JP2015173208A - Packaging board and electronic device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a packaging board having high mechanical strength, and an electronic device to which the packaging board is applied.SOLUTION: A packaging board 1 has a mount face 5 on at least one principal surface 3a of a board 3, on which an electronic part 13 is mounted. The mount face 5 is concaved in the form of a bowl. In this case, it is preferable that the mount face 5 is provided through a step portion S which is deeper than the principal surface 3a by at least one step, or the step portion S is a curved surface CS at the continuous place between a longitudinal inner surface Sv vertical to the principal surface 3a and a lateral inner surface Sh parallel to the principal surface 3a. The board 3 preferably has a via conductor V extending in the radial direction with respect to the mount face 5. An electronic device 11 is configured so that an electronic part 10 is packaged on the mount face 5 of the packaging board 1. Accordingly, a packaging board and an electronic device which have high mechanical strength can be obtained.

Description

  The present invention relates to a mounting substrate and an electronic device.

  FIG. 9A is a perspective view schematically showing an example of a conventional electronic device, and FIG. 9B is a sectional view taken along line XX in FIG. An electronic device 101 on which an electronic component 100 such as a crystal application product is mounted has a configuration in which a lid 103 is bonded to the upper surface of a mounting substrate 102. The mounting substrate 102 has a cavity portion 107 for housing the electronic component 100 on the main surface of the substrate formed of an insulating material such as ceramics or FR-4. (For example, see Patent Document 1).

  In recent years, electronic devices such as mobile phones and IC cards have become widespread. However, in addition to high performance, these electronic devices 101 are increasingly required to be smaller and thinner. The electronic component 100 incorporated in the electronic device 101 and the mounting substrate 102 for mounting the electronic component 100 are also required to be further reduced in size and thickness.

  However, in order to reduce the size and thickness of the electronic device 101, it is necessary to reduce the area of the mounting substrate 102 which is a base material of the electronic device 101 and to reduce the thickness t. When t becomes thinner, there is a problem that the mechanical strength is lowered.

JP 2010-135711 A

  Accordingly, an object of the present invention is to provide a mounting substrate having high mechanical strength and an electronic device using the same.

  The mounting board of the present invention is a mounting board provided with a mounting surface for mounting an electronic component on at least one main surface of the board, wherein the mounting surface is recessed in a bowl shape. .

  The electronic device according to the present invention is characterized in that an electronic component is mounted on the mounting surface of the mounting board.

  According to the present invention, it is possible to obtain a mounting substrate having high mechanical strength and an electronic device using the same.

(A) is an external appearance perspective view which shows typically one Embodiment of the board | substrate for mounting of this invention, (b) is the sectional view on the AA line of (a). (A) is an external appearance perspective view which shows the mounting board | substrate of the other aspect of this embodiment, (b) is BB sectional drawing of (a), and a mounting surface is one step deeper from the main surface. The structure provided via the step part which became is shown. It is a cross-sectional schematic diagram which shows the board | substrate for mounting of the other aspect of this embodiment, and shows the structure where the trough part of the level | step-difference part provided between the main surface and mounting surface of a board | substrate is a curved surface. is there. (A) is the external appearance perspective view which shows the mounting board | substrate of the other aspect of this embodiment, (b) is CC sectional view taken on the line of (a), and the via conductor formed in the mounting surface is The structure which has penetrated the board | substrate in the thickness direction is shown. (A) is an external appearance perspective view which shows the electronic device of this invention, (b) is the DD sectional view taken on the line of (a). It is a schematic diagram which shows the manufacturing process of the ceramic substrate for electronic component accommodation of this embodiment. FIG. 5 is a schematic diagram showing a manufacturing process of the ceramic substrate for housing electronic components having the structure shown in FIGS. 2 and 3, showing another manufacturing process of the ceramic substrate for housing electronic components of the present embodiment. FIG. 5 is a schematic diagram illustrating a manufacturing process of a ceramic substrate for storing electronic components having a structure shown in FIG. 4, showing a manufacturing process of another ceramic substrate for storing electronic components of the present embodiment. (A) is a perspective view which shows typically an example of the conventional package, (b) is XX sectional drawing of (a).

  Fig.1 (a) is an external appearance perspective view which shows typically one Embodiment of the mounting board | substrate of this invention, (b) is the sectional view on the AA line of (a). In the cross-sectional view of the mounting substrate 1 in FIG. 1B, the broken line B shown below the mounting surface 5 is shown as a comparison of the cross-sectional shape of the cavity of the conventional mounting substrate 101 shown in FIG. There is a difference in cross-sectional shape from the cavity of the mounting substrate 1 of the present embodiment.

