JP7225302B2 - Circuit board manufacturing method - Google Patents

Description

The present invention relates to a circuit board and its manufacturing method.

In circuit boards for LEDs and circuit boards for power modules, a structure is disclosed in which a lead frame is directly laminated on a metal base board via an insulating layer in order to improve heat dissipation (for example, Patent Documents 1 and 2). ). In this case, the edge surface discharge distance between the metal base substrate and the lead frame becomes short, which may cause a short circuit. Conventionally, the lead frame and metal base substrate are sealed with a sealing material to prevent short circuits, but there is still a risk of short circuits due to voids that occur during sealing. there were.

Japanese Patent No. 4220641 Japanese Patent No. 4862601

The present invention provides a circuit board that reduces the possibility of short circuits and has excellent electrical resistance by ensuring a sufficient edge surface discharge distance between a base board and a lead frame before sealing, and a method for manufacturing the same. The task is to provide

According to a first aspect of the present invention, there is provided a circuit board in which a base substrate made of metal or ceramics, a first insulating layer, and a circuit pattern are laminated in this order, wherein the circuit pattern is integrally formed from a metal foil. A lead frame extending outward from the circuit pattern is formed by molding, the lead frame has a portion extending outward from the peripheral edge of the base substrate, and the first insulating layer comprises: According to another aspect of the present invention, there is provided a circuit board covering the lower surface of the extension portion of the lead frame by having an extension part laminated on the lower surface of the extension portion of the lead frame.

According to another aspect of the present invention, the first insulating layer is the remaining side surface of the lead frame adjacent to the extension portion among the side surfaces of the lead frame. An area adjacent to the underside of the leadframe coated with a layer is further coated.

Furthermore, according to another aspect of the present invention, the first insulating layer is an insulating layer containing a composition containing a thermosetting resin.

Furthermore, according to another aspect of the present invention, the circuit pattern and the lead frame are integrally formed by punching the metal foil.

Furthermore, according to another aspect of the present invention, the extension portion of the first insulation layer is the first insulation layer adjacent to the extension portion of the side surface of the base substrate. further covering the area adjacent to the top surface of the base substrate covered with the remainder of the insulating layer of .

Furthermore, according to another aspect of the present invention, a second insulating layer is further provided between the base substrate and the first insulating layer.

Furthermore, according to another aspect of the present invention, both the first insulating layer and the second insulating layer are insulating layers containing a composition containing a thermosetting resin, or One of the first insulating layer and the second insulating layer is an insulating layer containing a composition containing a thermosetting resin, and the other is an insulating layer containing an adhesive.

Furthermore, according to another aspect of the present invention, the extension of the first insulating layer is the remainder of the first insulating layer adjacent to the extension of the side surface of the second insulating layer. or further covering a region adjacent to the upper surface of the second insulating layer covered with, or the first insulating layer adjacent to the extension part of the side surface of the second insulating layer and a region of the side surface of the base substrate adjacent to the region of the side surface of the second insulating layer. .

According to another aspect of the present invention, there is provided the method for manufacturing the circuit board, comprising: forming the first insulating layer on one side of the metal foil to obtain a first laminate; obtaining a lead frame-integrated circuit pattern in which the circuit pattern and the lead frame are integrated and a second laminate having the first insulating layer by punching the body; and the base substrate with the first insulating layer interposed therebetween.

According to another aspect of the present invention, the first insulating layer before being laminated is an insulating layer containing a B-stage cured product of a composition containing a thermosetting resin.

According to another aspect of the present invention, there is provided the method for manufacturing the circuit board, comprising: obtaining a first laminate by forming the first insulating layer on one side of the metal foil; obtaining a lead frame-integrated circuit pattern in which the circuit pattern and the lead frame are integrated and a second laminate having the first insulating layer by punching the body; forming the second insulating layer on the second insulating layer to obtain a third laminate; and separating the second laminate and the third laminate from the first insulating layer and the second insulating A method of manufacturing a circuit board is provided that includes laminating through layers.

According to another aspect of the present invention, at least one of the first insulating layer and the second insulating layer before being laminated is a B-stage cured product of a composition containing a thermosetting resin. is an insulating layer containing

According to the present invention, a sufficient edge discharge distance is secured between the base substrate and the lead frame even before encapsulation. It has become possible to provide a circuit board and its manufacturing method that are excellent in terms of

1A is a top view schematically showing the configuration of a circuit board according to Embodiment 1. FIG. FIG. 1B is a cross-sectional view schematically showing the cross-sectional structure of the circuit board according to Embodiment 1 at a position corresponding to line XX shown in FIG. 1A. FIG. 1C is a cross-sectional view schematically showing the cross-sectional structure of the circuit board according to Embodiment 1 at a position corresponding to line YY shown in FIG. 1A. 1D is an enlarged view of the cross-sectional area _D1 shown in FIG. 1B of the circuit board according to Embodiment 1. FIG. FIG. 2A is a top view schematically showing the configuration of a circuit board according to Embodiment 2. FIG. FIG. 2B is a cross-sectional view schematically showing the cross-sectional structure of the circuit board according to Embodiment 2 at a position corresponding to line XX shown in FIG. 2A. FIG. 2C is a cross-sectional view schematically showing the cross-sectional structure of the circuit board according to Embodiment 2 at a position corresponding to line YY shown in FIG. 2A. 2D is an enlarged view of the cross-sectional area _D2 shown in FIG. 2B of the circuit board according to Embodiment 2. FIG. 3A is a top view schematically showing a process of manufacturing the circuit board according to Embodiment 1. FIG. FIG. 3B is a diagram schematically showing the steps of manufacturing the circuit board according to Embodiment 1, and schematically showing the configuration of a cross section at a position corresponding to line XX shown in FIG. 3A. It is a sectional view. 4A is a top view schematically showing a process of manufacturing a circuit board according to Embodiment 2. FIG. FIG. 4B is a diagram schematically showing a process for manufacturing a circuit board according to Embodiment 2, and schematically showing a cross-sectional configuration at a position corresponding to line XX shown in FIG. 4A. It is a sectional view.

