JP7121004B2 - Circuit component manufacturing method and circuit component - Google Patents

Description

The present invention relates to a circuit component (molded circuit component) manufacturing method and circuit component (molded circuit component).

In recent years, with the trend toward lighter and more electrified automobiles, there is a movement to replace metal parts of automobiles with foamed resin parts that are lightweight and have insulating properties. For this reason, research and practical application of methods for producing foam molded articles (foam molding) are being actively pursued. Polypropylene (PP) and acrylonitrile-butadiene-styrene copolymer resin (ABS), which are general-purpose engineering plastics (general-purpose engineering plastics), have conventionally been used for foam molding. Glass fiber reinforced resins such as polyamide 6 and polyamide 66, which have a certain degree of heat resistance, are also used for foam molding. The foaming agents used in foam molding are roughly classified into two types, physical foaming agents and chemical foaming agents, but chemical foaming agents are difficult to apply to high-melting-point materials. For this reason, the foam injection molding method using a high-pressure supercritical fluid as a physical foaming agent is adopted for the foam molding of the glass fiber reinforced resin having high heat resistance (for example, Patent Documents 1 to 3). .

The normal heat-resistant temperature of the above-mentioned general-purpose engineering plastics is about 100°C, but for applications that are expected to be used in a higher temperature environment, polyphenylene sulfide (PPS), liquid crystal polymer ( LCP) and other super engineering plastics (super engineering plastics) are used. PPS is a super engineering plastic that excels in cost performance and has the fastest growing adoption in automotive parts. Applications of LCP are expanding in small parts such as high-precision connectors. Patent Documents 4 and 5 disclose a method for producing a PPS foam molded article.

In recent years, MIDs (Molded Interconnected Devices) have been put to practical use in smartphones and the like, and are expected to expand their application in the automobile field in the future. A MID is a device in which a three-dimensional circuit is formed on the surface of a molded body with a metal film, and can contribute to weight reduction and thinning of products and reduction in the number of parts (for example, Patent Documents 6 and 7).

MIDs mounted with light emitting diodes (LEDs) have also been proposed. Since the LED generates heat when energized, it is necessary to dissipate the heat from the rear surface, and it is important to improve the heat dissipation of the MID. Patent Documents 8 and 9 propose composite parts in which an MID and a metal heat dissipation material are integrated.

Further, a method has been proposed in which a conductive filler is mixed with a resin and molded to enhance the heat dissipation of the resin molding itself (eg, Patent Document 10).

Japanese Patent No. 2625576 Japanese Patent No. 3788750 Japanese Patent No. 4144916 JP-A-2013-60508 JP 2012-251022 A European Patent No. 1274288 Japanese Patent No. 5022501 Japanese Patent No. 3443872 JP 2017-199803 A JP 2015-108058 A

In order to meet the need for weight reduction of automobile parts, molded circuit parts such as MIDs disclosed in Patent Documents 6 and 7 are required to be further reduced in weight. Therefore, it is expected to reduce the weight of molded circuit parts by using a foam molded body having a small specific gravity for the molded circuit parts. SUMMARY OF THE INVENTION The present invention solves the above problems and provides a molded circuit component that is lightweight.

In addition, the method for producing a PPS foam molded article disclosed in Patent Documents 4 and 5 includes a step of holding the PPS molded article in a pressurized inert gas atmosphere to permeate the inert gas, and This is a so-called batch type production method, which includes a step of heating and foaming the impregnated PPS under normal pressure. Therefore, there is a problem that the productivity is inferior to that of continuous molding such as injection molding and extrusion molding.

The foam molding method using a physical foaming agent disclosed in Patent Documents 1 to 3 is continuous molding with high productivity, and is a foam molding technique that does not require a relatively large amount of resin. Therefore, in principle, the methods disclosed in Patent Documents 1 to 3 are considered to be capable of foaming super engineering plastics such as PPS. However, recent automobile parts are required to have extremely high heat resistance. According to the studies of the inventors of the present application, as disclosed in Patent Documents 1 to 3, a foamed molded article manufactured using a conventional high-pressure physical foaming agent and a molded circuit component using the same are resin materials It was found that sufficient heat resistance could not be obtained even if a super engineering plastic was used for the material.

The present invention is intended to solve the above problems, and provides a method for manufacturing a molded circuit component having high heat resistance and light weight, including continuous molding with high productivity.

Furthermore, if the resin molded body, which is the base material of circuit parts such as MID, has sufficient heat dissipation performance, the metal heat dissipation member disclosed in Patent Documents 8 and 9 becomes unnecessary, and the cost of circuit parts can be reduced. . However, for example, if a conductive filler as disclosed in Patent Document 10 is added to a thermoplastic resin to obtain the heat dissipation required for electronic parts, the fluidity of the thermoplastic resin during molding is reduced. . As a result, the moldability deteriorates, and the resin molding cannot obtain sufficient dimensional accuracy.

If the holding pressure is increased for molding in order to improve the dimensional accuracy of the resin molded body, burrs may occur in the resin molded body. If burrs occur, secondary processing for deburring is required. In addition, if molding is performed with a high mold clamping pressure in order to suppress the generation of burrs, the life of the mold will be shortened. These increase the manufacturing cost of circuit components and reduce mass productivity.

The present invention solves these problems, and provides a circuit component (MID) using a base material that is a resin molded body, which can achieve both mass productivity and heat dissipation.

According to the first aspect of the present invention, the substrate, which is a circuit component and is a foam molded body containing a thermoplastic resin, the circuit pattern formed on the substrate, and the mounting surface of the substrate and a mounting component electrically connected to the circuit pattern, wherein the circuit pattern is formed on the roughened portion on the substrate. .

In this aspect, the thermoplastic resin includes a super engineering plastic, and when the circuit component is heated and the surface temperature of the circuit component is maintained at 240 ° C. to 260 ° C. for 5 minutes, the thickness of the circuit component due to heating may be -2% to 2%. A reflow furnace may be used to heat the circuit components.

In this aspect, the circuit component is the foam molded body containing the thermoplastic resin and an insulating thermally conductive filler and having a density reduction rate of 0.5% to 10%, and the mounting surface and the a portion of the base material having a rear surface facing a mounting surface, and the circuit pattern formed on a surface of the base material including the mounting surface; WHEREIN: 0.1 mm or more may be sufficient as the distance from the said mounting surface to the said back surface. A density reduction rate of the base material may be 1 to 7%. In addition, in the portion of the base material on which the mounted component is mounted, the distance from the mounting surface to the back surface may exceed 0.5 mm, and foam cells may be formed between the mounting surface and the back surface. may have Further, a recess defined by side walls and a bottom surface is formed on the back surface, the mounted component is mounted on the mounting surface corresponding to the bottom surface, and the distance from the mounting surface to the bottom surface is 0.1 mm to 0.1 mm. It may be 1.5 mm. An area of the bottom surface per mounted component arranged on the mounting surface corresponding to the bottom surface may be 0.4 cm ² to 4 cm ² .

A non-through hole or a through hole may be formed from the mounting surface toward the bottom surface, and an electroless plating film may be formed on the inner wall of the hole. Further, a concave portion may be formed in the mounting surface of the base material where the mounted component is mounted, and an electroless plating film may be formed on the surface of the concave portion.

The mounting component may be an LED, and the circuit pattern may include an electroless plating film. Further, the back surface may not be provided with a heat radiating member. The thermoplastic resin may include super engineering plastic, and the super engineering plastic may include polyphenylene sulfide or liquid crystal polymer.

According to the second aspect of the present invention, a plasticization zone in which a thermoplastic resin is plasticized and melted to become a molten resin, and a starvation zone in which the molten resin is in a starvation state, physical foaming in the starvation zone A method for manufacturing a circuit component using a plasticizing cylinder having an inlet for introducing an agent, wherein the thermoplastic resin is plasticized and melted to form the molten resin in the plasticizing zone. introducing a pressurized fluid containing the physical blowing agent at a constant pressure into the starvation zone to maintain the constant pressure in the starvation zone; and starving the molten resin in the starvation zone. contacting the starved molten resin with a pressurized fluid containing a physical blowing agent at the constant pressure in the starvation zone while maintaining the starvation zone at the constant pressure; and molding the molten resin in contact with a pressurized fluid containing A circuit component manufacturing method is provided, wherein the constant pressure is 0.5 MPa to 12 MPa.

In this aspect, the super engineering plastic may contain polyphenylene sulfide or a liquid crystal polymer. Further, the super engineering plastic may contain polyphenylene sulfide, and the constant pressure may be 2 MPa to 12 MPa. The physical blowing agent may be nitrogen.

In the starvation zone, the pressurized fluid containing the physical blowing agent may pressurize the molten resin, and the constant pressure may be maintained in the starvation zone at all times during the production of the foam molded article. The plasticizing cylinder has an introduction speed adjusting container connected to the introduction port, and the manufacturing method further includes supplying a pressurized fluid containing the physical foaming agent to the introduction speed adjusting container, A pressurized fluid comprising a physical blowing agent at said constant pressure may be introduced into said starvation zone from a rate regulating vessel. The introduction port may be open at all times, and the introduction speed adjusting vessel and the starvation zone may be maintained at the constant pressure during the production of the foam molded article.

The circuit pattern contains an electroless plating film, and the formation of the circuit pattern on the surface of the foamed molded product is a catalyst containing a polymer having at least one of an amide group and an amino group on the surface of the foamed molded product. forming an activity hindrance layer, heating or irradiating a part of the surface of the foam molded body on which the catalytic activity hindering layer is formed, and electrolessly plating the heated or light irradiated surface of the foam molded body applying a catalyst; and bringing an electroless plating solution into contact with the surface of the foam molded article to which the electroless plating catalyst has been applied to form the electroless plating film on the heated portion or the light-irradiated portion of the surface. may include The polymer may be a hyperbranched polymer.

The present invention can provide lightweight circuit components (molded circuit components).

4 is a flow chart showing a method for manufacturing a foam molded article according to the first embodiment. It is a schematic diagram showing a manufacturing apparatus of a foaming molding used in a first embodiment. 4 is a flow chart showing a method of forming a circuit pattern on the surface of the foam molded article in the first embodiment. It is a figure explaining the method of forming a circuit pattern on the surface of the foam molding in 1st Embodiment. FIG. 5(a) is a schematic top view of the circuit component of the second embodiment, and FIG. 5(b) is a schematic cross-sectional view taken along line B1-B1 in FIG. 5(a). FIG. 6 is a partially enlarged view of the circuit component shown in FIG. 5(b). FIG. 7(a) is a schematic top view showing the structure of the circuit component shown in FIG. 5(a) during manufacture, and FIG. 7(b) is a schematic cross-sectional view taken along line B3-B3 of FIG. 7(a). be. FIG. 8(a) is a schematic top view showing another halfway structure of the circuit component shown in FIG. 5(a); It is a diagram. FIG. 9 is a schematic cross-sectional view of a circuit component of Modification 1 of the second embodiment. FIG. 10 is a schematic cross-sectional view of a circuit component of Modification 2 of the second embodiment.

[First Embodiment]
A method for manufacturing a molded circuit component according to the present embodiment will be described with reference to the flow chart shown in FIG. In this embodiment, first, a foam molded body is produced (steps S1 to S5 in FIG. 1), and a circuit pattern is formed on the surface of the foam molded body (step S6 in FIG. 1) to obtain a molded circuit component. Here, the term "molded circuit component" means a component in which an electric circuit is formed on the surface of a resin molded body.

<Production equipment for foam molding>
First, a manufacturing apparatus for manufacturing a foam molded article used in this embodiment will be described. In this embodiment, a foam molded article is manufactured using a manufacturing apparatus (injection molding apparatus) 1000 shown in FIG. The manufacturing apparatus 1000 mainly includes a plasticizing cylinder 210 in which a screw 20 is installed, a cylinder 100 which is a physical foaming agent supply mechanism for supplying the physical foaming agent to the plasticizing cylinder 210, and a mold provided with a mold. A clamping unit (not shown) and a control device (not shown) for controlling the operation of the plasticizing cylinder 210 and the mold clamping unit are provided. The molten resin that is plasticized and melted in the plasticizing cylinder 210 flows from right to left in FIG. Therefore, inside the plasticizing cylinder 210 of this embodiment, the right hand in FIG. 2 is defined as "upstream" or "rear", and the left hand is defined as "downstream" or "forward".

The plasticizing cylinder has a plasticizing zone 21 in which a thermoplastic resin is plasticized and melted to become a molten resin, and a starvation zone 23 downstream of the plasticizing zone 21 in which the molten resin starves. The “starvation state” is a state in which the molten resin does not fill the starvation zone 23 but does not fill the starvation zone 23 . Therefore, in the starvation zone 23, there exists a space other than the portion occupied by the molten resin. Also, an inlet 202 for introducing the physical foaming agent is formed in the starvation zone 23 , and the inlet 202 is connected to an introduction speed adjusting container 300 . The cylinder 100 supplies the physical blowing agent to the plasticizing cylinder 210 through the introduction speed adjusting container 300 .

Although the manufacturing apparatus 1000 has only one starvation zone 23, the manufacturing apparatus used in this embodiment is not limited to this. For example, in order to promote penetration of the physical foaming agent into the molten resin, the starvation zone 23 and a plurality of inlets 202 formed therein are provided, and the physical foaming agent is introduced into the plasticizing cylinder 210 from the plurality of inlets 202. It may be a structure that Moreover, although the manufacturing apparatus 1000 is an injection molding apparatus, the manufacturing apparatus used in this embodiment is not limited to this, and may be, for example, an extrusion molding apparatus.

<Method for manufacturing molded circuit parts>
(1) Plasticization and Melting of Thermoplastic Resin First, in the plasticizing zone 21 of the plasticizing cylinder 210, the thermoplastic resin is plasticized and melted to form a molten resin (step S1 in FIG. 1). In the present embodiment, it is preferable to use a super engineering plastic (hereinafter referred to as "super engineering plastic" as appropriate) as the thermoplastic resin. In general, plastics with a continuous use temperature of 150° C. or higher are classified as super engineering plastics, and the definition of super engineering plastics in this specification also follows this. Many super engineering plastics contain benzene rings in their molecular chains, so the molecular chains are thick and strong. Even if the ambient temperature rises, the molecules will not move easily, so it has excellent heat resistance. Among fluororesins, there are resins classified as super engineering plastics that are excellent in heat resistance without having a benzene ring structure. This is because the fluororesin is very stable when combined with carbon.

Super engineering plastics are roughly divided into amorphous (transparent) resins and crystalline resins. Examples of amorphous (transparent) resins include polyphenylsulfone (PPSU), polysulfone (PSU), polyarylate (PAR), and polyetherimide (PEI). Examples of crystalline resins include polyether Ether ketone (PEEK), polyphenylene sulfide (PPS), polyether sulfone (PES), polyamideimide (PAI), liquid crystal polymer (LCP), polyvinylidene fluoride (PVDF). The super engineering plastics of the present embodiment may be used singly or in combination of two or more, or may be polymer alloys containing these engineering plastics. As the super engineering plastic used in the present embodiment, a crystalline resin that facilitates the formation of fine cells is preferable, and among these, polyphenylene sulfide (PPS) and liquid crystal polymer (LCP) are more preferable.