  The mounting substrate 1 of this embodiment includes a mounting surface 5 for mounting an electronic component on at least one main surface 3a of the substrate 3, and the mounting surface 5 has a bowl-like shape. ing. In other words, the mounting substrate 1 of the present embodiment has a so-called curved surface CS shape in which the mounting surface 5 having a cavity structure gradually becomes deeper from the peripheral edge portion 5a side toward the central portion 5c side.

  When the mounting surface 5 has such a structure, as shown in FIG. 1B, a so-called well-shaped shape in which the mounting surface 5 is deeply dug in the thickness direction (in FIG. Compared to the conventional configuration, the thickness of the mounting surface 5 in the vicinity of the peripheral portion 5a is thick, and the concave meniscus portion M surrounded by the curved surface CS and the broken line B remains on the substrate 3. Therefore, the amount of bending of the substrate 3 can be reduced. Moreover, since the mounting surface 5 is the curved surface CS, the stress is easily dispersed even when a load is applied to the substrate 3 including the mounting surface 5. As a result, a mounting substrate having high mechanical strength can be obtained.

  Although not shown in FIGS. 1A and 1B, a lid as shown in FIGS. 9A and 9B is also provided on the mounting surface 5 of the mounting substrate 1. In this case, since the mounting surface 5 has a shape (curved surface CS) recessed in a bowl shape as described above, the lid body can be placed in the middle of the curved surface CS, and the lid body can be easily installed, Even if the lid is placed on the mounting substrate 1, the total thickness can be reduced.

  And as a structure which is easy to install a cover body in the mounting surface 5 of the mounting substrate 1, a thing as shown to Fig.2 (a) (b) can be mentioned.

FIG. 2A is an external perspective view showing a mounting substrate according to another aspect of the present embodiment. (B) is the BB sectional drawing of (a), and shows the structure where the mounting surface 5 is provided via the level | step-difference part S which became one step deep from the main surface 3a. Here, the solid line marked on the mounting surface 5 in FIG. 2A indicates the mountain fold portion Y, and the broken line indicates the valley fold portion T. In FIG. 2, the vertical inner wall surface perpendicular to the main surface 3a of the substrate 3 in the stepped portion S is represented by Sv, and the horizontal inner wall surface parallel to the main surface 3a is represented by Sh. A step S is formed by the vertical inner wall surface Sv and the horizontal inner wall surface Sh.

  In addition to the mounting surface 5 being recessed in a bowl shape, when a stepped step portion S is provided on the peripheral portion of the mounting surface 5, the electronic device 11 shown in FIGS. 5A and 5B described later. As described above, the lid 15 is fitted in the bowl-shaped recessed portion, whereby the deformation of the substrate 3 is suppressed, and the mechanical strength of the mounting substrate 1 when the lid 15 is fitted is further increased. be able to.

  Further, when the mounting surface 5 is provided with the stepped portion S, the depth from the main surface 3a to the bottom of the mounting surface 5 that is recessed in a bowl shape can be increased, so that the size of the electronic component is limited. However, this is suitable for realizing a mounting form in which the electronic component does not protrude from the main surface 3a. In this case, since the bottom portion of the mounting surface 5 is still in the shape of a bowl, the strength of the substrate 3 is maintained.

  At this time, the depth d of the stepped portion S is preferably as thin as possible as long as even a part of the lid 15 can be embedded in the substrate 3. For example, the depth d should be 1/3 or less of the thickness t of the substrate 3. desirable. 2 (a) and 2 (b) only show a structure in which the stepped portion S has one stage. However, in the mounting substrate of the present embodiment, the stepped portion S is configured by a plurality of stages, such as two stages and three stages. Even if it is done, the same effect can be acquired.

  FIG. 3 is a schematic cross-sectional view showing a mounting substrate according to another aspect of the present embodiment, where a valley fold portion T of a stepped portion S provided between the main surface 3a of the substrate 3 and the mounting surface 5 is a curved surface. It shows the structure that is CS. In FIG. 3, the shape of the stepped portion S shown in FIG. 2B is indicated by a broken line B, the vertical inner wall surface perpendicular to the main surface 3a of the substrate 3 is Sv, and the horizontal inner wall surface parallel to the main surface 3a. Is represented by the symbol Sh.

