JP2014107372A - Circuit module and manufacturing method of the same - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a circuit module in which a metal film has high adhesion and provide a manufacturing method of the circuit module.SOLUTION: A circuit module manufacturing method according to one embodiment includes step of: forming an encapsulation layer for covering electronic components on a wiring board having a plurality of unit regions in each of which the electronic component is mounted; bonding a first metal film on a top face of the encapsulation layer; forming cut grooves for partitioning the plurality of unit regions from above the metal film to a depth reaching the inside of the wiring board; and forming a second metal film for covering the first metal film and lateral faces exposed in the cut grooves in respective encapsulation layers of the plurality of unit regions.

Description

  The present invention relates to a circuit module having an electromagnetic shielding function and a manufacturing method thereof.

  2. Description of the Related Art A circuit module is known that includes a wiring board, a plurality of electronic components mounted on the surface thereof, a sealing layer that covers the electronic components, and external connection terminals formed on the back surface of the wiring board. As this type of circuit module, one having an electromagnetic shield that prevents leakage of electromagnetic waves to the outside of the module and intrusion of electromagnetic waves from the outside is known. Such an electromagnetic shield is composed of, for example, a conductive resin film, a metal film, or the like that covers the sealing layer (see Patent Documents 1 and 2).

  Patent Document 2 describes a method for manufacturing a circuit module in which a metal film is formed on a sealing layer by a plating method. However, since the sealing layer is generally formed of a resin material, the adhesion between the metal film and the sealing layer is low, and the metal film may peel off at the interface of the sealing layer.

  On the other hand, desmear treatment is known as a base treatment for plating a metal film on a resin material (see Patent Document 3). By performing the desmear treatment, irregularities are formed on the surface of the resin, and the adhesion with the metal film can be enhanced by an anchor effect.

JP 2004-172176 A JP 2004-193187 A JP 2011-162806 A

  The desmear treatment liquid is generally strongly alkaline such as permanganic acid. Thereby, at the time of desmear treatment, in order to protect the external connection terminals and the like from etching by the desmear treatment liquid, it is necessary to mask the back surface of the wiring board with an alkali-resistant tape or the like. However, when the tape is peeled off, a large stress is applied to the module, and cracks and cracks may occur.

  Therefore, a circuit module that can improve the adhesion between the metal film and the sealing layer without desmearing is desired.

  In view of the circumstances as described above, an object of the present invention is to provide a circuit module having high adhesion of a metal film and a method for manufacturing the circuit module.

In order to achieve the above object, a method of manufacturing a circuit module according to an aspect of the present invention forms a sealing layer that covers the electronic component on a wiring board having a plurality of unit regions each mounted with the electronic component. Process.
A first metal film is bonded to the top surface of the sealing layer.
The cutting grooves that define the plurality of unit regions are formed with a depth that reaches the inside of the wiring substrate from above the first metal film.
A second metal film is formed to cover the side surface exposed in the cutting groove of the sealing layer in each of the plurality of unit regions and the first metal film.

In order to achieve the above object, a circuit module according to an embodiment of the present invention includes a wiring board, a sealing layer, a first metal film, and a second metal film.
The wiring board has a surface on which electronic components are mounted.
The sealing layer has a main surface facing the surface and a side surface formed continuously around the main surface, is formed on the wiring board, and covers the electronic component.
The first metal film includes an adhesive layer bonded to the main surface and a metal layer laminated on the adhesive layer.
The second metal film covers the side surface of the sealing layer and the metal layer.

It is a schematic sectional drawing which shows the circuit module which concerns on one Embodiment of this invention. It is a figure explaining the manufacturing method of the said circuit module, Comprising: It is a schematic sectional drawing which shows the structure of a wiring board. It is a figure explaining the manufacturing method of the said circuit module, Comprising: It is a schematic sectional drawing explaining the mounting process of an electronic component. It is a figure explaining the manufacturing method of the said circuit module, Comprising: It is a schematic sectional drawing explaining the formation process of a sealing layer. It is a figure explaining the manufacturing method of the said circuit module, Comprising: It is a schematic sectional drawing explaining the adhesion process of a 1st metal film. It is a figure explaining the manufacturing method of the said circuit module, Comprising: It is a schematic sectional drawing explaining the formation process of a cutting groove. It is a figure explaining the manufacturing method of the said circuit module, Comprising: It is a schematic sectional drawing which shows the aspect by which the back surface of the wiring board was coat | covered with the masking tape as preparation for forming a 2nd metal film. It is a figure explaining the manufacturing method of the said circuit module, Comprising: It is a schematic sectional drawing explaining the formation process of a 2nd metal film. It is a figure explaining the manufacturing method of the said circuit module, Comprising: It is a schematic sectional drawing explaining the formation process of a 3rd metal film. It is a figure explaining the manufacturing method of the said circuit module, Comprising: It is a schematic sectional drawing which shows the aspect from which the said masking tape was removed. It is a figure explaining the manufacturing method of the said circuit module, Comprising: It is a schematic sectional drawing explaining an individualization process. It is a schematic sectional drawing which shows the structure of the circuit module which concerns on one comparative example of the said embodiment. It is a schematic sectional drawing which shows the structure of the circuit module which concerns on the other comparative example of the said embodiment.

A method for manufacturing a circuit module according to an embodiment of the present invention includes a step of forming a sealing layer that covers the electronic component on a wiring board having a plurality of unit regions each mounted with the electronic component.
A first metal film is bonded to the top surface of the sealing layer.
The cutting grooves that define the plurality of unit regions are formed with a depth that reaches the inside of the wiring substrate from above the first metal film.
A second metal film is formed to cover the side surface exposed in the cutting groove of the sealing layer in each of the plurality of unit regions and the first metal film.