BEST MODE FOR CARRYING OUT THE INVENTION Hereinafter, embodiments of the present invention will be described with reference to the drawings.
(Embodiment 1)
FIG. 1A is a top view schematically showing the configuration of the circuit board 10 according to Embodiment 1, and FIG. 1B is a diagram of the circuit board 10 according to Embodiment 1 taken along line XX shown in FIG. 1A. 2 is a cross-sectional view schematically showing the configuration of a cross section at a position corresponding to . 1A and 1B, the circuit board 10 includes a base board 4, a first insulating layer 3, a circuit pattern 1, and a lead frame 2. As shown in FIG.

The circuit pattern 1 and the lead frame 2 are integrally formed from metal foil, and as shown in FIGS. 1A and 2B, the circuit pattern 1 and the lead frame 2 are integrated. In this specification, such a structure in which the circuit pattern 1 and the lead frame 2 are integrally molded from metal foil is referred to as a "lead frame integrated circuit pattern" or the like. The circuit pattern 1 formed here may be further etched to form a finer circuit pattern. Alternatively, a separately formed circuit board may be laminated on the circuit pattern 1 . In this specification, the term "lead frame" means a component (part) having a function of connecting with external wiring.

As shown in FIGS. 1A and 2B, a circuit board 10 according to Embodiment 1 is formed by laminating lead frame integrated circuit patterns (1, 2) and a base board 4 with a first insulating layer 3 interposed therebetween. It has the following structure.

As shown in FIGS. 1A and 1B, the lead frame 2 has a portion extending outward from the peripheral edge of the base substrate 4 (hereinafter referred to as “extending portion A ₁ ”). As described above, the lead frame 2 is formed together with the circuit pattern ₁ by integral molding from metal foil. In _FIG. A site (remainder) adjacent to _A2 .

The first insulating layer 3 has an extension portion B laminated on the lower surface of the extension portion _A1 of the lead frame 2 . By covering the lower surface of the extension portion _A1 of the lead frame 2 with the extension portion B of the first insulating layer 3, a sufficient edge surface is formed between the base substrate 4 and the lead frame 2 even before sealing. Since the discharge distance is ensured, a short circuit between the base substrate 4 and the lead frame 2 can be prevented.

The coverage of the lower surface of the extension portion _A1 of the lead frame 2 with the extension portion B of the first insulating layer 3 is preferably 0.5 to 100%, more preferably 2 to 50%, and further It is preferably 5 to 40%.

In circuit board 10 according to Embodiment 1, first insulating layer 3 has a first fillet and a second fillet, as described below.

FIG. 1C is a cross-sectional view schematically showing the cross-sectional structure of the circuit board according to Embodiment 1 at a position corresponding to line YY shown in FIG. 1A. As shown in FIG. 1C, the end portion of the lead frame 2 (the portion surrounded by the dashed frame C in FIG. 1C) is covered with the first insulating layer 3 . The side surface rising from the end of the lead frame 2 surrounded by the dashed frame C is the side surface of the remaining portion A2 adjacent to the extension portion _A1 shown in FIG. 1B among the side surfaces of the lead frame ₂ . . That is, FIG. 1C shows that the side surface of the remaining portion _A2 of the lead frame 2 and the area adjacent to the lower surface of the lead frame 2 covered with the first insulating layer 3 is covered with the first insulating layer 3. indicates that the Thus, not only the lower surface of the remainder A2 of the lead frame ₂ but also the side surfaces of the remainder _A2 and adjacent to the lower surface covered with the first insulation layer are covered with the first insulation layer 3. This further reduces the possibility of short circuits between the base substrate 4 and the lead frame 2 . Hereinafter, the shape of the insulating layer covering the end portion of the lead frame or the like as shown in 3a in FIG. 1C is referred to as a "fillet shape". The shape shown in 3a in FIG. 1C in which the end portion of the remaining portion _A2 adjacent to the extension portion A1 of the lead frame ₂ is covered with the first insulating layer 3 is called a "first fillet". .

In the circuit board 10 according to Embodiment 1, the first insulating layer 3 further has a second fillet described below.
1D is an enlarged view of the cross-sectional area _D1 shown in FIG. 1B of the circuit board according to Embodiment 1. FIG. As shown in FIGS. 1B and 1D, the end portion of the base substrate 4 (the portion of the base substrate 4 surrounded by the frame _D1 ) is covered with the first insulating layer 3 to form a fillet shape. In this way, not only the lower surface of the extension portion _A1 of the lead frame 2 but also the area of the side surface of the base substrate 4 surrounded by the frame _D1 , that is, the first portion of the side surface of the base substrate 4 is formed. The area adjacent to the upper surface of the base substrate 4 covered with the remaining portion of the first insulating layer 3 adjacent to the extension B of the insulating layer 3 is also covered with the extension B of the first insulating layer 3, The possibility of short circuits between the base substrate 4 and the leadframe 2 is further reduced. Hereinafter, the shape in which the end portion of the base substrate 4 is covered with the extended portion B of the first insulating layer 3 is referred to as a "second fillet", as shown in 3b in FIG. 1D.

