Module, module component composing the module, and method of manufacturing the module

To provide a compact module that is capable of achieving a low profile and that has excellent high-frequency characteristics, a module includes a parent board; first and second child boards arranged so as to face the parent board; multiple electronic components that include first electrodes and second electrodes electrically connected to the first electrodes, respectively, on both opposing faces, the first electrodes being connected to the first child board, the second electrodes being connected to the parent board; and multiple electronic components that include first electrodes and second electrodes electrically connected to the first electrodes, respectively, on both opposing faces, the first electrodes being connected to the second child board, the second electrodes being connected to the parent board.

BACKGROUND

Technical Field

The present disclosure relates to a module including two circuit boards and electronic components, such as integrated circuits (ICs) and chip capacitors, which are arranged between the circuit boards, a module component composing the module, and a method of manufacturing the module.

Background Art

Columnar conductors for connecting to an external mother board or the like are mounted on a circuit board in a module as illustrated inFIG. 10(refer to Patent Document 1). A module100includes a circuit board101having wiring electrodes formed on the surface thereof or formed therein; multiple electronic components102which are mounted on one principal surface of the circuit board101and which include chip components102a, such as chip capacitors, and an IC102b, which is a semiconductor device; multiple columnar conductors103mounted on the one principal surface of the circuit board101; and a resin layer104with which the electronic components102and the columnar conductors103are covered. An end face of each columnar conductor103exposed on the surface of the resin layer104is connected to a certain electrode formed on an external mother board or the like with, for example, solder to connect the circuit board101to the mother board or the like.

At this time, each columnar conductor103has a function to electrically connect the circuit board101to the external mother board or the like, a function as a spacer to arrange each electronic component102between the circuit board101and the mother board, and a fixing function to fix the circuit board101on the mother board.

Patent Document 1: Japanese Unexamined Patent Application Publication No. 2004-71961 (refer to paragraphs 0023 to 0026 and FIG. 1 and so on)

BRIEF SUMMARY

However, the mounting of each columnar conductor103on the circuit board101in the above manner requires the mounting area to be ensured on the circuit board101and it is difficult to reduce the size of the module100. In addition, it is necessary to make the length of each columnar conductor103longer than the height of each electronic component102mounted on the circuit board101from the circuit board101. This hinders low profile of the module100.

The wiring electrode to connect each columnar conductor103to a certain terminal of the corresponding electronic component102is formed on the circuit board101. The area of the principal surface of the circuit board and the number of layers of the circuit board may be increased by the amount corresponding to the formation of the wiring electrodes. In such a case, the reduction in size and the low profile of the module are hindered. In addition, when high-frequency waves are used for the module100, an increase in length of the wiring electrode may increase unnecessary impedance and a parasitic component, such as parasitic inductance and/or increase unnecessary radiant waves to cause a problem of deterioration in high-frequency characteristics of the module100.

In order to resolve the above problems, the present disclosure provides a compact module that is capable of achieving low profile and that is excellent in high-frequency characteristics.

The present disclosure provides a module including a first circuit board; a second circuit board arranged so as to face the first circuit board; and a functional component that includes a first electrode and a second electrode electrically connected to the first electrode on both opposing faces. The first electrode is connected to the first circuit board, and the second electrode is connected to the second circuit board.

Since the second electrode of the functional component, which is connected to the second circuit board, is electrically connected to the first electrode, it is not necessary to provide the columnar conductor to electrically connect the first electrode of the functional component to the second circuit board, unlike the module in related art. Accordingly, since it is not necessary to ensure the area in which the columnar conductor is mounted in each of the first circuit board and the second circuit board, the areas of the principal surfaces of the first circuit board and the second circuit board are capable of being decreased, thereby reducing the size of the module.

In the configuration in which the first circuit board is connected to the second circuit board with the columnar conductors, as in the module in the related art, since the lengths of the columnar conductors are required to be greater than the heights of the functional components from the first child board, it is difficult to achieve the low profile of the module. However, with the above configuration, the functional component includes the first electrode and the second electrode on both opposing faces, and the first circuit board is connected to the second circuit board by connecting the first electrode to the first circuit board and connecting the second electrode to the second circuit board. Accordingly, the distance between the first child board and the second circuit board is capable of being substantially equal to the height of the functional component from the first child board. Consequently, it is possible to achieve the low profile of the module.

For example, when each functional component is connected to the second circuit board with the columnar conductor, as in the module in the related art, it is necessary to provide the wiring electrode used to connect each functional component to the columnar conductor on the first circuit board, as described above. However, with the above configuration, since the first electrode is connected to the second circuit board via the second electrode electrically connected to the first electrode, it is not necessary to provide the wiring electrode to connect the first electrode to the columnar conductor on the first circuit board. Accordingly, since the area of the principal surface of the first child board or the number of layers of the first child board is decreased by the amount corresponding to the non-provision of the wiring electrode, it is possible to reduce the size of the module and to achieve the low profile of the module. Also when the second electrode is connected to the first circuit board, since the second electrode is connected to the first circuit board via the first electrode electrically connected to the second electrode without necessarily providing the wiring electrode on the second circuit board, it is possible to reduce the size of the module and to achieve the low profile of the module.

It is not necessary to provide the wiring electrode on the child board. Accordingly, for example, when high-frequency signals are used for the module, it is possible to prevent an increase in unnecessary impedance and an increase in a parasitic component, such as parasitic inductance, which are caused by the increase in length of the wiring electrode, and it is possible to prevent an increase in unnecessary radiant waves occurring from the wiring electrode. Accordingly, the module having excellent high-frequency characteristics is provided.

A board-side electrode may be formed on a face facing the second circuit board of the first circuit board, and the first electrode may be connected to the board-side electrode with solder. In this case, it is possible to connect the board-side electrode on the first circuit board to the first electrode of the functional component with the solder, which is commonly used as the material for connection of electrodes.

At least one of the board-side electrode, the first electrode, and the solder may contain Cu-M alloy (M indicates Mn or Ni). In this case, since high melting point Sn—Cu-M alloy (M indicates Mn or Ni) is formed in the connection portion between the board-side electrode and the first electrode, it is possible to prevent a position shift of the functional component and/or a solder (the solder to connect the board electrode to the electrode) drip, which is caused by the melting of the alloy forming the connection portion between the board-side electrode and the first electrode due to the heat generated in the subsequent connection of the second electrode of the functional component to the second circuit board with the solder.

An amount of M contained in the Cu-M alloy may be 5% by weight to 30% by weight. The high melting point of the Sn—Cu-M alloy (M indicates Mn or Ni) forming the connection portion between the board-side electrode on the first circuit board and the first electrode of the functional component is considered to be realized by an intermetallic compound formed between Sn and the Cu-M alloy. Accordingly, the inventor varied the amount of M contained in the Cu-M alloy by experiment and measured the remaining percentage of Sn, low melting point metal, which does not contribute to the formation of the intermetallic compound in the connection portion between the board-side electrode and the first electrode. The measurement indicated that the remaining percentage of Sn is reduced when the amount of M contained in the Cu-M alloy is 5% by weight to 30% by weight.

