ELECTRONIC CIRCUIT PACKAGE

Disclosed herein is an electronic circuit package includes: a substrate having a power supply pattern; an electronic component mounted on a surface of the substrate; a mold resin covering the surface of the substrate so as to embed therein the electronic component; a magnetic film formed so as to contact at least a top surface of the mold resin; and a metal film electrically connected to the power supply pattern and covering the mold resin through the magnetic film.

BACKGROUND OF THE INVENTION

Field of the Invention

The present invention relates to an electronic circuit package and, more particularly, to an electronic circuit package provided with a composite shielding function having both an electromagnetic shielding function and a magnetic shielding function.

Description of Related Art

In recent years, an electronic device such as a smartphone is equipped with a high-performance radio communication circuit and a high-performance digital chip, and an operating frequency of a semiconductor IC used therein tends to increase. Further, adoption of an SIP (System-In Package) having a 2.5D or 3D structure, in which a plurality of semiconductor ICs are connected by a shortest wiring, is accelerated, and modularization of a power supply system is expected to accelerate. Further, an electronic circuit module having a large number of modulated electronic components (collective term of components, such as passive components (an inductor, a capacitor, a resistor, a filter, etc.), active components (a transistor, a diode, etc.), integrated circuit components (an semiconductor IC, etc.) and other components required for electronic circuit configuration) is expected to become more and more popular, and an electronic circuit package which is a collective term for the above SIP, electronic circuit module, and the like tends to be mounted in high density along with sophistication, miniaturization, and thinning of an electronic device such as a smartphone. However, this tendency poses a problem of malfunction and radio disturbance due to noise. The problem of malfunction and radio disturbance is difficult to be solved by conventional noise countermeasure techniques. Thus, recently, self-shielding of the electronic circuit package has become accelerated, and an electromagnetic shielding using a conductive paste or a plating or sputtering method has been proposed and put into practical use, and higher shielding characteristics are required in the future.

In order to realize the higher shielding characteristics, a composite shielding structure is proposed in recent years. The composite shielding structure has both an electromagnetic shielding function and a magnetic shielding function. In order to realize the composite shielding structure, it is necessary to form, in an electronic circuit package, an electromagnetic shielding by a conductive film (metal film) and a magnetic shielding by a magnetic film.

For example, an electronic circuit module described in Japanese Patent Application Laid-Open No. 2010-087058 has a configuration in which a metal film and a magnetic layer are laminated in this order on a surface of a mold resin. Further, a semiconductor package described in U.S. Patent Publication No. 2011/0304015 has a configuration in which a shield case (shield can) obtained by laminating a magnetic layer and a metal film is bonded to a mold resin by an adhesive.

However, study of the present inventors reveals the following problems. That is, with the configuration like Japanese Patent Application Laid-Open No. 2010-087058 in which a metal film and a magnetic layer are laminated in this order on a surface of a mold resin, a sufficient shield effect cannot be obtained as an electronic circuit package for mobile communication device required to have a higher shield effect in the future. On the other hand, the configuration like U.S. Patent Publication No. 2011/0304015 in which the shield case is bonded by an adhesive is disadvantageous for height reduction and makes it difficult to connect the metal film to a grand pattern on a substrate.

SUMMARY

The object of the present invention is therefore to provide an electronic circuit package capable of achieving both a high composite-shield effect and height reduction.

An electronic circuit package according to the present invention includes a substrate having a power supply pattern; an electronic component mounted on a surface of the substrate; a mold resin covering the surface of the substrate so as to embed therein the electronic component; a magnetic film formed so as to contact at least a top surface of the mold resin; and a metal film connected to the power supply pattern and covering the mold resin through the magnetic film.

According to the present invention, the magnetic film and metal film are formed on the top surface of the mold resin in this order, so that high composite-shield characteristics can be obtained. In addition, the magnetic film is directly formed on the top surface of the mold resin without intervention of an adhesive or the like. This is advantageous for height reduction.

In the present invention, the magnetic film preferably further contacts the side surface of the mold resin. With this configuration, the composite-shield characteristics can be enhanced in the side surface direction. In this case, the magnetic film preferably covers a part of the side surface of the substrate.

In the present invention, the magnetic film may be a film formed of a composite magnetic material in which magnetic fillers are dispersed in a thermosetting resin material, or a thin film, a foil or a bulk sheet formed of a soft magnetic material or a ferrite. When the film formed of a composite magnetic material is used, the magnetic filler is preferably formed of a ferrite or a soft magnetic metal, and a surface of the filler is preferably insulation-coated.

Preferably, in the present invention, the metal film is mainly composed of at least one metal selected from a group consisting of Au, Ag, Cu, and Al, and more preferably, the surface of the metal film is covered with an antioxidant film.

