Electronic circuit module

There is provided an electronic circuit module that prevents a bonding force between ground wiring and a shield from decreasing and maintains successfully a desirable shield effect. The electronic circuit module includes a core layer also functioning as the ground wiring, each face OS of each first protrusion of the core layer facing to an end face of a shield is adjacent to faces OS of an outer cover made of an insulating synthetic resin facing to the end face of the shield, and the end face of the shield is bonded to both of the each face OS of each first protrusion facing to the end face of the shield and the faces OS of the outer cover facing to the end face of the shield.

CROSS-REFERENCE TO A RELATED APPLICATION

This application claims priority under 35 U.S.C. §119 to Japanese Patent Application No. JP 2012-245166 filed on Nov. 7, 2012, the entire content of which is hereby incorporated herein by reference in its entirety.

FIELD

The present disclosure relates to an electronic circuit module including a sealing portion covering a mount component mounted on a substrate with built-in component, and a shield covering the sealing portion.

BACKGROUND

This kind of an electronic circuit module includes a substrate with built-in component, mount components mounted on the substrate with built-in component, a sealing portion covering the mount components, and a shield covering the sealing portion as shown inFIG. 3in Japanese Patent Application Laid-open No. 2009-004584. In the electronic circuit module, predetermined electronic circuits including built-in components and mount components are three-dimensionally constructed. The shield is connected to ground wiring of the substrate with built-in component, and prevents noises from outside.

In general, the shield in the above-described electronic circuit module is formed of a metal. If the shield is formed of a conductive synthetic resin, the following defects may be induced. In other words, a bonding force between the metal and the synthetic resin tends to be lower than that between the metals or the synthetic resins. If the shield is formed of the conductive synthetic resin, the bonding force between the shield and the ground wiring made of a metal is decreased over time, which induces a local peeling at a boundary. As a result, a conduction property between the shield and the ground wiring is decreased and a desirable shield effect is not easily obtainable.

SUMMARY

In view of the above-described circumstances, it is desirable to provide an electronic circuit module that prevents a bonding force between ground wiring and a shield from decreasing to avoid a decrease in conduction therebetween and maintains successfully a desirable shield effect, even when the ground wiring of a substrate with built-in component is made of a metal and the shield is made of a conductive synthetic resin.

According to an embodiment of the present disclosure, there is provided an electronic circuit module including a substrate with built-in component; a mount component mounted on the substrate with built-in component; a sealing portion covering the mount component; and a shield made of a conductive synthetic resin covering the sealing portion,the substrate with built-in component having a core layer made of a metal also functioning as ground wiring, an outer cover made of an insulating synthetic resin covering a side face of the core layer, and a first protrusion integrated with the core layer that protrudes outwardly from the side face of the core layer and has an end face exposed at the outer cover,a face of the first protrusion facing to an end face of the shield being adjacent to a face of the outer cover facing to the end face of the shield, andthe end face of the shield bonded to both of the face of the first protrusion facing to the end face of the shield and the face of the outer cover facing to the end face of the shield.

According to the present disclosure, there is provided an electronic circuit module that prevents a bonding force between ground wiring and a shield from decreasing to avoid a decrease in conduction therebetween and maintains successfully a desirable shield effect, even when the ground wiring of a substrate with built-in component is made of a metal and the shield is made of a conductive synthetic resin.

DETAILED DESCRIPTION OF THE EMBODIMENTS

Structure of Electronic Circuit Module

An electronic circuit module10shown inFIGS. 1 to 5includes a substrate11with built-in component, mount components12mounted on the substrate11with built-in component, a sealing portion13covering the mount components12and a shield14covering the sealing portion13. A predetermined electronic circuit including built-in components11band the mount components12is three-dimensionally constructed.

Positions of the longitudinal sectional views shown inFIGS. 2 to 4(see the lines L1to lines L3ofFIG. 1) are different. As a matter of convenience, section structures shown inFIGS. 2 to 4are the same excluding a side of a core layer11adescribed later.

In each section structure shown inFIGS. 2 to 4, the substrate11with built-in component includes the core layer11a, a built-in component11bstored in a storage portion11a1disposed within the core layer11a, an insulation portion11cdisposed in a space between the built-in component11band the storage portion11a1, three insulation layers11dto11fdisposed at an upper surface (one face in a thickness direction) of the core layer11a, and three insulation layers11gto11idisposed at a bottom layer (the other face in the thickness direction) of the core layer11a. AlthoughFIGS. 2 to 4show the storage portion11a1having penetrating holes, the storage portion11a1having no penetrating holes may be used as long as the built-in components11bcan be stored.

