance can be ensured by the surface gold plating layer 22d while ensuring strength by the copper plating layer 22b and the electroless nickel plating layer 22c.

  In a state where the mold is clamped in this way, the cavity C is filled with a molten resin and cured to form the resin sealing portion 40.

  Then, when the resin sealing portion 40 is formed, finally, the aggregate substrate can be diced by a cut line with a dicer to obtain the light emitting device 10 shown in FIG.

  Thus, since the light emitting device 10 using the printed wiring board 20 according to the present embodiment can suppress the occurrence of light emission failure due to the peeling of the plating pattern, it is possible to prevent the yield from deteriorating. . Therefore, the light emitting device 10 can obtain high reliability.

  By making the chamfered surface S a single plane or a polygonal plane in which two or more planes are continuously connected, the chamfered surface S can be easily formed by router processing or the like. Further, by forming the chamfered surface S in a substantially arc shape, there is no place where the pressing force at the time of clamping is concentrated, so that a larger pressing force can be withstood.

  In the present embodiment, the cathode electrode 221 and the anode electrode 222 are continuously formed from the mounting surface T1 side through the end surface T2 to the back surface T3 side, but the mounting surface T1 and the end surface T2 are formed. The present invention can also be applied to a printed wiring board in which a plating pattern is provided along any corner of the corner K1 formed by or the corner K2 formed by the back surface T3 and the end surface T2.

  In the present embodiment, the light emitting device has been described as an example. However, the metal is formed along the corner formed by one surface and the end surface of the original substrate, or the corner formed by the other surface opposite to the one surface and the end surface. As long as the printed wiring board is formed with a plating pattern using a thin film, another electronic component may be mounted.

  Further, in this embodiment, the insulating substrate 21 provided with the copper foil layer 22a formed in a predetermined pattern is used as the base substrate. However, the insulating substrate not provided with the copper foil layer is used as the base substrate, or the copper foil. A substrate on which a plating pattern is formed can be used as an original substrate.

  According to the present invention, since the plating pattern is prevented from being peeled in mold clamping when the resin sealing portion is molded, the yield can be prevented from being deteriorated and high reliability can be obtained. It is suitable for a printed wiring board in which a plating pattern of a metal thin film is formed along a corner formed by a corner formed by and the other formed on the side opposite to one surface and an end surface.

BRIEF DESCRIPTION OF THE DRAWINGS The figure for demonstrating the light-emitting device using the printed wiring board based on embodiment of this invention (A) is the perspective view seen from the back side, (B) is a front view, (C) is a top view, (D ) Is a back view Enlarged sectional view of the end of the printed wiring board shown in FIG. (A) to (C) are diagrams showing respective steps for explaining a method of manufacturing a printed wiring board. (A) And (B) is an enlarged view of the edge part of the printed wiring board in each manufacturing process The figure which shows the modification of a chamfer The figure which shows the state where the light emitting element is mounted on the collective substrate Sectional view showing the clamped state Partially enlarged sectional view showing the end of the clamped state A perspective view of a conventional light emitting device mounted on a mounting board Partial perspective view of a collective substrate in the manufacturing process of a conventional light emitting device Sectional drawing for demonstrating the manufacturing method of a resin sealing part

Explanation of symbols

DESCRIPTION OF SYMBOLS 10 Light-emitting device 20 Printed wiring board 21 Insulating board 22 Wiring pattern 22a Copper foil layer 22b Copper plating layer 22c Electroless nickel plating layer 22d Surface gold plating layer 23 Resist film 30 Light emitting element 31 Wire 40 Resin sealing part 221 Cathode electrode 221x Upper surface cathode Electrode part 221y End face cathode electrode part 221z Bottom face cathode electrode part 222 Anode electrode 222x Top face anode electrode part 222y End face anode electrode part 222z Bottom face anode electrode part C Cavity D1 Upper mold D2 Lower mold K1, K2 Corner part S, S1, S2 Chamfered surface T1 Mounting surface T2 End surface T3 Back surface

Claims (5)

In a printed wiring board that is wired by applying a predetermined pattern of plating with a metal thin film to the original substrate,
A plating pattern is formed along one or both of a corner portion formed by one surface and an end surface of the original substrate, and a corner portion formed by the other surface and the end surface opposite to the one surface,
A printed wiring board, wherein chamfered surfaces are formed at corners of the original substrate. The printed circuit board according to claim 1, wherein the chamfered surface is a single plane or a polygonal plane in which two or more planes are continuously connected. The printed wiring board according to claim 1, wherein the chamfered surface is formed in a substantially arc shape. The printed wiring board according to claim 1, wherein the plating pattern is continuously formed from one surface side of the original substrate to the other surface side through an end surface. The printed wiring board according to claim 1, wherein the plating pattern is formed of a multilayer plating layer.

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