In addition, since the first insulating layer 3 has the second fillet 3b, the adhesion between the base substrate 4 and the lead frame integrated circuit pattern is improved, which is advantageous when bending the lead frame.

In Embodiment 1, the base substrate 4 is made of metal or ceramics.
A metal substrate as the base substrate 4 is made of, for example, a single metal or an alloy. As the material of the metal substrate, for example, aluminum, iron, copper, aluminum alloy, or stainless steel can be used. The metal substrate may further contain a non-metal such as carbon. For example, the metal substrate as the base substrate 4 may contain aluminum compounded with carbon. Also, the metal substrate may have a single-layer structure or a multi-layer structure.

Metal substrates have high thermal conductivity. Typically, the metal substrate 2 has a thermal conductivity of 60 W·m ⁻¹ ·K ⁻¹ or higher.
The metal substrate may or may not have flexibility. The thickness of the metal substrate is, for example, in the range 0.2-5 mm.

As the ceramic substrate as the base substrate 4, for example, alumina, silicon nitride, aluminum nitride, silicon carbide, and boron nitride can be used. The thickness of the ceramic substrate is, for example, within the range of 0.2-5 mm.

In Embodiment 1, the first insulating layer 3 preferably contains a composition containing a thermosetting resin, and more preferably contains a composition containing a thermosetting resin and an inorganic filler. When the first insulating layer 3 contains such a mixture, it becomes an insulating layer with excellent thermal conductivity and heat dissipation properties.

Examples of the thermosetting resin contained in the resin composition contained in the first insulating layer 3 include cyanate resin, epoxy resin, phenol resin, urea resin, melamine resin, acrylic resin, urethane resin, maleimide resin, and benzoxazine. Resins, polyimide resins, polyamideimide resins, unsaturated polyester resins, silicone resins, diallyl phthalate resins, alkyd resins and the like can be mentioned. As the thermosetting resin, one type may be used alone, or two or more types may be used in combination.

Examples of inorganic fillers contained in the resin composition contained in the first insulating layer 3 include alumina, aluminum nitride, boron nitride, silicon nitride, magnesium oxide, and silicon oxide. It is preferable to use one or more selected from these.

In a system containing an inorganic filler, the exothermic reaction accompanying curing tends to be suppressed by the presence of the inorganic filler. Specifically, the inorganic filler absorbs reaction heat, which slows down the curing reaction, and the surface functional groups of the inorganic filler inhibit the curing reaction of the thermosetting resin. Therefore, a surface-treated inorganic filler may be used, and it is preferable to use an inorganic filler in an appropriate combination with a curing accelerator, which will be described later. As the surface treatment of the inorganic filler, for example, the surface of the inorganic filler may be modified with a functional group that can chemically bond with the thermosetting resin with reaction, or with a functional group that is highly compatible with the thermosetting resin. It may be modified (e.g., cyanate group, epoxy group, amino group, hydroxyl group, carboxyl group, vinyl group, styryl group, methacrylic group, acrylic group, ureido group, mercapto group, sulfide group, isocyanate group, etc.), for example, Silane coupling treatment, plasma treatment, or the like is used.

In Embodiment 1, the ratio of the inorganic filler contained in the resin composition contained in the first insulating layer 3 is preferably 50 to 90% by volume based on the total volume of the thermosetting resin components. The inorganic filler content is more preferably 60 to 80% by volume. If the filling rate is too low, the desired thermal conductivity cannot be obtained and the inorganic filler tends to precipitate. On the other hand, if the filling rate is too high, the viscosity will be too high, making it impossible to obtain a uniform coating film and possibly causing more pore defects.

The resin composition contained in the first insulating layer 3 may contain a curing accelerator. The curing accelerator is not particularly limited. Organic metal salts such as acetonate cobalt (III), phenol compounds such as phenol, bisphenol A and nonylphenol, tertiary amines, tertiary amine salts, phosphines, phosphonium salts and the like.

The resin composition contained in the first insulating layer 3 may contain a curing agent. The curing agent is not particularly limited, and examples thereof include amine-based, thiol-based, acid anhydride-based, phenol-based, imidazole-based, dicyandiamide, and boron trifluoride-amine complexes.

In Embodiment 1, the resin composition contained in first insulating layer 3 may further contain other components. Other components that the insulating layer may contain include, for example, coupling agents such as silane coupling agents and titanium coupling agents, ion adsorbents, anti-settling agents, anti-hydrolysis agents, leveling agents, and antioxidants. agents and the like.

In Embodiment 1, the lead frame-integrated circuit pattern in which the circuit pattern 1 and the lead frame 2 are integrated is obtained by integral molding (for example, punching) from metal foil. A metal foil consists of a single metal or an alloy, for example. Copper or aluminum, for example, can be used as the material of the metal foil. The thickness of the metal foil is, for example, in the range of 10-500 μm.

Next, a method for manufacturing the circuit board according to Embodiment 1 will be described.
3A is a top view schematically showing the process of manufacturing the circuit board according to Embodiment 1, and FIG. 3B schematically shows the configuration of the cross section at the position corresponding to line XX shown in FIG. 3A. FIG. 3 is a schematic cross-sectional view;

The method for manufacturing a circuit board according to Embodiment 1 includes the following steps (i) to (iii).

(i) obtaining a first laminate by forming a first insulating layer 3 on one side of the metal foil S (1, 2) (FIGS. 3A(a) and 3B(a));
(ii) By punching the first laminate, a second laminate having a lead frame-integrated circuit pattern in which the circuit pattern 1 and the lead frame 2 are integrated and the first insulating layer 3 is obtained. that (FIGS. 3A(b) and 3B(b)), and
(iii) Laminating the second laminate and the base substrate 4 with the first insulating layer 3 interposed therebetween (FIGS. 3A(c) and 3B(c)).