The insulation layer11ehas two signal wirings11j, and a T type conductor via11kpenetrating through the insulation layer11d. The insulation layers11eand11hhave an I type conductor via11lpenetrating through the insulation layer11d, the core layer11aand the insulation layer11gsuch that the I type conductor via11lis not contacted with the core layer11a. At an upper surface of the insulation layer11f, four T type conductor vias11mare disposed penetrating through the insulation layer11f. At the insulation layer11h, three T type conductor vias11nare disposed penetrating through the insulation layer11g. At a lower surface of the insulation layer11i, four T type conductor vias11oare disposed penetrating through the insulation layers11ih. Although no symbols are added, an insulation portion is disposed in a space between the conductor via111and an inner wall of a penetrating hole11a2, and an insulation portion is also disposed in a space within the conductor via11l.

Further, a lower surface of the conductor via11kis connected to an upper surface of the core layer11a, lower surfaces of the two conductor vias11mamong the four conductor vias11mare connected to upper surfaces of two signal wirings11d, a lower surface of one conductor via11mamong the rest two conductor vias11mis connected to an upper surface of the conductor via11k, and a lower surface of the rest one conductor via11mis connected to an upper surface of the conductor via11l. Upper surfaces of the two conductor vias11namong the three conductor vias11nare connected to terminals of the built-in component11b, and an upper surface of the rest one conductor via11nis connected to a lower surface of the core layer11a. Upper surfaces of the two conductor vias11oamong the four conductor vias11oare connected to lower surfaces of the two conductor vias11n, an upper surface of one conductor via11oamong the rest two conductor vias11ois connected to a lower surface of the one conductor via11n, and an upper surface of the rest one conductor via11ois connected to a lower surface of the conductor via11l.

Although not shown in the section structures shown inFIGS. 2 to 4, the substrate11with built-in component includes signal wirings and conductor vias other than those described above, and also includes the ground wiring other than the core layer11a.

The core layer11ais made of a metal such as copper and a copper alloy, has a thickness, for example, of 35 to 500 μm, and also functions as the ground wiring. The built-in component11bis an electronic component such as a capacitor, an inductor, a resistor, a filter chip and an IC chip. InFIGS. 2 to 4, one built-in component11bis shown, but the number of the built-in component11bis not especially limited.

Each of the insulation layers11dto11fand11gto11iis made of an insulating thermosetting synthetic resin including an epoxy resin, polyimide, a bismaleimide triazine resin or the above-described resin containing a reinforcing filler such as glass fiber, and has a thickness, for example, of 5 to 50 μm. Also, the insulation portion11c, the insulation portion (no symbol) disposed in the space between the conductor via111and an inner wall of the penetrating hole11a2, and the insulation portion (no symbol) disposed in the space within the conductor via111are made of an insulating thermosetting synthetic resin including an epoxy resin, polyimide, a bismaleimide triazine resin or the above-described resin containing a reinforcing filler such as glass fiber.

Here, referring toFIGS. 1 and 5, a structure of side faces of the core layer11awill be described in detail. The core layer11ahas a substantially rectangular shape at an upper contour, and integrally has two first protrusions11a4and two second protrusions11a5that protrude outwardly from four side faces11a3. The first protrusions11a4are positioned at an upper side of the core layer11ain a thickness direction, and the second protrusions11a5are positioned at lower side of the core layer11ain the thickness direction. The first protrusions11a4and the second protrusions11a5are arranged alternately staggered in the respective side faces11a3at spaces CL in a direction orthogonal to the thickness direction of the core layer11a.

The first protrusions11a4and the second protrusions11a5are rectangular parallelepiped. A width W11a4of the first protrusion11a4and a width W11a5of the second protrusion11a5are almost same, and are within a range of 200 to 600 μm, for example. The space CL therebetween is also within a range of 200 to 600 μm, for example. A height H11a4of the first protrusion11a4is lower than a height H11a5of the second protrusion11a5, the height H11a4of the first protrusion11a4is within a range of 50 to 200 μm, for example, and the height H11a5of the second protrusion11a5is within a range of 100 to 300 μm, for example. A protruded dimension P11a4of the first protrusion11a4and a protruded dimension P11a5of the second protrusion11a5are almost same, and are within a range of 50 to 200 μm, for example. End faces PS of the both are almost in parallel with the side faces11a3of the core layer11a, and are almost in plane with respective end faces of the insulation layers11gto11i(seeFIGS. 2 and 3). Each face OS of each first protrusion11a4facing to an end face14aof the shield14is almost in parallel with the upper surface of the core layer11a(seeFIG. 2), and a distance D11a4therebetween is, for example, 50 to 200 μm. At an upper surface of each side face11a3, a strip-like side face zone CS (see a hatched zone inFIG. 5, andFIGS. 2 to 4) corresponding to the distance D11a4is disposed. A lower surface US of each second protrusion11a5is almost in plane with the lower surface of the core layer11a.