  The first metal film is bonded to the top surface of the sealing layer. Here, “the top surface of the sealing layer” refers to a surface of the outer surface of the sealing layer that faces the wiring board. Thereby, since the second metal film is formed on the sealing layer via the first metal film, the adhesion can be improved. Moreover, the side surface of the sealing layer is formed as a part of the side wall surface of the cutting groove by the cutting process. At this time, for example, the cutting tool forms a cutting groove by rotating, linearly moving, or the like while being in contact with the sealing layer or the like. As a result, friction between the tool and the sealing layer occurs, the side surface of the sealing layer is roughened, and fine irregularities are formed. That is, between the second metal film and the side surface of the sealing layer, an anchor effect is generated by the roughened side surface, and adhesion can be improved. Accordingly, the second metal film can be configured to have high adhesion over the entire surface, and it is possible to prevent problems such as peeling of the second metal film without performing a base treatment such as desmear treatment on the sealing layer. Can do.

In the step of forming the second metal film, the second metal film may be formed by a plating method.
Thereby, even when the aspect ratio of the cutting groove is high, the second metal film can be uniformly formed on the side wall surface and the bottom surface of the cutting groove. Furthermore, the second metal film can be easily formed at low cost.

Furthermore, a third metal film that covers the second metal film may be formed after the step of forming the second metal film.
As a result, a two-layer metal film of the second and third metal films can be employed as the electromagnetic shield structure. Thereby, the selectivity of the material of each metal film can be increased, and a shield film that is easy to manufacture and excellent in durability can be formed.

In the step of forming the third metal film, the third metal film may be formed by a plating method.
Thereby, the third metal film can be easily formed at low cost. Furthermore, the third metal film can be uniformly formed on the second metal film formed on the side wall surface and the bottom surface of the cutting groove in a shape following the cutting groove.

Specifically, the first metal film has an adhesive layer and a metal layer formed on the adhesive layer,
The step of bonding the first metal film may bond the adhesive layer to the top surface.

In the step of forming the cutting groove, the cutting groove may be formed at a depth reaching an internal wiring layer formed in the wiring board.
Thereby, the second electrode film formed in the cutting groove and the internal wiring layer can be electrically connected. Therefore, for example, the electromagnetic shielding effect of the second electrode film can be further enhanced by connecting the internal wiring layer to the ground potential.

The step of forming the cutting groove forms the cutting groove with a first width,
In the method of manufacturing the circuit module, after the step of forming the second metal film, the wiring board is cut along the cutting groove with a second width narrower than the first width, Each unit area may be divided into pieces.
Thereby, a several unit area | region can be separated into pieces easily by cutting. Further, by cutting with a width narrower than the width of the cutting groove, each unit region can be separated into pieces without cutting the second metal film or the like formed on the side wall surface of the cutting groove.

A circuit module according to an embodiment of the present invention includes a wiring board, a sealing layer, a first metal film, and a second metal film.
The wiring board has a surface on which electronic components are mounted.
The sealing layer has a main surface facing the surface and a side surface formed continuously around the main surface, is formed on the wiring board, and covers the electronic component.
The first metal film includes an adhesive layer bonded to the main surface and a metal layer laminated on the adhesive layer.
The second metal film covers the side surface of the sealing layer and the metal layer.

  The first metal film is bonded with the adhesive layer facing the main surface of the sealing layer. The second metal film is formed on a metal layer bonded onto the sealing layer via an adhesive layer. As a result, the adhesion of the second metal film can be improved, and the peeling or cracking of the second metal film due to mechanical impact or external force can be suppressed. Furthermore, the difference in thermal expansion coefficient between the second metal film and the first metal film can be reduced, and the generation of thermal stress in the second metal film can also be suppressed. Therefore, product damage or the like can be suppressed and a stable shielding effect can be maintained.

The side surface may be a roughened surface.
Thereby, the said side can exhibit an anchor effect between the 2nd metal film. Therefore, it becomes possible to improve the adhesion between the side surface of the sealing layer and the second metal film.

The sealing layer and the adhesive layer may be formed of the same resin material.
Thereby, a sealing layer and an adhesive layer can be adhere | attached more firmly. Furthermore, the thermal expansion coefficients of the sealing layer and the adhesive layer can be made substantially the same, and the generation of thermal stress can be suppressed.

Further, the first metal film and the second metal film may be formed of copper.
Thereby, the second metal film can be easily formed by plating while suppressing the cost. In addition, the adhesion between the first and second metal films can be enhanced. Furthermore, by making the thermal expansion coefficients of the first and second metal films substantially the same, generation of thermal stress can be further suppressed.

Furthermore, you may comprise the 3rd metal film which covers the said 2nd metal film. Further, the third metal film may be formed of nickel.
Thereby, an electromagnetic shielding function can be improved more. Further, by forming the third metal film from nickel, a structure having high strength and high corrosion resistance can be obtained.

  Hereinafter, embodiments of the present invention will be described with reference to the drawings.

[Circuit module]
FIG. 1 is a schematic cross-sectional view showing a circuit module according to an embodiment of the present invention. In the figure, the X, Y, and Z axes indicate three axial directions orthogonal to each other, and the Z-axis direction corresponds to the thickness direction of the circuit module. For easy understanding, the thickness and size of each part are exaggerated.