  In the mounting substrate 1, it is desirable that the stepped portion S has a curved surface CS at a continuous portion between the vertical inner wall surface Sv perpendicular to the main surface 3a and the horizontal inner wall surface Sh parallel to the main surface 3a. When the mounting surface 5 formed on the main surface 3a of the substrate 3 has a shape as shown in FIG. 3, the stepped portion S is bent at a predetermined angle as shown in FIGS. Since the (valley folded portion T) is eliminated and the concave meniscus portion M can be left in the stepped portion S, the mounting substrate 1 having higher mechanical strength than the structure shown in FIGS. 2A and 2B is obtained. be able to.

  4A is an external perspective view showing a mounting substrate according to another aspect of the present embodiment, and FIG. 4B is a cross-sectional view taken along the line CC of FIG. 4A and is formed in the mounting surface 5. This shows a structure in which the via conductor V penetrates the substrate 3 in the thickness direction.

  The mounting substrate 1 of the present embodiment is also suitable for the substrate 3 having the via conductor V. For example, when the via conductor V has a structure in which one end of the via conductor V is exposed on the mounting surface 5 of the substrate 3 and the other end penetrates the main surface 3b opposite to the mounting surface 5 of the substrate 3, It is desirable that V be arranged so as to extend in the direction of the line with respect to the mounting surface 5. Here, the state in which the via conductor V extends in the normal direction with respect to the mounting surface 5 is a range in which the axis of the via conductor V is changed not only in the direction perpendicular to the mounting surface 5 but also by ± 10 °. It is meant to include what is in

By the way, for example, an electronic component such as an LSI (Large Scale Integrated circuit) is mounted on the mounting surface of the mounting substrate 1, and the mounting substrate is mounted on an external circuit substrate which is a motherboard. In this case, the mounting board plays a role of matching resistance components such as impedance between the electronic component and the external circuit board between the electronic component and the external circuit board. . Usually, the pitch of the connection pads on the mounting surface of the mounting substrate (sometimes called the primary mounting side) corresponds to the pitch of the connection pads of the electronic component. The pitch of the connection pads on the reverse side (sometimes referred to as the secondary mounting side) opposite to the one corresponds to the wiring pitch of the external circuit board, so the pitch of the connection pads is larger than the mounting surface side. ing. For this reason, in a normal mounting substrate, a wiring circuit formed on the surface or inside is formed through an insulating layer, the wiring circuit is developed through a via conductor penetrating the insulating layer, and the mounting surface 5 side The wiring pitch is designed to increase from the primary mounting side to the secondary mounting side on the back surface.

  On the other hand, in the mounting substrate 1 of the present embodiment shown in FIGS. 4A and 4B, the via conductor V is disposed so as to extend in the radial direction with respect to the mounting surface 5, and therefore the mounting substrate. Even if the pitch of the connection pads on the mounting surface 5 side of 1 is small, the pitch of the connection pads exposed on the back surface side can be widened regardless of the development of the wiring circuit. In such a mounting substrate 1, the number of via conductors can be reduced by the amount that can reduce the number of wiring circuit layers, and thus a smaller mounting substrate 1 can be obtained.

  FIG. 5A is an external perspective view showing the electronic device of the present invention, and FIG. 5B is a sectional view taken along the line DD of FIG. The electronic device 11 of the present embodiment is characterized in that an electronic component 13 such as a crystal resonator is mounted on the mounting surface 5 of the mounting substrate 1 described above. In this electronic device 11, the mounting surface 5 has a shape that is recessed in a bowl shape (curved surface CS). Therefore, for the reasons described above, the amount of bending of the mounting substrate 1 can be reduced, and high mechanical strength can be achieved. An electronic device 11 having the same can be obtained. In the electronic device 11 of the present embodiment, the electronic component 13 may be resin-sealed as necessary. However, if the lid 15 is provided so as to cover the mounting surface 5, the mounting substrate 1 is more It can be made difficult to deform. Further, a conductor layer for connecting to the electronic component 13 or an external power source may be provided on the surface or inside of the mounting substrate 1.

Next, a method for manufacturing a mounting substrate and an electronic device according to the present embodiment will be described. FIG. 6 is a schematic diagram showing a manufacturing process of the mounting substrate of the present embodiment. First, as shown in FIG. 6A, a green sheet 21 for forming the substrate 3 is prepared. The green sheet 21 is obtained, for example, from a mixed powder in which an Al ₂ O ₃ powder is a main component and a predetermined amount of SiO ₂ powder and MgO powder is added thereto.