Areas excluding the side face zone CS at each side face11a3of the core layer11a, the first protrusions11a4and the second protrusions11a5are covered with an outer cover11pmade of an insulating thermosetting synthetic resin including an epoxy resin, polyimide, a bismaleimide triazine resin or the above-described resin containing a reinforcing filler such as glass fiber (seeFIGS. 2 to 4). A thickness of the outer cover11pis almost same as the protruded dimension P11a4of the first protrusion11a4and the protruded dimension P11a5of the second protrusion11a5, and has a thickness, for example, of 50 to 200 μm. End faces PS of the first protrusion11a4and end faces PS of the second protrusion11a5are exposed at each side face of the outer cover11p(seeFIGS. 2 and 3).

In addition, each face OS of each first protrusion11a4facing to the end face14aof the shield14is almost in plane with the faces OS of the outer cover11pfacing to the end face14aof the shield14. Also, each face OS of each first protrusion11a4facing to the end face14aof the shield14is adjacent to the faces OS of the outer cover11pfacing to the end face14aof the shield14. In other words, the end face14aof the shield14is bonded to both of each face OS of each first protrusion11a4facing to the end face14aof the shield14and the faces OS of the outer cover11pfacing to the end face14aof the shield14, and an end inner face (no symbol) of the shield14is bonded to the side face zone CS of the core layer11a(seeFIGS. 2 to 4). In contrast, as a position of each second protrusion11a5is lower than a position of each first protrusion11a4, the shield14is not bonded to each second protrusion11a5.

In each section structure shown inFIGS. 2 to 4, each mount component12is an electronic component such as a capacitor, an inductor, a resistor, a filter chip and an IC chip. One terminal of the mount component12is connected to the upper surface of the two conductor vias11mamong the four conductor vias11m, and the other terminal of the mount component12is connected to the upper surface of the rest two conductor vias11m. In order to connect each mount component12to the conductor via11m, soldering such as a reflow method is utilized. Although two mount components12are shown inFIGS. 2 to 4, the number of the mount components12is not especially limited.

In each section structure shown inFIGS. 2 to 4, the sealing portion13is disposed at the upper surface of the substrate11with built-in component such that the sealing portion13covers the mount components12. The sealing portion13is rectangular parallelepiped in appearance, and each side face is almost in plane with each end face of the insulation layers11dto11f. The sealing portion13is made of an insulating thermosetting synthetic resin including an epoxy resin, polyimide, a bismaleimide triazine resin or the above-described resin containing a reinforcing filler such as glass fiber, and its height is set such that the mount components12are fully covered.

In each section structure shown inFIGS. 2 to 4, the shield14is disposed such that the shield14covers the surface of the sealing portion13and side face zone CS of the core layer11aof the substrate11with built-in component (seeFIGS. 2 to 5). The shield14is rectangular parallelepiped in appearance (seeFIG. 1), and each side face is almost in plane with each side face of the outer cover11pand each end face of the insulation layers11gto11i. The shield14is made of a conductive thermosetting synthetic resin including an epoxy resin containing a conductive filler such as metal fibers, polyimide containing the conductive filler, a bismaleimide triazine resin containing the conductive filler, and has a thickness, for example, of 50 to 200 μm. Bonding of the shield14to the core layer11a, each first protrusion11a4and the outer cover11pis described above.

Method of Producing Electronic Circuit Module

When the electronic circuit module10is produced, a multiple substrate SB where a plurality of substrates with built-in component11are connected in a matrix is prepared, as shown inFIGS. 6A,6B and6C.FIG. 6Ais a major portion longitudinal sectional view of the multiple substrate SB having the section structure shown inFIG. 2.FIG. 6Bis a major portion longitudinal sectional view of the multiple substrate SB having the section structure shown inFIG. 3.FIG. 6Cis a major portion longitudinal sectional view of the multiple substrate SB having the section structure shown inFIG. 4.