The formation of the first insulating layer 3 on the metal foil S(1,2) in step (i) can be performed by a known method. For example, the insulating layer-forming composition is applied to one side of the metal foil S (1, 2), and the coating is dried as necessary. As a method for applying the insulating layer-forming composition, for example, a roll coating method, a bar coating method, a screen printing method, or the like can be used. Coating may be performed by a continuous method or by a single plate method.

In another embodiment, the composition for forming an insulating layer is applied to a base material such as a PET film and dried to form a coating film in advance, which is then thermally transferred to one side of the metal foil S (1, 2). good too.

In the step (ii), the metal foils S (1, 2) and the first insulating layer 3 laminated thereon are integrally patterned into a predetermined shape by punching to form the lead frame integrated circuit pattern and the first insulating layer 3. A second laminate with one insulating layer 3 is obtained.

Lamination of the second laminate and the base substrate 4 in step (iii) can be performed by a known method. For example, it can be carried out by heat lamination or vacuum pressure bonding, and may be heated if necessary.

The second laminate and the base substrate 4 are preferably laminated in step (iii) so that the first fillet 3a and the second fillet 3b are formed on the first insulating layer 3 . That is, the ends of the remainder _A2 of the lead frame are the first fillets 3a covered with the first insulating layer 3 (FIGS. 1A to 1C), and the ends of the base substrate 4 are the first insulating layer Preferably, a second fillet 3b (FIGS. 1A, 1B, 1D) covered by an extension B of 3 is formed. In order to obtain such a structure, the lamination of the second laminate and the base substrate 4 in step (iii) is preferably performed by pressure bonding. The insulating layer 3 is preferably an insulating layer containing a B-stage cured product of the thermosetting resin-containing composition.

Here, the "B stage" is an intermediate stage of the reaction of thermosetting resin, in which the material softens and expands when heated, but does not melt completely even when it comes into contact with a certain liquid. Or it refers to the stage of not dissolving.

In the manufacturing method described above, the metal foil S (1, 2) and the first insulating layer 3 are laminated on the base substrate 4 in the form of a laminated body obtained by integrally punching the metal foil S (1, 2). 2, the lower surface of the extension portion _A1 of the lead frame 2 can be covered with the extension portion B of the first insulating layer 3. As shown in FIG. It is a known technology to use a lead frame integrated circuit pattern formed by punching metal foil in a circuit board (for example, Patent Document 2), but there is a lead frame integrated circuit pattern in which an insulating layer is not laminated. was laminated on the base substrate on which the insulating layer was formed, the structure in which the lower surface of the extension portion _A1 was covered with the extension of the insulating layer was not adopted. Further, in the method for manufacturing a circuit board described in Patent Document 1, after an insulating layer is formed on a base substrate _, a lead frame is crimped by a vacuum press or the like. There was no structure covered by an extension of the insulating layer.

(Embodiment 2)
FIG. 2A is a top view schematically showing the configuration of the circuit board 20 according to Embodiment 2, and FIG. 2B shows the circuit board 20 according to Embodiment 2 taken along line XX shown in FIG. 2A. 2 is a cross-sectional view schematically showing the configuration of a cross section at a position corresponding to . 2A and 2B, the circuit board 20 includes a base board 14, a second insulating layer 15, a first insulating layer 13, a circuit pattern 11, and a lead frame 12. .

The circuit pattern 11 and the lead frame 12 are integrally formed from metal foil. As shown in FIGS. 2A and 2B, the circuit pattern 11 and the lead frame 12 are integrated into a lead frame integrated circuit. constitutes a pattern.

As shown in FIGS. 2A and 2B, in the circuit board 20 according to the second embodiment, the lead frame-integrated circuit patterns (11, 12) and the base board 14 form the first insulating layer 13 and the second insulating layer. It has a laminated structure with layers 15 interposed therebetween.

As shown in FIGS. 2A and 2B, the lead frame 12 comprises an extension portion _A1 extending outward from the periphery of the base substrate 14 and a remaining portion _A2 adjacent to the extension portion _A1 . The first insulating layer 13 has an extension portion B laminated on the lower surface of the extension portion _A1 of the lead frame 12 . By covering the lower surface of the extension portion _A1 of the lead frame 2 with the extension portion B of the first insulating layer 13, a sufficient edge is formed between the base substrate 14 and the lead frame 12 even before resin encapsulation. Since the surface discharge distance can be secured, a short circuit between the base substrate 14 and the lead frame 12 can be prevented.

A preferable coverage rate of the lower surface of the extension portion A1 of the lead frame ₁₂ by the extension portion B of the first insulating layer 13 is the same as that of the circuit board according to the first embodiment described above.

In the circuit board 20 according to the second embodiment, the first insulating layer 13 has a first fillet and a second fillet, similar to the first insulating layer 3 in the circuit board 10 according to the first embodiment. have

FIG. 2C is a cross-sectional view schematically showing the cross-sectional structure of the circuit board according to Embodiment 2 at a position corresponding to line YY shown in FIG. 2A.
As shown in FIG. 2C, in the circuit board 20 according to the second embodiment, the first insulating layer 13 is provided at the extension portion _A1 of the lead frame 12, similarly to the circuit board 10 according to the first embodiment. The end of the adjacent leadframe remainder _A2 has a first fillet covered with a first insulating layer 13 . The first insulating layer 13 has a first fillet shape, i.e. not only the bottom surface of the remainder _A2 of the lead frame 12, but also the side surface of the remainder _A2 , covered with the first insulation layer. By also covering the area adjacent to the lower surface with the first insulating layer 13, the possibility of a short circuit between the base substrate 14 and the lead frame 12 is further reduced.