The first electrode of the functional component may be connected to the first circuit board at substantially the center. When the first circuit board is thermally contracted, the amount of contraction of the first child board at the center is smaller than that on the fringe. Specifically, the stress applied on the connection portion between the first electrode and the first circuit board when the first electrode of the functional component is connected to the center of the first circuit board is lower than that when the first electrode of the functional component is connected to the fringe of the first circuit board. Accordingly, the connection of the first electrode of the functional component to substantially the center of the first circuit board improves the reliability of the connection between the first circuit board and the functional component.

The module may include multiple functional components. Since the first electrode is connected to the first circuit board and the second electrode is connected to the second circuit board in each functional component, each functional component has the fixing function to fix one of the first circuit board and the second circuit board to the other thereof. Accordingly, fixing one of the first circuit board and the second circuit board to the other thereof using the multiple functional components improves the fixing function, compared with a case in which one of the first circuit board and the second circuit board is fixed to the other thereof using one functional component.

The second electrode of part of the functional components may be connected to a dummy electrode provided on the second circuit board. With this configuration, for example, even when there is the electronic component that is not required to be electrically connected to the second circuit board, among the electronic components, the connection of the second electrode of the functional component to the dummy electrode provided on the second circuit board allows the electronic component to contribute to the improvement of the fixing function of both of the circuit boards by the functional components.

The module may further include a first electronic component mounted on a face opposite to a connection face with the functional component of either one of the first circuit board and the second circuit board. Mounting the first electronic component also on a face opposite to the connection face with the functional component of one of the first circuit board and the second circuit board in this manner allows the components in the module to be mounted with a high density.

The module may further include a first sealing resin layer which is provided over a face on which the first electronic component is mounted of either one of the first circuit board and the second circuit board and with which the first electronic component is covered. With this configuration, it is possible to protect the first electronic component with the first sealing resin layer.

In addition, for example, when the first electrode of the functional component is connected to the connection face with the functional component of the first circuit board and the first circuit board-component assembly produced by mounting the first electronic component on the mounting face of the first circuit board is mounted on the second circuit board using a general component mounting apparatus, the mounting capability of the first circuit board-component assembly on the second circuit board is improved. Specifically, performing the suctioning (picking up) of the first circuit board-component assembly by the component mounting apparatus in the portion where the first sealing resin layer is formed, which is provided on the mounting face of the first circuit board, allows the first circuit board-component assembly to be mounted on the second circuit board without necessarily any damage of the first electronic component. In addition, since making the surface of the first sealing resin layer flat allows a larger suction face to be ensured when the first circuit board-component assembly is suctioned by the component mounting apparatus, the first circuit board-component assembly is easily mounted on the second circuit board.

The module may further include a second sealing resin layer with which the first electronic component and either one of the first circuit board and the second circuit board are covered and with which a connection face with the functional component of the other of the first circuit board and the second circuit board is covered. With this configuration, it is possible to protect one of the circuit boards, the functional component, and the first electronic component, which are arranged on the connection face with the functional component of the other of the first circuit board and the second circuit board, with the second sealing resin layer.

The module may further include a third sealing resin layer with which the first sealing resin layer is covered and with which a connection face with the functional component of the other of the first circuit board and the second circuit board is covered. With this configuration, it is possible to improve the mounting capability of the first circuit board-component assembly on the second circuit board with the first sealing resin layer, as described above, and it is possible to protect the first circuit board-component assembly and the functional component with the third sealing resin layer.

An area of either one of the first circuit board and the second circuit board viewed in plan (in a direction perpendicular to a largest surface of the first circuit board and the second circuit board) may be greater than an area of the other thereof. The module may further include a second electronic component mounted on an area that is on a connection face with the functional component of either one of the first circuit board and the second circuit board, which has an area greater than that of the other, and that is not overlapped with the other viewed in plan. A height of the second electronic component may be greater than a distance between the first circuit board and the second circuit board.

Mounting the second electronic component the height of which is greater than the distance between the first circuit board and the second circuit board on an area that is on the connection face with the functional component of either one of the first circuit board and the second circuit board, which has an area greater than that of the other, and that is not overlapped with the other viewed in plan in this manner allows the low profile of the module to be achieved, compared with a configuration in which the second electronic component is arranged between the first circuit board and the second circuit board, which are overlapped with each other viewed in plan.

The present disclosure provides a module component mounted on a mounting board. The module component includes a first circuit board arranged so as to face the mounting board in the mounting of the module component on the mounting board; and a functional component which includes a first electrode and a second electrode electrically connected to the first electrode on both opposing faces. The first electrode is connected to the first circuit board. The module component is mounted on the mounting board by connecting the second electrode of the functional component to the mounting board.

With this configuration, since provision of the columnar conductor to connect the first electrode of each functional component in the module component to the mounting board is not required, it is not necessary to ensure the area in which the columnar conductor is to be mounted on the first circuit board. Accordingly, the area of the principal surface of the first circuit board is reduced, thereby reducing the size of the mounting board.

In the configuration in which the columnar conductors for connection to the mounting board are provided in the mounting board, as in the related art, since the lengths of the columnar conductors are required to be greater than the heights of the functional components from the first child board, it is difficult to achieve the low profile of the module component. However, with the above configuration, since the module component is mounted on the mounting board without necessarily providing the columnar conductors by connecting the second electrode of each functional component to the mounting board, it is possible to achieve the low profile of the module component.

When the mounting board is connected to the first electrode of each functional component with the columnar conductor, as in the related art, it is necessary to provide the wiring electrode to connect the columnar conductor to the first electrode on the first circuit board. However, with the above configuration, since the first electrode is mounted on the mounting board via the second electrode electrically connected to the first electrode, it is not necessary to provide the wiring electrode to connect the first electrode to the columnar conductor on the first circuit board. Accordingly, since the area of the principal surface of the first child board or the number of layers of the first child board is decreased by the amount corresponding to the non-provision of the wiring electrode, it is possible to reduce the size of the module component and to achieve the low profile of the module component. In addition, for example, when the high-frequency waves are used for the module component, it is possible to prevent an increase in unnecessary impedance and an increase in a parasitic component, such as parasitic inductance, which are caused by the increase in length of the wiring electrode, and it is possible to prevent an increase in unnecessary radiant waves occurring from the wiring electrode. Accordingly, the module component having excellent high-frequency characteristics is provided.

A board-side electrode may be formed on a face facing the mounting board of the first circuit board, and the first electrode may be connected to the board-side electrode with solder. In this case, it is possible to connect the board-side electrode on the first circuit board to the first electrode of the functional component with the solder, which is commonly used as the material for connection of electrodes.