  The circuit module 1 according to the present embodiment includes a wiring board 2, a sealing layer 4, a first metal film 5, a second metal film 6, and a third metal film 7. The second metal film 6 and the third metal film 7 constitute a shield film 8 in this embodiment.

  The circuit module 1 has a substantially rectangular parallelepiped shape as a whole. The size is not particularly limited. For example, the length along the X-axis direction and the Y-axis direction is 2 to 40 mm. Moreover, thickness is not specifically limited, For example, it is comprised by 0.7-2.5 mm.

  In the circuit module 1, a plurality of electronic components 3 are arranged on a wiring board 2, and a sealing layer 4, a first metal film 5, a second metal film 6, and a third metal film are provided so as to cover them. 7 is formed. Hereinafter, the configuration of each part of the circuit module 1 will be described.

(Wiring board)
The wiring board 2 has a front surface 21 and a back surface 22 configured in a substantially rectangular shape that is, for example, the same as the overall dimensions of the circuit module 1, and is formed of a multilayer wiring board having a thickness of, for example, about 0.3 mm. The front surface 21 and the back surface 22 are, for example, surfaces that are substantially orthogonal to the Z-axis direction, and are disposed to face each other in the Z-axis direction. The material constituting the insulating layer of the substrate 2 is, for example, a glass epoxy material, but is not limited thereto, and an insulating ceramic material or the like can also be used.

  A plurality of electronic components 3 are mounted on the surface 21. Specifically, the plurality of electronic components 3 include various components such as an integrated circuit (IC), a capacitor, an inductor, a resistor, a crystal resonator, a duplexer, a filter, and a power amplifier. The plurality of electronic components 3 are typically mounted on the surface 21 by solder, adhesive, bonding wires, or the like.

  The wiring layer of the wiring substrate 2 is typically made of copper foil, and is disposed on the front surface 21, the back surface 22, and the inner layer portion of the wiring substrate 2. The wiring layer is patterned into a predetermined shape, thereby constituting the external connection terminal 23, the land portion 24, and the internal wiring layer 25, respectively. The external connection terminal 23 is formed on the back surface 22 and is connected to, for example, a control board (not shown) of an electronic device on which the circuit module 1 is mounted. The land portion 24 is formed on the surface 21 and the electronic component 3 is mounted thereon. Further, an insulating film such as a solder resist may be formed in a region where the land portion 24 of the surface 21 is not formed (not shown). These wiring layers are electrically connected to each other via via conductors (not shown).

  Further, as part of the internal wiring layer 25, a GND terminal 25g connected to the ground (GND) potential is formed. For example, the GND terminal 25g is disposed adjacent to a stepped portion 26 formed on the periphery of the wiring substrate 2 and connected to the inner surface of the second electrode film 6 covering the stepped portion 26. The GND terminal 25g is connected to the ground wiring of the control board via the external connection terminal 23.

(Sealing layer)
The sealing layer 4 is formed on the wiring board 2 so as to cover the electronic component 3. Specifically, the sealing layer 4 is formed in a substantially rectangular parallelepiped shape as a whole, a main surface 41 facing the surface 21 in the Z-axis direction, and four side surfaces 42 formed continuously around the main surface 41. And have. Each side surface 42 is formed substantially perpendicular to the main surface 41, for example. The four side surfaces 42 are not distinguished from each other in the following description and are denoted by the same reference numerals. Further, the thickness of the sealing layer 4 in the Z-axis direction, that is, the thickness from the surface 21 to the main surface 41 is configured to be larger than the thickest electronic component 3 in the Z-axis direction. Is configured to be larger than 0.1 mm.

  The sealing layer 4 is formed of an insulator, and in this embodiment, an epoxy resin that is a thermosetting resin is employed. The epoxy resin may be added with a filler for the purpose of improving the strength. For example, the epoxy resin may contain 70% by weight or more of an inorganic filler having a filler diameter of 100 μm or less.

  As will be described later, the sealing layer 4 is formed by cutting a sealing resin layer formed on a large-area collective substrate for each predetermined unit region. Therefore, the side surface 42 of the sealing layer 4 becomes a roughened surface by contacting with a cutting tool or the like during cutting. That is, fine irregularities are formed on the side surface 42.

(First metal film)
The 1st metal film 5 is arrange | positioned on the main surface 41 of the sealing layer 4, and is comprised as a resin film with metal foil. The first metal film 5 includes an adhesive layer 51 and a metal layer 52, and is configured in a substantially rectangular shape having the same size as the main surface 41 as a whole, for example.

  The adhesive layer 51 is configured as a resin adhesive film, for example, and is adhered to the main surface 41. The adhesive layer 51 may be formed of the same resin material as the material of the sealing layer 4 and is formed of an epoxy resin in the present embodiment. The thickness of the adhesive layer 51 is not particularly limited, but is about 5 to 30 μm, for example.

  The metal layer 52 is formed of copper in this embodiment. That is, the metal layer 52 is a copper foil laminated on the adhesive layer 51, and is configured integrally with the adhesive layer 51 in the present embodiment. The thickness of the metal layer 52 is not particularly limited, but is formed with a thickness of about 1 to 10 μm, for example.

(Shield film)
The shield film 8 functions as an electromagnetic shield of the circuit module 1 and prevents leakage of electromagnetic waves generated from the electronic component 3 to the outside of the circuit module 1 and intrusion of electromagnetic waves from the outside. In this embodiment, the shield film 8 is composed of a two-layer metal film that covers the first metal film 5 and the sealing layer 4, and includes a second metal film 6 and a third metal film 7.