Polyphenylene sulfide (PPS) has advantages such as relatively low cost, chemical stability, high dimensional accuracy, and high strength. On the other hand, PPS has problems that burrs are likely to occur during molding, warping is likely to occur when glass long fibers or the like are mixed, and specific gravity is high. In this embodiment, by foam-molding PPS, burrs and warping can be suppressed, and the specific gravity can be reduced. Liquid crystal polymer (LCP) has the advantage that burrs are less likely to occur during molding and high dimensional accuracy can be obtained even in thin-walled molded parts, due to its large dependence on the shear rate of the molten resin. In automotive parts, LCP is used in connectors that require high heat resistance. On the other hand, LCP has the problem of being expensive and having a large specific gravity. In this embodiment, by foam-molding LCP, the specific gravity can be reduced, and the amount used is reduced compared to a solid molded body (non-foamed molded body) of the same size, so cost reduction can also be achieved.

Various inorganic fillers such as glass fiber, talc, and carbon fiber may be kneaded into the thermoplastic resin of the present embodiment. By mixing an inorganic filler functioning as a nucleating agent for foaming and an additive for increasing melt tension into the thermoplastic resin, the foamed cells can be made finer. The thermoplastic resin of the present embodiment may contain various general-purpose additives as necessary.

In addition, in the present embodiment, only super engineering plastic is used as the thermoplastic resin, but depending on the application of the foam molded product, a general-purpose thermoplastic resin that is not a super engineering plastic may be used to the extent that the heat resistance of the foam molded product is not affected. may be mixed and used. In the present embodiment, the main component of the thermoplastic resin forming the foam molded article is super engineering plastic. For example, the proportion of super engineering plastic in the thermoplastic resin forming the foam molded article is 60% to 100% by weight. Preferably, 95% to 100% by weight is more preferred. Moreover, in this embodiment, physical foaming is used as a foaming agent, and a chemical foaming agent is not used together. Therefore, the super engineering plastic, which is the thermoplastic resin of this embodiment, does not contain a chemical foaming agent. Due to the high melting temperature of super engineering plastics, it is difficult to use chemical blowing agents together.

In this embodiment, the thermoplastic resin is plasticized and melted in a plasticizing cylinder 210 in which the screw 20 shown in FIG. 2 is installed. A band heater (not shown) is provided on the outer wall surface of the plasticizing cylinder 210, which heats the plasticizing cylinder 210 and further heats sheared by rotation of the screw 20, thereby plasticizing the thermoplastic resin. melted.

(2) Maintaining Pressure in Starvation Zone Next, a constant pressure physical blowing agent is introduced into the starvation zone 23 to maintain the constant pressure in the starvation zone 23 (step S2 in FIG. 1).

A pressurized fluid is used as the physical blowing agent. In this embodiment, "fluid" means any one of liquid, gas, and supercritical fluid. Moreover, the physical blowing agent is preferably carbon dioxide, nitrogen, or the like from the viewpoint of cost and environmental load. Since the pressure of the physical foaming agent of the present embodiment is relatively low, for example, from a cylinder storing fluid such as a nitrogen cylinder, a carbon dioxide cylinder, an air cylinder, etc., the fluid taken out after being decompressed to a certain pressure by a pressure reducing valve can be used. In this case, the cost of the entire manufacturing apparatus can be reduced because the booster is not required. Also, if necessary, a fluid pressurized to a predetermined pressure may be used as a physical foaming agent. For example, when nitrogen is used as the physical blowing agent, the physical blowing agent can be produced by the following method. First, nitrogen is purified through a nitrogen separation membrane while compressing atmospheric air with a compressor. Next, the purified nitrogen is pressurized to a predetermined pressure using a booster pump, a syringe pump, or the like to generate a physical foaming agent. Compressed air may also be used as a physical blowing agent. In this embodiment, the physical blowing agent and the molten resin are not subjected to forced shear kneading. Therefore, even if compressed air is used as a physical blowing agent, oxygen, which has a low solubility in the molten resin, is difficult to dissolve in the molten resin, and oxidative deterioration of the molten resin can be suppressed.

The pressure of the physical blowing agent introduced into the starvation zone 23 is constant, and the pressure of the starvation zone 23 is maintained at the same constant pressure as the introduced physical blowing agent. The pressure of this foaming agent is, for example, 0.5 MPa to 12 MPa, preferably 2 MPa to 12 MPa, more preferably 2 MPa to 10 MPa, and even more preferably 2 MPa to 8 MPa. Moreover, the pressure of the physical foaming agent is preferably 1 MPa to 6 MPa. The optimum pressure varies depending on the type of molten resin, but by setting the pressure of the physical blowing agent to 0.5 MPa or more, the amount of physical blowing agent necessary for foaming can penetrate into the molten resin, and the foaming property of the foamed molded product is improved. improves. Further, by setting the pressure of the physical blowing agent to 12 MPa or less, the heat resistance of the foam molded product is improved, the generation of swirl marks is suppressed, and the load on the apparatus can be reduced. The expression that the pressure of the physical foaming agent that pressurizes the molten resin is "constant" means that the fluctuation range of the pressure with respect to the predetermined pressure is preferably within ±20%, more preferably within ±10%. The starvation zone pressure is measured, for example, by a pressure sensor 27 provided in the starvation zone 23 of the plasticizing cylinder 210 . The starvation zone 23 moves back and forth in the plasticizing cylinder 210 as the screw 20 advances and retreats, but the pressure sensor 27 shown in FIG. It is provided at a position existing within the zone 23 . Also, the position facing the inlet 202 is always within the starvation zone 23 . Therefore, although the pressure sensor 27 is not provided at the position facing the introduction port 202, the pressure indicated by the pressure sensor 27 and the pressure at the position facing the introduction port 202 are substantially the same. In addition, in the present embodiment, only the physical blowing agent is introduced into the starvation zone 23, but other pressurized fluids other than the physical blowing agent are simultaneously introduced into the starvation zone 23 to the extent that the effect of the present invention is not affected. may In this case, the pressurized fluid containing the physical blowing agent introduced into the starvation zone 23 has the constant pressure mentioned above.

In this embodiment, as shown in FIG. 2 , the physical foaming agent is supplied from the cylinder 100 to the starvation zone 23 through the introduction port 202 via the introduction speed adjusting container 300 . The physical foaming agent is introduced in the starvation zone 23 from the introduction port 202 without passing through a pressure increasing device or the like after being decompressed to a predetermined pressure using the decompression valve 151 . In this embodiment, the introduction amount of the physical foaming agent introduced into the plasticizing cylinder 210, introduction time, etc. are not controlled. Therefore, a mechanism for controlling them, for example, a driven valve using a check valve, an electromagnetic valve, or the like is not required, and the introduction port 202 does not have a driven valve and is always open. In this embodiment, the pressure of the physical foaming agent supplied from the cylinder 100 is kept constant from the decompression valve 151 through the introduction speed adjusting container 300 to the starvation zone 23 in the plasticizing cylinder 210. be.

The physical foaming agent introduction port 202 has a larger inner diameter than the physical foaming agent introduction port of the conventional manufacturing apparatus. The reason why the inner diameter of the inlet 202 can be increased in this way is that the amount of molten resin in the starvation zone 23 facing the inlet 202 during molding is smaller than in the conventional manufacturing apparatus. Therefore, even a relatively low-pressure physical foaming agent can be efficiently introduced into the plasticizing cylinder 210 . Further, even if a part of the molten resin contacts the inlet 202 and solidifies, it can function as an inlet without being completely blocked due to the large inner diameter. For example, when the inner diameter of the plasticizing cylinder 210 is large, that is, when the outer diameter of the plasticizing cylinder is large, it is easy to increase the inner diameter of the introduction port 202 . On the other hand, if the inner diameter of the introduction port 202 is extremely large, the molten resin will stagnate, resulting in poor molding. Rise. Specifically, the inner diameter of the introduction port 202 is preferably 20% to 100%, more preferably 30% to 80%, of the inner diameter of the plasticizing cylinder 210 . Alternatively, regardless of the inner diameter of the plasticizing cylinder 210, the inner diameter of the introduction port 202 is preferably 3 mm to 150 mm, more preferably 5 mm to 100 mm. Here, the inner diameter of the introduction port 202 means the inner diameter of the opening on the inner wall 210 a of the plasticizing cylinder 210 . Moreover, the shape of the inlet 202, that is, the shape of the opening on the inner wall 210a of the plasticizing cylinder 210 is not limited to a perfect circle, and may be an ellipse or a polygon. When the shape of the introduction port 202 is elliptical or polygonal, the diameter of a perfect circle having the same area as the area of the introduction port 202 is defined as the "inner diameter of the introduction port 202".

Next, the introduction speed adjusting container 300 connected to the introduction port 202 will be described. The introduction speed adjusting container 300 connected to the introduction port 202 has a volume equal to or greater than a certain value, thereby slowing down the flow rate of the physical foaming agent introduced into the plasticizing cylinder 210, so that the physical foaming agent is introduced into the introduction speed adjusting container 300. You can secure the time you can stay. The introduction speed adjusting container 300 is directly connected to a plasticizing cylinder 210 heated by a band heater (not shown) arranged around it, so that the heat of the plasticizing cylinder 210 is conducted to the introducing speed adjusting container 300. be. As a result, the physical foaming agent inside the introduction speed adjusting container 300 is heated, the temperature difference between the physical foaming agent and the molten resin is reduced, and the temperature of the molten resin with which the physical foaming agent contacts is suppressed from being extremely lowered. It is possible to stabilize the amount (permeation amount) of the physical blowing agent dissolved in the molten resin. That is, the introduction speed adjusting container 300 functions as a buffer container having a function of heating the physical foaming agent. On the other hand, if the volume of the introduction speed adjusting container 300 is too large, the cost of the entire device increases. The volume of the introduction speed adjusting container 300 depends on the amount of molten resin existing in the starvation zone 23, but is preferably 5 mL to 20 L, more preferably 10 mL to 2 L, even more preferably 10 mL to 1 L. By setting the volume of the introduction speed adjusting container 300 within this range, it is possible to secure a time during which the physical foaming agent can stay while considering the cost.

As will be described later, the physical foaming agent is consumed in the plasticizing cylinder 210 by contacting and permeating the molten resin. In order to keep the pressure in the starvation zone 23 constant, the consumed physical blowing agent is introduced into the starvation zone 23 from the introduction rate adjusting vessel 300 . If the volume of the introduction speed adjusting container 300 is too small, the replacement frequency of the physical blowing agent becomes high, so the temperature of the physical blowing agent becomes unstable, and as a result, there is a possibility that the supply of the physical blowing agent becomes unstable. Therefore, the introduction speed adjusting container 300 preferably has a volume capable of retaining the amount of physical foaming agent consumed in the plasticizing cylinder for 1 to 10 minutes. Also, for example, the volume of the introduction speed adjusting container 300 is preferably 0.1 to 5 times, more preferably 0.5 to 2 times, the volume of the starvation zone 23 to which the introduction speed adjusting container 300 is connected. In this embodiment, the volume of the starvation zone 23 is the area (23) in which the portion of the empty plasticizing cylinder 210 containing no molten resin, where the diameter of the shaft of the screw 20 and the depth of the screw flight is constant. means the volume of Since the introduction port 202 is always open, the introduction speed adjusting container 300 and the starvation zone 23 are always kept at a constant pressure of the physical foaming agent during the production of the foam molded product.

(3) Starvation of Molten Resin Next, the molten resin is made to flow into the starvation zone 23, and the molten resin is starved in the starvation zone 23 (step S3 in FIG. 1). The starvation state is determined by the balance between the amount of molten resin sent from the upstream of the starvation zone 23 to the starvation zone 23 and the amount of molten resin sent from the starvation zone 23 to the downstream thereof. becomes.

In this embodiment, the molten resin is starved in the starvation zone 23 by providing the compression zone 22 in which the molten resin is compressed and the pressure increases upstream of the starvation zone 23 . The compression zone 22 is provided with a large-diameter portion 20A in which the diameter of the shaft of the screw 20 is made larger (thicker) than that of the plasticizing zone 21 located on the upstream side, and the screw flights are gradually shallowed. A sealing portion 26 is provided adjacent to the downstream side of 20A. The seal portion 26 has a large (thick) shaft diameter of the screw 20 like the large-diameter portion 20A, and is not provided with a screw flight. It is By increasing the diameter of the shaft of the screw 20, the large-diameter portion 20A and the seal portion 26 reduce the clearance between the inner wall of the plasticizing cylinder 210 and the screw 20, thereby reducing the amount of resin to be supplied downstream. can increase the flow resistance of Therefore, in this embodiment, the large-diameter portion 20A and the seal portion 26 are mechanisms that increase the flow resistance of the molten resin. The sealing portion 26 also has the effect of suppressing the backflow of the physical foaming agent, that is, the movement of the physical foaming agent from the downstream side to the upstream side of the sealing portion 26 .

Due to the presence of the large-diameter portion 20A and the seal portion 26, the resin flow rate supplied from the compression zone 22 to the starvation zone 23 decreases, the molten resin is compressed in the compression zone 22 on the upstream side, the pressure increases, and the starvation rate on the downstream side increases. Zone 23 is underfilled with molten resin (starved state). In order to promote the starvation state of the molten resin, the screw 20 has a structure in which the shaft diameter of the portion located in the starvation zone 23 is smaller (thinner) and the screw flight is deeper than the portion located in the compression zone 22. have Furthermore, the screw 20 has a structure in which the shaft diameter of the portion located there is smaller (thinner) and the screw flight is deeper over the entire starvation zone 23 compared to the portion located in the compression zone 22. is preferred. Furthermore, throughout the starvation zone 23, the shaft diameter of the screw 20 and the depth of the screw flight are preferably substantially constant. Thereby, the pressure in the starvation zone 23 can be kept substantially constant, and the starvation state of the molten resin can be stabilized. In this embodiment, the starvation zone 23 is formed in a portion of the screw 20 where the diameter of the shaft of the screw 20 and the depth of the screw flight are constant, as shown in FIG.

The mechanism for increasing the flow resistance of the molten resin provided in the compression zone 22 is a mechanism for temporarily reducing the flow area through which the molten resin passes in order to limit the flow rate of the resin supplied from the compression zone 22 to the starvation zone 23. If there is, it is not particularly limited. Although both the large-diameter portion 20A of the screw and the seal portion 26 are used in this embodiment, only one of them may be used. Mechanisms for increasing the flow resistance other than the large-diameter portion 20A of the screw and the seal portion 26 include a structure in which screw flights are provided in the opposite direction to other portions, a labyrinth structure provided on the screw, and the like.