In the present invention, it is preferable that the power supply pattern is exposed to a side surface of the substrate and that the metal film contacts the exposed power supply pattern. With this configuration, it is possible to easily and reliably connect the metal film to the power supply pattern.

As described above, according to the present invention, it is possible to realize both high composite shielding effect and reduction in height.

DETAILED DESCRIPTION OF THE EMBODIMENTS

First Embodiment

FIG. 1is a cross-sectional view illustrating a configuration of an electronic circuit package11A according to the first embodiment of the present invention.

As illustrated inFIG. 1, the electronic circuit package11A according to the present embodiment includes a substrate20, a plurality of electronic components31and32mounted on the substrate20, a mold resin40covering a front surface21of the substrate20so as to embed the electronic components31and32, a magnetic film50covering the mold resin40, and a metal film60covering the mold resin40and the magnetic film.

Although the type of the electronic circuit package11A according to the present embodiment is not especially limited, examples thereof include a high-frequency module handling a high-frequency signal, a power supply module performing power supply control, an SIP (System-In-Package) having a 2.5D structure or a 3D structure, and a semiconductor package for radio communication or digital circuit. Although only two electronic components31and32are illustrated inFIG. 1, more electronic components are incorporated actually.

The substrate20has a double-sided and multilayer wiring structure in which a large number of wirings are embedded therein and may be any type of substrate including: a thermosetting resin based organic substrate such as an FR-4, an FR-5, a BT, a cyanate ester substrate, a phenol substrate, or an imide substrate; a thermoplastic resin based organic substrate such as a liquid crystal polymer; an LTCC substrate; an HTCC substrate; and a flexible substrate. In the present embodiment, the substrate20has a four-layer structure including wiring layers formed on the front surface21and a back surface22and two wiring layers embedded therein. Land patterns23are an internal electrode for connecting to the electronic components31and32. The land patterns23and each of the electronic components31and32are electrically and mechanically connected to each other through a respective solder24(or a conductive paste). For example, the electronic component31is a semiconductor chip such as a controller, and electronic component32is a passive component such as a capacitor or a coil. Some electronic components (e.g., thinned semiconductor chip) may be embedded in the substrate20.

The land patterns23are connected to external terminals26formed on the back surface22of the substrate20through internal wirings25formed inside the substrate20. Upon actual use, the electronic circuit package11A is mounted on an unillustrated mother board, and land patterns on the mother board and the external terminals26of the electronic circuit package11A are electrically connected. A material for a conductor forming the land patterns23, internal wirings25, and external terminals26may be a metal such as copper, silver, gold, nickel, chrome, aluminum, palladium, indium, or a metal alloy thereof or may be a conductive material using resin or glass as a binder; however, when the substrate20is an organic substrate or a flexible substrate, copper or silver is preferably used in terms of cost and conductivity. The above conductive materials may be formed by using various methods such as printing, plating, foil lamination, sputtering, vapor deposition, and inkjet.

Out of the internal wirings25illustrated inFIG. 1, internal wirings25G are power supply patterns. The power supply patterns25G are typically ground patterns to which a ground potential is to be applied; however, it is not limited to the ground patterns as long as the power supply patterns25G are a pattern to which a fixed potential is to be applied.

The mold resin40covers the surface21of the substrate20so as to embed therein the electronic components31and32. In the present embodiment, a side surface42of the mold resin40and a side surface27of the substrate20form the same plane. As a material for the mold resin40, a material based on a thermosetting material or a thermoplastic material and blended with fillers for adjusting a thermal expansion coefficient can be used.

A top surface41of the mold resin40is covered with the magnetic film50, and the top surface41and magnetic film50directly contact each other without intervention of an adhesive or the like. The magnetic film50may be a film formed of a composite magnetic material in which magnetic fillers are dispersed in a thermosetting resin material, a thin film formed of a soft magnetic material or a ferrite, or a foil or a bulk sheet and serves as a magnetic shield.

When the film formed of a composite magnetic material is selected as the magnetic film50, an epoxy resin, a phenol resin, a silicone resin, a diallyl phthalate resin, a polyimide resin, an urethane resin, and the like may be used as the thermosetting resin material, and the magnetic film50can be formed by using a thick-film formation method such as a printing method, a molding method, a slit nozzle coating method, a spray method, a dispensing method, an injection method, a transfer method, a compression molding method, or a lamination method using an uncured sheet-like resin. Using the thermosetting resin material can increase reliability (heat resistance, insulation performance, impact resistance, falling resistance) required for electronic circuit packages.