  The second metal film 6 is configured to cover the metal layer 52 of the first metal film 5, the side surface 42 of the sealing layer 4, and the stepped portion 26 of the wiring substrate 2. That is, in this embodiment, the second metal film 6 is continuous with the main surface orthogonal to the Z-axis direction, four side surfaces that are formed continuously from the periphery of the main surface, and orthogonal to the main surface. And a flange portion formed in the step portion 26 and substantially parallel to the main surface.

  With the above configuration, the second metal film 6 covers the electronic component 3 via the sealing layer 4 and can electrically shield the electronic component 3 from the outside of the circuit module 1. Further, the second metal film 6 is maintained at the ground potential by being electrically connected to the GND terminal 25g exposed at the step portion 26. Therefore, a higher electromagnetic shielding function can be exhibited.

  The material for forming the second metal film 6 is not particularly limited as long as it is a conductor, but copper is employed in the present embodiment, similarly to the metal layer 52. The thickness of the second metal film 6 is not particularly limited, and can be, for example, about 0.3 to 10 μm.

  The third metal film 7 is formed so as to cover the second metal film 6. The shape of the third metal film 7 is not particularly limited, but is formed following the second metal film 6. For example, the third metal film 7 is formed continuously from the main surface perpendicular to the Z-axis direction and the periphery of the main surface. It may have four side surfaces orthogonal to the surface, and may further have a flange portion formed continuously with the four side surfaces and parallel to the main surface.

  The material for forming the third metal film 7 is not particularly limited as long as it is a conductor, and nickel is employed in this embodiment. Accordingly, the third metal film 7 can be configured to have excellent corrosion resistance, and the stability of the entire shield film 8 can be improved. The thickness of the third metal film 7 is not particularly limited, and can be about 1 to 10 μm, for example.

  The circuit module 1 configured as described above includes a metal layer 52 that is bonded onto the sealing layer 4 via the adhesive layer 51, and a second metal film 7 that is formed on the metal layer 52. Thus, by using a metal material for the base of the second metal film 7, the adhesion of the second metal film 7 can be enhanced. Furthermore, as described above, the side surface 42 of the sealing layer 4 is roughened. Thereby, in the side surface 42, it becomes possible to improve adhesiveness with the 2nd metal film 7 by the anchor effect. Therefore, peeling of the second metal film 7 and the like can be suppressed, and product damage of the circuit module 1 can be further suppressed. Furthermore, the electromagnetic shielding function of the circuit module 1 can be stably maintained, and leakage of electromagnetic waves to the outside, intrusion of electromagnetic waves from the outside, and the like can be effectively suppressed.

  In the present embodiment, the sealing layer 4 and the adhesive layer 51 can be formed of the same resin material. Thereby, the thermal expansion coefficients of the sealing layer 4 and the adhesive layer 51 can be made substantially the same, and damage such as peeling or cracking between the sealing layer 4 and the adhesive layer 51 can be suppressed. Moreover, the adhesiveness of the adhesive layer 51 to the sealing layer 4 can be further enhanced.

  Further, by forming the metal layer 52 and the second metal film 7 with the same metal material, it becomes possible to further improve the adhesion. Furthermore, the coefficient of thermal expansion of the metal layer 52 and the second metal film 7 can be made substantially the same, and damage such as peeling or cracking between the metal layer 52 and the second metal film 7 can be further suppressed. it can. In addition, by adopting copper for the second metal film 7, the same material as that of the GND terminal 25g formed of copper foil can be used. Thereby, the contact resistance between the second metal film 7 and the GND terminal 25g can be reduced, which can contribute to the improvement of the electromagnetic shielding function.

  Next, a method for manufacturing the circuit module 1 configured as described above will be described.

[Method for manufacturing circuit module]
2 to 11 are schematic cross-sectional views illustrating a method for manufacturing the circuit module 1. The circuit module manufacturing method according to the present embodiment includes a wiring board preparation step, an electronic component mounting step, a sealing layer forming step, a first metal film bonding step, and a cutting groove forming step. , A second metal film forming step, a third metal film forming step, and a singulation step. Hereinafter, each step will be described.

(Wiring board preparation process)
FIG. 2 is a schematic cross-sectional view showing the configuration of the wiring board.

  First, the wiring board 20 is prepared. The wiring board 20 is configured as a large-area collective board on which a plurality of wiring boards 2 are imposed. Hereinafter, the above-described wiring board 2 will be described as each unit region 10 on the wiring board 20. On the wiring board 20, a plurality of unit regions 10 are arranged adjacent to each other in the X-axis direction and the Y-axis direction. In FIG. 2, a separation line L <b> 10 that partitions the unit regions 10 is shown. The separation line L10 may be virtual or may be actually drawn on the wiring board 20 by printing or the like.

  The wiring board 20 has a front surface 210 that is a mounting surface of the electronic component 3 and a back surface 220 that faces the front surface 210. A predetermined wiring pattern is formed for each unit region 10 on the front surface 210, the back surface 220, and the inner layer portion of the wiring substrate 20. FIG. 2 shows an external electrode 230 formed on the back surface 220, a land portion 240 formed on the front surface 210, and an internal wiring layer 250 as wiring patterns. These wiring patterns correspond to the external connection terminals 23, the land portions 24, and the internal wiring layers 25, respectively, when separated.

  The wiring substrate 20 is formed up to the third metal film 70 through each process to be described later, and is cut (full cut) for each unit region 10 along the separation line L10 in the final singulation process. As a result, a plurality of circuit modules 1 are manufactured from one wiring board 20.