At least one of the board-side electrode, the first electrode, and the solder may contain Cu-M alloy (M indicates Mn or Ni). In this case, since the high melting point Sn—Cu-M alloy is formed in the connection portion between the board-side electrode and the first electrode, it is possible to prevent a position shift of the functional component and/or a solder (the solder to connect the board electrode to the electrode) drip, which is caused by the melting of the alloy forming the connection portion between the board-side electrode and the first electrode due to the heat generated in the subsequent connection of the second electrode of the functional component to the mounting board with the solder.

An amount of M contained in the Cu-M alloy may be 5% by weight to 30% by weight. As described above, the high melting point of the Sn—Cu-M alloy (M indicates Mn or Ni) forming the connection portion between the board-side electrode on the first circuit board and the first electrode of the functional component is considered to be realized by an intermetallic compound formed between Sn and the Cu-M alloy. Accordingly, the inventor varied the amount of M contained in the Cu-M alloy by experiment and measured the remaining percentage of Sn, low melting point metal, which does not contribute to the intermetallic compound in the connection portion between the board-side electrode and the first electrode. The measurement indicated that the remaining percentage of Sn is reduced when the amount of M contained in the Cu-M alloy is 5% by weight to 30% by weight.

The present disclosure provides a method of manufacturing a module. The method includes preparing a board-component assembly which includes a functional component having a first electrode and a second electrode electrically connected to the first electrode on both opposing faces and a first circuit board, the first electrode being connected to the first circuit board; mounting the board-component assembly on a second circuit board by arranging a connection face with the first electrode of the functional component of the first circuit board so as to face one principal surface of the second circuit board and connecting the second electrode of the functional component to the one principal surface of the second circuit board; and forming a resin layer so that the one principal surface of the second circuit board and the board-component assembly mounted on the one principal surface of the second circuit board are covered with the resin layer.

In this case, mounting the board-component assembly on the second circuit board by connecting the second electrode electrically connected to the first electrode of the functional component to the one principal surface of the second circuit board allows the module in which the first electrode of the functional component is connected to the second circuit board to be manufactured. Accordingly, it is possible to manufacture the compact module capable of achieving the low profile, compared with the configuration in the related art in which the first electrode of the functional component is connected to the second circuit board with the columnar conductor.

According to the present disclosure, the module includes a first circuit board; a second circuit board arranged so as to face the first circuit board; and a functional component that includes a first electrode and a second electrode electrically connected to the first electrode on both opposing faces. The first electrode is connected to the first circuit board, and the second electrode is connected to the second circuit board. Since the second electrode of the functional component connected to the second circuit board is electrically connected to the first electrode, it is not necessary to provide the columnar conductor in order to connect the first electrode of the functional component to the second circuit board, unlike the module in the related art. Accordingly, since it is not necessary to ensure the area in which the columnar conductor is mounted in each of the first circuit board and the second circuit board, the areas of the principal surfaces of the first circuit board and the second circuit board are capable of being decreased, thereby reducing the size of the module.

DESCRIPTION OF EMBODIMENTS

First Embodiment

A module1according to a first embodiment of the present disclosure will now be described with reference toFIG. 1.FIG. 1is a cross-sectional view of the module1according to the first embodiment.

The module1according to the present embodiment includes a parent board2, a first child board-component assembly3, a second child board-component assembly4, electronic components5aand5b, and a resin layer8, as illustrated inFIG. 1. The first child board-component assembly3, the second child board-component assembly4, and the electronic components5aand5bare mounted on one principal surface of the parent board2. For example, the module1is used as a power supply circuit module or a radio circuit module. The first child board-component assembly3and the second child board-component assembly4each correspond to a board-component assembly of the present disclosure.

The parent board2is made of, for example, resin, ceramics, glass, or the like. Multiple mounting electrodes6used to mount the first child board-component assembly3, the second child board-component assembly4, and both of the electronic components5aand5bare formed on the one principal surface of the parent board2and outer electrodes7used to connect the module1to the outside are formed on the other principal surface of the parent board2. Via conductors (not illustrated), wiring electrodes (not illustrated), and so on are also formed in the parent board2. The parent board2corresponds to a second circuit board of the present disclosure.

The first child board-component assembly3includes a first child board3aarranged so as to face the parent board2, multiple electronic components3bto3emounted on one principal surface of the first child board3a, and multiple electronic components3fto3kmounted on the other principal surface of the first child board3a. The electronic components3fto3kare arranged between the parent board2and the first child board3a. In the present embodiment, the area of the first child board3aviewed in plan is made smaller than that of the parent board2. The first child board3acorresponds to a first circuit board of the present disclosure and each of the electronic components3bto3emounted on the one principal surface of the first child board3acorresponds to a first electronic component of the present disclosure.

Each of the electronic components3bto3kis formed of any of chip components including an IC, a chip capacitor, and a chip inductor, which are made of Si, GaAs, or the like. For example, a bypass capacitor, a chip resistor, a 0-ohm resistor (jumper chip), a fuse, a varistor, a filter, a ferrite bead, or a common-mode choke coil may be used as the electronic component.

As illustrated inFIG. 1, the three electronic components3fto3h(each of the electronic components3fto3his a chip component, such as a chip capacitor or a chip inductor, in the present embodiment), among the electronic components3fto3karranged between the parent board2and the first child board3a, are connected to both the first child board3aand the parent board2. The electronic components3fto3hinclude first electrodes3f1to3h1and second electrodes3f2to3h2, respectively, on both opposing faces. The first electrodes3f1to3h1are connected to the first child board3aand the second electrodes3f2to3h2are connected to the parent board2.

Specifically, the electronic component3fhas the two first electrodes3f1formed on its face facing the first child board3a, the electronic component3ghas the two first electrodes3g1formed on its face facing the first child board3a, and the electronic component3hhas the two first electrodes3h1formed on its face facing the first child board3a. The electronic component3fhas the two second electrodes3f2formed on its face facing the parent board2, the electronic component3ghas the two second electrodes3g2formed on its face facing the parent board2, and the electronic component3hhas the two second electrodes3h2formed on its face facing the parent board2. The first electrodes3f1to3h1are directly connected to board-side electrodes31formed on a face facing the parent board2of the first child board3a(the other principal surface of the first child board3a) with solder. The second electrodes3f2to3h2are directly connected to the mounting electrodes6of the parent board2with solder. In order to facilitate the connection to the first child board3aand the parent board2in each of the electronic components3fto3h, the electronic components3fto3hmay have substantially the same height from the other principal surface of the first child board3a.