The mechanism for increasing the flow resistance of the molten resin may be provided on the screw as a separate member such as a ring from the screw, or may be provided integrally with the screw as a part of the structure of the screw. If the mechanism for increasing the flow resistance of the molten resin is provided as a ring or the like, which is a separate member from the screw, the size of the clearance portion, which is the flow path of the molten resin, can be changed by changing the ring, so that the flow of the molten resin can be easily performed. There is an advantage that the magnitude of the flow resistance can be changed.

In addition to the mechanism that increases the flow resistance of the molten resin, a backflow prevention mechanism (sealing mechanism) that prevents the molten resin from flowing back from the starvation zone 23 to the compression zone 22 upstream is provided between the compression zone 22 and the starvation zone 23. This also allows the molten resin to be starved in the starvation zone 23 . For example, a seal mechanism such as a ring or steel ball that can be moved upstream by the pressure of the physical foaming agent can be used. However, since the backflow prevention mechanism requires a drive unit, there is a risk of resin stagnation. Therefore, a mechanism that does not have a drive unit and increases flow resistance is preferable.

In this embodiment, in order to stabilize the starvation state of the molten resin in the starvation zone 23, the amount of thermoplastic resin supplied to the plasticizing cylinder 210 may be controlled. This is because if the amount of thermoplastic resin supplied is too large, it will be difficult to maintain the starvation state. In this embodiment, a general-purpose feeder screw 212 is used to control the amount of thermoplastic resin supplied. The rate of molten resin metering in the starvation zone 23 is greater than the plasticization rate in the compression zone 22 due to the limited supply of thermoplastic resin. As a result, the density of the molten resin in the starvation zone 23 is stably lowered, promoting the permeation of the physical foaming agent into the molten resin.

In this embodiment, the length of the starvation zone 23 in the flow direction of the molten resin is preferably long in order to secure the contact area and contact time between the molten resin and the physical blowing agent. The adverse effect that the length becomes long occurs. Therefore, the length of the starvation zone 23 is preferably 2 to 12 times the inner diameter of the plasticizing cylinder 210, more preferably 4 to 10 times. Also, the length of starvation zone 23 preferably covers the full range of metering strokes in injection molding. That is, the length of the starvation zone 23 in the flow direction of the molten resin is preferably equal to or longer than the length of the metering stroke in injection molding. The screw 20 moves forward and backward as the molten resin is plasticized, metered, and injected. A mouth 202 can be located (formed) within the starvation zone 23 . In other words, no zone other than the starvation zone 23 will come to the position of the inlet 202 even if the screw 20 moves forward and backward during the production of the foam molding. Thereby, the physical foaming agent introduced from the introduction port 202 is always introduced into the starvation zone 23 during the production of the foam molded product. By thus providing a starvation zone having a sufficient and appropriate size (length) and introducing a constant pressure physical blowing agent therein, the starvation zone 23 can be easily maintained at a constant pressure. In this embodiment, the length of the starvation zone 23 is substantially the same as the length of the portion of the screw 20 where the shaft diameter and screw flight depth of the screw 20 are constant, as shown in FIG.

Additionally, a flow rate adjustment zone 25 may be provided between the compression zone 22 and the starvation zone 23 . Comparing the flow rate of the molten resin in the compression zone 22 upstream of the flow rate adjustment zone 25 and the flow rate of the molten resin in the starvation zone 23 downstream, the flow rate of the molten resin in the starvation zone 23 is higher. The inventors of the present application provided a flow rate adjustment zone 25 as a buffer zone between the compression zone 22 and the starvation zone 23 to suppress this rapid change (increase) in the flow rate of the molten resin. The inventors have found that the foamability of the foamed molded product obtained by this method is improved. The details of why the foamability of the foam molded product is improved by providing the flow rate adjustment zone 25 as a buffer zone between the compression zone 22 and the starvation zone 23 are unknown. It is speculated that one of the reasons is that the physical foaming agent and the molten resin that have flowed in from the starvation zone 23 are forcibly kneaded due to the retention of , and the kneading time is lengthened. In the present embodiment, the portion of the plasticizing screw 20 shown in FIG. and recompress. Furthermore, by providing a notch in the screw flight, the flow rate of the molten resin is adjusted. The decompression section and the compression section can be formed, for example, by changing the depth of the screw flight, in other words, by changing the size (thickness) of the screw diameter.

(4) Contact between molten resin and physical blowing agent Next, while the starvation zone 23 is kept at a constant pressure, the starved molten resin is brought into contact with the physical blowing agent at a constant pressure in the starvation zone 23 (Fig. 1 step S4). That is, in the starvation zone 23, the molten resin is pressurized with a constant pressure by a physical foaming agent. Since the starvation zone 23 is not filled with the molten resin (starved state) and has a space in which the physical foaming agent can exist, the physical foaming agent and the molten resin can be efficiently brought into contact with each other. The physical blowing agent that comes into contact with the molten resin permeates the molten resin and is consumed. When the physical blowing agent is consumed, the physical blowing agent remaining in the introduction speed adjusting container 300 is supplied to the starvation zone 23 . This keeps the pressure in the starvation zone 23 at a constant pressure, and the molten resin continues to contact the physical blowing agent at constant pressure.

In conventional foam molding using a physical foaming agent, a predetermined amount of high-pressure physical foaming agent is forcibly introduced into a plasticizing cylinder within a predetermined time. Therefore, it is necessary to pressurize the physical blowing agent to a high pressure and accurately control the amount of introduction into the molten resin, the introduction time, etc., and the physical blowing agent is in contact with the molten resin only for a short introduction time. . In contrast, in the present embodiment, instead of forcibly introducing the physical blowing agent into the plasticizing cylinder 210, the physical blowing agent is continuously plasticized at a constant pressure so that the pressure in the starvation zone 23 is constant. The physical foaming agent is continuously brought into contact with the molten resin. This stabilizes the amount of physical foaming agent dissolved in the molten resin (permeation amount), which is determined by temperature and pressure. Moreover, since the physical foaming agent of this embodiment is always in contact with the molten resin, a necessary and sufficient amount of the physical foaming agent can penetrate into the molten resin. As a result, the foamed molded article produced in the present embodiment has finer foam cells despite the fact that the physical foaming agent is used at a lower pressure than in the conventional molding method using a physical foaming agent.

In addition, since the production method of the present embodiment does not require control of the introduction amount of the physical foaming agent, the introduction time, etc., drive valves such as check valves and electromagnetic valves, and control mechanisms for controlling these are unnecessary. Equipment costs can be reduced. Moreover, since the physical foaming agent used in this embodiment has a lower pressure than the conventional physical foaming agent, the load on the apparatus is also small.

In this embodiment, the starvation zone 23 is kept at a constant pressure all the time during the production of successive foamed bodies in the injection molding cycle. That is, all steps of the method for producing a foam molded product are carried out while continuously supplying the physical blowing agent at a constant pressure in order to compensate for the consumed physical blowing agent in the plasticizing cylinder. In addition, in the present embodiment, for example, when injection molding is continuously performed for a plurality of shots, the molten resin for the next shot is supplied during the injection process, the cooling process for the molded body, and the process for taking out the molded body. Prepared in a plasticizing cylinder, the next shot of molten resin is pressurized at a constant pressure by a physical foaming agent. In other words, in the continuous injection molding of multiple shots, the molten resin and the physical foaming agent at a constant pressure are always present and in contact with each other in the plasticizing cylinder. One cycle of injection molding including a plasticizing and weighing process, an injection process, a cooling process of the molded body, a taking-out process, etc. is carried out in a state of being constantly pressurized at a constant pressure by the agent. Similarly, when performing continuous molding such as extrusion molding, the molten resin and the physical blowing agent at a constant pressure are always present and in contact with each other in the plasticizing cylinder. is always pressurized at a constant pressure by a physical blowing agent.

(5) Foam molding Next, the molten resin in contact with the physical foaming agent is molded into a foam molding (step S5 in FIG. 1). The plasticizing cylinder 210 used in this embodiment has a recompression zone 24 located downstream of the starvation zone 23 and adjacent to the starvation zone 23 where the molten resin is compressed to increase pressure. First, the rotation of the plasticizing screw 20 causes the molten resin in the starvation zone 23 to flow to the recompression zone 24 . The molten resin containing the physical blowing agent is pressure regulated in the recompression zone 24, pushed forward of the plasticizing screw 20 and metered. At this time, the internal pressure of the molten resin pushed forward of the plasticizing screw 20 is controlled as screw back pressure by a hydraulic motor or an electric motor (not shown) connected to the rear of the plasticizing screw 20 . In this embodiment, the internal pressure of the molten resin extruded forward of the plasticizing screw 20, that is, the screw back pressure is , is preferably controlled to be about 1 to 6 MPa higher than the pressure in the starvation zone 23 which is kept constant. In this embodiment, a check ring 50 is provided at the tip of the screw 20 so that the compressed resin in front of the screw 20 does not flow back to the upstream side. As a result, the pressure in the starvation zone 23 is not affected by the resin pressure in front of the screw 20 during metering.

The molding method of the foam molded article is not particularly limited, and the molded article can be molded by, for example, injection foam molding, extrusion foam molding, foam blow molding, or the like. In this embodiment, injection foam molding is performed by injecting and filling a weighed molten resin from a plasticizing cylinder 210 shown in FIG. 2 into a cavity (not shown) in a mold. In injection foam molding, the mold cavity is filled with molten resin with a filling capacity of 75% to 95% of the mold cavity volume, and the short shot method is used to fill the mold cavity while the bubbles expand. Alternatively, a core-back method may be used in which the mold cavity is filled with molten resin in a filling amount of 100% of the mold cavity volume, and then the cavity volume is expanded to cause foaming. Since the resulting foamed molded article has foamed cells inside, shrinkage of the thermoplastic resin during cooling is suppressed, sink marks and warpage are reduced, and a molded article with a low specific gravity can be obtained. The shape of the foam molded article is not particularly limited. It may be in the form of a sheet or cylinder formed by extrusion molding, or a complex shape formed by injection molding.

In the method for producing a foamed molded product described above, since it is not necessary to control the introduction amount of the physical foaming agent into the molten resin, the introduction time, etc., a complicated control device can be omitted or simplified, and the device cost can be reduced. Further, in the method for producing a foam molded article of the present embodiment, the starved molten resin is brought into contact with the physical foaming agent under the constant pressure in the starvation zone 23 while the pressure in the starvation zone 23 is maintained at a constant pressure. This makes it possible to stabilize the amount of physical foaming agent dissolved in the molten resin (permeation amount) by a simple mechanism.

(6) Molding of Circuit Pattern Next, a circuit pattern is formed on the surface of the obtained foam molded product (step S6 in FIG. 1). The method of forming the circuit pattern on the foam molded article is not particularly limited, and a general-purpose method can be used, for example, it can be formed by plating. For example, there is a method of first forming a plated film on the surface of the foam molded article, patterning the formed plated film with a photoresist, and removing the plated film on the portion other than the circuit pattern by etching. Alternatively, a method may be used in which a laser beam is irradiated to a portion where a circuit pattern is desired to be formed on the foam molded body to roughen the surface or to impart functional groups, and a plating film is formed only on the laser beam irradiated portion. Also, the circuit pattern may be formed using the methods disclosed in JP-A-2017-31441 and JP-A-2017-160518.

A method of forming a circuit pattern used in this embodiment will be described below with reference to FIGS. 3 and 4. FIG. First, the catalytic activity hindrance layer 61 is formed on the surface of the foam molded body 60 (step S11 in FIG. 3 and FIG. 4(a)). Next, a part of the surface of the foam molded body on which the catalytic activity hindrance layer 61 is formed, that is, the part where the circuit pattern is to be formed is heated or irradiated with light (step S12 in FIG. 3). In this embodiment, laser drawing is performed on the portion where the circuit pattern is to be formed. The portion 60a irradiated with the laser beam is heated, and the catalytic activity obstructing layer 61 of the heated portion is removed (FIG. 4(b)). An electroless plating catalyst is applied to the surface of the laser-drawn foam molded body 60 (step S13 in FIG. 3), and then an electroless plating solution is brought into contact (step S14 in FIG. 3). In this method, the catalytic activity impeding layer 61 impedes (prevents) the catalytic activity of the electroless plating catalyst applied thereon. Therefore, formation of an electroless plating film is suppressed on the catalytic activity hindering layer 61 . On the other hand, since the catalytic activity hindering layer 61 is removed from the laser drawn portion 60a, an electroless plated film 62 is formed. By the method described above, a molded circuit component 600 having a circuit pattern formed on the surface of the foam molded body 60 by the electroless plating film 62 is obtained (FIG. 4(c)).

The catalytic activity hindering layer preferably contains, for example, a polymer having at least one of an amide group and an amino group (hereinafter referred to as "amide group/amino group-containing polymer" as appropriate). The amide group/amino group-containing polymer acts as a catalytic activity inhibitor that hinders (obstructs) or reduces the catalytic activity of the electroless plating catalyst. Although the mechanism by which the amide group/amino group-containing polymer interferes with the catalytic activity of the electroless plating catalyst is not clear, the amide group and amino group are adsorbed, coordinated, reacted, etc., with the electroless plating catalyst. It is speculated that the plating catalyst becomes unable to act as a catalyst.

Any amide group/amino group-containing polymer can be used, but from the viewpoint of hindering the catalytic activity of the electroless plating catalyst, a polymer having an amide group is preferable, and a branched polymer having a side chain is preferable. . In the branched polymer, the side chain preferably contains at least one of an amide group and an amino group, more preferably the side chain contains an amide group. Preferably, the branched polymer is a dendritic polymer. A dendritic polymer is a polymer composed of a molecular structure that repeats regular and frequent branching, and is classified into a dendrimer and a hyperbranched polymer. A dendrimer is a spherical polymer with a diameter of several nanometers and has an orderly and complete dendritic structure centered on a core molecule. It is a polymer with perfect dendritic branching. Among dendritic polymers, a hyperbranched polymer is preferable as the branched polymer of the present embodiment because it is relatively easy to synthesize and inexpensive.

The laser beam, electroless plating catalyst, and electroless plating solution used for laser drawing are not particularly limited, and general-purpose ones can be appropriately selected and used. In forming the circuit pattern, other types of electroless plated film or electrolytic plated film may be further laminated on the electroless plated film. The plating film 62 that forms the circuit pattern may be planarly formed only on one surface of the foam molded body 60, or may be formed over a plurality of surfaces of the foam molded body 60, or on a three-dimensional surface including a spherical surface. It may be three-dimensionally formed along. When the plated film 62 is three-dimensionally formed over a plurality of surfaces of the foam molded body 60 or along the surface of a three-dimensional shape including a spherical surface, the plated film 62 acts as a three-dimensional electric circuit. A molded circuit component 600 having a predetermined pattern of plating film 62 acts as a three-dimensional circuit molded component (MID).