(Electronic component mounting process)
FIG. 3 is a schematic cross-sectional view for explaining a mounting process of the electronic component 3 and shows an aspect in which the electronic component 3 is arranged on the wiring board 20.

  In this step, the electronic component 3 is mounted on the wiring board 20 via the land portion 240. As a mounting method of the electronic component 3, for example, a reflow method is adopted. Specifically, first, a metal mask penetrating a portion corresponding to the land portion 240 is disposed on the surface 210, and a solder paste is applied to the surface 210 by a screen printing method or the like. Next, the plurality of electronic components 3 are mounted on the predetermined land portion 240 via the printed solder paste. Thereafter, the wiring board 20 on which the electronic component 3 is mounted is carried into a reflow furnace and heated to a temperature higher than the melting point of the solder to melt (reflow) the solder paste. The heating temperature at this time can be, for example, 20 ° C. or more higher than the melting point of the solder. Thereby, each electronic component 3 is electrically and mechanically joined on the surface 210.

  You may perform the washing | cleaning process which removes the organic substance (flux residue) contained in the solder paste remaining around the land part 240 after the mounting process. If the organic matter remains around the land portion 240, it may cause a defect such as an insulation failure or a contact failure due to the generation of a leakage current, which may cause a malfunction. Therefore, the above-described problems can be prevented by washing these organic substances. Specifically, first, the organic matter around the land portion 240 is cleaned on the surface 210 with a cleaning liquid such as an organic solvent. After the cleaning, the wiring board 20 is dried at a predetermined temperature, and the cleaning liquid is sufficiently volatilized.

(Sealing layer formation process)
FIG. 4 is a schematic cross-sectional view for explaining the formation process of the sealing layer 40 and shows an aspect in which the sealing layer 40 covering the electronic component 3 is formed on the wiring board 20.

  The sealing layer 40 is formed on the wiring board 20 so as to cover the electronic component 3. The sealing layer 40 is formed thicker in the Z-axis direction than the plurality of electronic components 3. For example, the sealing layer 40 can be formed to be thicker by about 0.1 mm or more than the thickest electronic component 3 in the Z-axis direction among the plurality of electronic components 3. Thereby, the electronic component 3 can be reliably covered with the sealing layer 40, and problems such as deterioration of the electronic component 3 due to intrusion of outside air and a short circuit between the electronic component 3 and the first metal film 5 are prevented. be able to.

  The formation method of the sealing layer 40 is not particularly limited, and for example, a liquid or paste-like sealing resin material may be applied on the surface 210 by a screen printing method and then cured by a predetermined treatment. The coating method may be a spin coating method or the like. Alternatively, as a method for forming the sealing layer 5, a molding method, a potting method, or the like can be applied.

  The curing method of the sealing resin can be appropriately selected according to the material of the sealing resin. In this embodiment, since the sealing layer 40 is formed of an epoxy resin that is a thermosetting resin, the resin can be cured by heat treatment. The method of heat treatment is not particularly limited, but may be heated stepwise at different temperatures, for example, heated at two steps. After the heat treatment, the sealing resin is cooled to about room temperature, and the sealing layer 40 is formed. At this time, for example, the cooling may be gradually performed at 0.5 ° C./min or less. Thereby, generation | occurrence | production of the crack etc. accompanying rapid cooling of sealing resin can be prevented. In order to accelerate curing, a predetermined amount of a curing agent may be mixed in the sealing resin material. When an epoxy resin is used, for example, an acid anhydride type or amine type curing agent can be used.

  Moreover, you may perform the process which removes the void (bubble) of sealing resin material after application | coating of the sealing layer 5, and before hardening processing as needed. For example, when the sealing resin material has viscosity, a void may be formed in the gap between the land portion 240 and the electronic component 3. Then, the wiring board 20 after resin supply is conveyed to a vacuum chamber etc., and the pressure in the said vacuum chamber is reduced to a predetermined degree of vacuum. As a result, the void can be removed, and then the pressure is increased (recovered) to about atmospheric pressure. Further, such a decrease and increase in pressure may be repeated for a predetermined cycle. Alternatively, the generation of voids can be suppressed by applying the sealing resin material itself under vacuum.

  The sealing layer 40 formed in this way has a top surface 410 facing the surface 210 in the Z-axis direction, and is configured to cover the entire surface 210 of the wiring board 20. The top surface 410 constitutes the outer surface of the sealing layer 40 and is a surface formed to face the surface 210 in the Z-axis direction. Further, the top surface 410 constitutes the main surface 41 of the sealing layer 4 of each circuit module 1 after being separated into individual pieces.

(Adhesion process of the first metal film)
FIG. 5 is a schematic cross-sectional view for explaining the bonding process of the first metal film 50 and shows a mode in which the first metal film 50 is bonded to the top surface 410 of the sealing layer 40.

  The first metal film 50 includes an adhesive layer 510 and a metal layer 520 laminated on the adhesive layer 510, and is configured as a resin film with metal foil. The first metal film 50 is bonded to the top surface 410 of the sealing layer 40. That is, the first metal film 50 is bonded with the adhesive layer 510 facing the top surface 410 side. The metal layer 520 is disposed on the adhesive layer 510 facing outward.

  The adhesive layer 510 is formed of an epoxy resin that is a thermosetting resin in the present embodiment, and is semi-cured (B-staged) in advance during this process. For this reason, the adhesive layer 510 has adhesiveness and is easily affixed on the sealing layer 40.