In the electronic component3f, each first electrode3f1is electrically connected to the corresponding second electrode3f2with a side-face electrode3f3. In the electronic component3g, each first electrode3g1is electrically connected to the corresponding second electrode3g2with a side-face electrode3g3. In the electronic component3h, each first electrode3h1is electrically connected to the corresponding second electrode3h2with a side-face electrode3h3. The first electrodes3f1to3h1are not limitedly connected to the second electrodes3f2to3h2with the side-face electrodes3f3to3h3, respectively. The first electrodes3f1to3h1may be connected to the second electrodes3f2to3h2, respectively, with columnar conductors, such as via conductors or post electrodes, wiring electrodes, or the likes provided in the electronic components3fto3h.

Each of the electronic components3fto3hconnected to both the parent board2and the first child board3acorresponds to a functional component of the present disclosure. The functional component is a component functioning as a capacitor, an inductor, a drive circuit, or the like in the module1and is not a component used only for conduction, such as a columnar conductor that connects layers to each other. For example, when the module1is used as a power management module and a bypass capacitor is used as the functional component arranged between the circuit and the ground, the efficiency and load regulation characteristics are improved. A 0-ohm resistor (jumper chip) may be used as the functional component arranged on the circuit. Arrangement of a fuse varistor allows overcurrent to be prevented. When the module1is used as a radio circuit module, use of a filter, a ferrite bead, a common-mode choke coil, or the like as the functional component allows noise to be reduced to improve high-frequency characteristics.

As described above, the connection of the first electrodes3f1to3h1in the electronic components3fto3h, respectively, to the first child board3aand the connection of the second electrodes3f2to3h2in the electronic components3fto3h, respectively, to the parent board2fix the first child board-component assembly3(the first child board3a) to the parent board2. In addition, since the first electrodes3f1to3h1are electrically connected to the second electrodes3f2to3h2with the side-face electrodes3f3to3h3, respectively, it is possible to electrically connect the first child board3ato the parent board2without necessarily providing the columnar conductors, unlike the module in the related art.

The second child board-component assembly4has substantially the same configuration as that of the first child board-component assembly3described above. The second child board-component assembly4includes a second child board4aarranged so as to face the parent board2, multiple electronic components4band4cmounted on one principal surface of the second child board4a, and multiple electronic components4dto4fmounted on the other principal surface of the second child board4a. The electronic components4dto4fare arranged between the parent board2and the second child board4a. In the present embodiment, the area of the second child board4aviewed in plan is made smaller than that of the parent board2. The second child board4aalso corresponds to the first circuit board of the present disclosure and each of the electronic components4band4cmounted on the one principal surface of the second child board4aalso corresponds to the first electronic component of the present disclosure.

Each of the electronic components4bto4fis formed of any of chip components including an IC, a chip capacitor, and a chip inductor, which are made of Si, GaAs, or the like, like the electronic components3bto3kin the first child board-component assembly3. For example, a bypass capacitor, a chip resistor, a 0-ohm resistor (jumper chip), a fuse, a varistor, a filter, a ferrite bead, or a common-mode choke coil may be used as each of the electronic components4bto4f.

As illustrated inFIG. 1, the two electronic components4dand4e(each of the electronic components4dand4eis a chip component, such as a chip capacitor or a chip inductor, in the present embodiment), among the electronic components4dto4farranged between the parent board2and the second child board4a, are connected to both the second child board4aand the parent board2, as in the first child board-component assembly3. The electronic component4dhas two first electrodes4d1formed on its face facing the second child board4aand the electronic component4ehas two first electrodes4e1formed on its face facing the second child board4a. The electronic component4dhas two second electrodes4d2formed on its face facing the parent board2and the electronic component4ehas two second electrodes4e2formed on its face facing the parent board2. The first electrodes4d1and4e1are directly connected to the board-side electrodes31formed on a face facing the parent board2of the second child board4a(the other principal surface of the second child board4a) with solder. The second electrodes4d2and4e2are directly connected to the parent board2with solder.

In the electronic component4d, each first electrode4d1is electrically connected to the corresponding second electrode4d2with a side-face electrode4d3. In the electronic component4e, each first electrode4e1is electrically connected to the corresponding second electrode4e2with a side-face electrode4e3. The first electrodes4d1and4e1are not limitedly connected to the second electrodes4d2and4e2with the side-face electrodes4d3and4e3, respectively. The first electrodes4d1and4e1may be connected to the second electrodes4d2and4e2, respectively, with columnar conductors, such as via conductors or post electrodes, wiring electrodes, or the likes provided in the electronic components4dand4e. Each of the electronic components4dand4econnected to both the parent board2and the second child board4aalso corresponds to the functional component of the present disclosure.

As described above, the connection of the first electrodes4d1and4e1in the electronic components4dand4e, respectively, to the second child board4aand the connection of the second electrodes4d2and4e2in the electronic components4dand4e, respectively, to the parent board2fix the second child board-component assembly4(the second child board4a) to the parent board2. In addition, since the first electrodes4d1and4e1are electrically connected to the second electrodes4d2and4e2with the side-face electrodes4d3and4e3, respectively, it is possible to electrically connect the second child board4ato the parent board2without necessarily providing the columnar conductors, unlike the module in the related art.

Each of the electronic components5aand5bmounted on the one principal surface of the parent board2is formed of any of chip components including an IC, a chip capacitor, and a chip inductor, which are made of Si, GaAs, or the like, as in the electronic components3bto3kin the first child board-component assembly3and the electronic components4bto4fin the second child board-component assembly4. In addition, as illustrated inFIG. 1, the electronic components5aand5bare mounted in areas that are not overlapped with the first and second child boards3aand3bwhen the one principal surface of the parent board2is viewed in plan. Here, a height h of the electronic component5afrom the one principal surface of the parent board2is made greater than, for example, a distance H between the first child board3aand the parent board2. The electronic component5acorresponds to a second electronic component of the present disclosure.

The resin layer8is made of, for example, epoxy resin. The first child board-component assembly3, the second child board-component assembly4, the electronic components5aand5b, and the one principal surface of the parent board2, which is a connection face with the functional components (the electronic components3fto3h,4d, and4e), are covered with the resin layer8. The resin layer8corresponds to a second sealing resin layer of the present disclosure.

(Method of Manufacturing Module1)

A method of manufacturing the module1will now be described with reference toFIGS. 2A-2C.FIGS. 2A-2Cinclude diagrams for describing the method of manufacturing the module1.FIG. 2AtoFIG. 2Cillustrate steps.

First, as illustrated inFIG. 2A, the first child board-component assembly3, the second child board-component assembly4, the two electronic components5aand5b, and the parent board2are prepared. The first child board-component assembly3is produced by mounting the electronic components3bto3kon both principal surfaces of the first child board3ausing a surface mount technology. The second child board-component assembly4is produced by mounting the electronic components4bto4fon both principal surfaces of the second child board4ausing a surface mount technology. The parent board2has the multiple mounting electrodes6formed on one principal surface thereof and has the multiple outer electrodes7for connection to the outside, which are formed on the other principal surface thereof. Solder paste9is applied in advance on each of the mounting electrodes6formed on the one principal surface of the parent board2using a print technology or the like.