Although the molded circuit component 600 manufactured in the present embodiment described above has a catalytic activity impeding layer 61 as shown in FIG. 4(c), the present embodiment is not limited to this. The manufacturing method of this embodiment may further include a step of removing the catalytic activity hindrance layer 61 from the surface of the foam molded article 60 . As a method for removing the catalytic activity hindering layer 61 from the foam molded article 60, there is a method of washing the foam molded article 60 with a washing liquid to dissolve and remove the amide group/amino group-containing polymer with the washing liquid. The cleaning liquid is not particularly limited as long as it dissolves the amide group/amino group-containing polymer and does not alter the properties of the foamed molded article 60, and it depends on the material of the foamed molded article 60 and the type of the amide group/amino group-containing polymer. can be selected as appropriate.

<Molded circuit parts>
A molded circuit component 600 of the present embodiment includes a base material, which is a foam molded body 60 containing a thermoplastic resin, and a circuit pattern formed on the base material, and is lightweight. Further, the inventors of the present application have found that a molded circuit component having high heat resistance can be manufactured by the manufacturing method of the present embodiment. The super engineering plastic used in the production method of the present embodiment has a high normal heat resistance temperature of 150° C. or higher. However, in general, foam molded products have lower heat resistance than solid molded products (non-foam molded products), and foam molded products manufactured using conventional high-pressure physical foaming agents use super engineering plastics as thermoplastic resins. Even if it is used, sufficient heat resistance cannot be obtained. A molded circuit component using a conventional super engineering plastic foamed molded body, for example, when passed through a reflow furnace, the foamed cells expand, causing problems such as an increase in the thickness of the molded body. On the other hand, the molded circuit component obtained in the present embodiment, for example, when the molded circuit component is heated and the surface temperature of the molded circuit component is maintained at 240 ° C. to 260 ° C. for 5 minutes, the molded circuit component by heating is -2% to 2%, preferably -1% to 1%. Further, the molded circuit component obtained in the present embodiment has a thickness change rate of −2 when the surface temperature of the molded circuit component is maintained at 200° C. to 260° C. for 3 to 10 minutes, for example. % to 2%, preferably -1% to 1%. A molded circuit component having such high heat resistance undergoes little change in shape even when passed through a reflow furnace for lead-free soldering, and bulges and the like are less likely to occur.

Here, "rate of change in thickness of molded circuit component due to heating" is defined by the following equation. Incidentally, the molded circuit component can be heated by, for example, a reflow furnace.

(Da−Db)/Db×100 (%)
Db: Thickness of molded circuit part before heating
Da: Thickness of molded circuit component after heating

The high heat resistance of the molded circuit component of the present embodiment is achieved by using a super engineering plastic as the thermoplastic resin and applying a constant pressure of the physical foaming agent brought into contact with the starved molten resin within a specific range of, for example, 0.5 MPa to 12 MPa. is assumed to be caused by Conventional foam molding using a supercritical fluid or the like uses a high-pressure physical foaming agent of 15 to 20 MPa on average. The production method of the present embodiment differs from conventional foam molding in that the physical foaming agent is brought into contact with the molten resin at a relatively low and constant pressure. The inventors of the present application have found that the constant pressure of the physical foaming agent is, for example, 12 MPa or less, preferably 10 MPa or less, more preferably 8 MPa or less, and even more preferably 6 MPa or less, so that the heat resistance of the foamed molded product is improved. I found out. Furthermore, by lowering the constant pressure of the physical blowing agent, poor appearance (swirl marks) can be improved. The lower limit of the constant pressure of the physical blowing agent is 0.5 MPa or more, preferably 1 MPa or more, more preferably 2 MPa or more, from the viewpoint of permeating the molten resin with the amount of physical blowing agent necessary for foaming.

Although the mechanism by which the molded circuit component of the present embodiment has high heat resistance is unknown, a specific type of thermoplastic resin (super engineering plastic) and a specific range of physical foaming agent constant pressure (for example, 0.5 MPa ~ 12 MPa), there is a possibility that some kind of structural change, for example, a very microscopic structural change that is different from the conventional foam molded product, occurred in the molded circuit component of the present embodiment. In addition, it is presumed that the residual foaming agent in the foam-molded article expands upon heating and adversely affects the heat resistance of the foam-molded article. Therefore, it is considered that the reason why the foam molded article of the present embodiment has high heat resistance is simply that the amount of residual foaming agent in the foam molded article is small. However, according to the studies of the inventors, for example, even if the residual foaming agent is degassed to some extent from the conventional foamed molded article by annealing or the like, heat resistance equivalent to that of the foamed molded article of the present embodiment cannot be obtained. It has been found that swelling and the like occur due to heating. Therefore, it is presumed that the amount of residual foaming agent is not the main factor in the high heat resistance of the foam molded article of this embodiment. Note that the above considerations are speculations made by the inventors based on current knowledge, and do not limit the scope of the present invention.

The constant pressure of the physical foaming agent in this embodiment is, for example, 0.5 MPa to 12 MPa, but there is a more preferable range depending on the type of super engineering plastic. For example, when the super engineering plastic is polyphenylene sulfide (PPS), the constant pressure of the physical blowing agent is preferably 2 MPa to 12 MPa, more preferably 2 MPa to 10 MPa, and even more preferably 2 MPa to 8 MPa. When the super engineering plastic is a liquid crystal polymer (LCP), the constant pressure of the physical blowing agent is preferably 1 MPa to 6 MPa. When the type of super engineering plastic and the constant pressure range of the physical blowing agent are in the above combination, a foamed molded article with better foamability and higher heat resistance can be obtained, and the occurrence of swirl marks can be suppressed.

In the molded circuit component manufactured in the present embodiment, the average cell diameter of the foam cells contained therein is preferably 100 μm or less, more preferably 50 μm or less. When the average cell diameter of the foamed cells is within the above range, the sidewalls of the cells become small, so that the foamed cells are less likely to expand when heated, and as a result, the heat resistance of the foamed molded product is further improved. The average cell diameter of foamed cells can be obtained, for example, by image analysis of a cross-sectional SEM photograph of a foamed molded product.

In the molded circuit component manufactured in the present embodiment, the thickness of the foamed part in which the foamed cells are formed is preferably 0.5 mm or more, more preferably 1 mm or more, and more preferably 2 mm. The above is even more preferable. When the thickness is within the above range, a sufficiently thick skin layer can be formed on the molded body. The skin layer can suppress the expansion of the foamed cells when the molded circuit component is heated, thereby further improving the heat resistance of the molded circuit component. In particular, when LCP is used as a super engineering plastic, it is difficult for the internal gas containing the physical foaming agent to escape from the LCP foam molded product. By increasing the thickness of the foamed portion, the expansion of the foamed cells due to the expansion of the contained gas is suppressed, and the heat resistance of the molded circuit component using LCP is further improved. In addition, in the molded circuit component manufactured in the present embodiment, the thickness of the foamed part in which the foamed cells are formed may be 3 mm or less, 2 mm or less, or 1 mm or less. may be As the thickness of the foamed portion becomes thinner, the rate of change in the thickness of the molded circuit component due to heating tends to increase. Also in the foamed portion, the rate of change in the thickness of the molded circuit component due to heating can be suppressed to -2% to 2%, preferably -1% to 1%.

In this embodiment, the foam molded article may be further annealed before the circuit pattern is formed. By heating the foam-molded article in the annealing treatment, the inclusion gas containing the physical foaming agent can be degassed from the foam-molded article. As a result, expansion of the foam cells due to expansion of the contained gas is suppressed, and the heat resistance of the molded circuit component is further improved.

[Second embodiment]
<Circuit parts>
In this embodiment, a circuit component 700 shown in FIGS. 5A, 5B and 6 will be described. A circuit component 700 of this embodiment includes a base material 10 that is a foam molded body containing a thermoplastic resin, and a circuit pattern 70 formed on the base material 10, and is lightweight. Further, the circuit component 700 is preferably a plate-like foam molded body having a density reduction rate of 0.5% to 10%, and has a mounting surface 10a and a back surface 10b facing the mounting surface 10a. 10, a circuit pattern 70 formed on the surface of the substrate 10 including the mounting surface 10a, and a mounted component 30 mounted on the mounting surface 10a of the substrate 10 and electrically connected to the circuit pattern 70. have

The base material 10 contains a thermoplastic resin and preferably an insulating thermally conductive filler, and has foam cells 11 therein.

As the thermoplastic resin, it is preferable to use a heat-resistant, high-melting thermoplastic resin that has solder reflow resistance. For example, aromatic polyamides such as 6T nylon (6TPA), 9T nylon (9TPA), 10T nylon (10TPA), 12T nylon (12TPA), MXD6 nylon (MXDPA) and their alloy materials, polyphenylene sulfide (PPS), liquid crystal polymer (LCP), polyetheretherketone (PEEK), polyetherimide (PEI), polyphenylsulfone (PPSU) and the like can be used. Among them, polyphenylene sulfide is inexpensive among so-called super engineering plastics (super engineering plastics), and is therefore preferable as the thermoplastic resin of the present embodiment. These thermoplastic resins may be used alone or in combination of two or more. Moreover, in this embodiment, the mounting component 30 is mounted by soldering. For this reason, the thermoplastic resin used for the substrate 10 preferably has a melting point of 260° C. or higher, more preferably 290° C. or higher, so as to enable soldering. However, this is not the case when low-temperature solder is used to mount the mounting component 30 .

Here, the insulating thermally conductive filler is a filler having a thermal conductivity of 1 W/m·K or more, excluding conductive heat dissipating materials such as carbon. Examples of insulating thermally conductive fillers include ceramic powders such as aluminum oxide, silicon oxide, magnesium oxide, magnesium hydroxide, boron nitride, and aluminum nitride, which are inorganic powders with high thermal conductivity. In order to increase the contact ratio between the fillers and enhance heat transferability, rod-shaped fillers such as wollastonite, and plate-shaped fillers such as talc and boron nitride may be mixed. The insulating thermally conductive filler is contained in the base material 10 in an amount of, for example, 10% to 90% by weight, preferably 30% to 80% by weight. When the blending amount of the insulating thermally conductive filler is within the above range, the circuit component 700 of the present embodiment can obtain sufficient heat dissipation.

The base material 10 may further contain rod-like or needle-like fillers such as glass fibers and calcium titanate to control its strength. Moreover, the base material 10 may contain general-purpose various additives added to a resin molding as needed.

The base material 10 is preferably a foam molded article having a density reduction rate of 0.5% to 10%. The density reduction rate of the substrate 10 is more preferably 1% to 7%, and even more preferably 4% to 6%. By setting the density reduction rate of the base material 10 within the above range, the moldability of the base material 10 is enhanced and the circuit component 700 can obtain sufficient heat dissipation. Here, the density reduction rate of the foamed molded body is the ratio of the density of the solid molded body and the density of the foamed molded body to the density of the non-foamed molded body (solid molded body) molded using the same material as the foamed molded body. is the percentage of the difference. Since the foamed molded product contains foamed cells (bubbles), it has a smaller specific gravity than a solid molded product. For example, a density reduction rate of 5% for the foamed molded body means that the density (95%) of the foamed molded body is reduced by 5% with respect to the density (100%) of the solid molded body. .

Since the circuit pattern 70 is formed on the resin substrate 10 which is an insulator, it is preferably formed by electroless plating. Therefore, the circuit pattern 70 may include an electroless plating film such as an electroless nickel phosphor plating film, an electroless copper plating film, an electroless nickel plating film, etc. Among them, the electroless nickel phosphor plating film may be included. preferable. The circuit pattern 70 may be formed by laminating another type of electroless plated film or electrolytic plated film on the electroless plated film on the resin substrate 10 . By increasing the total thickness of the plating film, the electrical resistance of the circuit pattern 70 can be reduced. From the viewpoint of reducing electrical resistance, the circuit pattern 70 preferably includes an electroless copper plating film, an electrolytic copper plating film, an electrolytic nickel plating film, or the like. In addition, a plating film of gold, silver, tin, or the like may be formed on the outermost surface of the circuit pattern 70 in order to improve the solder wettability of the plating film.

By providing a gold-plated film on the outermost surface of the circuit pattern 70, the wettability of the solder can be improved and corrosion of the circuit pattern can be prevented. However, providing the gold plating film on the entire outermost surface of the circuit pattern 70 increases the cost. In order to prevent the corrosion of the circuit pattern 70 while suppressing the cost increase, on the mounting surface 10a, areas other than the mounting portion 12 to which the mounting component 30 is soldered are covered with a resist, and the outermost surface of the circuit pattern formed on the mounting portion 12 is covered. A gold plating film may be formed only on the . In the mounting portion 12, the solder wettability is improved by the gold plating film and the corrosion of the circuit pattern is suppressed.

The mounted component 30 is electrically connected to the circuit pattern 70 by the solder 31 and generates heat when energized to serve as a heat source. Examples of the mounted component 30 include LEDs (light emitting diodes), power modules, ICs (integrated circuits), thermal resistors, and the like. In this embodiment, an LED is used as the mounting component 30 . Mounted component 30 is mounted on mounting surface 10a of substrate 10 . The circuit pattern 70 is formed on the surface of the base material 10 including the mounting surface 10a in order to electrically connect with the mounted component 30. As shown in FIG.

In the portion (mounting portion 12) of the substrate 10 where the mounting component 30 is mounted, the distance from the mounting surface 10a to the back surface 10b (thickness d of the mounting portion 12) is preferably 0.1 mm or more. More preferably, it exceeds 5 mm. Here, the distance from the mounting surface 10a to the rear surface 10b (thickness d of the mounting portion 12) is the distance from the mounting surface 10a to the rear surface 10b of the mounting portion 12 in the direction of the perpendicular m to the mounting surface 10a. Moreover, when the thickness d of the mounting portion 12 is not constant, it is preferable that the thickness d varies within the above range. In this embodiment, the base material 10 is a plate-like body, and the back surface 10b is the surface opposite to the mounting surface 10a. Further, since the base material 10 of the present embodiment is a plate-like body with a constant thickness, the thickness d is also the thickness of the base material 10 .

From the viewpoint of allowing the heat generated by the mounted component 30 to escape to the rear surface 10b, the thinner the thickness d, the better. However, if the thickness d of the mounting portion 12 is too thin, the fluidity of the resin in the mounting portion 12 is reduced during molding of the base material 10, resulting in deterioration of moldability. Moreover, the mechanical strength of the base material 10 is lowered, making it difficult for the base material 10 to stand alone. If the base material 10 cannot stand on its own, for example, it is necessary to attach a support member such as a metal plate to the back surface 10b of the base material 10 to support the base material 10, which increases the cost. In this embodiment, by giving the mounting portion 12 an appropriate thickness, it is possible to prevent deterioration of the moldability and mechanical strength of the base material 10, and to prevent an increase in cost because a support member for the base material 10 is unnecessary. . When the mechanical strength of the substrate 10 is important, the thickness d is preferably 0.6 mm or more. Moreover, the upper limit of the thickness d is not particularly limited, and can be appropriately determined based on the application of the circuit component 700 . From the viewpoint of cost, the thickness d is, for example, 2.5 mm or less.