  The bonding method of the first metal film 50 is not particularly limited. For example, after the adhesive layer 510 is placed on the sealing layer 40, the adhesive layer 510 is heated under vacuum using a vacuum laminator or the like and is pressure-bonded onto the sealing layer 40. Thereby, it becomes possible to adhere | attach these, without generating a bubble etc. between the contact bonding layer 510 and the sealing layer 40. FIG. The adhesive layer 510 is fixed on the sealing layer 40 by being cured by heat treatment or the like after the pressure bonding.

(Cutting groove forming process)
FIG. 6 is a schematic cross-sectional view illustrating a process for forming a cutting groove, and shows a mode in which a cutting groove L20 is formed inside the first metal film 50, the sealing layer 40, and the wiring board 20. In this step, the cutting groove L20 having a predetermined shape is formed by, for example, a dicer, and the wiring board 20 is half cut.

  The cutting groove L20 is formed along the separation line L10 so as to partition the plurality of unit regions 10. That is, the cutting grooves L20 are formed in a lattice shape along the X-axis direction and the Y-axis direction as a whole. Here, when the short direction in the XY plane of the cutting groove L20 is defined as “width”, the cutting groove L20 is formed with the first width W1. In this step, the cutting groove L20 having the first width W1 can be formed by using a dicing blade having a width corresponding to the first width W1. The first width W1 is not particularly limited, but can be, for example, about 0.3 mm to 1.0 mm.

  The cutting groove L20 has a bottom surface having a width substantially the same as the first width W1. The shape of the bottom surface is not particularly limited to a flat surface or a curved surface. The separation line L10 travels along the bottom surface.

  In this embodiment, the cutting groove L20 is formed with a depth reaching the internal wiring layer 250 of the wiring board 20 from the first metal film 50. More specifically, the cutting groove L20 is formed with a depth at which the side surface of the internal wiring layer 250 is exposed on the side wall surface of the cutting groove L20. For example, the internal wiring layer 25g is exposed on the bottom surface of the cutting groove L20. It may be a depth. This depth is designed so as not to impair the strength of the substrate, but is generally about 0.05 to 0.4 mm. As a result, the wiring substrate 20 including the internal wiring layer 250, the sealing layer 40, and the first metal film 50 are exposed on the side wall surface of the cutting groove L20.

  By this step, the first metal film 50 (adhesive layer 510, metal layer 520), sealing layer 40, and wiring internal wiring layer 250 are divided for each unit region 10 of the wiring board 20. As a result, the first metal film 5 (adhesive layer 51, metal layer 52), sealing layer 4 and internal wiring layer 25 are formed. A portion of the internal wiring layer 25 exposed in the cutting groove L20 constitutes a GND terminal 25g.

  Further, a side surface 42 constituting a part of the side wall surface of the cutting groove L20 is formed on the side surface of the sealing layer 4. The side surface 42 is formed by contacting with a dicing blade that rotates and moves linearly, and is worn. Therefore, the side surface 42 is roughened and fine irregularities are formed.

(Second metal film forming step)
7 and 8 are schematic cross-sectional views for explaining a process of forming the second metal film 60. FIG. 7 shows that the back surface 220 is covered with the masking tape M as a preparation for forming the second metal film 60. FIG. 8 shows an embodiment in which the second metal film 60 is formed. In this step, the second metal film 60 made of, for example, copper is formed by a plating method.

  In this step, for example, an electroplating step is performed after the electroless plating step. Thereby, the metal film can be uniformly deposited on the insulator without being limited to the conductor, and the metal film can be efficiently grown. In addition, it is not restricted to this, Only an electroless-plating process may be sufficient.

  In this step, before the electroless plating step is performed, the back surface 220 is previously covered with a protective tape such as a masking tape M. In the electroless plating step according to this step, the entire substrate including the wiring substrate 20 is immersed in the plating solution, so that the metal is deposited on the entire outer peripheral surface including the resin material. As a result, if a metal film (plating) is formed in a region other than the external electrode 230 on the back surface 220, it may cause insulation failure. Therefore, in the present embodiment, the back surface 220 is covered with the masking tape M to prevent metal deposition on the back surface 220. The masking tape M is not particularly limited, and a masking tape having a relatively weak adhesive strength that does not lose the adhesiveness to the immersion of the plating solution can be employed. Note that the side surface of the wiring board 20 is typically cut out during the singulation process, and no problem occurs even if a metal film is formed. Therefore, the presence or absence of the masking tape M is not particularly limited.

  Then, the entire substrate including the wiring board with the masking tape M and the sealing layer is immersed in a plating solution, and an electroless plating process is performed. This makes it possible to deposit a metal film on the entire outer peripheral surface of the module structure, such as on the sealing layer 40, which is an insulator, the wiring substrate 20, and the masking tape M. A metal film is also deposited on the side wall surface and the bottom surface of the cutting groove L20.

  Next, in the electrolytic plating process, the metal film formed in the electroless plating process is used as a seed layer to further grow the metal film, thereby forming the second metal film 60. Thereby, the second metal film 60 having a thickness of about 0.3 μm to 10 μm, for example, is formed on the entire outer peripheral surface including the inside of the cutting groove L20. In the present embodiment, not only the electroless plating method but also an electroplating method with a relatively small film thickness and a relatively high film formation rate is employed to efficiently grow a metal film having a desired thickness. It becomes possible.

(Third metal film forming step)
FIG. 9 is a schematic cross-sectional view for explaining a process of forming the third metal film 70 and shows an aspect in which the third metal film 70 covering the second metal film 60 is formed. Also in this step, the third metal film 70 made of, for example, nickel is formed by plating. For example, an electrolytic plating method is employed as a method of forming the third metal film 70, but an electroless plating method may be employed. The third metal film 70 is formed following the second metal film 60 with a thickness of about 1 μm to 10 μm, for example.