As the magnetic filler, a ferrite or a soft magnetic metal is preferably used, and a soft magnetic metal having a high bulk permeability is more preferably used. As the ferrite or soft magnetic metal, one or two or more metals selected from a group consisting of Fe, Ni, Zn, Mn, Co, Cr, Mg, Al, and Si and oxides thereof may be used. Specific examples include a ferrite (Ni—Zn ferrite, Mn—Zn ferrite, Ni—Cu—Zn ferrite, etc.), a permalloy (Fe—Ni alloy), a super permalloy (Fe—Ni—Mo alloy), a sendust (Fe—Si—Al alloy), an Fe—Si alloy, an Fe—Co alloy, an Fe—Cr alloy, an Fe—Cr—Si alloy, and Fe. The shape of the magnetic filler is not especially limited; however, it may be formed into a spherical shape for a high filling level, and fillers of a plurality of particle sizes may be blended for a densest filling structure. In order to maximize a shield effect by a permeability real component and a thermal conversion effect by a loss of a permeability imaginary component, the magnetic filler is more preferably formed by adding flat powder having an aspect ratio of 5 or more.

Preferably, the surface of the magnetic filler is insulation-coated by an oxide of a metal such as Si, Al, Ti, or Mg, or an organic material for enhancing fluidity, adhesion, and insulation performance. The insulation coating may be formed by coating a thermosetting material on the surface of the magnetic filler. Alternatively, an oxide film may be formed as the insulation coating by dehydration reaction of a metal alkoxide, and in this case, formation of a silicon oxide coating film is most preferable. More preferably, organic functional coupling treatment is applied to the formed coating film.

The composite magnetic material can be formed on the top surface41of the mold resin using a known method such as a printing method, a molding method, a slit nozzle coating method, a spray method, a dispensing method, or a lamination method using an uncured sheet-like resin.

When the thin film formed of a soft magnetic material or a ferrite is selected as the magnetic film50, one or two or more metals selected from a group consisting of Fe, Ni, Zn, Mn, Co, Cr, Mg, Al, and Si and oxides thereof may be used. In this case, the magnetic film50can be formed on the top surface41of the mold resin40by using a plating method, a spray method, an AD method, and a thermal spraying method, as well as a thin-film formation method such as a sputtering method or a vapor-deposition method. In this case, the material for the magnetic film50may be appropriately selected from a required permeability and frequency; however, in order to enhance a shield effect on a lower frequency side (kHz to 100 MHz), an Fe—Co alloy, an Fe—Ni alloy, an Fe—Al alloy, or an Fe—Si alloy is most preferably used. On the other hand, in order to enhance a shield effect on a higher frequency side (50 to several hundreds of MHz), a ferrite film formed of NiZn, MnZn, or NiCuZn, or Fe is most preferably used.

When a foil or a bulk sheet is used as the magnetic film50, the foil or bulk sheet is previously set in a die for forming the mold resin40. This allows the magnetic film50to be directly formed on the top surface41of the mold resin40.

The top and side surfaces51and52of the magnetic film50, the top and side surfaces41and42of the mold resin40and the side surface27of the substrate20are covered with the metal film60. The metal film60serves as an electromagnetic shielding and is preferably mainly composed of at least one metal selected from a group consisting of Au, Ag, Cu, and Al. The metal film60preferably has a resistance as low as possible and most preferably uses Cu in terms of cost. An outer surface of the metal film60is preferably covered with an anticorrosive metal such as SUS, Ni, Cr, Ti, or brass or an antioxidant film made of a resin such as an epoxy resin, a phenol resin, an imide resin, an urethane resin, or a silicone resin. The reason for this is that the metal film60undergoes oxidative deterioration by an external environment such as heat or humidity; and, therefore, the aforementioned treatment is preferable to suppress and prevent the oxidative deterioration. A formation method for the metal film60may be appropriately selected from known methods, such as a sputtering method, a vapor-deposition method, an electroless plating method, an electrolytic plating method. Before formation of the metal film60, pretreatment for enhancing adhesion, such as plasma treatment, coupling treatment, blast treatment, or etching treatment, may be performed. As a base of the metal film60, a high adhesion metal film such as a titanium film, a chromium film, or an SUS film may be formed thinly in advance.

As illustrated inFIG. 1, the power supply patterns25G are exposed to the side surfaces27of the substrate20. The metal film60covers the side surfaces27of the substrate20and is thereby electrically connected to the power supply pattern25G.

Although not especially limited, it is desirable that a resistance value at an interface between the metal film60and the magnetic film50is equal to or larger than 106Ω. According to this configuration, an eddy current generated when electromagnetic wave noise enters the metal film60hardly flows in the magnetic film50, which can prevent deterioration in the magnetic characteristics of the magnetic film50due to inflow of the eddy current. The resistance value at the interface between the metal film60and the magnetic film50refers to a surface resistance of the magnetic film50when the metal film60and magnetic film50directly contact each other and to a surface resistance of an insulating film when the insulating film is present between the metal film60and the magnetic film50.