In the circuit board 20 according to the second embodiment, the first insulating layer 13 further has a second fillet, like the circuit board 10 according to the first embodiment described above.
FIG. 2D is an enlarged view of the cross-sectional area _D2 shown in FIG. 2B of the circuit board according to the second embodiment. As shown in FIGS. 2B and 2D, the end portion (surrounded by the frame D ₂ ) of the laminate (hereinafter referred to as the “third laminate”) composed of the base substrate 14 and the second insulating layer 15 The third laminate portion) is covered with a first insulating layer 13 to form a second fillet 13b. In this way, not only the lower surface of the extension portion A1 of the lead frame ₁₂ , but also the area surrounded by the frame _D1 in the side surface of the third laminate, that is, the side surface of the third laminate. , the area adjacent to the upper surface of the third laminate covered with the remainder of the first insulating layer 13 adjacent to the extension B of the first insulating layer 13 is also covered by the extension B of the first insulating layer 13. The coating further reduces the possibility of shorting between base substrate 14 and leadframe 12 .

Further, since the first insulating layer 13 has the second fillet 13b, the adhesion between the third laminate having the base substrate 14 and the second insulating layer 15 and the lead frame integrated circuit pattern is improved. , when bending the lead frame.
2B and 2D, the second fillet 13b covers both the side surfaces of the second insulating layer 15 and the base substrate 4, but the second fillet 13b covers the side surface of the second insulating layer 15. It may be in the form of covering only.

The first insulating layer 13 and the second insulating layer 15 included in the circuit board according to the second embodiment will be described below.
In Embodiment 2, at least one of the first insulating layer 13 and the second insulating layer 15 preferably contains a composition containing a thermosetting resin, and contains a thermosetting resin and an inorganic filler. More preferably, it contains a composition that When at least one of the insulating layers contains such a mixture, the insulating layer has excellent thermal conductivity and heat dissipation properties.

The thermosetting resin contained in the composition containing a thermosetting resin is the same as that described in the first embodiment. Also, the inorganic filler, curing accelerator, and other components that the composition containing the thermosetting resin may contain are the same as those described in the first embodiment.

In Embodiment 2, the first insulating layer 13 and the second insulating layer 15 may both be insulating layers containing a composition containing a thermosetting resin, or the first insulating layer 13 and the One of the second insulating layers 15 may be an insulating layer containing a composition containing a thermosetting resin, and the other may be an insulating layer containing an adhesive.

Examples of the adhesive include, but are not limited to, natural rubber, acrylic acid ester copolymer, silicone rubber, and urethane resin.

In the second embodiment, the lead frame-integrated circuit pattern in which the circuit pattern 11 and the lead frame 12 are integrated is obtained by integral molding (for example, punching) from metal foil. The metal foil is the same as the metal foil used in the first embodiment described above.
In Embodiment 2, base substrate 14 is similar to base substrate 4 used in Embodiment 1 described above.

Next, a method for manufacturing a circuit board according to Embodiment 2 will be described.
FIG. 4A is a top view schematically showing the process of manufacturing a circuit board according to Embodiment 2, and FIG. 4B is a schematic cross-sectional configuration at a position corresponding to line XX shown in FIG. 4A. FIG. 3 is a schematic cross-sectional view;

A method for manufacturing a circuit board according to Embodiment 2 includes the following steps (i) to (iv).

(i) obtaining a first laminate by forming a first insulating layer 13 on one side of the metal foil S (1, 2) (FIGS. 4A(a) and 4B(a));
(ii) A second laminate having a lead frame-integrated circuit pattern in which the circuit pattern 11 and the lead frame 12 are integrated and the first insulating layer 13 is formed by punching the first laminate. obtaining (FIGS. 4(b) and 4B(b)),
(iii) forming a second insulating layer 15 on one side of the base substrate 14 to obtain a third laminate (FIGS. 4(d) and 3B(d)); and
(iv) Laminating the second laminate and the third laminate with the first insulating layer 13 and the second insulating layer 15 interposed therebetween (FIGS. 4(e) and 4B(e)).

The formation of the first insulating layer 3 on the metal foil S(1,2) in step (i) can be performed by a known method. For example, it is as described in the circuit board manufacturing method according to the second embodiment.

In the step (ii), the metal foils S (1, 2) and the first insulating layer 13 laminated thereon are integrally patterned into a predetermined shape by punching to form a lead frame integrated circuit pattern and a first insulating layer 13. A second laminate with one insulating layer 13 is obtained.

Formation of the second insulating layer 15 on the base substrate 14 in step (iii) can be performed by a known method. For example, the insulating layer-forming composition is applied to one side of the base substrate 14, and the coating is dried as necessary. As a method for applying the insulating layer-forming composition, for example, a roll coating method, a bar coating method, a screen printing method, or the like can be used. Coating may be performed by a continuous method or by a single plate method.

In another embodiment, a coating film may be formed in advance by applying the composition for forming an insulating layer to a base material such as a PET film and drying it, and then thermally transferring this to one side of the base substrate 14 .

Lamination of the second laminate and the third laminate in step (iv) can be performed by a known method. For example, it can be carried out by heat lamination or vacuum pressure bonding, and may be heated if necessary.