In general, when the thickness of the foam molded body is 0.2 mm or less, or 0.5 mm or less, the foam molded body mainly consists of a skin layer, and little core layer is formed inside. Foam cells are difficult to form. When the thickness d of the mounting portion 12 is 0.2 mm or less, or 0.5 mm or less, the heat dissipation to the back surface 10b is improved because there are almost no foam cells inside. On the other hand, when the thickness d of the mounting portion 12 exceeds 0.5 mm, there is a possibility that the foam cells 11 exist inside the mounting portion 12, which tends to reduce heat dissipation. However, since the base material 10 of the present embodiment contains an insulating thermally conductive filler, it is possible to ensure a certain degree of heat dissipation, and also has the advantage of improving the mechanical strength as described above.

The circuit component 700 of this embodiment described above can achieve both mass productivity and heat dissipation as described below. The base material 10 is a foam molding. Therefore, even with a thermoplastic resin containing an insulating thermally conductive filler, the fluidity of the molten resin is improved by containing a foaming agent during molding. Furthermore, the bubbling pressure improves the transferability of the mold, and the substrate 10 can obtain sufficient dimensional accuracy. Since the moldability of the base material 10 is improved in this manner, it is not necessary to perform molding with increased holding pressure or mold clamping pressure, and the occurrence of burrs is also suppressed. Thereby, the manufacturing cost of the circuit component 700 can be suppressed, and the mass productivity is improved. On the other hand, since the foamed molded product contains foamed cells, it tends to have improved heat insulation and lower heat dissipation. However, in the base material 10 of the present embodiment, by specifying the density reduction rate within the relatively low range described above, as shown in FIG. Foam cells 11 are mainly present in core layer 14 . Therefore, the surface (mounting surface 10a) of the base material 10 on which the mounting component 30 serving as a heat source is mounted is less affected by the foamed cells 11, and the insulating thermally conductive filler is oriented in the direction of resin flow. good heat dissipation.

Furthermore, although the base material 10 of this embodiment is a foam molded article, it has solder reflow resistance. Since the foamed molded product contains foamed cells, swelling on the surface is likely to occur during solder reflow. However, the density of the foam cells 11 in the base material 10 can be made relatively low by specifying the density reduction rate of the base material 10 within the relatively low range described above. Also, the amount of the foaming agent remaining inside the resin can be reduced. It is presumed that this improves the solder reflow resistance of the substrate 10 . Furthermore, the substrate 10 of the present embodiment can reduce the amount of foaming agent used by specifying the density reduction rate within the relatively low range described above. For example, when using a physical blowing agent as a blowing agent, a relatively low-pressure physical blowing agent can be used. This makes it easier to form the circuit pattern 70 on the surface because it is less likely that an appearance defect will occur during foam molding. Furthermore, in the circuit component 700 of the present embodiment, since the substrate 10 has sufficient heat dissipation performance, it is not necessary to provide a heat dissipation member made of metal. This can reduce costs.

In the present embodiment, the circuit pattern 70 is formed only on one surface (mounting surface 10a) of the plate-shaped substrate 10 as shown in FIGS. , the present embodiment is not limited to this. The base material 10 is not limited to a plate-like body, and may have any shape according to the application of the circuit component 700 . The circuit pattern 70 may be three-dimensionally formed over a plurality of surfaces of the substrate 10 or along a three-dimensional surface including a spherical surface. When the circuit pattern 70 is three-dimensionally formed over a plurality of surfaces of the substrate 10 or along a three-dimensional surface including a spherical surface, the circuit component 700 functions as a three-dimensional molded circuit component.

Further, when the thermoplastic resin is super engineering plastic, the circuit component 700 of the present embodiment may have heat resistance equivalent to that of the molded circuit component 600 of the first embodiment (see FIG. 4(c)). . That is, when the circuit component 700 is heated and the surface temperature of the circuit component 700 is maintained at 240° C. to 260° C. for 5 minutes, even if the change rate of the thickness of the circuit component 700 due to heating is −2% to 2%. well, preferably -1% to 1%. Further, the circuit component 700 obtained in the present embodiment has a thickness change rate of −2 when the surface temperature of the circuit component 700 is maintained at 200° C. to 260° C. for 3 minutes to 10 minutes, for example. % to 2%, preferably -1% to 1%. A circuit component having such high heat resistance undergoes little change in shape even when passed through a reflow furnace for lead-free soldering, and bulges and the like are less likely to occur.

<Method for manufacturing circuit parts>
A method of manufacturing circuit component 700 will be described. First, preferably, a thermoplastic resin containing an insulating thermally conductive filler is foam-molded to obtain a foam-molded article (substrate 10) having a density reduction rate of preferably 0.5% to 10%. The substrate 10 is preferably foam-molded using a physical foaming agent such as carbon dioxide or nitrogen. Types of foaming agents include chemical foaming agents and physical foaming agents. However, chemical foaming agents have a low decomposition temperature, making it difficult to foam high-melting resin materials. A resin having a high melting point and high heat resistance is preferably used for the base material 10 . If a physical foaming agent is used, the substrate 10 can be foam-molded using a high melting point resin. As a molding method using a physical foaming agent, MuCell (registered trademark) using a supercritical fluid and a low-pressure foaming molding method that does not require high-pressure equipment proposed by the present inventors (for example, see WO2017/007032 described) can be used.

When molding the base material 10 using the low-pressure foam molding method described in WO2017/007032, the pressure of the physical foaming agent introduced into the plasticizing cylinder of the foam injection molding machine, the filling rate of the resin into the mold By adjusting the above, the density reduction rate of the foam molded article can be adjusted. In the low-pressure foam molding method, the pressure of the physical foaming agent introduced into the plasticizing cylinder is, for example, 10 MPa or less, preferably 6 MPa or less, more preferably 2 MPa or less.

Further, the base material 10 is manufactured by a manufacturing method similar to that of the foam molded article 60 of the first embodiment using the manufacturing apparatus (injection molding apparatus) 1000 shown in FIG. 2 used in the first embodiment. good too.

Next, a circuit pattern 70 is formed on the surface of the substrate 10 including the mounting surface 10a. A method for forming the circuit pattern 70 is not particularly limited, and a general-purpose method can be used. For example, a method of forming a plated film on the entire mounting surface 10a, patterning the plated film with a photoresist, and removing the plated film from portions other than the circuit pattern by etching; A method of roughening the base material and forming a plated film only on the portion irradiated with the laser beam can be used. Also, the circuit pattern 70 may be formed by a method similar to that of the circuit pattern of the first embodiment.

In this embodiment, the circuit pattern 70 is formed by the method described below. First, a catalytic activity hindrance layer is formed on the surface of the substrate 10 . Next, the part where the electroless plating film is to be formed, that is, the part where the circuit pattern 70 is to be formed, of the mounting surface 10a of the substrate 10 on which the catalytic activity hindrance layer is formed is laser drawn. As a result, a laser drawn portion 15 is formed on the mounting surface 10a (FIGS. 7A and 7B). An electroless plating catalyst is applied to the laser-drawn surface of the substrate 10, and then an electroless plating solution is brought into contact. The catalytic activity impeding layer impedes (prevents) the catalytic activity of the electroless plating catalyst applied thereon. Therefore, formation of an electroless plating film is suppressed on the catalytic activity hindering layer. On the other hand, in the laser drawn portion 15, an electroless plated film is formed because the catalytic activity hindrance layer is removed. As a result, a circuit pattern 70 is formed from the electroless plating film on the laser drawn portion 15 (FIGS. 8A and 8B).

The catalytic activity hindering layer can be formed using a resin (catalyst deactivator) that hinders catalytic activity. As the catalyst deactivator, polymers having amide groups and dithiocarbamate groups in side chains are preferred. It is presumed that the amide group and dithiocarbamate group in the side chain act on metal ions serving as electroless plating catalysts and prevent them from exerting their catalytic ability. Moreover, the catalyst deactivator is preferably a dendritic polymer such as a dendrimer or a hyperbranched polymer. As the catalyst deactivator, for example, a polymer disclosed in JP-A-2017-160518 can be used, and an interference layer can be formed on the substrate surface by the method disclosed in the same patent publication.

The laser light and laser drawing method used for laser drawing are not particularly limited, and a general-purpose laser light and laser drawing method can be appropriately selected and used. In the laser-drawn portion 15, as shown in FIG. 7B, the catalytic activity hindering layer (not shown) may be removed and the surface of the substrate 10 may be roughened. This makes it easier for the electroless plating catalyst to be adsorbed on the laser-drawn portion 15 .

The electroless plating catalyst is not particularly limited, and a general-purpose one can be appropriately selected and used. Also, as the electroless plating catalyst, for example, a plating catalyst solution containing a metal salt such as palladium chloride disclosed in JP-A-2017-036486 may be used. When a plating catalyst liquid containing a metal salt is used as the electroless plating catalyst, a pretreatment liquid that promotes adsorption of the electroless plating catalyst may be applied to the substrate before applying the plating catalyst liquid to the substrate. As the pretreatment liquid, for example, an aqueous solution containing a nitrogen-containing polymer such as polyethyleneimine can be used.

The electroless plating solution and electroless plating method are not particularly limited, and a general-purpose electroless plating solution and electroless plating method can be appropriately selected and used. The electroless plating solution contains reducing agents such as sodium hypophosphite and formalin. As the electroless plating solution, electroless nickel plating solution, electroless nickel phosphorus plating solution, electroless copper plating solution, electroless palladium plating solution, etc. can be used. An electroless nickel plating solution (electroless nickel phosphorous plating solution) containing sodium hypophosphite having a high phosphate as a reducing agent and being a stable plating solution is preferred. In forming the circuit pattern 70, another type of electroless plated film or electrolytic plated film may be laminated on the electroless plated film.

In addition, as described above, in order to prevent corrosion of the circuit pattern 70 while suppressing the cost increase, on the mounting surface 10a, areas other than the mounting portion 12 to which the mounting component 30 is soldered are covered with a resist, and the resist is formed on the mounting portion 12. A gold plating film may be formed only on the outermost surface of the circuit pattern 70 to be applied. A circuit pattern of such an aspect can be formed, for example, by the following method. First, a solder resist (manufactured by Taiyo Ink Co., Ltd., for example) is applied to the entire surface including the mounting surface 10a of the substrate 10 on which the circuit pattern is formed except for the gold plating film on the outermost surface to form a resist layer. Next, using a laser beam, the resist layer on the mounting surface 10a of the mounting portion 12 is removed to form an opening, and the circuit pattern is exposed in the opening. Then, a gold plating film is formed only on the outermost surface of the circuit pattern exposed in the opening.

After the circuit pattern 70 is formed on the substrate 10 , the mounting component 30 is mounted on the mounting surface 10 a of the substrate 10 and electrically connected to the circuit pattern 70 . Thus, the circuit component 700 of this embodiment is obtained. The mounting method is not particularly limited, and a general-purpose method can be used. For example, a solder reflow method in which the substrate 10 with the mounted component 30 placed thereon is passed through a high-temperature reflow furnace, or a laser beam is applied to the substrate 10 and the mounted component. The mounting component 30 may be soldered to the base material 10 by a laser soldering method (spot mounting) in which the interface of the component 30 is irradiated and soldered.

[Modification 1]
Next, Modification 1 of the second embodiment shown in FIG. 9 will be described. The substrate 10 of the circuit component 700 shown in FIG. 5 described above is a plate-like body having a constant thickness, but the present embodiment is not limited to this. For example, like a circuit component 400 of this modified example shown in FIG. 9, a concave portion 45 defined by a side wall 45a and a bottom surface 45b may be provided on the back surface 40b of the base material 40. FIG. A mounted component 30 is mounted on the mounting surface 40a corresponding to the bottom surface 45b. A circuit component 400 of this modified example has the same configuration as the circuit component 700 shown in FIG. 5 except for the concave portion 45 .

In this modified example, a recess 45 is provided in the back surface 40b to reduce the thickness d1 of the mounting portion 42 in which the mounting component 30 is provided, thereby thinning the core layer in the mounting portion 42. FIG. As a result, heat transfer in the thickness direction of the mounting portion 42 is improved, and heat generated by the mounted component 30 can be easily released to the rear surface 40b. Thereby, the heat dissipation of the circuit component 400 can be further improved.

As a form of reducing the thickness d1 of the mounting portion 42, a form of providing a recess in the mounting surface 40a is also conceivable. However, if the mounting surface 40a is uneven, it may become difficult to form the circuit pattern 70. FIG. For example, when forming a pattern of an electroless plated film using the above-described catalytic activity hindering layer, it may be difficult to obtain a contrast of the plated film on an uneven surface. In this modification, by providing the unevenness on the back surface 40b, the heat dissipation of the circuit component 400 can be improved without adversely affecting the formation of the circuit pattern 70 on the mounting surface 40a.

A distance d1 from the mounting surface 40a to the bottom surface 45b is preferably 0.1 mm to 1.5 mm, for example. Here, the distance d1 from the mounting surface 40a to the bottom surface 45b is the distance from the mounting surface 40a to the bottom surface 45b in the direction perpendicular to the mounting surface 40a. Moreover, when the distance d1 is not constant, it is preferable that the distance d1 fluctuates within the above range. By setting the distance d1 within the above range, the moldability and mechanical strength of the substrate 40 can be prevented from being lowered, and the heat dissipation of the circuit component 400 can be improved.

In this modified example, one mounting component 30 is mounted on the mounting surface 40a corresponding to the bottom surface 45b of one recess 45, as shown in FIG. However, this embodiment is not limited to this. For example, a plurality of mounting components 30 may be mounted on the mounting surface 40 a corresponding to the bottom surface 45 b of one recess 45 . The area of the bottom surface 45b may be larger or smaller than the area of the bottom surface of the mounted component 30, and the area of the bottom surface 45b and the area of the bottom surface of the mounted component 30 may be substantially the same.

The area of the bottom surface 45b per mounted component 30 placed on the mounting surface 40a corresponding to the bottom surface 45b is, for example, 4 cm ² or less, preferably 0.4 cm ² to 4 cm ² . As the area of the bottom surface 45b increases, the heat dissipation improves, but the moldability and mechanical strength of the concave portion 45 decrease. By setting the area of the bottom surface 45b within the above range, it is possible to achieve a balance between heat dissipation, formability, and mechanical strength.

The thickness d2 of the portion of the substrate 40 other than the mounting portion 42 is, for example, 0.6 mm to 2.5 mm from the viewpoint of mechanical strength and cost.

The concave portion 45 may be formed at the same time when the base material 40 is molded. For example, the base material 40 of this modified example can be molded using a mold having convex portions corresponding to the concave portions 45 in the mold cavity.

[Modification 2]
Next, Modification 2 of the second embodiment shown in FIG. 10 will be described. As shown in FIG. 10, the circuit component 500 of this modified example is provided with a concave portion 55 defined by a side wall 55a and a bottom surface 55b on the rear surface 50b of the base material 51. As shown in FIG. A through hole 56 is formed from the mounting surface 50 a of the mounting portion 52 on which the mounted component 30 is mounted to the bottom surface 55 b , and an electroless plated film 71 is formed on the inner wall of the through hole 56 . The inside of the through-hole 56 of this modified example is filled with an electroless plated film 71 . The electroless plated film 71 of the through hole 56 is connected to the mounting component 30 via the circuit pattern 70 and the solder 31 . A circuit component 500 of this modified example has the same configuration as the circuit component 400 shown in FIG. 9 except for the through holes 56 .