Next, as illustrated inFIG. 2B, the first child board-component assembly3, the second child board-component assembly4, and the electronic components5aand5bare mounted at certain positions on the one principal surface of the parent board2using a component mounting apparatus. Then, the parent board2having the first child board-component assembly3, the second child board-component assembly4, and the electronic components5aand5bmounted thereon is put into a reflow oven or the like to mount the first child board-component assembly3, the second child board-component assembly4, and the electronic components5aand5bon the parent board2.

Finally, as illustrated inFIG. 2C, the resin layer8is formed so that the first child board-component assembly3, the second child board-component assembly4, the electronic components5aand5b, and the one principal surface of the parent board2, which is the connection face with the electronic components3fto3h,4d, and4e, are covered with the resin layer8to manufacture the module1. Here, the resin layer8may be formed with various methods including a compression molding method, a transfer molding method, and a print method. As described above, mounting the first and second child board-component assemblies3and4on the parent board2connects the first electrodes3f1to3h1,4d1, and4e1of the electronic components3fto3h,4d, and4ein both of the child board-component assemblies3and4to the parent board2. Accordingly, compared with the configuration of the module in the related art in which the first electrodes3f1to3h1,4d1, and4e1are connected to the parent board2with the columnar conductors, it is possible to manufacture the compact module1capable of achieving the low profile.

Accordingly, according to the above embodiment, since the first electrodes3f1to3h1of the electronic components3fto3h(the functional components), which are connected to the first child board3a, are electrically connected to the second electrodes3f2to3h2connected to the parent board2with the side-face electrodes3f3to3h3in the first child board-component assembly3, it is not necessary to provide the columnar conductors in the module in the related art, for example, in order to electrically connect the first electrodes3f1to3h1of the electronic components3fto3hto the parent board2. Consequently, since it is not necessary to ensure the areas in which the columnar conductors are mounted in the first child board3aand the parent board2, the areas of the principal surfaces of the first child board3aand the parent board2are capable of being decreased, thereby reducing the size of the module1. Since the second child board-component assembly4has substantially the same configuration as that of the first child board-component assembly3, the same advantages are achieved.

In the configuration in which the first child board3a(or the second child board4a) is connected to the parent board2with the columnar conductors, as in the module in the related art, since the lengths of the columnar conductors are required to be greater than the heights of the electronic components3fto3k(or the electronic components4dto4f), arranged between the first child board3a(or the second child board4a) and the parent board2, from the first child board3a(or the second child board4a), it is difficult to achieve the low profile of the module1. However, according to the above embodiment, it is not necessary to provide the columnar conductors, the distance between the first child board3a(or the second child board4a) and the parent board2is capable of being substantially equal to the height of the electronic components3fto3k(or the electronic components4dand4e) from the first child board3a(or the second child board4a) (the height of the tallest electronic component). Accordingly, it is possible to achieve the low profile of the module1.

For example, when the first electrode3f1of the electronic component3f(the functional component) in the first child board-component assembly3is connected to the parent board2with the columnar conductor, as in the module in the related art, it is necessary to provide the wiring electrode used to connect the first electrode3f1to the columnar conductor on the first child board3a. In such a case, the area of the principal surface of the first child board3aor the number of layers of the first child board3amay require to be increased. In contrast, it is not necessary to provide the wiring electrode used to connect the first electrode3f1to the columnar conductor on the first child board3ain the above embodiment because the first electrode3f1is electrically connected to the second electrode3f2connected to the parent board2via the side-face electrode3f3. Accordingly, since the area of the principal surface of the first child board3aor the number of layers of the first child board3ais decreased by the amount corresponding to the non-provision of the wiring electrodes, it is possible to reduce the size of the module1and to achieve the low profile of the module1.

Since it is not necessary to provide the wiring electrodes on the parent board2also when the second electrode3f2is to be connected to the first child board3a, it is possible to decrease the area of the principal surface of the parent board2and the number of layers of the parent board2, thereby reducing the size of the module1and achieving the low profile of the module1. Since the second child board-component assembly4has substantially the same configuration as that of the first child board-component assembly3, the same advantages are achieved.

It is not necessary to provide the wiring electrodes on the first child board3a(or the second child board4a). Accordingly, for example, when the high-frequency waves are used for the module1, it is possible to prevent an increase in unnecessary impedance and an increase in a parasitic component, such as parasitic inductance, which are caused by the increase in length of the wiring electrodes, and it is possible to prevent an increase in unnecessary radiant waves occurring from the wiring electrodes. Accordingly, the module1having excellent high-frequency characteristics is provided.

In the first child board-component assembly3, since the first electrodes3f1to3hof the electronic components3fto3h(the functional components) are connected to the first child board3aand the second electrodes3f2to3h2of the electronic components3fto3h(the functional components) are connected to the parent board2, each of the electronic components3fto3hhas the fixing function to fix the first child board3ato the parent board2. Since the fixing function is achieved by the multiple (three in the above embodiment) electronic components3fto3h(the functional components) in the above embodiment, the fixing function is improved, compared with a case in which the fixing function is achieved by one electronic component (the functional component). Since the second child board-component assembly4has substantially the same configuration as that of the first child board-component assembly3, the same advantages are achieved.

In addition to the mounting of the electronic components3fto3k(or the electronic components4dand4e) on the other principal surface of the first child board3a(or the second child board4a), the electronic components3bto3e(or the electronic components4band4c) are mounted also on the one principal surface of the first child board3a(or the second child board4a). Accordingly, it is possible to mount the electronic components3bto3kand4bto4fin the module1with a high density. Since the configuration is adopted in which the first child board-component assembly3having the multiple electronic components3bto3kmounted therein and the second child board-component assembly4having the multiple electronic components4bto4fmounted therein are mounted on the parent board2, it is possible to mount the electronic components3bto3kand4bto4fin the module1with a high density, thereby reducing the size of the module1.

Since the resin layer8with which the first child board-component assembly3, the second child board-component assembly4, the electronic components5aand5b, and the one principal surface of the parent board2are covered is formed in the module1, it is possible to protect the first child board-component assembly3, the second child board-component assembly4, the electronic components5aand5b, and the one principal surface of the parent board2.

Mounting the electronic component5athe height of which from the one principal surface of the parent board2is greater than the distance between the first child board3aand the parent board2in an area that is not overlapped with the first child board3aand the second child board4awhen the one principal surface of the parent board2is viewed in plan allows the low profile of the module1to be achieved, compared with a configuration in which the electronic component5ais mounted on either of both of the principal surfaces of the first child board3a.

Second Embodiment

A module1aaccording to a second embodiment of the present disclosure will now be described with reference toFIG. 3.FIG. 3includes diagrams for describing a method of manufacturing the module1a.FIG. 3(a)toFIG. 3(c)illustrate steps.