The stacking of the second stack and the third stack in step (iv) can be performed so that the first fillet 13a and the second fillet 13b are formed on the first insulating layer 13. preferable. That is, the end of the remainder _A2 of the lead frame is the first fillet 13a covered with the first insulating layer 13 (FIGS. 2A-2C), and the end of the third laminate is the first fillet 13a. Preferably, a second fillet 13b (FIGS. 2A, 2B, 2D) covered by the extension B of the insulating layer 13 is formed. In order to obtain such a structure, the lamination of the second laminate and the third laminate in step (iv) is preferably performed by crimping. At least one of the first insulating layer 13 and the second insulating layer 15 is preferably an insulating layer containing a B-stage cured product of the thermosetting resin-containing composition.

In the manufacturing method described above, the metal foil S (1, 2) and the first insulating layer 13 are laminated in the form of a laminate obtained by integrally punching the laminate including the base substrate 14. As shown in FIGS. 2A and 2B, a structure in which the lower surface of the extension portion _A1 of the lead frame 12 is covered with the extension portion B of the first insulating layer 13 can be employed.

Examples of the invention are described below. The present invention is not limited to these.
<Material for insulating layer>
Thermosetting resin composition 1 and adhesive 1 shown below were used as the insulating layer material.
(Resin composition 1)
Bisphenol A type epoxy resin (hereinafter also referred to as “BA type epoxy resin”) (trade name “EXE850”; manufactured by DIC Corporation) 100 parts by mass and imidazole as a curing agent (trade name “2E4MZ”; Shikoku Kasei Co., Ltd. (manufactured by Showa Denko Co., Ltd.) is added, and then 50% by volume of alumina ("AS40"; manufactured by Showa Denko Co., Ltd.) is added to the entire resin and stirred at room temperature with a planetary stirrer until the mixture becomes uniform. By doing so, a thermosetting resin composition (resin composition 1) was obtained.
(Adhesive 1)
Acrylic resin adhesive

(Example 1)
First insulating layer: resin composition 1 (B stage) / second insulating layer: none (step 1)
The resin composition 1 obtained above was applied to a release-treated PET film so that the thickness of the insulating layer after forming the circuit board was 150 μm to form an insulating layer. Then, the insulating layer was B-staged by preheating to a level that could be thermally transferred to the copper foil, and laminated on the copper foil. (See FIGS. 3A(a) and 3B(a))
(Step 2)
The laminated body obtained in step 1 was punched by a press to obtain a lead frame-integrated laminated body. (See FIGS. 3A(b) and 3B(b))

(Step 3)
The PET film was peeled off from the lead frame-integrated laminate obtained in step 2, and the laminate was laminated on aluminum as a base substrate by thermal lamination so as not to create voids in the bonding surface.
(Step 4)
The laminate obtained in step 3 was adhered by heating and curing to produce a circuit board 1 in which the lead frame integrated circuit pattern was laminated on the base board via the first insulating layer. (See FIGS. 3A(c) and 3B(c))

(Example 2)
First insulating layer: resin composition 1 (B stage) / second insulating layer: resin composition 1 (C stage)
(Step 1)
The resin composition 1 obtained above was applied to a release-treated PET film so that the thickness of the insulating layer on the circuit pattern side after forming the circuit board was 75 μm to form an insulating layer. Then, the insulating layer was B-staged by preheating to a level that could be thermally transferred to the copper foil, and laminated on the copper foil. (See FIGS. 4A(a) and 4B(a))
(Step 2)
The laminated body obtained in step 1 was punched by a press to obtain a lead frame-integrated laminated body. (See FIGS. 4A(b) and 4B(b))

(Step 3)
Resin composition 1 was applied to a PET film different from that used in step 1, which had been subjected to release treatment so that the thickness of the insulating layer on the side of the base substrate after forming the circuit board was 75 μm, to form an insulating layer. Next, the insulating layer was B-staged by preheating to a level at which it could be thermally transferred to the base substrate, and laminated on aluminum as the base substrate. After that, it was heat-treated up to the C stage. (See FIGS. 4A(d) and 4B(d))
(Step 4)
The PET film was peeled off from the lead frame-integrated laminate obtained in step 2, and the laminate obtained in step 3 was laminated by heat lamination so as not to create voids on the bonding surfaces.
(Step 5)
The laminate obtained in step 4 was adhered by heating and curing to fabricate a circuit board 2 in which the lead frame integrated circuit pattern was laminated on the base board via the first insulating layer and the second insulating layer. (See FIGS. 4A(e) and 4B(e))

(Example 3)
First insulating layer: Resin composition 1 (B stage) / Second insulating layer: Resin composition 1 (B stage)
(Step 1)
The resin composition 1 obtained above was applied to a release-treated PET film so that the thickness of the insulating layer on the circuit pattern side after forming the circuit board was 75 μm to form an insulating layer. Then, the insulating layer was B-staged by preheating to a level that could be thermally transferred to the copper foil, and laminated on the copper foil. (See FIGS. 4A(a) and 4B(a))
(Step 2)
The laminated body obtained in step 1 was punched by a press or the like to obtain a laminated body integrated with a lead frame. (See FIGS. 4A(b) and 4B(b))

(Step 3)
Resin composition 1 was applied to a PET film different from that used in step 1, which had been subjected to release treatment so that the thickness of the insulating layer on the side of the base substrate after forming the circuit board was 75 μm, to form an insulating layer. Next, the insulating layer was B-staged by preheating to a level at which it could be thermally transferred to aluminum as a base substrate, and laminated on the base substrate. (See FIGS. 4A(d) and 4B(d)) (Step 4)
The PET film was removed from each of the lead frame-integrated laminate obtained in step 2 and the laminate obtained in step 3, and both were laminated by thermal lamination so as not to create voids on the bonding surfaces.