In order to make a resistance value at an interface between the metal film60and the magnetic film50equal to or higher than 106Ω, a material having a sufficiently high surface resistance is used as the material for the magnetic film50or a thin insulating material is formed on the top surface51of the magnetic film50.FIG. 2is a cross-sectional view illustrating a configuration of an electronic circuit package11B according to a modification. The electronic circuit package11B ofFIG. 2differs from the electronic circuit package11A ofFIG. 1in that a thin insulating film70is interposed between the magnetic film50and the metal film60. By interposing the insulating film70, it is possible to make a resistance value at an interface between the metal film60and the magnetic film50equal to or higher than 106Ω even when a material having a comparatively low resistance value is used as the material for the magnetic film50, thereby making it possible to prevent deterioration in magnetic characteristics due to an eddy current.

As described above, in the electronic circuit package11A (and11B) according to the present embodiment, the magnetic film50and metal film60are laminated in this order on the top surface41of the mold resin40. With this configuration, as compared with a case where the magnetic film50and metal film60are laminated in the reverse order, electromagnetic noise radiated from the electronic components31and32can be shielded more effectively. This is because the electromagnetic wave noise radiated from the electronic components31and32is partially absorbed when it passes through the magnetic film50, and the remaining electromagnetic wave noise that has not been absorbed is partially reflected by the metal film60and passes through the magnetic film50once again. In this manner, the magnetic film50acts on the incident electromagnetic wave noise twice, thereby effectively shielding the electromagnetic wave noise radiated from the electronic components31and32.

Further, in the electronic circuit package11A (and11B) according to the present embodiment, the magnetic film50is directly formed on the top surface41of the mold resin40without intervention of an adhesive or the like. This is advantageous for height reduction. In addition, in the present embodiment, the magnetic film50is formed only on the top surface41of the mold resin40, so that the metal film60can be easily connected to the power supply pattern25G.

The following describes a manufacturing method for the electronic circuit package11A according to the present embodiment.

FIGS. 3 to 6are process views for explaining a manufacturing method for the electronic circuit package11A.

As illustrated inFIG. 3, an assembly substrate20A having a multilayer wiring structure is prepared. A plurality of the land patterns23are formed on the front surface21of the assembly substrate20A, and a plurality of the external terminals26are formed on the back surface22of the assembly substrate20A. Further, a plurality of the internal wirings25including the power supply patterns25G are formed in an inner layer of the assembly substrate20A. A dashed line a inFIG. 3denotes apart to be cut in a subsequent dicing process. As illustrated inFIG. 3, the power supply patterns25G are provided at a position overlapping the dashed line a in a plan view.

Then, as illustrated inFIG. 3, the plurality of electronic components31and32are mounted on the front surface21of the assembly substrate20A so as to be connected to the land patterns23. Specifically, the solder24is provided on the land pattern23, followed by mounting of the electronic components31and32and by reflowing, whereby the electronic components31and32are connected to the land patterns23.

Then, as illustrated inFIG. 4, the front surface21of the assembly substrate20A is covered with the mold resin40so as to embed the electronic components31and32in the mold resin40. Examples of the formation method for the mold resin40may include, transfer molding, compression molding, injection molding, cast molding, vacuum cast molding, dispense molding, and molding using a slit nozzle.

Then, as illustrated inFIG. 5, the magnetic film50is directly formed on the top surface41of the mold resin40. In this case, in order to enhance adhesion between the mold resin40and magnetic film50, the top surface41of the mold resin40may be subjected to blast treatment or etching treatment to form a physical unevenness thereon, subjected to surface modification by plasma or short-wavelength UV irradiation, or subjected to organic functional coupling treatment.

When the film formed of a composite magnetic material is used as the magnetic film50, a thick-film formation method such as a printing method, a molding method, a slit nozzle coating method, a spray method, a dispensing method, an injection method, a transfer method, a compression molding method, or a lamination method using an uncured sheet-like resin can be used. When the magnetic film50is formed by using the printing method, slit nozzle method, spraying method, or dispensing method, the viscosity of the composite magnetic material is preferably controlled as needed. The viscosity control may be made by diluting the composite magnetic material with one or two or more solvents having a boiling point of 50° C. to 300° C. The thermosetting material mainly consists of a main agent, a curing agent, and a curing accelerator; however, two or more kinds of main agent or curing agent may be blended according to required characteristics. Further, two or more kinds of solvents may be mixed: a coupling agent for enhancing adhesion and fluidity, a fire retardant for flame retardancy, a dye and a pigment for coloration, a non-reactive resin material for imparting flexibility, and a non-magnetic filler for adjusting a thermal expansion coefficient may be blended. The materials may be kneaded or dispersed by a known means such as a kneader, a mixer, a vacuum defoaming stirring machine, or a three-roll mill.