  After the third metal film 70 is formed, the masking tape M is removed. FIG. 10 is a schematic cross-sectional view showing an aspect in which the masking tape M is removed. As a result, the second and third metal films 60 and 70 formed on the surface of the masking tape M are also removed together with the masking tape M. As described above, a masking tape M having a relatively weak adhesive force can be employed in the present embodiment. Thereby, when peeling off the masking tape M, the stress which generate | occur | produces in the circuit module 1 can be reduced and damage can be prevented.

(Individualization process)
FIG. 11 is a schematic cross-sectional view for explaining the singulation process, and shows an aspect in which the wiring board 20 is cut and singulated. In this step, the wiring substrate 20 is cut along the cutting groove L20, and the plurality of unit regions 10 are separated into pieces.

  More specifically, the wiring board 20 is cut (full cut) along the separation line L10 that runs on the bottom surface of the cutting groove L20 by, for example, a dicer. The wiring board 20 is cut with a second width W2 that is narrower than the first width W1. At this time, a dicing blade having a width corresponding to the second width W2 may be used. The second width W2 is not particularly limited, but may be 0.2 to 0.9 mm, for example. Thereby, it is possible to cut only the bottom surface of the cutting groove L20 without cutting away the second and third metal films 60 and 70 formed on the side wall surface of the cutting groove L20.

  By this step, the second and third metal films 60 and 70 and the wiring board 20 are divided for each unit region 10. As a result, the second and third metal films 6 and 7 and the wiring substrate 2 are formed in addition to the first metal film 5 and the sealing layer 4 already formed. Moreover, the level | step-difference part 26 of the wiring board 2 is formed by cutting a part of bottom face of the cutting groove L20 (refer FIG. 1). Thereby, the circuit module 1 which has the above-mentioned structure is produced.

  The circuit module 1 is manufactured through the above steps. In the circuit module manufacturing method according to the present embodiment, the first metal film 5 is bonded onto the sealing layer 4 by using the adhesive force of the adhesive layer 51. Thereby, the adhesiveness to the sealing layer 4 of the 2nd metal film 6 can be improved, and malfunctions, such as peeling, can be prevented. Therefore, it can be set as the structure excellent in handling property and durability.

  Furthermore, in this embodiment, the metal layer 52 and the second metal film 6 are formed of copper, which is the same metal material. This makes it easy to cause the first metal film 5 to function as a plating seed layer and to deposit the second metal film 6 on the first metal film 5. Furthermore, the adhesion between the second metal film 6 and the first metal film 5 can be enhanced.

  Further, by adopting nickel as the material of the third metal film 7, it is possible to obtain a structure having high strength and corrosion resistance while keeping the material cost relatively low.

  Further, by forming the second and third metal films 6 and 7 by the plating method, the second and third metal films 6 and 7 are uniformly formed inside the cutting groove L20 having a high aspect ratio. can do. Thereby, the side surface 42 of the sealing layer 4 can be reliably covered. Furthermore, referring to FIG. 9, it is possible to separate the third metal films 7 respectively formed on the side wall surfaces of the facing cutting grooves L <b> 20 more than the second width. Therefore, it becomes possible to cut easily using a dicer.

  Here, FIG. 12 and FIG. 13 are schematic cross-sectional views illustrating the configuration of a circuit module according to a comparative example of the present embodiment. The operational effects of the circuit module 1 according to the present embodiment will be described in more detail with reference to the circuit modules 1A and 1B described in FIGS.

  A circuit module 1A shown in FIG. 12 includes a wiring board 2A and a sealing layer 4A. The circuit module 1A is different from the circuit module 1 in that the conductive resin film 6A is provided as a shield film. The conductive resin film 6A has a configuration in which conductive particles are dispersed in a base resin material. For this reason, the conductive resin film 6A has high adhesion also to the sealing layer 4A made of a resin material.

  However, the conductive resin film 6A often uses silver or the like as a conductive material, which is disadvantageous in cost.

  On the other hand, the circuit module 1B shown in FIG. 13 includes a wiring substrate 2B and a sealing layer 4B, and further includes metal films 6B and 7B formed by plating as a shield film. By adopting the plating method, the selectivity of the materials of the metal films 6B and 7B can be improved, and the metal films 6B and 7B can be formed at a relatively low cost.

  However, when forming the metal film 6B on the sealing layer 4B, it is necessary to roughen the surface of the sealing layer 4B in advance before the plating step to ensure adhesion by an anchor effect. As a method for roughening a resin material, for example, desmear treatment is known (see Patent Document 3).

  The desmear treatment is a treatment in which the surface of the resin material is oxidatively decomposed with a treatment liquid mainly composed of a strong alkali salt such as permanganate. Desmear treatment is generally used to remove smear (resin remaining around the via) when mechanically forming vias on the wiring board, but as a base treatment during plating treatment, unevenness is formed on the resin material. Also used to form structures. In the desmear process, since the entire module structure is immersed in the processing solution, there is a possibility that the external electrode and the like are oxidized and decomposed. Therefore, in order to protect from the desmear treatment liquid, it is necessary to cover the mounting portion with a masking tape or the like.

  As such a masking tape, one having alkali resistance is adopted, and many of them have relatively strong adhesive force. Therefore, when the tape is peeled off, a large stress is applied to the circuit module 1B, and a crack or a crack may occur. In addition, when the process of forming the cutting groove is performed as in the present embodiment, the thickness of the wiring board is thinner in the area under the cutting groove than in the other areas (see FIG. 6 and the like). In particular, cracks, cracks, and the like were liable to occur in this area.