(Step 5)
The laminate obtained in step 4 was adhered by heat curing to produce a circuit board 3 in which the lead frame integrated circuit pattern was laminated on the base board via the first insulating layer and the second insulating layer. (See FIGS. 4A(e) and 4B(e))

(Example 4)
First insulating layer: resin composition 1 (C stage) / second insulating layer: resin composition 1 (B stage)
(Step 1)
The resin composition 1 obtained above was applied to a release-treated PET film so that the thickness of the insulating layer on the circuit pattern side after forming the circuit board was 75 μm to form an insulating layer. Then, the insulating layer was B-staged by preheating to a level that could be thermally transferred to the copper foil, and laminated on the copper foil. (See FIGS. 4A(a) and 4B(a)).

(Step 2)
After the laminate obtained in step 1 was heat-treated to be in the C-stage, it was stamped with a press to obtain a lead frame-integrated laminate. (See FIGS. 4A(b) and 4B(b)).
Note that the timing of changing the insulating layer from the B-stage state to the C-stage is not limited to this. For example, the laminated body obtained in step 1 may be punched by a press to obtain a lead frame-integrated laminated body, and then heat-treated to form a C-stage.

(Step 3)
Resin composition 1 was applied to a PET film different from that used in step 1, which had been subjected to release treatment so that the thickness of the insulating layer on the side of the base substrate after forming the circuit board was 75 μm, to form an insulating layer. Next, the insulating layer was B-staged by preheating to a level at which it could be thermally transferred to aluminum as a base substrate, and laminated on the base substrate. (See FIGS. 4A(d) and 4B(d)).

(Step 4)
The PET film was peeled off from the laminate obtained in step 3, and the lead frame-integrated laminate obtained in step 2 was laminated by heat lamination so as not to create voids on the bonding surfaces.
(Step 5)
The laminate obtained in step 4 was adhered by heat curing to produce a circuit board 4 in which the lead frame integrated circuit pattern was laminated on the base board via the first insulating layer and the second insulating layer. (See FIGS. 4A(e) and 4B(e)).

(Example 5)
First insulating layer: adhesive / second insulating layer: resin composition 1 (C stage)
(Step 1)
An acrylic resin-based adhesive is applied to a release-treated PET film so that the thickness of the insulating layer on the circuit pattern side after forming the circuit board is 20 μm to form an insulating layer, which is then laminated to a copper foil. bottom. (See FIGS. 4A(a) and 4B(a)).
(Step 2)
The laminate obtained in step 1 was punched by a press to obtain a lead frame-integrated laminate. (See FIGS. 4A(b) and 4B(b)).

(Step 3)
Resin composition 1 was applied to a PET film different from that used in step 1, which had been subjected to release treatment so that the thickness of the insulating layer on the side of the base substrate after formation of the circuit board was 130 μm, to form an insulating layer. Next, the insulating layer was B-staged by preheating to a level at which it could be thermally transferred to aluminum as a base substrate, and laminated on the base substrate. After that, it was heat-treated up to the C stage. (See FIGS. 4A(d) and 4B(d)).
(Step 4)
The PET film was peeled off from the lead frame-shaped laminate obtained in step 2, and the laminate obtained in step 2 was laminated by thermal lamination so as not to create voids on the bonding surfaces. Thus, a circuit board 5 was produced in which the lead frame integrated circuit pattern was laminated on the base board via the first insulating layer and the second insulating layer. (See FIGS. 4A(e) and 4B(e))

(Example 6)
First insulating layer: resin composition 1 (B stage) / second insulating layer: adhesive (step 1)
The resin composition 1 obtained above was applied to a release-treated PET film so that the thickness of the insulating layer on the circuit pattern side after forming the circuit board was 130 μm to form an insulating layer. Then, the insulating layer was B-staged by preheating to a level that could be thermally transferred to the copper foil, and laminated on the copper foil. (See FIGS. 4A(a) and 4B(a)).
(Step 2)
The laminate obtained in step 1 was punched by a press to obtain a lead frame-integrated laminate. (See FIGS. 4A(b) and 4B(b)).

(Step 3)
An acrylic resin-based adhesive is applied to a release-treated PET film so that the thickness of the insulating layer on the base substrate side after the circuit board is formed is 20 μm, and can be thermally transferred to the base substrate by preheating. It was B-staged to the level and laminated on aluminum as a base substrate. (See FIGS. 4A(d) and 4B(d)).
(Step 4)
The PET film was removed from each of the lead frame-integrated laminate obtained in step 2 and the laminate obtained in step 3, and both were laminated by thermal lamination so as not to create voids on the bonding surfaces.
(Step 5)
The laminate obtained in step 4 was adhered by heat curing to fabricate a circuit board 6 in which the lead frame integrated circuit pattern was laminated on the base board via the first insulating layer and the second insulating layer. (See FIGS. 4A(e) and 4B(e)).

(Comparative example)
First insulating layer: None / Second insulating layer: Resin composition 1 (B stage)
(Step 1)
Resin composition 1 was applied to a release-treated PET film to form a coating film. Next, the insulating layer was B-staged by preheating to a level at which it could be thermally transferred to the base substrate, and laminated on aluminum as the base substrate.