When the thin film formed of a soft magnetic material or a ferrite is used as the magnetic film50, a plating method, a spray method, an AD method, and a thermal spraying method, as well as a thin-film formation method such as a sputtering method or a vapor-deposition method may be used. When a foil or a bulk sheet is used as the magnetic film50, the foil or bulk sheet is previously set in a die for forming the mold resin40. This allows the magnetic film50to be directly formed on the top surface41of the mold resin40.

When the insulating film70is interposed between the magnetic film50and the metal film60as in the modification illustrated inFIG. 2, after formation of the magnetic film50, an insulating material such as a thermosetting material, a heat-resistant thermoplastic material, an Si oxide, a low-melting point glass may be thinly formed on the top surface51of the magnetic film50.

Then, as illustrated inFIG. 6, the assembly substrate20A is cut along the dashed line a to divide the assembly substrate20A into individual substrates20. In the present embodiment, the power supply patterns25G pass the dashed line a as a dicing position. Thus, when the assembly substrate20A is cut along the dashed line a, the power supply patterns25G are exposed from the side surface27of the substrate20.

Then, the metal film60is formed so as to cover the top and side surfaces51and52of the magnetic film50, the top and side surfaces41and42of the mold resin40, and side surface27of the substrate20, whereby the electronic circuit package11A according to the present embodiment is completed. Examples of a formation method for the metal film60may include a sputtering method, a vapor-deposition method, an electroless plating method, and an electrolytic plating method. Before formation of the metal film60, pretreatment for enhancing adhesion, such as plasma treatment, coupling treatment, blast treatment, or etching treatment, may be performed. As a base of the metal film60, a high adhesion metal film such as a titanium film or a chromium film may be formed thinly in advance.

As described above, according to the manufacturing method for the electronic circuit package11A of the present embodiment, the magnetic film50is directly formed on the top surface41of the mold resin40, so that there is no need to use an adhesive or the like, thus being advantageous for height reduction. In addition, the power supply pattern25G is exposed by cutting the assembly substrate20A, so that the metal film60can be easily and reliably connected to the power supply pattern25G.

Second Embodiment

FIG. 7is a cross-sectional view illustrating a configuration of an electronic circuit package12A according to the second embodiment of the present invention.

As illustrated inFIG. 7, an electronic circuit package12A according to the present embodiment is the same as the electronic circuit package11A according to the first embodiment illustrated inFIG. 1except for shapes of the substrate20and metal film60. Thus, inFIG. 7, the same reference numerals are given to the same elements as inFIG. 1, and repetitive descriptions will be omitted.

In the present embodiment, the side surface27of the substrate20is formed stepwise. Specifically, a side surface lower portion27bprotrudes from a side surface upper portion27a. The metal film60is not formed over the entire side surface of the substrate20but formed so as to cover the side surface upper portion27aand a step portion27c. That is, the side surface lower portion27bis not covered with the metal film60. Also in the present embodiment, the power supply patterns25G are exposed from the side surface upper portion27aof the substrate20, so that the metal film60is connected to the power supply patterns25G at the exposed portion. When a material having relatively low resistance value is used as the magnetic film50, it is desirable that the thin insulating film70interposed between the magnetic film50and the metal film60is used as in an electronic circuit package12B according to a modification illustrated inFIG. 8.

FIGS. 9 and 10are process views for explaining a manufacturing method for the electronic circuit package12A.

First, the magnetic film50is formed on the top surface41of the mold resin40by using the method described inFIGS. 3 to 5. Then, as illustrated inFIG. 9, a groove43is formed along the dashed line a denoting the dicing position. The groove43is formed so as to completely cut the mold resin40and so as not to completely cut the assembly substrate20A. As a result, the side surface42of the mold resin40and side surface upper portion27aand step portion27cof the substrate20are exposed inside the groove43. A depth of the groove43is set so as to allow at least the power supply patterns25G to be exposed from the side surface upper portion27a. When the insulating film70is interposed between the magnetic film50and the metal film60as in the modification illustrated inFIG. 8, an insulating material such as a thermosetting material, a heat-resistant thermoplastic material, an Si oxide, a low-melting point glass may be thinly formed on the top surface51of the magnetic film50before forming the groove43.

Then, as illustrated inFIG. 10, the metal film60is formed by using a sputtering method, a vapor-deposition method, an electroless plating method, an electrolytic plating method, or the like. As a result, the top surface51of the magnetic film50and inside of the groove43are covered with the metal film60. At this time, the power supply patterns25G exposed to the side surface upper portion27aof the substrate20are connected to the metal film60.

Then, the assembly substrate20A is cut along the dashed line a to divide the assembly substrate20A into individual substrates20, whereby the electronic circuit package12A according to the present embodiment is completed.

As described above, according to the manufacturing method for the electronic circuit package12A of the present embodiment, formation of the groove43allows the metal film60to be formed before dividing the assembly substrate20A into individual substrates20, thereby forming the metal film60easily and reliably.