In this modified example, by providing the through holes 56 filled with the electroless plating film 71, the heat generated by the mounting component 30 can be easily released to the rear surface 50b through the electroless plating film 71. FIG. Thereby, the heat dissipation of the circuit component 500 can be further improved. Further, by forming the electroless plated film 71 inside the through-hole 56, it is possible to suppress a decrease in the mechanical strength of the mounting portion 52 in which the through-hole 56 is formed.

The through holes 56 may be formed by laser processing, for example. The electroless plated film 71 inside the through hole 56 may be formed at the same time as the circuit pattern 70 is formed of the electroless plated film, for example.

Although the through hole 56 is provided in this modified example, the present embodiment is not limited to this, and the hole provided in the mounting surface 50a does not necessarily have to penetrate to the bottom surface 55b. That is, a non-through hole may be provided instead of the through hole 56. For example, a recess may be formed from the mounting surface 50a of the mounting portion 52 toward the bottom surface 55b, and an electroless plating film may be formed on the surface of the recess. . From the viewpoint of forming an electroless plating film, the through holes are preferable because the electroless plating solution flows easily. On the other hand, from the viewpoint of the mechanical strength of the mounting portion 52 and the corrosion prevention of the electroless plated film formed inside, it is preferable that the hole provided in the mounting surface 50a be a concave portion that does not penetrate to the bottom surface 55b. Even if it is a concave portion, it is effective in improving the heat dissipation of the circuit component 500 . The depth of the recess from the mounting surface 50a of the mounting portion 52 toward the bottom surface 55b can be arbitrarily determined as long as it is deeper than the thickness of the electroless plating film forming the circuit pattern. Further, the concave portion is not limited to a hole extending in a direction perpendicular to the mounting surface 50a, and may be a groove extending on the mounting surface 50a.

The present invention will be further described below using examples and comparative examples. However, the present invention is not limited to the examples and comparative examples described below.

[Production of sample 1-1]
A foam-molded article was produced, and a circuit pattern was formed on the foam-molded article with a plating film to obtain a molded circuit component (Sample 1-1). Polyphenylene sulfide (PPS) (manufactured by Polyplastics Co., Ltd., Gelafide 1130T6) was used as the thermoplastic resin, and nitrogen was used as the physical foaming agent in the production of the foamed molded article. The pressure of the physical foaming agent introduced into the starvation zone of the plasticizing cylinder was 1 MPa.

(1) Foam-molded article manufacturing apparatus A foam-molded article was manufactured using the manufacturing apparatus 1000 shown in FIG. 2 used in the above-described embodiment. Details of the manufacturing apparatus 1000 will be described. As described above, the manufacturing apparatus 1000 is an injection molding apparatus, and includes a plasticizing cylinder 210, a cylinder 100 which is a physical foaming agent supply mechanism for supplying the physical foaming agent to the plasticizing cylinder 210, and a mold provided with a mold. A clamping unit (not shown) and a control device (not shown) for controlling the operation of the plasticizing cylinder 210 and the mold clamping unit are provided.

The nozzle tip 29 of the plasticizing cylinder 210 is provided with a shut-off valve 28 that is opened and closed by driving the air cylinder, so that the inside of the plasticizing cylinder 210 can be maintained at a high pressure. A mold (not shown) is in close contact with the tip of the nozzle 29, and molten resin is injected and filled from the tip of the nozzle 29 into a cavity formed by the mold. On the upper side surface of the plasticizing cylinder 210, a resin supply port 201 for supplying the thermoplastic resin to the plasticizing cylinder 210 and an introduction port 202 for introducing the physical foaming agent into the plasticizing cylinder 210 are arranged in order from the upstream side. is formed. A resin supply hopper 211, a feeder screw 212, and an introduction speed adjusting container 300 are arranged in the resin supply port 201 and the introduction port 202, respectively. The cylinder 100 is connected to the introduction speed adjusting container 300 by a pipe 154 via a pressure reducing valve 151 , a pressure gauge 152 and an open valve 153 . A sensor 27 is also provided within the starvation zone 23 of the plasticizing cylinder 210 to monitor the pressure in the starvation zone 23 .

The screw 20 is arranged rotatably and forwards and backwards within the plasticizing cylinder 210 in order to accelerate the plasticizing and melting of the thermoplastic resin and to meter and inject the molten resin. As described above, the screw 20 is provided with the sealing portion 26 and the large diameter portion 20A of the screw 20 as a mechanism for increasing the flow resistance of the molten resin.

In the plasticizing cylinder 210, thermoplastic resin is supplied from the resin supply port 201 into the plasticizing cylinder 210, and the thermoplastic resin is plasticized by a band heater (not shown) to become molten resin, and the screw 20 rotates forward. sent downstream by Due to the presence of the seal portion 26 and the large-diameter portion 20A provided in the screw 20, the molten resin is compressed and the pressure is increased on the upstream side of the seal portion 26, and the molten resin is compressed in the starvation zone 23 downstream of the seal portion 26. It becomes underfilled (starvation state). The molten resin sent further downstream is recompressed and weighed near the tip of the plasticizing cylinder 210 before injection.

As a result, in the plasticizing cylinder 210, from the upstream side, the plasticizing zone 21 in which the thermoplastic resin is plasticized and melted, the compression zone 22 in which the molten resin is compressed and the pressure increases, and the flow rate of the molten resin are adjusted. A flow rate adjusting zone 25, a starvation zone 23 in which the molten resin is not filled, and a recompression zone 24 in which the molten resin depressurized in the starvation zone is compressed again are formed.

In the manufacturing apparatus 1000, the inner diameter of the plasticizing cylinder 210 was 22 mm, and the inner diameter of the inlet 202 was 6 mm. Thus, the inner diameter of inlet 202 was approximately 27% of the inner diameter of plasticizing cylinder 210 . Also, the volume of the introduction rate adjusting vessel 300 was approximately 80 mL, and the volume of the starvation zone 23 was 110 mL. Therefore, the volume of the introduction rate regulation vessel 300 was approximately 0.7 times the volume of the starvation zone 23 . Also, a mold with a cavity size of 5 cm×5 cm×2 mm was used.

(2) Manufacture of Foam Molded Body As the cylinder 100, a nitrogen cylinder with a volume of 47 L filled with nitrogen at 14.5 MPa was used. First, the value of the pressure reducing valve 151 is set to 1 MPa, the cylinder 100 is opened, and the gas is supplied from the inlet port 202 of the plasticizing cylinder 210 via the pressure reducing valve 151, the pressure gauge 152, and the introduction speed adjusting container 300 to the starvation zone 23. 1 MPa of nitrogen was supplied to the The cylinder 100 was kept open at all times during the production of the compact.

In the plasticizing cylinder 210, band heaters (not shown) are used to heat the plasticizing zone 21 to 320 to 300°C, the compression zone 22 to 320°C, the flow rate adjustment zone 25 and the starvation zone 23 to 300°C, and the recompression zone 24 to 320°C. °C. Then, resin pellets of thermoplastic resin (PPS) were supplied to the plasticizing cylinder 210 from the resin supply hopper 211 while the feeder screw 212 was rotated at 30 rpm, and the screw 20 was rotated forward. As a result, the thermoplastic resin is heated and kneaded in the plasticizing zone 21 to form a molten resin.

The number of rotations of the feeder screw 212 was determined by molding a solid molded article (non-foamed molded article) in advance to set the molding conditions (conditioning) and determine the number of rotations at which the resin pellets were starved and supplied. Here, the starvation supply of resin pellets means that in the plasticizing zone 21, during the supply of resin pellets, the state in which the plasticizing cylinder is not filled with the resin pellets or the molten resin is maintained, and the supplied resin pellets or the molten resin is maintained. , means that the flight of the screw 20 is exposed. Confirmation of the starvation supply of the resin pellets includes, for example, a method of confirming the presence or absence of resin pellets or molten resin on the screw 20 with an infrared sensor or a visualization camera. The feeder screw 212 used was provided with a transparent window, and the state of the plasticizing zone 21 immediately below the resin supply port 201 was visually confirmed through the transparent window.

The back pressure of the screw 20 is 3 MPa (physical foaming agent pressure: 1 MPa + 2 MPa = 3 MPa), and the screw 20 is rotated forward at a rotation speed of 100 rpm to flow the molten resin from the plasticization zone 21 to the compression zone 22, and further flow It was flowed to the rate regulation zone 25 and the starvation zone 23.

Since the molten resin flows into the flow rate adjusting zone 25 and the starvation zone 23 from the gaps between the screw large diameter portion 20A and the seal portion 26 and the inner wall of the plasticizing cylinder 210, the amount of molten resin supplied to the starvation zone 23 is was restricted. As a result, the molten resin was compressed in the compression zone 22 to increase the pressure, and the starvation zone 23 on the downstream side was filled with the molten resin (starvation state). In the starvation zone 23, the molten resin is not filled (starved state), so there is a physical blowing agent (nitrogen) introduced from the inlet 202 in the space where the molten resin does not exist, and the physical blowing agent causes the molten resin to pressurized.

Further, the molten resin was sent to the recompression zone 24 and recompressed, and as the screw 20 retreated, one shot of the molten resin was weighed at the tip of the plasticizing cylinder 210 . After that, the shut-off valve 28 was opened, and the molten resin was injection-filled into the cavity so that the filling rate was 90% of the volume of the cavity to form a flat plate-shaped foam-molded product (short-shot method). The mold temperature was 150°C. After molding, the foam-molded article was taken out from the mold after waiting for the foam-molded article to cool. The cooling time was 10 seconds.

20 shots of injection molding of the molded articles described above were continuously performed to obtain 20 foam molded articles. The pressure in the starvation zone 23 in the plasticizing cylinder 210 was measured by the pressure sensor 27 at all times during the production of 20 foamed moldings. As a result, the pressure in starvation zone 23 was always constant at 1 MPa. Moreover, the value of the pressure gauge 152, which indicates the pressure of nitrogen supplied to the starvation zone 23, was always 1 MPa during the production of the foam molded product. From the above, the molten resin was constantly pressurized with nitrogen of 1 MPa in the starvation zone 23 through one cycle of injection molding including the plasticization weighing process, the injection process, the cooling process of the molded body, the take-out process, etc. , and during continuous molding of 20 molded bodies, it was confirmed that the molten resin was always pressurized by nitrogen in the starvation zone 23 .

(3) Formation of circuit pattern A circuit pattern formed of a plated film was formed on the foam molded body by the method described below.

(a) Synthesis of catalytic activity inhibitor An amide group is introduced into a commercially available hyperbranched polymer (Hypertech HPS-200, manufactured by Nissan Chemical Industries, Ltd.) represented by formula (1), and represented by formula (2). We synthesized a hyperbranched polymer with

First, a hyperbranched polymer represented by formula (1) (1.3 g, dithiocarbamate group: 4.9 mmol), N-isopropylacrylamide (NIPAM) (1.10 g, 9.8 mmol), α,α'-azo Bisisobutyronitrile (AIBN) (81 mg, 0.49 mmol) and dehydrated tetrahydrofuran (THF) (10 mL) were added to the Schlenk tube, and freeze degassing was performed three times. Then, using an oil bath, the reaction mixture was stirred overnight (18 hours) at 70° C. After completion of the reaction, the reaction mixture was cooled with ice water and appropriately diluted with THF. It was then reprecipitated in hexane and the resulting solid product was vacuum dried at 60° C. overnight. NMR (nuclear magnetic resonance) measurement and IR (infrared absorption spectrum) measurement of the product were performed. As a result, it was confirmed that an amide group was introduced into the commercially available hyperbranched polymer represented by Formula (1) to produce a polymer represented by Formula (2). The molecular weight of the product was then determined by GPC (gel permeation chromatography). The molecular weights were number average molecular weight (Mn) = 9,946 and weight average molecular weight (Mw) = 24,792. was value. The yield of the hyperbranched polymer represented by formula (2) was 92%.

(b) Formation of Catalytic Activity Hindering Layer The polymer represented by the synthesized formula (2) was dissolved in methyl ethyl ketone to prepare a polymer solution having a polymer concentration of 0.5% by weight. The molded foamed article was dipped in the prepared polymer solution at room temperature for 5 seconds and then dried in a 85° C. dryer for 5 minutes. As a result, a catalytic activity hindering layer was formed on the surface of the foamed molded article. The film thickness of the catalytic activity hindrance layer was about 70 nm.

(c) Laser drawing Using a 3D laser marker (manufactured by Keyence, fiber laser, output 50 W) on the surface of the foamed molded article on which the catalytic activity hindrance layer is formed, at a processing speed of 2000 mm / s, the part corresponding to the circuit pattern was laser drawn. The line width of the drawing pattern was 0.3 mm, and the minimum distance between adjacent drawing lines was 0.5 mm. By laser drawing, it was possible to remove the catalytic activity hindrance layer in the laser drawn portion.

(d) Application of Electroless Plating Catalyst and Formation of Plating Film The laser-drawn foam molded product is immersed in a palladium chloride solution (manufactured by Okuno Chemical Industry Co., Ltd., Activator) for 5 minutes to apply an electroless plating catalyst. did. The foam molded article to which the electroless plating catalyst was applied was washed with water, and then immersed in an electroless nickel phosphorus plating solution (manufactured by Okuno Chemical Industry Co., Ltd., Top Nicolon LPH-L, pH 6.5) at 60° C. for 10 minutes. A nickel phosphorous film (electroless nickel phosphorous plated film) was selectively grown to a thickness of about 1 μm on the laser-drawn portion of the foam molded product.

A 10 μm electrolytic copper plating film, a 1 μm electrolytic nickel plating film, and a 0.1 μm electrolytic gold plating film were further laminated in this order on the nickel phosphorous film of the laser-drawn portion by a general-purpose method to form a circuit pattern.

[Production of samples 1-2 to 1-10]
Sample 1- except that the pressure of the physical blowing agent introduced into the starvation zone of the plasticizing cylinder was 2 MPa, 4 MPa, 6 MPa, 8 MPa, 10 MPa, 12 MPa, 14 MPa, 18 MPa and 0.4 MPa, respectively, in the production of the foamed molding. Samples 1-2 to 1-10 (molded circuit components) were manufactured in the same manner as in 1.

The pressure in the starvation zone 23 inside the plasticizing cylinder 210 was measured by the pressure sensor 27 at all times during the production of the foamed molding of each sample. As a result, the starvation zone 23 pressure was the same constant pressure as the physical blowing agent introduced. Also, the value of the pressure gauge 152, which indicates the pressure of nitrogen supplied to the starvation zone 23, was always a constant pressure set for each sample during the production of the foam molded product. From the above, through one cycle of injection molding including the plasticization weighing process, the injection process, the cooling process of the molded body, the take-out process, etc., in the starvation zone 23, the molten resin is always It was confirmed that the pressure was applied and that the molten resin was always pressurized by nitrogen in the starvation zone 23 during the continuous molding of 20 molded bodies.