In a core layer SBa of the multiple substrate SB, there are a connection portion SBb (seeFIG. 6A) that is cut and forms one of the two first protrusions11a4shown inFIG. 2and a connection portion SBb (seeFIG. 6B) that is cut and forms one of the two second protrusions11a5shown inFIG. 3. At a lower side of the connection portion SBb shown inFIG. 6A, there is a concave portion including an inner face SBc corresponding to the side face11a3. At an upper side of the connection portion SBb shown inFIG. 6B, there is a concave portion including an inner face SBc corresponding to the side face11a3. Both concave portions are filled with an insulating material corresponding to the outer cover11p. There are no connection portions SBb inFIG. 6C, the inner face SBc corresponding to the side face11a3is filled with the insulating material corresponding to the outer cover11p. Then, the mount components12are mounted on the multiple substrate SB by a reflow solder method.

Next, an upper surface of the multiple substrate SB is coated with a sealing material EN corresponding to the sealing portion13to cover the mount components12, and the sealing material EN is cured, as shown inFIGS. 7A and 7E. Then, a slit GR is formed from top to bottom at a boundary (see a dashed-dotted line) of each substrate11with built-in component using a dicing machine etc., as shown inFIGS. 7B and 7F. A width Wg of the slit GR substantially corresponds to a space facing the inner faces SBc each other corresponding to the side faces11a3, and a depth Dgr is such that the slit GR enters into an upper surface of the connection portion SBb shown inFIG. 6A. In this way, the sealing portion13for each substrate11with built-in component is produced.

Next, as shown inFIGS. 7C and 7G, a shielding material SH corresponding to the shield14is coated and cured so that the sealing portion13of the multiple substrate is covered and the slit GR is filled. Then, as shown inFIGS. 7D and 7H, each substrate11with built-in component is cut at the boundary (see the dashed-dotted line) using a dicing machine etc. As a width Wct of a cut mark CT is smaller than a width Wgr of the slit GR, the first protrusions11a4, the second protrusions11a5and the outer cover11premain on each substrate11with built-in component. Also, as a part of the connection portion SBb is cut upon the formation of the slit GR, cutting can be easily done as compared with the case that a part of the connection portion SBb is not cut.

Advantageous Effects of Electronic Circuit Module

The circuit module10has a configuration that the substrate11with built-in component includes the core layer11amade of a metal also functioning as the ground wiring, the outer cover11pmade of the insulating synthetic resin covering the side face11a3of the core layer11a, and the two first protrusions11a4that protrude outwardly from each side face11a3of the core layer11aand have the end faces PS integral with the core layer11aexposed at the outer cover11p, each face OS of each first protrusion11a4facing to the end face14aof the shield14is adjacent to the faces OS of the outer cover11pfacing to the end face14aof the shield14, and the end face14aof the shield14is bonded to both of the each face OS of each first protrusion11a4facing to the end face14aof the shield14and the faces OS of the outer cover11pfacing to the end face14aof the shield14.

In other words, the end face14aof the shield14can be bonded to the faces OS facing to the end face14aof the shield14in the outer cover11pmade of the insulating synthetic resin with a strong bonding force by bonding of the synthetic resins, even when the shield14is made of the conductive synthetic resin. At the same time, based on this bonding, bonding of the end face14aof the shield14and the faces OS facing to the end face14aof the shield14in each first protrusion11a4made of a metal can be successfully maintained. In summary, the bonding of the shield14to each first protrusion11a4made of a metal is not easily degraded as time elapses, even when the shield14is made of the conductive synthetic resin. In this way, a decrease in conductivity between the shield14and each first protrusion11a4made of a metal is avoided to successfully maintain a shielding effect.

In addition, as the two first protrusions11a4are disposed at the side faces11a3of the core layer11a, the end face14aof the shield14and the faces OS facing to the end face14aof the shield14in each first protrusion11a4made of a metal can be bonded successfully, a bond area is increased to enhance the conductivity between the shield14and each first protrusion11a4made of a metal.

Also, as each end face PS of each first protrusion11a4is exposed at the outer cover11p, each end face PS of each first protrusion11a4can be used as the ground terminal

The circuit module10has a configuration that there is the distance D11a4between each face OS of each first protrusion11a4facing to an end face14aof the shield14and one face in a thickness direction of the core layer11a, the side face zone CS corresponding to the distance D11a4is disposed at each side face11a3of the core layer11a, the end face14aof the shield14is bonded to both of each face OS of each first protrusion11a4facing to the end face14aof the shield14and the faces OS of the outer cover11pfacing to the end face14aof the shield14, and the end inner face of the shield14is bonded to the side face zone CS of the core layer11a.