Third Embodiment

FIG. 11is a cross-sectional view illustrating a configuration of an electronic circuit package13A according to the third embodiment of the present invention.

As illustrated inFIG. 11, the electronic circuit package13A according to the present embodiment differs from the electronic circuit package11A ofFIG. 1according to the first embodiment in that the magnetic film50covers not only the top surface41of the mold resin40, but also the side surface42. Other configurations are the same as those of the electronic circuit package11A according to the first embodiment. Thus, inFIG. 11, the same reference numerals are given to the same elements as inFIG. 1, and repeated descriptions will be omitted.

In the present embodiment, the side surface42of the mold resin40is fully covered with the magnetic film50, and thus, a part where the mold resin40and metal film60contact each other does not substantially exist. With this configuration, a composite-shield effect in the side surface of the mold resin40can be enhanced. In particular, electromagnetic noise radiated in a side surface direction of the mold resin40is effectively shielded.

When a material having a comparatively low resistance value is used as the material for the magnetic film50, the thin insulating film70is preferably interposed between the top surface51of the magnetic film50and the metal film60as in an electronic circuit package13B ofFIG. 12according to a modification, and more preferably, the thin insulating film70is interposed between the top surface51and side surface52of the magnetic film50and the metal film60as in an electronic circuit package13C ofFIG. 13according to another modification.

In the examples illustrated inFIGS. 11 to 13, the side surface52of the magnetic film50and the side surface27of the substrate20form substantially the same plane; however, it is not essential in the present invention. For example, as in an electronic circuit package13D ofFIG. 14according to another modification, a configuration may be adopted, in which the side surface42of the mold resin40and the side surface27of the substrate20form the same plane and, at the same time, the side surface42of the mold resin40is covered by the magnetic film50. Further, as in an electronic circuit package13E ofFIG. 15according to another modification, a side surface of a wiring pattern28formed on the surface21of the substrate20may be covered with the magnetic film50.

FIGS. 16 to 18are process views for explaining a manufacturing method for the electronic circuit package13A.

First, the mold resin40is formed by the method described usingFIGS. 3 and 4. Then, as illustrated inFIG. 16, a groove44having a width W1is formed along a dashed line a indicating a dicing position (SeeFIG. 3). The groove44has a depth almost completely cutting the mold resin40and not reaching the inner wiring25formed in the substrate20. As a result, the side surface42of the mold resin40and the surface21of the substrate20are exposed inside the groove44.

Then, as illustrated inFIG. 17, the magnetic film50is formed to fill the groove44. Although it is not essential to completely fill the groove44with the magnetic film50, when the groove44is filled with the magnetic film50, the magnetic film needs to have a certain film thickness, so that it is necessary to use the composite magnetic material as the magnetic film50. Thus, the magnetic film50is directly formed on the top surface41and side surface42of the mold resin40, and the surface21of the substrate20exposed to the bottom of the groove44is also covered with the magnetic film50. Further, as in the modification illustrated inFIG. 12, when the insulating film70is interposed between the top surface51of the magnetic film50and the metal film60, after formation of the magnetic film50, an insulating material such as a thermosetting material, a heat-resistant thermoplastic material, an Si oxide or a low-melting point glass may be thinly formed on the top surface51of the magnetic film50.

Then, as illustrated inFIG. 18, a groove45having a width W2is formed along the dashed line a to cut the assembly substrate20A into a plurality of substrates20. At this time, The width W2of the groove45needs to be smaller than the width W1of the groove44. As a result, the substrate20A is segmented into individual substrates20with the magnetic film50formed inside the groove44remaining. Further, as in the modification illustrated inFIG. 13, when the insulating film70is interposed between the top surface51and side surface52of the magnetic film50and the metal film60, the side surface52of the magnetic film50is exposed by formation of the groove45without segmentation of the assembly substrate20A, then an insulating material such as a thermosetting material, a heat-resistant thermoplastic material, an Si oxide or a low-melting point glass is thinly formed on the top surface51and side surface52of the magnetic film50, followed by cutting of the assembly substrate20A.

Then, the metal film60is formed so as to cover the top surface51and side surface52of the magnetic film50and the side surface27of the substrate20, whereby the electronic circuit package13A according to the present embodiment is completed.

As described above, in the manufacturing method for the electronic circuit package13A according to the present embodiment, the two grooves44and45having different widths are sequentially formed, whereby the side surface42of the mold resin40can be covered with the magnetic film50without use of a complicated process.

Fourth Embodiment

FIG. 19is a cross-sectional view illustrating a configuration of an electronic circuit package14A according to the fourth embodiment of the present invention.

As illustrated inFIG. 19, the electronic circuit package14A according to the present embodiment has the same configuration as that of the electronic circuit package13A ofFIG. 11according to the third embodiment except for shapes of the substrate20and metal film60. Thus, inFIG. 19, the same reference numerals are given to the same elements as inFIG. 11, and repeated descriptions will be omitted.