[Evaluation of Samples 1-1 to 1-10]
Samples 1-1 to 1-10 (molded circuit components) were evaluated by the method described below. The evaluation results of each sample are shown in Tables 1 and 2 together with the pressure of the physical foaming agent used during the production of the foam molded article of each sample.

(1) Foamability of foam molded product The shape and cross-section of the foam molded product were observed, and the foamability of the foam molded product was evaluated according to the following evaluation criteria. In addition, the specific gravity of the foam-molded article judged as A in the following criteria was lower by about 10% than that of the solid-molded article.

<Evaluation criteria for foamability>
A: Sufficiently foamed.
The foamed molded product completely fills the cavity of the mold, and the foamed cells formed inside the foamed molded product are fine (the cell diameter is about 30 to 50 μm).
B: Foaming.
Although the foam molding does not completely fill the cavity of the mold, there is no unfilled portion at the end of the cavity. That is, the flow end of the molten resin reaches the end of the cavity. Enlarged cells (having a cell diameter of about 100 to 200 μm) are occasionally found in the foam cells formed inside the foam molded article.
C: Only part of the molded article is foamed.
There is an unfilled portion at the end of the mold cavity. That is, the flow end of the molten resin does not reach the end of the cavity. The foam cells formed in the vicinity of the ends of the foamed molded product (near the flow end of the molten resin) are enlarged (the cell diameter is about 100 to 200 μm).

(2) Rate of Change in Thickness of Molded Circuit Part by Heating Test From each of the 20 molded circuit parts of Samples 1-1 to 1-10 prepared above, 5 pieces each were selected at random. First, for each molded circuit component, the length of the portion corresponding to the thickness of the flat plate (the portion corresponding to the width of the mold cavity of 2 mm) was measured at four locations (thickness Db). After that, the heating test described below was performed. First, assuming a reflow furnace for lead-free solder, the molded circuit component was placed in an electric furnace heated to a set temperature of 250°C. A thermocouple was brought into contact with the surface of the molded circuit component to measure the surface temperature, and it was confirmed that the maximum reaching temperature was 240°C to 260°C. Five minutes after the maximum surface temperature was reached, the molded circuit component was removed from the electric furnace. The time for which the molded circuit component was allowed to stand in the electric furnace was about 8-9 minutes. After cooling the molded circuit component to room temperature, the thickness of the portion where the thickness was measured before heating was measured again (thickness Da), and the rate of change in the thickness of the molded circuit component due to the heating test was determined by the following equation.

(Da−Db)/Db×100 (%)
Db: Thickness of molded circuit part before heating
Da: Thickness of molded circuit component after heating

For each molded circuit component, the rate of change in thickness was determined at 4 locations, and further, the rate of change in thickness was similarly determined for 5 molded circuit components for each sample (4 locations x 5 = 20 locations in total). Then, the average value of the rate of change in thickness at these 20 locations was taken as the rate of change in thickness of the molded circuit component obtained by the heating test of each sample.

(3) Surface swelling after heating test The surface of the molded circuit component after the heating test was observed, and the presence or absence of surface swelling was evaluated according to the following evaluation criteria.

<Evaluation Criteria for Surface Blisters after Heating Test>
A: There is no blistering on the surface of the molded circuit component.
B: Part of the surface of the molded circuit component has a small bulge (less than 1 mm in diameter).
C: There is a large bulge on the surface of the molded circuit component (1 mm to 3 mm in diameter).
D: There is a large bulge on the surface of the molded circuit component (diameter of 3 mm or more).

(4) Swirl Marks on Surface of Foamed Mold The surface of the molded circuit component was observed before the heating test, and the presence or absence of swirl marks on the surface of the foam molded product was evaluated according to the following evaluation criteria.

<Swirl mark evaluation criteria>
A: Swirl marks are not generated or are generated very slightly.
B: Swirl marks are generated on part of the surface of the foam molded article.
C: Swirl marks are generated on the entire surface of the foamed molded article, and the surface of the foamed molded article is white and cloudy.

Samples 1-1 to 1-7 in which the pressure of the physical foaming agent used in the production of the foamed molding is 1 to 12 MPa, the foaming property of the foamed molding is good, and the change in the thickness of the molded circuit part by the heating test. It was confirmed that the heat resistance was high because the modulus was small and the swelling on the surface was small. Furthermore, the occurrence of swirl marks was also suppressed. In addition, samples 1-2 to 1-6, in which the pressure of the physical foaming agent used in the production of the foamed molding is 2 to 10 MPa, have better foamability, higher heat resistance, and less swirl marks. It was less.

Samples 1-8 and 1-9, in which the pressure of the physical foaming agent used in the production of the foamed molding exceeds 12 MPa, compared to Samples 1-1 to 1-7, changes in the thickness of the molded circuit parts due to the heating test. The rate was large, and the swelling on the surface was also large. From this, it was found that the heat resistance was lower than that of Samples 1-1 to 1-7. Also, in Samples 1-8 and 1-9, the occurrence of swirl marks was remarkable. Sample 1-10, in which the pressure of the physical foaming agent used in the production of the foamed molding is less than 0.5 MPa, had insufficient foamability compared to Samples 1-1 to 1-7. .

[Production of samples 2-1 to 2-8]
A liquid crystal polymer (LCP) (Hori Plastics, Laperos S135) was used as the thermoplastic resin, and the pressure of the physical blowing agent (nitrogen) introduced into the starvation zone of the plasticizing cylinder was 0.5 MPa, 1 MPa, 2 MPa, 4 MPa, respectively. Samples 2-1 to 2-8 (molded circuit parts) were produced in the same manner as sample 1-1 except that the pressure was 6 MPa, 8 MPa, 10 MPa and 0.4 MPa.

The pressure in the starvation zone 23 inside the plasticizing cylinder 210 was measured by the pressure sensor 27 at all times during the production of the foamed molding of each sample. As a result, the starvation zone 23 pressure was the same constant pressure as the physical blowing agent introduced. Also, the value of the pressure gauge 152, which indicates the pressure of nitrogen supplied to the starvation zone 23, was always a constant pressure set for each sample during the production of the foam molded product. From the above, through one cycle of injection molding including the plasticization weighing process, the injection process, the cooling process of the molded body, the take-out process, etc., in the starvation zone 23, the molten resin is always It was confirmed that the pressure was applied and that the molten resin was always pressurized by nitrogen in the starvation zone 23 during the continuous molding of 20 molded bodies.

[Evaluation of Samples 2-1 to 2-8]
Samples 2-1 to 2-8 (molded circuit parts) prepared above were evaluated for the following (1) to (4) in the same manner as samples 1-1 to 1-10 described above.
(1) Expandability of foam molded product (2) Rate of change in thickness of foam molded product by heating test (3) Surface swelling after heat test (4) Swirl mark on foam molded product surface

The evaluation results of each sample are shown in Table 3 together with the pressure of the physical foaming agent used in producing the foam molded article of each sample.

Samples 2-1 to 2-7, in which the pressure of the physical foaming agent used in the production of the foamed molding was 0.5 to 10 MPa, had good foaming properties, and the rate of change in the thickness of the foamed molding due to the heating test was small. Therefore, it was confirmed that the heat resistance was high. Furthermore, the occurrence of swirl marks was also suppressed. In addition, samples 2-2 to 2-5, in which the pressure of the physical foaming agent used in the production of the foamed molding is 1 to 6 MPa, have better foamability, higher heat resistance, and less swirl marks. rice field.

Sample 2-8, in which the pressure of the physical foaming agent used in the production of the foamed article was 0.4 MPa, had insufficient foamability compared to Samples 2-1 to 2-7.

[Sample 3-1]
A circuit component 700 was manufactured using the plate-like substrate 10 shown in FIG. Also, an LED (light emitting diode) was used as the mounting component 30 .

(1) Molding of base material Polyphenylene sulfide (PPS) (DIC, TZ-2010-A1, thermal conductivity 1 W/m K) containing aluminum oxide, etc., is used as a thermoplastic resin containing an insulating thermally conductive filler. board. Using the molding apparatus disclosed in FIG. 2 of WO2017/007032 as the molding apparatus and pressurized nitrogen as the physical foaming agent, a plate-like (50 mm×80 mm×2 mm) foam molded article was molded. The density reduction rate of the foam was set to 5% by adjusting the amount of molten resin filled into the mold. The molding conditions were as follows: introduction pressure of physical foaming agent: 2 MPa, resin temperature: 350° C., mold temperature: 150° C., injection speed: 50 mm/s, mold clamping pressure: 3 tf, holding pressure: 0 (zero).

The external appearance of the molded foamed article was observed with an optical microscope. During molding, the variation in thickness of the foam-molded product was within 5 μm from the portion located at the mold gate to the portion located at the end of the mold, and the thickness of the foam-molded product was uniform. In addition, no burrs of a size that can be confirmed with a microscope were generated in the portion (end of flow) located at the end of the mold for the molded product. Furthermore, the cross section of the foam molded article was observed by SEM. No foam cells were observed in the skin layer from the surface of the molded article to a depth of about 100 μm. Fine foamed cells with an average cell diameter of about 50 μm were confirmed in the core layer at a depth of about 100 μm from the surface of the molded article.

(2) Formation of Circuit Pattern A circuit pattern 70 formed of a plating film was formed on the substrate 10 by the method described below.

(a) Formation of catalytic activity hindering layer A catalytic activity hindering layer containing the hyperbranched polymer represented by formula (2), which is a catalyst deactivator, used in the production of sample 1-1 above, on the surface of the base material. formed. The hyperbranched polymer represented by Formula (2) was synthesized by the method disclosed in JP-A-2017-160518.

A polymer solution having a polymer concentration of 0.3% by weight was prepared by dissolving the synthesized polymer represented by formula (2) in methyl ethyl ketone. The substrate was immersed in the room temperature polymer solution for 5 seconds and then dried in an 85° C. dryer for 5 minutes. As a result, a catalytic activity hindering layer having a film thickness of about 50 nm was formed on the substrate surface.

(b) Laser drawing Using a 3D laser marker (manufactured by Keyence, fiber laser, output 50 W) on the surface of the substrate 10 on which the catalytic activity hindrance layer is formed, overwriting is performed three times at a processing speed of 800 mm / s, A portion corresponding to the circuit pattern 70 was drawn with a laser. The line width of the drawing pattern was 0.3 mm, and the minimum distance between adjacent drawing lines was 0.5 mm. By laser drawing, the catalytic activity hindering layer of the laser drawn portion 15 (see FIGS. 7(a) and (b)) could be removed. Moreover, the surface of the laser-drawn portion 15 was roughened, and the filler contained in the base material 10 was exposed. The laser roughening depth was about 50 μm.

(c) Pretreatment for imparting catalyst Polyethylenimine (PEI) with a weight average molecular weight of 70,000 (manufactured by Wako Pure Chemical Industries, 30% by weight solution) and calcium hypophosphite (manufactured by Daido Pharmaceutical Co., Ltd.) are mixed with water, and PEI is added. A pretreatment liquid was prepared so that the compounding amount (solid content concentration) was 1 g/L and the compounding amount of calcium hypophosphite was 5 g/L. The substrate 10 was immersed in the prepared pretreatment liquid at room temperature for 5 minutes.

(d) Washing of substrate The substrate was washed by immersing it in room temperature water stirred by air bubbling for 5 minutes.

(e) Application of Electroless Plating Catalyst The substrate 10 was immersed in a commercially available palladium chloride (PdCl ₂ ) aqueous solution (manufactured by Okuno Chemical Industry Co., Ltd., activator, palladium chloride concentration: 150 ppm) adjusted to 35° C. for 5 minutes. After removing the substrate from the aqueous palladium chloride solution, it was washed with water.

(f) Electroless Plating The base material 10 was immersed in an electroless nickel phosphorus plating solution (manufactured by Okuno Chemical Industry Co., Ltd., Top Nicolon LPH-L, pH 6.5) adjusted to 60° C. for 10 minutes. A nickel phosphorous film (electroless nickel phosphorous plating film) was grown to a thickness of about 1 μm on the laser-drawn portion 15 on the substrate 10 .

On the nickel phosphorous film, a 20 μm electrolytic copper plating film, a 1 μm electrolytic nickel plating film, and a 0.1 μm electrolytic gold plating film were laminated in this order by a general-purpose method to form a circuit pattern 70 .

(3) Mounting of Mounted Components As the mounted component 30, a surface mount type high brightness LED (NS2W123BT manufactured by Nichia Corporation, 3.0 mm×2.0 mm×height 0.7 mm) was used. On the mounting surface 10 a of the mounting portion 12 of the substrate 10 , three mounting components (LEDs) 30 and solder 31 are arranged at positions where they can be electrically connected to the circuit pattern 70 . The average thickness of the solder was set to about 20 μm. As shown in FIG. 5(a), three mounting components 30 are connected in series. Next, the substrate 10 was passed through a reflow oven (solder reflow). The base material 10 was heated in the reflow furnace to reach a maximum temperature of about 240° C., and the time during which the base material 10 was heated at the maximum temperature was about 1 minute. Mounting component 30 was mounted on substrate 10 by solder 31 to obtain circuit component 700 (sample 3-1). No blistering occurred in the substrate 10 due to solder reflow.

[Sample 3-2]
The circuit shown in FIG. 9 was fabricated in the same manner as for sample 3-1, except that a substrate 40 (FIG. 9) having a concave portion 45 formed on the back surface 40b was used instead of the plate-shaped substrate 10 (FIG. 5). A part 400 was manufactured.

(1) Molding of base material Using the same material and apparatus as those of Sample 3-1, a foam molded article was molded under the same molding conditions. However, using a mold having three convex portions corresponding to the concave portions 45 in the mold cavity, the concave portions 45 were formed simultaneously with the molding of the base material 40 . The foam molded body has a plate shape (50 mm x 80 mm x 2 mm), and has a concave portion 45 defined by a side wall 45a and a bottom surface 45b on a rear surface 40b corresponding to a mounting surface 40a on which three mounting components (LEDs) 30 are mounted. have The area of the bottom surface 45b was 4 mm×4 mm=0.16 cm ² , and the distance d1 from the mounting surface 40a to the bottom surface 45b was 0.6 mm. The area of the bottom surface 45b (0.16 cm ² ) was set larger than the area of the bottom surface of the mounting component 30 (3 mm×2 mm=0.06 cm ² ).

The appearance of the resulting foamed molded product was observed with an optical microscope. Although the thickness (d1) of the mounting portion 52 is thinner than the portion other than the mounting portion 52, there was no problem in filling the resin. Further, similarly to the sample 3-1, the variation width of the thickness of the foam molded body was within 5 μm, and the thickness (d2) of the portion other than the mounting portion 52 was uniform. In addition, no burrs of a size that can be confirmed with a microscope were generated in the portion (end of flow) located at the end of the mold for the molded product. Furthermore, the cross section of the foam molded article was observed by SEM. In the mounting portion 52 having a small thickness (d1), there were fewer foamed cells inside the core layer than in the portion other than the mounting portion 52 .