The module1aof the present disclosure differs from the module1of the first embodiment described above with reference toFIG. 1in that the module1ais further provided with a resin layer8aand a resin layer8a, as illustrated inFIG. 3. The one principal surface of the first child board3ain the first child board-component assembly3(the face on which the electronic components3bto3eare mounted) and the electronic components3bto3emounted on the one principal surface are covered with the resin layer8a. The one principal surface of the second child board4ain the second child board-component assembly4(the face on which the electronic components4band4care mounted) and the electronic components4band4cmounted on the principal surface are covered with the resin layer8b. Since the remaining configuration is the same as that of the module1of the first embodiment, a description of the remaining configuration of the module1ais omitted herein with the same reference numerals used.

(Method of Manufacturing Module1a)

The first child board-component assembly3, the second child board-component assembly4, the electronic components5aand5b, and the parent board2are prepared in the same manner as in the method of manufacturing the module1of the first embodiment described above with reference toFIG. 2A. Here, the resin layer8ais formed so that the one principal surface of the first child board3aand the electronic components3bto3emounted on the one principal surface are covered with the resin layer8ain the first child board-component assembly3(refer toFIG. 3A). The resin layer8bis formed so that the one principal surface of the second child board4aand the electronic components4band4cmounted on the one principal surface are covered with the resin layer8balso in the second child board-component assembly4(refer toFIG. 3A). The resin layers8aand8bmay be formed with various methods including a compression molding method, a transfer molding method, and a print method.

Next, as illustrated inFIG. 3B, the first child board-component assembly3having the resin layer8aformed thereon, the second child board-component assembly4having the resin layer8bformed thereon, and the electronic components5aand5bare mounted at certain positions on the one principal surface of the parent board2using a general component mounting apparatus. Then, the parent board2having the first child board-component assembly3, the second child board-component assembly4, and the electronic components5aand5bmounted thereon is put into a reflow oven or the like to mount the first child board-component assembly3, the second child board-component assembly4, and the electronic components5aand5bon the parent board2. In order to facilitate the mounting (for example, suction of the components) with the component mounting apparatus, the surfaces of the resin layer8aformed in the first child board-component assembly3and the resin layer8bformed in the second child board-component assembly4may be made flat. Each of the resin layer8aand the resin layer8bcorresponds to a first sealing resin layer of the present disclosure.

Finally, as illustrated inFIG. 3C, a resin layer8ccorresponding to a third sealing resin layer of the present disclosure) is formed so that the first child board-component assembly3including the resin layer8a, the second child board-component assembly4including the resin layer8b, and the one principal surface of the parent board2(the connection face with the electronic components3fto3kand the electronic components4dto40are covered with the resin layer8cto manufacture the module1a. The resin layer8cmay also be formed with various methods including a compression molding method, a transfer molding method, and a print method. The module1amay have a configuration in which the resin layer8cis not formed. The resin layer8cmay be made of the same resin as that of the resin layers8aand8bor may be made of resin different from that of the resin layers8aand8b.

Accordingly, according to the present embodiment, since the resin layer8ais formed on the one principal surface of the first child board3ain the first child board-component assembly3and the resin layer8bis formed on the one principal surface of the second child board4ain the second child board-component assembly4, the electronic components3bto3emounted on the one principal surface of the first child board3aand the electronic components4band4cmounted on the one principal surface of the second child board4aare protected with the resin layers8aand8b. Specifically, for example, in the mounting of the first child board-component assembly3and the second child board-component assembly4on the parent board2, suctioning (picking up) the resin layer8aand the resin layer8bwith a suction portion of the component mounting apparatus prevents the electronic components3bto3emounted on the one principal surface of the first child board3aand the electronic components4band4cmounted on the one principal surface of the second child board4afrom being damaged in the mounting.

Since making the surfaces of the resin layers8aand8bflat ensures large suction areas when the first child board-component assembly3and the second child board-component assembly4are suctioned with the suction portion of the component mounting apparatus, the suction of the first child board-component assembly3and the second child board-component assembly4with the component mounting apparatus is facilitated to improve the mounting capability of both of the assemblies3and4on the parent board2.

Since the first child board-component assembly3, the second child board-component assembly4, and the electronic components5aand5bare further covered with the resin layer8c, it is possible to protect the components mounted on the one principal surface of the parent board2(the first child board-component assembly3, the second child board-component assembly4, and the electronic components5aand5b) while improving the mounting capability of the first child board-component assembly3and the second child board-component assembly4on the parent board2.

Third Embodiment

A module1baccording to a third embodiment of the present disclosure will now be described with reference toFIG. 4.FIG. 4is a cross-sectional view of the module1b.

The module1baccording to the present embodiment differs from the module1of the first embodiment described above with reference toFIG. 1in that multiple electronic components10ato10dare mounted also on the other principal surface of the parent board2, as illustrated inFIG. 4. Since the remaining configuration is the same as that of the module1of the first embodiment, a description of the remaining configuration of the module1bis omitted herein with the same reference numerals used.

In this case, the electronic components10ato10dare mounted on the other principal surface opposite to the one principal surface of the parent board2, on which the first child board-component assembly3, the second child board-component assembly4, and so on are mounted, using a surface mount technology and multiple columnar conductors11for connection to the outside are provided. In addition, a resin layer8dwith which the electronic components10ato10dand the columnar conductors11are covered is also provided on the other principal surface of the parent board2. Each of the columnar conductors11may be, for example, a via conductor, a post electrode, or a pin conductor.

According to the present embodiment, since the electronic components10ato10dare mounted also on the other principal surface of the parent board2, it is possible to mount the components in the module1bwith a high density.

Fourth Embodiment

A module1caccording to a fourth embodiment of the present disclosure will now be described with reference toFIG. 5.FIG. 5is a partial cross-sectional view of the module1cand illustrates a portion where the first child board-component assembly3in the module1cis arranged.

The module1caccording to the present embodiment differs from the module1of the first embodiment described above with reference toFIG. 1in that the electronic component3k, which is not connected to the parent board2in the module1of the first embodiment, among the electronic components3fto3karranged between the first child board3ain the first child board-component assembly3and the parent board2, is also connected to the parent board2, as illustrated inFIG. 5. Since the remaining configuration is the same as that of the module1of the first embodiment, a description of the remaining configuration of the module1cis omitted herein with the same reference numerals used.

In this case, as illustrated inFIG. 5, the electronic component3kincludes two first electrodes3k1on a face facing the first child board3aand two second electrodes3k2on a face facing the parent board2. Both of the first electrodes3k1are connected to the other principal surface of the first child board3aand both of the second electrodes3k2are connected to dummy electrodes6athat are provided on the one principal surface of the parent board2and that are not connected to any electrode or the like in the parent board2.