In the present embodiment, as in the second embodiment, the side surface lower portion27bof the substrate20protrudes from the side surface upper portion27a, and the metal film60is formed so as to cover the side surface upper portion27aand step portion27c. Also in the present embodiment, the power supply pattern25G is exposed to the side surface upper portion27aof the substrate20, and the metal film60is connected to the power supply pattern25G through the side surface upper portion27a. When a material having a comparatively low resistance value is used as the material for the magnetic film50, the thin insulating film70is preferably interposed between the top surface51(and side surface52) of the magnetic film50and the metal film60as in an electronic circuit package14B ofFIG. 20according to a modification.

FIGS. 21 and 22are process views for explaining a manufacturing method for the electronic circuit package14A.

First, the magnetic film50is formed on the top surface41of the mold resin40and inside the groove44by the method described usingFIGS. 3, 4, 16, and 17. Then, as illustrated inFIG. 21, a groove46having a width W3is formed along the dashed line a indicating the dicing position (SeeFIG. 3). The groove46has a depth completely cutting the mold resin40and not completely cutting the substrate20. The width W3is made smaller than the width W1of the groove44ofFIG. 16. As a result, the side surface52of the magnetic film50and the side surface upper portion27aand step portion27cof the substrate20are exposed inside the groove46. The depth of the side surface upper portion27aneeds to be set to at least a depth allowing the power supply pattern25G to be exposed.

Then, as illustrated inFIG. 22, the metal film60is formed using a sputtering method, a vapor-deposition method, an electroless plating method, an electrolytic plating method, or the like. As a result, the top surface51of the magnetic film50and inside of the groove46are covered with the metal film60. At this time, the power supply pattern25G exposed to the side surface upper portion27aof the substrate20is connected to the metal film60.

Then, the assembly substrate20A is cut along the dashed line a to segment the assembly substrate20A into individual substrates20, whereby the electronic circuit package14A according to the present embodiment is completed.

As described above, according to the manufacturing method for the electronic circuit package14A of the present embodiment, the metal film60can, similarly to the second embodiment, be formed before substrate segmentation, thereby facilitating formation of the metal film60.

Fifth Embodiment

FIG. 23is a cross-sectional view illustrating a configuration of an electronic circuit package15A according to the fifth embodiment of the present invention.

As illustrated inFIG. 23, the electronic circuit package15A according to the present embodiment differs from the electronic circuit package13A ofFIG. 11according to the third embodiment in that the magnetic film50covers a part of the side surface27of the substrate20. Other configurations are the same as those of the electronic circuit package13A according to the third embodiment. Thus, inFIG. 23, the same reference numerals are given to the same elements as inFIG. 11, and repeated descriptions will be omitted.

In the present embodiment, the side surface27of the substrate20has a step shape. Specifically, a side surface lower portion27eof the substrate20protrudes from a side surface upper portion27d. The magnetic film50is formed so as to cover the top surface41and side surface42of the mold resin40and to further cover the side surface upper portion27dand a step portion27fof the substrate20. The side surface lower portion27eof the substrate20is not covered with the magnetic film50, and the power supply pattern25G exposed to the side surface lower portion27econtacts the metal film60.

With this configuration, an interface between the surface21of the substrate20and the mold resin40is covered with the magnetic film50. In general, a solder resist is formed on the surface21of the substrate20and, when moisture contained in the substrate20or the mold resin40expands at the time of reflow, a peeling may occur between the substrate and solder resist or between the mold material and the solder resist, a crack may occur in the solder resist, mold material, or the substrate, and swelling, peeling, or the like may occur in the metal film60formed as an electromagnetic shield film. Further, the solder24that joins and fixes electronic components is melted around a MAX reflow temperature, so that a stress occurs due to volume expansion of the solder, which may accelerate the above phenomenon. However, in the present embodiment, the interface between the surface21of the substrate20and the mold resin40is retained by the magnetic film50with high adhesion, so that the above peeling is unlikely to occur. In particular, when the composite magnetic material is used as the material for the magnetic film50, not only the interface between the substrate20and the mold resin40can be physically retained with high adhesion, but also moisture reaching the interface between the substrate20and the mold resin40can be moved through the composite magnetic material which is the material for the magnetic film50. This can effectively prevent the peeling between the substrate and the solder resist or between the mold material and the solder resist, crack in the solder resist, mold material, or the substrate, and swelling, peeling, or the like in the metal film60formed as an electromagnetic shield film, thus increasing reliability.

The electronic circuit package15A according to the present embodiment can be manufactured by forming the groove44more deeply in the process illustrated inFIG. 16.