(2) Formation of Circuit Pattern and Mounting of Mounting Components By the same method as in sample 3-1, circuit pattern 70 is formed on mounting surface 40a, mounting component 30 is mounted, and circuit component 400 (sample 3-2 ).

[Sample 3-3]
In place of the plate-like substrate 10 (FIG. 5), a substrate 51 (FIG. 10) having recesses 55 and through-holes 56 filled with an electroless plating film 71 was used. -1, a circuit component 500 shown in FIG. 10 was manufactured.

(1) Molding of base material Using the same material and apparatus as those of Sample 3-1, a foam molded article was molded under the same molding conditions. However, the mold used for Sample 3-2 was used to mold the base material 51 having the concave portion 55 formed in the back surface 50b. The base material 51 before forming the through holes 56 is the same as the base material 40 of the sample 3-2.

(2) Formation of circuit pattern and through-holes After forming a catalytic activity hindering layer by the same method as sample 3-1, laser drawing was performed. At the time of laser drawing, the through hole 56 extending from the mounting surface 50a of the mounting portion 52 to the bottom surface 55b of the recess 55 is formed by laser light along with the laser drawing portion 15 (see FIGS. 7A and 7B) corresponding to the wiring pattern. formed. The diameter of the through-holes 56 was 0.2 mm, and six through-holes 56 were formed for each LED 30 .

Next, pretreatment for catalyst application, cleaning of the substrate, application of electroless plating catalyst, and electroless plating were performed in this order by the same method as for sample 3-1. As a result, the electroless plated film on the laser-drawn portion 15 and the electroless plated film 71 inside the through hole 56 were simultaneously formed. Next, an electrolytic copper plating film, an electrolytic nickel plating film, and an electrolytic gold plating film were laminated in this order on the electroless plating film of the laser-drawn portion 15 by the same method as in Sample 3-1 to form a circuit pattern 70. .

(3) Mounting of Mounting Component A mounting component 30 was mounted on the mounting surface 50a by the same method as that for the sample 3-1 to obtain a circuit component 500 (sample 3-3).

[Sample 3-4]
A circuit component 700 (sample 3-4) shown in FIG. 5 was manufactured in the same manner as for sample 3-1, except that the density reduction rate of the foam molded body as the base material was set to 0.5%. In molding the base material, the introduction pressure of the physical foaming agent was set to 1 MPa, and the filling amount of the molten resin into the mold was adjusted to set the density reduction rate to 0.5%. In addition, the mold clamping pressure and holding pressure were adjusted so as not to generate burrs on the compact. Other molding conditions were the same as those for sample 3-1.

[Sample 3-5]
A circuit component 700 (sample 3-5) shown in FIG. 5 was manufactured in the same manner as for sample 3-1, except that the density reduction rate of the foam molded body as the base material was set to 1%. In molding the base material, the introduction pressure of the physical foaming agent was set to 1 MPa, and the filling amount of the molten resin into the mold was adjusted to set the density reduction rate to 1%. In addition, the mold clamping pressure and holding pressure were adjusted so as not to generate burrs on the compact. Other molding conditions were the same as those for sample 3-1.

[Sample 3-6]
A circuit component 700 (sample 3-6) shown in FIG. 5 was manufactured in the same manner as for sample 3-1, except that the density reduction rate of the foamed molded body as the base material was set to 7%. In the molding of the base material, the introduction pressure of the physical foaming agent was set to 2 MPa, and the filling amount of the molten resin into the mold was adjusted to set the density reduction rate to 7%. Also, the mold clamping pressure was adjusted so as not to generate burrs on the compact. Other molding conditions were the same as those for sample 3-1.

[Sample 3-7]
A circuit component 700 (sample 3-7) shown in FIG. 5 was manufactured in the same manner as for sample 3-1, except that the density reduction rate of the foam molded body as the base material was set to 10%. In molding the base material, the introduction pressure of the physical foaming agent was set to 2 MPa, and the filling amount of the molten resin into the mold was adjusted to set the density reduction rate to 10%. Also, the mold clamping pressure was adjusted so as not to generate burrs on the compact. Other molding conditions were the same as those for sample 3-1.

[Sample 3-8]
A circuit component having the same configuration as Sample 3-1 was manufactured, except that a non-foamed molded body (solid molded body) was used as the base material.

(1) Molding of base material A non-foamed molded article was molded using the same materials and equipment as those of Sample 3-1. No physical blowing agent was introduced into the plasticizing cylinder in order to form a non-foamed molding. The resin temperature and mold temperature were the same as those of sample 3-1. However, in Sample 3-8, since the fluidity of the molten resin is low, sink marks occur in the molded body unless pressure is applied during injection molding. Therefore, a holding pressure of 40 MPa was applied for 5 seconds. The clamping pressure for preventing the mold from opening during molding was 40 tf.

The appearance of the resulting foamed molded product was observed with an optical microscope. During molding, the width of variation in the thickness of the foam molded product from the portion located at the mold gate to the portion located at the end of the mold was 10 μm, which was worse than the variation width of 5 μm for sample 3-1. Moreover, a burr having a length of about 50 μm was generated in the portion corresponding to the mold parting surface of the molded body, and the level required secondary processing for deburring.

(2) Formation of circuit pattern and mounting of mounting parts By the same method as sample 3-1, a circuit pattern is formed on the mounting surface of the molded body, mounting parts are mounted, and circuit parts (sample 3-8) got

[Sample 3-9]
A circuit component 700 (sample 3-9) shown in FIG. 5 was manufactured in the same manner as for sample 3-1, except that the density reduction rate of the foamed molded body as the base material was set to 15%. In molding the base material, the introduction pressure of the physical foaming agent was set to 4 MPa, and the filling amount of the molten resin into the mold was adjusted to set the density reduction rate to 15%. Other molding conditions were the same as those for sample 3-1.

[Evaluation of Circuit Components]
The following evaluations were performed on the manufactured circuit components (Samples 3-1 to 3-9). Table 4 shows the results.

(1) Heat Dissipation of Circuit Components A power supply was connected to each of the manufactured circuit components (Samples 3-1 to 3-9), and a DC current of 300 mA was passed through to turn on the LED 30 . Thirty minutes after the temperature of the LED 30 was sufficiently stabilized, the temperature of the LED 30 was measured. The temperature of the LED 30 was measured by fixing a thermocouple between electrodes on the rear surface of the LED 30 .

(2) Mass productivity of substrate (molded article) The mass productivity of the substrate (molded article) was evaluated according to the following evaluation criteria.

<Evaluation criteria for mass production>
◯: Molding was possible under molding conditions of mold clamping pressure of less than 5 tf and holding pressure of less than 10 MPa, and no burrs occurred on the molded body.
Δ: Molding was possible under the molding conditions of mold clamping pressure: 5 to 10 tf, holding pressure: 10 to 20 MPa, and no burrs occurred on the molded body.
x: Molding was possible under molding conditions of clamping pressure of 35 tf or more and holding pressure of 40 MPa or more, and burrs occurred in the molded body.

As shown in Table 4, the circuit components of Samples 3-1 to 3-7 kept the temperature of the LED as low as 90° C. or less, had high heat dissipation, and had good mass productivity. Samples 3-1 to 3-3 having different substrate shapes and the same other conditions are compared. The temperature of the LED is lower in the circuit component 400 (FIG. 9) in which the concave portion is provided in the base material of the sample 3-2 than in the circuit component 700 (FIG. 5) of the sample 3-1 using the plate-shaped base material. Furthermore, the temperature of the LED was lower in the circuit component 500 (FIG. 10) having recesses and through holes in the base material of sample 3-3. That is, samples 3-3, 3-2, and 3-1 had higher heat dissipation properties in that order.

In addition, Samples 3-1, 3-4 to 3-7 and 3-9, which have different density reduction rates of the base material and are otherwise identical, are compared. Samples 3-1, 3-5 and 3-6, in which the density reduction rate of the base material was 1 to 7%, had particularly high heat dissipation and good mass productivity of molded bodies. The temperature of the LEDs of Samples 3-1, 3-5 and 3-6 is almost the same as when the non-foamed molded body is used as the base material (Sample 3-8), and the heat dissipation is equivalent to that of the non-foamed molded body. It was confirmed that the Compared to samples 3-1, 3-5 and 3-6, sample 3-4 with a density reduction rate of 0.5% has a slightly lower mass productivity, and sample 3-7 with a density reduction rate of 10% , the temperature of the LED was slightly high. In addition, Sample 3-9, in which the density reduction rate of the substrate was 15%, had good mass productivity of the molded body, but compared to Samples 3-1, 3-5, and 3-6, the LED temperature was high, and heat dissipation decreased. In Sample 3-9, in which the density reduction rate of the base material is high, the thermal resistance of the base material increases due to the quenching effect of the foam cells, so it is presumed that the effect of the insulating thermally conductive filler in the base material is reduced.

On the other hand, Sample 3-8, which used a non-foamed molded article as a base material, was low in mass productivity of the molded article.

The manufacturing method of the present invention can simplify the device mechanism related to the physical foaming agent. In addition, a foam molded article having excellent foamability can be produced efficiently at low cost. Additionally, molded circuit components can be produced that have high heat resistance. Further, the circuit component (MID) of the present invention can achieve both productivity and heat dissipation. Therefore, it is possible to suppress the temperature of the circuit components from becoming high due to the heat generated by the mounted components such as LEDs.

20 screw 21 plasticization zone 22 compression zone 23 starvation zone 24 recompression zone 25 flow rate adjustment zone 26 seal portion 27 pressure sensor 100 cylinder 210 plasticization cylinder 300 introduction speed adjustment container 1000 manufacturing apparatus 10, 40, 51 base material 70 circuit Pattern 30 Mounted component (LED)
11 foam cells 700, 400, 500 circuit parts

Claims (18)

a circuit component,
a base material, which is a foam molded body containing a thermoplastic resin and an insulating thermally conductive filler and having a density reduction rate of 0.5% to 10% ;
a circuit pattern formed on the substrate;
a mounting component mounted on the mounting surface of the base material and electrically connected to the circuit pattern;
The base material is
a core layer inside the substrate and containing foam cells;
a skin layer that is in the range from the surface of the base material to a depth of 100 μm and does not contain foam cells,
A circuit component , wherein the substrate includes a roughened portion formed in a skin layer of the mounting surface and formed in a portion where the circuit pattern is formed . The thermoplastic resin includes a super engineering plastic,
When the circuit component is heated and the surface temperature of the circuit component is maintained at 240° C. to 260° C. for 5 minutes, the change rate of the thickness of the circuit component due to heating is -2% to 2%. The circuit component according to claim 1. The circuit component is
Having the base material having the mounting surface and a back surface facing the mounting surface,
2. The circuit component according to claim 1, wherein a distance from said mounting surface to said back surface is 0.1 mm or more in a portion of said base material on which said component is mounted. 4. The circuit component according to claim 3, wherein the base material has a density reduction rate of 1 to 7%. 5. The circuit component according to claim 3, wherein the distance from the mounting surface to the back surface exceeds 0.5 mm in the portion of the substrate where the mounting component is mounted. 6. The circuit component according to claim 5, wherein foam cells are provided between the mounting surface and the back surface in the portion of the base material on which the mounting component is mounted. A recess defined by a side wall and a bottom surface is formed on the back surface,
the mounting component is mounted on the mounting surface corresponding to the bottom surface;
5. The circuit component according to claim 3, wherein the distance from said mounting surface to said bottom surface is 0.1 mm to 1.5 mm. 8. The circuit component according to claim 7, wherein an area of said bottom surface per mounted component arranged on said mounting surface corresponding to said bottom surface is 0.4 cm ² to 4 cm ² . 9. The circuit component according to claim 7, wherein a non-through hole or a through hole is formed from the mounting surface toward the bottom surface, and an electroless plating film is formed on the inner wall of the hole. 9. The circuit component according to claim 7, wherein a concave portion is formed in the mounting surface of the base material where the mounted component is mounted, and an electroless plating film is formed on the surface of the concave portion. The circuit component according to any one of claims 3 to 10, wherein the circuit pattern contains an electroless plating film. 12. The circuit component according to any one of claims 3 to 11, wherein no heat radiating member is provided on the back surface. 13. The circuit component according to any one of claims 3 to 12, wherein said thermoplastic resin comprises a super engineering plastic. 14. The circuit component according to any one of claims 1 to 13, wherein the thermoplastic resin comprises super engineering plastic, and the super engineering plastic comprises polyphenylene sulfide or liquid crystal polymer. It has a plasticization zone in which a thermoplastic resin is plasticized and melted to become a molten resin, and a starvation zone in which the molten resin is starved, and an inlet for introducing a physical blowing agent is formed in the starvation zone. A method for manufacturing a circuit component using a plasticized cylinder comprising:
plasticizing and melting the thermoplastic resin into the molten resin in the plasticizing zone;
introducing a pressurized fluid containing the physical blowing agent at a constant pressure into the starvation zone and maintaining the starvation zone at the constant pressure;
Starving the molten resin in the starvation zone;
contacting the starved molten resin with a pressurized fluid containing a physical blowing agent at the constant pressure in the starvation zone while maintaining the constant pressure in the starvation zone;
Molding the molten resin in contact with a pressurized fluid containing the physical foaming agent into a foamed molding;
Forming a circuit pattern on the surface of the foam molded body,
The thermoplastic resin is a super engineering plastic, the constant pressure is 0.5 MPa to 12 MPa ,
The circuit component is
a base material, which is a foam molded body containing a thermoplastic resin and an insulating thermally conductive filler and having a density reduction rate of 0.5% to 10%;
a circuit pattern formed on the substrate;
a mounting component mounted on the mounting surface of the base material and electrically connected to the circuit pattern;
The base material is
a core layer inside the substrate and containing foam cells;
a skin layer that is in the range from the surface of the base material to a depth of 100 μm and does not contain foam cells,
A method of manufacturing a circuit component , wherein the substrate is formed in a skin layer of the mounting surface and includes a roughened portion formed in a portion where the circuit pattern is formed . 16. The method of manufacturing a circuit component according to claim 15, wherein the super engineering plastic comprises polyphenylene sulfide or liquid crystal polymer. 16. The method of manufacturing a circuit component according to claim 15, wherein the super engineering plastic contains polyphenylene sulfide, and the constant pressure is 2 MPa to 12 MPa. wherein the circuit pattern includes an electroless plating film, and forming the circuit pattern on the surface of the foam molded body;
forming a catalytic activity hindrance layer containing a polymer having at least one of an amide group and an amino group on the surface of the foam molded article;
Heating or irradiating a part of the surface of the foam molded article on which the catalytic activity hindering layer is formed;
applying an electroless plating catalyst to the surface of the foamed molded article that has been heated or irradiated with light;
15 to 17, comprising contacting an electroless plating solution to the surface of the foam molded article to which the electroless plating catalyst has been applied to form the electroless plating film on the heated portion or the light-irradiated portion of the surface. A method for manufacturing a circuit component according to any one of Claims 1 to 3.

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