(Step 2)
A copper foil was punched out by a press to obtain a lead frame-integrated circuit pattern.
(Step 3)
The PET film was peeled off from the laminate obtained in step 1, and the lead frame-integrated circuit pattern obtained in step 2 was laminated by heat lamination so as not to create voids on the bonding surfaces.
(Step 4)
The laminate obtained in step 3 was adhered by heat curing to produce a circuit board 1R in which the lead frame integrated circuit pattern was laminated on the base board with the insulating layer 2 interposed therebetween.

(Evaluation method)
The insulation between the circuit and the base metal was evaluated by measuring the withstand voltage by the following method. [Method of measuring withstand voltage]
Using B010 manufactured by Mitsubishi Cable Industries, Ltd., the test voltage was started from 0.5 k∨ and increased by 0.5 k∨ each time the test was cleared. The measurement conditions were 25 seconds for increasing the voltage up to the test voltage, 5 seconds for holding, and 15 seconds for decreasing the voltage. Table 1 shows the results.

It should be noted that the present invention is not limited to the above-described embodiments, and various modifications can be made in the implementation stage without departing from the scope of the invention. Further, each embodiment may be implemented in combination as appropriate, in which case the combined effect can be obtained. Furthermore, various inventions are included in the above embodiments, and various inventions can be extracted by combinations selected from a plurality of disclosed constituent elements. For example, even if some constituent elements are deleted from all the constituent elements shown in the embodiments, if the problem can be solved and effects can be obtained, the configuration with the constituent elements deleted can be extracted as an invention.

1 circuit pattern 2 lead frame 3 first insulating layer 4 base board 10 circuit board 11 circuit pattern 12 lead frame 13 first insulating layer 14 base board 15 second insulating layer 20 circuit board A ₁ extension part of lead frame A ₂ lead frame extensions A remainder of lead frame adjacent to ₁ B extension of first or second insulating layer C lead frame end faces 3a, 13a covered with first or second insulating layer Fillets 3b, 13b Second fillet

Claims (10)

A circuit board in which a base substrate made of metal or ceramics, a first insulating layer, and a circuit pattern are laminated in this order,
The circuit pattern is a lead frame-integrated circuit pattern having a lead frame extending outward from the circuit pattern by being integrally molded from a metal foil,
The lead frame has an extension part extending outward from the peripheral edge of the base substrate,
The first insulating layer has an extension part laminated on the lower surface of the extension part of the lead frame, thereby covering the lower surface of the extension part of the lead frame. and
obtaining a first laminate containing the metal foil and the insulating film by transferring the insulating film in the B-stage state onto the metal foil;
By patterning the first laminate, the lead frame integrated circuit pattern made of the metal foil pattern and the first insulating layer made of the insulating film pattern are simultaneously formed to form a second laminate. getting a body
laminating and crimping the second laminate and the base substrate so that the first insulating layer and the base substrate face each other;
Curing the first insulating layer from a B-stage state.
A method of manufacturing a circuit board comprising : 2. The method of manufacturing a circuit board according to claim 1, wherein the patterning of said first laminate is performed by punching. The first insulating layer is a side surface of the remaining portion of the lead frame adjacent to the extending portion among the side surfaces of the lead frame, and the lower surface of the lead frame covered with the first insulating layer. 3. The method of manufacturing a circuit board according to claim 1 or 2, wherein the area adjacent to the is covered. The extension of the first insulating layer covers a region of the side surface of the base substrate adjacent to the top surface of the base substrate covered with the remainder of the first insulating layer adjacent to the extension. 4. The method for manufacturing a circuit board according to any one of claims 1 to 3. 4. The method of manufacturing a circuit board according to any one of claims 1 to 3, wherein the coverage of the lower surface of the extending portion with the first insulating layer is 2 to 50%. A circuit board in which a base substrate made of metal or ceramics, a second insulating layer, a first insulating layer, and a circuit pattern are laminated in this order,
The circuit pattern is a lead frame-integrated circuit pattern having a lead frame extending outward from the circuit pattern by being integrally molded from a metal foil,
The lead frame has an extension part extending outward from the peripheral edge of the base substrate,
The first insulating layer has an extension part laminated on the lower surface of the extension part of the lead frame, thereby covering the lower surface of the extension part of the lead frame. and
obtaining a first laminate containing the metal foil and the insulating film by transferring the insulating film in the B-stage state onto the metal foil;
By patterning the first laminate, the lead frame integrated circuit pattern made of the metal foil pattern and the first insulating layer made of the insulating film pattern are simultaneously formed to form a second laminate. getting a body
forming the second insulating layer on the base substrate to obtain a third laminate including the base substrate and the second insulating layer;
laminating and crimping the second laminate and the third laminate such that the first insulating layer and the second insulating layer face each other;
Curing the first insulating layer from a B-stage state.
A method of manufacturing a circuit board comprising : 7. The method of manufacturing a circuit board according to claim 6 , wherein the patterning of said first laminate is performed by punching. The first insulating layer is a side surface of the remaining portion of the lead frame adjacent to the extending portion among the side surfaces of the lead frame, and the lower surface of the lead frame covered with the first insulating layer. 8. The method of manufacturing a circuit board according to claim 6 or 7, wherein the area adjacent to the is covered. The extension portion of the first insulation layer is covered with a remaining portion of the first insulation layer adjacent to the extension portion of the side surface of the second insulation layer. or adjacent to the region of the side surface of the second insulating layer and the region of the side surface of the base substrate of the side surface of the second insulating layer 9. The method of manufacturing a circuit board according to any one of claims 6 to 8, wherein the region is covered. 10. The method of manufacturing a circuit board according to any one of claims 6 to 9, wherein the coverage of the lower surface of the extension portion with the first insulating layer is 2 to 50%.

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