As described above, for example, when there is the electronic component3kthat is not required to be connected to the parent board2, among the electronic components3fto3kmounted on the other principal surface of the first child board3a, the provision of the dummy electrodes6aon the one principal surface of the parent board2and the connection of both of the second electrodes3k2of the electronic component3kto the dummy electrodes6aallow the electronic component3kto contribute to the improvement of the fixing function to fix the first child board3ato the parent board2. The present embodiment is also applicable to the second child board-component assembly4.

Fifth Embodiment

A module1daccording to a fifth embodiment of the present disclosure will now be described with reference toFIG. 6.FIG. 6is a partial cross-sectional view of the module1dand illustrates a portion where the first child board-component assembly3in the module1dis arranged.

The module1daccording to the present embodiment differs from the module1of the first embodiment described above with reference toFIG. 1in that first electrodes3p1and3q1in electronic components3pand3q, respectively, connected to both the first child board3ain the first child board-component assembly3and the parent board2are connected to the other principal surface of the first child board3aat substantially the center, as illustrated inFIG. 6. Since the remaining configuration is the same as that of the module1of the first embodiment, a description of the remaining configuration of the module1dis omitted herein with the same reference numerals used.

In this case, multiple electronic components3m,3n, and3pto3rare mounted on the other principal surface of the first child board3ain the first child board-component assembly3. The first electrodes3p1and3q1in the two electronic components3pand3q, respectively, arranged at substantially the center of the other principal surface of the first child board3a, among the electronic components3m,3n, and3pto3r, are connected to the first child board3aand second electrodes3p2and3q2are connected to the parent board2(the mounting electrodes6).

When the first child board3ais thermally contracted, the amount of contraction of the first child board3aat the center is smaller than that on the fringe. As a result, the stress applied on the connection portions between the first electrodes3p1and3q1and the first child board3awhen the first electrodes3p1and3q1in the electronic components3pand3q, respectively, are connected to the center of the first child board3ais lower than that when the first electrodes3p1and3q1in the electronic components3pand3q, respectively, are connected to the fringe of the first child board3a. Accordingly, the connection of the first electrodes3p1and3q1in the electronic components3pand3q, respectively, to substantially the center of the other principal surface of the first child board3aimproves the reliability of the connection between the first child board3aand the electronic components3pand3q.

Sixth Embodiment

A module1eaccording to a sixth embodiment of the present disclosure will now be described with reference toFIGS. 7A-7C.FIGS. 7A-7Cinclude diagrams for describing a method of manufacturing the module1e.FIG. 7AtoFIG. 7Cillustrate steps in the manufacturing method.

The module1eof the present embodiment differs from the module1of the first embodiment described above with reference toFIG. 1in a step of preparing a module component30corresponding to the first child board-component assembly3in the module1of the first embodiment in the method of manufacturing the module1e. Since the remaining configuration is the same as that of the module1of the first embodiment, a description of the remaining configuration of the module1eis omitted herein with the same reference numerals used. The method of manufacturing the module1ewill now be described.

First, as illustrated inFIG. 7A, the module component30, the electronic component5a, and a parent board20(corresponding to a mounting board of the present disclosure) are prepared. The module component30is produced by mounting the electronic components3bto3kon both principal surfaces of a first child board30ausing a surface mount technology. The parent board20has the multiple mounting electrodes6formed on one principal surface thereof and has the multiple outer electrodes7for connection to the outside, which are formed on the other principal surface thereof. The solder paste9is applied in advance on each of the mounting electrodes6formed on the one principal surface of the parent board20using a print technology or the like.

The preparation of the module component30to be mounted on the parent board20will be specifically described. In the mounting of the module component30on the parent board20, the multiple electronic components3bto3eare mounted on one principal surface of the first child board30aarranged so as to face the parent board20with solder and the multiple electronic components3fto3kare mounted on the other principal surface of the first child board30a(the face facing the parent board20) with solder.

Here, in each of the electronic components3fto3kmounted at the other principal surface side of the first child board30a, the electrodes involved in the connection and the solder (the solder paste) are made of any of combinations of materials illustrated inFIG. 8.FIG. 8is a table illustrating the combinations of the materials of component-side electrodes, the board-side electrodes31, and the solder paste. The first electrodes3f1to3h1of the electronic components3fto3h, respectively, at the other principal surface side of the first child board30a, which are connected to both the first child board30aand the parent board20, and electrodes for mounting the remaining electronic components3ito3kat the other principal surface side of the first child board30aon the first child board are collectively referred to as the component-side electrodes. Referring toFIG. 8, in a row of the board-side electrodes31, Cu-M indicates a plate electrode containing Cu—Mn alloy or Cu—Ni alloy and Ni/Au indicates a plate electrode in which Au layers are laminated on a Ni layer. In a row of the solder paste, Sn system indicates solder paste containing Sn and Cu—Mn indicates solder paste containing Cu—Mn alloy or Cu—Ni alloy. In a row of the component-side electrodes, Sn system indicates a plate electrode containing Sn and Cu-M indicates a plate electrode containing Cu—Mn alloy or Cu—Ni alloy.

In this case, in all the combinations of (i) to (vii) illustrated inFIG. 8, at least one of the component-side electrodes, the board-side electrodes31, and the solder paste contains the Cu-M alloy (M indicates Mn or Ni). With such combinations, after the electronic components3fto3kare mounted on the first child board30a, high melting point metal (Sn—Cu-M alloy) produced from an intermetallic compound formed between the Cu-M alloy and Sn is formed in connection portions between the electronic components3fto3kand the first child board30a.

The high melting point of the Sn—Cu-M alloy (M indicates Mn or Ni) is realized by the intermetallic compound formed between Sn and the Cu-M alloy. More stable high melting point alloy is considered to be produced with the increasing amount of the generated intermetallic compound. The amount of the generated intermetallic compound in the connection portions is considered to be increased with the decreasing remaining amount of the Sn component contained in the connection portions after the board-side electrodes31are connected to the component-side electrodes with the solder. Accordingly, the inventor prepared multiple samples (nine pieces of data inFIG. 9) in which the amount of M contained in the Cu-M alloy is varied by experiment and measured the remaining percentage of low melting point Sn that does not contribute to the formation of the intermetallic compound in the connection portions between the board-side electrodes31and the first electrodes3f1to3h1(the volume % of the remaining Sn in the connection portions).