In other words, the end face14aof the shield14can be bonded to the face OS facing to the end face14aof the shield14in the outer cover11pmade of the insulating synthetic resin with a strong bonding force by bonding of the synthetic resins, even when the shield14is made of the conductive synthetic resin. At the same time, based on this bonding, bonding of the end face14aof the shield14and the face OS facing to the end face14aof the shield14in each first protrusion11a4made of a metal, and bonding of the end inner face of the shield14and the side face zone CS can be successfully maintained. In summary, the bonding of the shield14to each first protrusion11a4made of a metal and the side face zone CS is not easily degraded as time elapses combining with an increase in the bond area, even when the shield14is made of the conductive synthetic resin. In this way, a decrease in conductivity between the shield14and each first protrusion11a4made of a metal is avoided to successfully maintain a shielding effect.

The circuit module10has a configuration that the core layer11aintegrally has the two second protrusions11a5that protrude outwardly from each side faces11a3, and each end face PS thereof is exposed at the outer cover11p, the positions of the second protrusions11a5in the thickness direction of the core layer11aare different from the positions of the first protrusions11a4in the thickness direction of the core layer11a, and the shield14is not bonded to each second protrusion11a5.

In other words, as the bonding force between each side face11a3of the core layer11aand the outer cover11pmade of the insulating synthetic resin can be enhanced based on the bonding of the outer cover11pand each second protrusion11a5, the bonding force between the outer cover11pand the each side face11a3of the core layer11ais prevented from decreasing to avoid possible peeling, even when the shield14is made of the conductive synthetic resin.

In addition, as the two second protrusions11a5are disposed at each side face11a3of the core layer11a, the bonding force is successfully increased by the second protrusions11a5, and the bonding force between the outer cover11pand the each side face11a3of the core layer11acan be successfully prevented from decreasing.

Also, as each end face PS of each second protrusion11a5is exposed at the outer cover11p, each end face PS of each second protrusion11a5can be used as the ground terminal

Alternative Embodiment of Electronic Circuit Module

In the above-mentioned <Structure of Electronic Circuit Module>, the two first protrusions11a4and the two second protrusions11a5are disposed at each side face11a3of the core layer11a. However, the advantageous effects 1 to 3 can be similarly provided even when the total number of the first protrusions11a4and the second protrusions11a5is 2, 3, or 5 or more, the number of the first protrusions11a4and the second protrusions11a5disposed at each side face11a3is not the same or the first protrusions11a4and the second protrusions11a5are not arranged alternately. Also, although the core layer11ahas a substantially rectangular shape at the upper contour, the advantageous effects 1 to 3 can be similarly provided as long as the core layer11ahas similar the first protrusions11a4and the second protrusions11a5, even when the upper contour has other shapes.

In the above-mentioned <Structure of Electronic Circuit Module>, the two first protrusions11a4and the two second protrusions11a5are disposed at each side face11a3of the core layer11a. However, the advantageous effects 1 and 2 can be similarly provided even when the second protrusions11a5is removed from each side face11a3, the total number of the first protrusions11a4is changed, or the upper contour of the core layer11ais changed.

In the above-mentioned <Structure of Electronic Circuit Module>, the side face zone CS is disposed at each side face11a3of the core layer11a. However, the advantageous effects 1 to 3 can be similarly provided even when the side face zone CS is excluded and each face of each first protrusion11a4facing to the end face14aof the shield14is in plane with one face in a thickness direction of the core layer11a, the total number of the first protrusions11a4is changed, or the upper contour of the core layer11ais changed.

In the above-mentioned <Structure of Electronic Circuit Module>, three insulation layers (no symbols are added) are disposed at the upper surface (one face in a thickness direction) of the core layer11aand three insulation layers (no symbols are added) are disposed at the bottom layer (the other face in the thickness direction) of the core layer11a. However, the advantageous effects 1 to 3 can be similarly provided even when the number of the insulation layers is changed, or the number of the built-in component11band the mount components12is changed, i.e., the electronic circuit three-dimensionally constructed is changed as appropriate.

While the embodiments of the present disclosure are described, it should be appreciated that the disclosure is not limited to the above-described embodiments, and variations and modifications may be made without departing from the spirit and scope of the present disclosure.