Also in the present embodiment, when a material having a comparatively low resistance value is used as the material for the magnetic film50, the thin insulating film70is preferably interposed between the top surface51(and side surface52) of the magnetic film50and the metal film60as in an electronic circuit package15B ofFIG. 24according to a modification.

FIG. 25is a cross-sectional view illustrating a configuration of an electronic circuit package15C according to a modification.

The electronic circuit package15C illustrated inFIG. 25differs from the electronic circuit package15A ofFIG. 23according to the fifth embodiment in that the magnetic film50covers a wiring pattern29exposed to the side surface27of the substrate20. Other configurations are the same as those of the electronic circuit package15A according to the fifth embodiment. Thus, inFIG. 25, the same reference numerals are given to the same elements as inFIG. 23, and repeated descriptions will be omitted.

The wiring pattern29contacting the magnetic film50may be a ground power supply pattern or a signal wiring. However, when a material having a high conductivity is used as the material for the magnetic film50, the same potential as the power supply pattern25G that the metal film60contacts needs to be applied to the wiring pattern29.

With this configuration, it is possible to prevent not only the peeling between the substrate and the solder resist or between the mold material and the solder resist, crack in the solder resist, mold material, or the substrate, and swelling, peeling, or the like in the metal film60formed as an electromagnetic shield film, but also a peeling in the interface between the substrate20and the wiring pattern29due to expansion of the moisture, thus ensuring higher reliability. Also in this case, by using the composite magnetic material as the material for the magnetic film50, peeling of the wiring pattern29can be prevented more effectively.

Also in the present embodiment, when a material having a comparatively low resistance value is used as the material for the magnetic film50, the thin insulating film70is preferably interposed between the top surface51(and side surface52) of the magnetic film50and the metal film60as in an electronic circuit package15D ofFIG. 26according to a modification.

While the preferred embodiments of the present invention have been described, the present invention is not limited thereto. Thus, various modifications may be made without departing from the gist of the invention, and all of the modifications thereof are included in the scope of the present invention.

EXAMPLES

An embodiment sample 1 having the same structure as that of the electronic circuit package11A illustrated inFIG. 1was actually produced. As the substrate20, a multilayer resin substrate having a planar size of 8.5 mm×8.5 mm and a thickness of 0.3 mm was used. As the magnetic film50, a composite magnetic material having a permeability μ=25 in which Fe-based spherical magnetic fillers are dispersed and mixed in a thermosetting resin was used. The magnetic film50was formed on the top surface41of the mold resin40by screen printing in a thickness of about 50 μm, followed by post-curing under predetermined conditions. As the metal film60, a laminated film of Cu (having a film thickness of 1 μm) and Ni (having a film thickness of 2 μm) was used.

As a comparative example, comparative samples 1 and 2 were produced. The comparative sample 1 was obtained by removing the magnetic film50from the embodiment sample 1, and comparative sample 2 was obtained by removing the metal film60from the embodiment sample 1. Thus, as the shield, the comparative sample 1 only has an electromagnetic shield formed by the metal film60, and the comparative sample 2 only has a magnetic shield formed by the magnetic film50.

Then, each of the above samples was reflow mounted on a shield characteristic evaluation substrate, and a noise attenuation amount therein was measured by a neighboring magnetic field measuring apparatus to evaluate shield characteristics. The results are illustrated in Table 1. The unit of numeric values is dBμV.

Table 1 reveals that the embodiment sample 1 is larger in noise attenuation amount than the comparative samples 1 and 2 and further reveals that the noise attenuation amount of the embodiment sample 1 is larger than a sum (A+B) of the noise attenuation amount (A) of the comparative sample 1 having only the metal film60as the shield and noise attenuation amount (B) of the comparative sample 2 having only the magnetic film50as the shield. That is, a composite-shield having a structure in which the magnetic film50and metal film60are laminated in this order can obtain a higher composite-shield effect than in a case where a shield effect obtained by the electromagnetic shield formed only by the metal film60and a shield effect obtained by the magnetic field formed only by the magnetic film50are simply added to each other.

Then, another embodiment sample 2 having the same structure as that of the electronic circuit package11A illustrated inFIG. 1and a comparative sample 3 having a structure in which the lamination order of the magnetic film50and metal film60of the embodiment sample 2 is reversed were produced. Then, each of the above samples was mounted on a shield characteristic evaluation substrate, and a noise attenuation amount therein was measured by a neighboring magnetic field measuring apparatus. The results are illustrated in Table 2. The unit of numeric values is dBμV.

Table 2 reveals that the comparative sample 3 having a structure in which the lamination order of the magnetic film and metal film60is reversed is smaller in noise attenuation amount than the embodiment sample 2. This reveals that by laminating the magnetic film50and metal film60in this order, a high composite-shield effect can be obtained. Table 2 further reveals that a difference (E-D) between the embodiment sample 2 and the comparative sample 3 becomes more remarkable in a low-frequency region.