  Therefore, according to the circuit module 1 according to the present embodiment, the second metal film 6 formed by the plating method is formed on the main surface 41 of the sealing layer 4 via the first metal film 5. . Thereby, the adhesiveness of the 2nd metal film 6 can be improved, without performing a desmear process. Accordingly, the selectivity of the masking tape can be increased, and the use of a tape having a lower adhesive strength can suppress the above-mentioned problems such as cracks and cracks.

  Furthermore, a dicer is used for forming the cutting groove L20 as described above. Thereby, the side wall surface of the cutting groove L20 including the side surface 42 is roughened. Therefore, also on the side surface 42, the adhesion with the second metal film 6 can be enhanced by the anchor effect.

  The embodiment of the present invention has been described above, but the present invention is not limited to this, and various modifications can be made based on the technical idea of the present invention.

  In the above embodiment, it has been described that the metal layer 52 of the first metal film 5 is formed of copper. However, the present invention is not limited to this, and other metals such as nickel may be employed.

  The material of the second metal film 6 is not limited to copper, and other metals such as nickel may be employed. Furthermore, the third metal film 7 is not limited to nickel. For example, in the case of the electroplating method, a metal such as silver or gold can be used, and in the case of the electroless plating method, a metal such as nickel, gold, or palladium can be used. Further, a metal film that covers the third metal film 7 may be further formed, and the shield film 8 may be configured to have three or more layers.

  Alternatively, a configuration without the third metal film 7 is also possible.

  Further, the materials of the sealing layer 4 and the adhesive layer 51 of the first metal film 5 are not limited to the epoxy resin, and other insulators can be employed. Of course, different materials may be used.

  In the above embodiment, it has been described that the second and third metal films 6 and 7 are formed by plating, but the present invention is not limited to this. For example, a vacuum process such as sputtering or vapor deposition may be used, or dipping or thermal spraying may be used.

  Moreover, the tool used for a cutting process is not restricted to a dicer, For example, you may use a router and a milling cutter. Further, in the cutting (cutting) in the singulation process, in addition to a method using a dicer, a router, or the like, when the wiring board 20 is formed of a brittle material such as ceramic, the wiring board 20 is sheared. A dividing method or the like can be appropriately employed. Further, the wiring board 20 may be divided by irradiating a laser or the like along the cutting groove L20.

DESCRIPTION OF SYMBOLS 1 ... Circuit module 2,20 ... Wiring board 3 ... Electronic component 4,40 ... Sealing layer 5,50 ... 1st metal film 6,60 ... 2nd metal film 7,70 ... 3rd metal film 10 ... Unit region 21, 210 ... Surface 25, 250 ... Internal wiring layer 41 ... Main surface 42 ... Side surface 51, 510 ... Adhesive layer 52, 520 ... Metal layer 410 ... Top surface L20 ... Cutting groove

Claims (14)

Forming a sealing layer covering the electronic component on a wiring board having a plurality of unit regions each mounted with the electronic component;
Adhering the first metal film to the top surface of the sealing layer,
A cutting groove that divides the plurality of unit regions is formed at a depth reaching the inside of the wiring board from the first metal film,
A method of manufacturing a circuit module, comprising: forming a second metal film that covers a side surface exposed in the cutting groove of the sealing layer in each of the plurality of unit regions and the first metal film. A method for manufacturing a circuit module according to claim 1,
The step of forming the second metal film includes forming the second metal film by a plating method. It is a manufacturing method of the circuit module of Claim 1 or 2, Comprising: After the process of forming a said 2nd metal film, the 3rd metal film which covers the said 2nd metal film is formed. Production method. A method of manufacturing a circuit module according to claim 3,
The step of forming the third metal film includes forming the third metal film by a plating method. A method for manufacturing a circuit module according to any one of claims 1 to 4,
The first metal film has an adhesive layer and a metal layer formed on the adhesive layer,
The step of adhering the first metal film includes adhering the adhesive layer to the top surface. A method for manufacturing a circuit module according to any one of claims 1 to 5,
The step of forming the cutting groove forms the cutting groove at a depth reaching an internal wiring layer formed in the wiring board. A method for manufacturing a circuit module according to any one of claims 1 to 6,
The step of forming the cutting groove forms the cutting groove with a first width,
The method for manufacturing the circuit module further includes, after the step of forming the second metal film, cutting the wiring board along the cutting groove with a second width narrower than the first width, A method for manufacturing a circuit module, in which each unit area is individually separated. A wiring board having a surface on which electronic components are mounted;
A sealing layer that has a main surface facing the surface and a side surface continuously formed around the main surface, is formed on the wiring board and covers the electronic component;
A first metal film having an adhesive layer adhered to the main surface, and a metal layer laminated on the adhesive layer;
A circuit module comprising: a second metal film that covers the side surface of the sealing layer and the metal layer. The circuit module according to claim 8, wherein
The side surface is a roughened surface circuit module. A circuit module according to claim 8 or 9, wherein
The circuit module is formed of the same resin material as the sealing layer and the adhesive layer. The circuit module according to claim 10, comprising:
The circuit module, wherein the resin material is a thermosetting resin. The circuit module according to any one of claims 8 to 11,
The first metal film and the second metal film are formed of copper. The circuit module according to any one of claims 8 to 12,
A circuit module further comprising a third metal film covering the second metal film. The circuit module according to claim 13,
The third metal film is formed of nickel.

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