The measurement indicated that the remaining Sn component is decreased to some extent when the amount of M contained in the Cu-M alloy is 5% by weight to 30% by weight and the remaining Sn component is further decreased when the amount of M contained in the Cu-M alloy is 10% by weight to 15% by weight, as illustrated inFIG. 9. Accordingly, in order to produce the high melting point alloy in the connection portions between the component-side electrodes and the board-side electrodes31, the amount of M contained in the Cu-M alloy may be 5% by weight to 30% by weight or 10% by weight to 15% by weight in the connection portions. The result of the measurement illustrated inFIG. 9was given by differential scanning calorimetry (DSC measurement). Specifically, boundary portions between the component-side electrodes and the board-side electrodes31were cut out in each sample and the remaining amount of Sn component was quantified from the amount of heat absorption at a melting-absorption peak of the melting temperature of Sn in a DSC chart created in the DSC measurement. Then, the percentage of the Sn component to the entire metallic component was calculated from the amount of Sn component as the “remaining percentage of the low melting point metal.”

Next, as illustrated inFIG. 7B, the module component30and the electronic component5a, which are prepared, are mounted at certain positions on the one principal surface of the parent board20using a general component mounting apparatus. Then, the parent board20having the module component30and the electronic component5amounted thereon is put into a reflow oven or the like to mount the module component30and the electronic component5aon the one principal surface of the parent board20. Here, the second electrodes3f2to3h2in the electronic components3fto3h, respectively, mounted on the other principal surface of the first child board30ain the module component30are connected to the corresponding mounting electrodes6on the parent board20using the solder that does not contain the Cu-M alloy (M indicates Mn or Ni) to mount the module component30on the parent board20. An upper face of the electronic component3d(IC) mounted on the one principal surface of the first child board30ais used for the pickup of the module component30by the component mounting apparatus.

As described above, since the high melting point Sn—Cu-M alloy is formed in the connection portion with the first child board30ain each of the electronic components3fto3kmounted on the other principal surface of the first child board30ain the module component30, the Sn—Cu-M alloy does not melt in the connection portion of each of the electronic components3fto3kin the reflow oven the temperature profile of which is set for the solder that does not contain the Cu-M alloy in the mounting of the module component30on the parent board20. Accordingly, in the present embodiment, the module component30is configured so that position shifts of the electronic components3fto3kand/or solder drips, which are caused by the melting of the alloy forming the connection portions of the electronic components3fto3k, are prevented even when the module component30is placed at a certain temperature (a temperature at which the solder that does not contain the Cu-M alloy melts) in the reflow oven.

Finally, as illustrated inFIG. 7C, the resin layer8is formed so that the module component30, the electronic component5a, and the one principal surface of the parent board20are covered with the resin layer8to manufacture the module1e. Here, the resin layer8may be formed with various methods including a compression molding method, a transfer molding method, and a print method.

The configuration in which any one of the component-side electrodes, the board-side electrodes31, and the solder paste contains the Cu-M alloy and the configuration involved in the amount of M contained in the Cu-M alloy (weight percent) are also applicable to the other embodiments described above.

Accordingly, according to the present embodiment, since the module component30is mounted on the parent board20by connecting the second electrodes3f2to3h2of the electronic components3fto3h, respectively, in the module component30to the parent board20, it is not necessary to provide the columnar conductors used to connect the first electrodes3f1to3h1of the electronic components3fto3h, respectively, in the module component30to the parent board20. Consequently, it is not necessary to ensure the areas in which the columnar conductors are mounted on the first child board30ain the module component30. As a result, the area of the principal surface of the first child board30ais capable of being decreased, thereby reducing the size of the module component30.

Since the configuration is adopted in which the board-side electrodes31are formed on the face facing the parent board20of the first child board30aand the first electrodes3f1to3h1of the functional components (the electronic components3fto3h, respectively) are connected to the board-side electrodes31with solder, it is possible to connect the board-side electrodes31on the first child board30ato the first electrodes3f1to3h1of the functional components with the solder, which is commonly used as the material for connection of the electrodes.

In the configuration in the related art in which the columnar conductors for the connection to the parent board20are provided in the module component30, since the lengths of the columnar conductors are required to be greater than the heights of the electronic components3fto3k, mounted on the other principal surface of the first child board30a, from the first child board30a, it is difficult to achieve the low profile of the module component30. However, with the above configuration, it is possible to mount the module component30on the parent board20without necessarily providing the columnar conductors by connecting the second electrodes3f2to3h2of the electronic components3fto3h, respectively, to the parent board20. Accordingly, it is possible to achieve the low profile of the module component30.

When the parent board20is connected to the first electrodes3f1to3h1of the electronic components3fto3h, respectively, via the columnar conductors, as in the related art, it is necessary to provide the wiring electrodes used to connect the columnar conductors to the first electrodes3f1to3h1on the first child board30a. However, with the above configuration, it is not necessary to provide the wiring electrodes used to connect the first electrodes3f1to3h1to the columnar conductors on the first child board30abecause the first electrodes3f1to3h1are mounted on the parent board20via the second electrodes3f2to3h2electrically connected to the first electrodes3f1to3h1. Accordingly, since the area of the principal surface of the first child board30aor the number of layers of the first child board30ais decreased by the amount corresponding to the non-provision of the wiring electrodes, it is possible to reduce the size of the module component30and to achieve the low profile of the module component30. In addition, for example, when high-frequency signals are used for the module component30, it is possible to prevent an increase in unnecessary impedance and an increase in a parasitic component, such as parasitic inductance, which are caused by the increase in length of the wiring electrodes, and it is possible to prevent an increase in unnecessary radiant waves occurring from the wiring electrodes. Accordingly, the module component30having excellent high-frequency characteristics is provided.

The present disclosure is not limited to these above embodiments and many changes and modified embodiments may be made without necessarily departing from the true spirit and scope of the disclosure.

For example, although the case has been described in the above embodiments in which the electronic components3fto3h,3p,3q,4d, and4econnected to both the first child board3aor30a(or the second child board4a) and the parent board2or20are chip components, such as chip capacitors, the electronic components3fto3h,3p,3q,4d, and4econnected to both the first child board3aor30a(or the second child board4a) and the parent board2or20may be ICs. In this case, a first electrode may be formed on a face of each IC, which faces the first child board3aor30a(or the second child board4a), a second electrode may be formed on a face of each IC, which faces the parent board2, and the first electrode may be electrically connected to the second electrode in the IC.

In addition, a configuration may be adopted in which all of the electronic components3fto3k,3m,3n,3pto3r, and4dto4farranged between the first child board3aor30a(or the second child board4a) and the parent board2or20are connected to both the first child board3aor30a(or the second child board4a) and the parent board2or20. In this case, for example, in the electronic components that are not required to be connected to the parent board2or20, among the electronic components3fto3k,3m,3n,3pto3r, and4dto4f, the second electrodes may be connected to the dummy electrodes6aprovided on the parent board2or20, as in the module1cof the fourth embodiment. This further improves the fixing function to fix the first child board3aor30a(or the second child board4a) to the parent board2or20by the electronic components3fto3k,3m,3n,3pto3r, and4dto4f.

INDUSTRIAL APPLICABILITY

The present disclosure is applicable to various modules each having electronic components arranged between two boards.

REFERENCE SIGNS LIST