  Next, as shown in FIG. 6B, the green sheet 21 is press-molded with a mold having a convex portion 23 having a spherical shape from one surface side of the green sheet 21. At this time, the part corresponding to the convex part 23 becomes a bowl-shaped concave part 25a.

  When the mounting surface 5 is shaped as shown in FIGS. 2 (a), 2 (b) and 3 (a), (b), the protrusions 23 corresponding to the shape of the mounting surface 5 after firing are provided. The provided mold may be used, but if the mounting surface 5 is shallow, a stepped portion is formed at the tip of the convex portion 23 as shown in FIGS. The mounting substrate 1 having the same shape can be obtained even by using a mold that can process only the portion S (the spherical convex portion 23 is not formed). In this case, it is preferable to use a ceramic material that undergoes firing shrinkage (linear shrinkage) by 15% or more before and after firing as the concave shaped body 25.

  FIG. 8 is a schematic view showing a process of manufacturing the mounting substrate shown in FIG. In this case, a via conductor pattern 27 is formed on the surface of the green sheet 21 where the mold protrusions 23 abut, and then pressed from the upper surface side by the mold. At this time, the conductor pattern 27 is embedded in the concave shaped body 25 so as to spread downward. Next, by firing the concave shaped body 25, a mounting substrate 1 as shown in FIG. 4 can be obtained.

After mixing SiO ₂ powder at 5% by mass and MgO powder at 2% by mass with respect to 93% by mass of Al ₂ O ₃ powder, 19% by mass of acrylic binder as organic binder and toluene as organic solvent. Then, a green sheet having an average thickness of 200 μm was prepared by a doctor blade method.

  Next, the produced green sheet is heated and pressed at a temperature of 80 ° C. using a mold and cut to form a concave molded body having a structure as shown in FIG. 1, FIG. 2, and FIG. did. Moreover, the conductor paste which has Mo as a main component was applied to the conductor pattern formed in the concave shape molded body of FIG. In addition, the sample having the structure shown in FIG. 9 was manufactured under the same pressure condition using a mold having a rectangular projection in a sectional view.

  Next, firing was performed in a reducing atmosphere at 1400 ° C. for 1 hour.

  Each of the obtained mounting substrates has a plane area of 5 mm × 5 mm, the depth of the concave portion is about ¼ to ３ of the substrate thickness, the average thickness of the substrate is 0.15 mm, The diameter of the recessed mounting surface was about 3 mm. The step portion was about 1/5 of the substrate thickness.

  Next, a strength test was performed on the obtained mounting substrate, and the strength of the mounting substrate was measured. The strength test was carried out using an autograph by a method in which the produced mounting substrate was supported at both ends and pressed with a steel rod having a diameter of 2 mm from the back side.

  As apparent from Table 1, among the prepared samples, the sample No. In Nos. 1 to 4, although the strength was 0.85 kgf or more, Sample No. No. 5 had a strength of 0.77 kgf.

DESCRIPTION OF SYMBOLS 1 ..... Mounting board 3 ...... Board 3a ... Main surface 5 ... Mounting surface 5a ... Peripheral part 5c ...・ ・ ・ ・ ・ Central part 11 ・ ・ ・ ・ ・ Electronic device 13 ・ ・ ・ ・ ・ Electronic component 15 ・ ・ ・ ・ ・ Cover body CS ・ ・ ・ ・ ・ Curved surface M ・ ・ ・ ・ ・ ・Recessed meniscus part S ... Step T ... Valley folding part Y ... Mountain folding part Sv ... Vertical inner wall surface Sh ...・ Horizontal inner wall surface V ・ ・ ・ ・ ・ ・ Via conductor 21 ・ ・ ・ ・ ・ ・ Green sheet 23 ・ ・ ・ ・ ・ ・ Convex part 25.

Claims (5)

  A mounting substrate comprising a mounting surface for mounting an electronic component on at least one main surface of the substrate, wherein the mounting surface is recessed in a bowl shape.   The mounting substrate according to claim 1, wherein the mounting surface is provided via a stepped portion that is at least one step deeper than the main surface.   The mounting substrate according to claim 2, wherein the stepped portion has a curved surface at a continuous portion between a vertical inner wall surface perpendicular to the main surface and a horizontal inner wall surface parallel to the main surface.   The mounting substrate according to claim 1, wherein the substrate has a via conductor extending in a ray direction with respect to the mounting surface.   An electronic device, wherein an electronic component is mounted on the mounting surface of the mounting substrate according to claim 1.

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