JP2019177704A - Method for joining metal component and resin, and integral molding of metal component and resin - Google Patents

Abstract

To provide a method for joining a metal component and a resin which can suppress deterioration of a bond strength between a metal component and a resin even when a heat shock is applied, and can comparatively easily join the metal component and the resin due to an anchor effect, and to provide an integral molding of the metal component and the resin.SOLUTION: A method for joining a metal component and a resin which is a method for joining a metal component and a resin for integrating the metal component and the resin includes: forming a recess on the surface of the metal component; forming a porous plating film having micropores on the surface of the metal component containing the recess; flowing the resin into the recess and the micropores of the porous plating film; and joining the metal component and the resin.SELECTED DRAWING: Figure 1

Description

  The present invention relates to a method for joining a metal part and a resin and an integrally molded product of the metal part and the resin.

  An integrally molded product of a metal part and a resin is manufactured, for example, by injecting a molten resin onto the surface of the metal part. In order to strengthen the bonding between the metal part and the resin, a method of forming fine irregularities on the surface of the metal part prior to the injection of the molten resin has been proposed. In Patent Document 1, micron-level irregularities are formed on a metal surface by pressing using a mold having fine irregularities formed thereon. In Patent Document 2, nano-level micropores are formed on a metal surface by chemical treatment (chemical etching). In Patent Document 3, a metal surface is laser-scanned to form a large number of protrusions (uneven portions). By filling molten resin into fine recesses formed by these methods, the adhesion at the metal / resin interface can be enhanced by the anchor effect (throwing effect).

  In Patent Document 4, in order to obtain a desired bonding strength with little variation in the bonding strength between the metal and the resin due to the anchor effect, the axis of the metal substrate surface is inclined at a predetermined angle with respect to the normal of the metal substrate surface. A method of forming a plurality of inclined holes and filling the inclined holes with a resin composition has been proposed.

JP 2012-64880 A Japanese Patent No. 4903881 Japanese Patent No. 4020957 JP 2009-51131 A

  In Patent Document 1, the metal surface is roughened by pressing, the contact area between the resin and the contact angle is increased, and the contact angle is randomized to increase the bite between the metal and the resin. Since it is not mechanical joining by the anchor effect like 3, the joining force in the peeling direction becomes a problem. Furthermore, it is necessary to form microscopic irregularities on the press mold, which complicates the manufacture of the mold, makes it difficult to duplicate, and deteriorates and determines the mold.

  As described in Patent Documents 2 and 3, when micron-level fine irregularities and nano-level micropores are formed on the metal surface and have an anchor effect, the initial adhesive strength is high, The anchor effect due to these fine irregularities and fine holes is that when an integrally molded product of metal parts and resin is subjected to thermal and mechanical repeated stress such as heat cycle, the fine anchor due to breakage of the fine resin part or resin creep It is assumed that it will deteriorate due to loss of function of the part. For example, since a metal and a resin have different linear expansion coefficients, a large thermal stress is generated at the interface between the two due to a temperature change. In general, since a resin has a larger linear expansion coefficient than that of a metal, thermal stress resulting from a difference in the linear expansion coefficient between the resin and the metal increases in an environment with a temperature change. For this reason, there is a possibility that interface peeling between the surface of the metal part and the resin occurs due to heat shock.

  In addition, when the molten resin does not sufficiently flow into fine irregularities and fine holes during insert molding, it is assumed that the bonding force is reduced or deteriorated. Therefore, special molding conditions are required such as increasing the temperature of the molten resin and increasing the injection pressure during insert molding in order to facilitate the flow of the resin into fine irregularities and fine holes. As a result, an increase in manufacturing cost, addition of device functions, generation of resin burrs, deterioration of shape accuracy, and the like can be problems.

  Furthermore, in patent document 2, a chemical wet process (etching process) and its pre-processing process are required with respect to a metal surface, and cost, lead time, environmental impact, etc. become a subject. In addition, there is a problem that the storage period from the etching process to the resin molding is limited.

  In Patent Document 4, an inclined hole having an opening diameter of about 0.05 to 1 mm and a depth of about 0.5 to 5 mm is formed. In Patent Document 4, when subjected to a heat cycle, thermal stress is generated between the resin and the metal due to the difference in linear expansion coefficient. Unlikely, it is considered that the anchoring effect by the resin filled in the inclined hole and the inclined hole on the surface of the metal part is hardly deteriorated.

  However, in Patent Document 4, since the anchor effect is obtained by the holes, it is necessary to form a large number of inclined holes in order to obtain a desired bonding strength between the metal and the resin. In Patent Document 4, in order to obtain stable bonding, a large number of inclined holes having different inclination directions are formed. For example, inclined holes having different inclination directions are formed in an annular shape on the surface of the metal part. It is difficult to easily form a large number of inclined holes having different inclination directions. Further, since the inclined hole is a closed hole, it is difficult to reliably fill the resin. Due to the air layer remaining in the blocking hole, there is a concern about the occurrence of peeling due to temperature change.

  An object of the present invention is to make it difficult for the bonding strength between a metal part and a resin to deteriorate even when subjected to a heat shock, and to relatively easily bond the metal part and the resin by an anchor effect. An object of the present invention is to provide a method for joining resin and resin and an integrally molded product of metal part and resin.

  The metal part-resin joining method according to the present invention is a metal part-resin joining method for integrating a metal part and a resin, wherein a recess is formed on the surface of the metal part, and the surface of the metal part including the recess A porous plating film having micropores is formed in the resin, and a resin is poured into the recesses and the micropores of the porous plating film to join the metal part and the resin.

  In addition, the metal part and resin integral molded product according to the present invention is a metal part and resin integral molded product, and is formed on the surface of the metal part including the concave part and the concave part formed on the surface of the metal part. A porous plating film having micropores and a resin formed on the surface of the porous plating film, and the resin is filled and bonded to the concave portions and the micropores of the porous plating film. Features.

  According to the present invention, even when subjected to a heat shock, the bonding strength between the metal part and the resin is not easily deteriorated, and the metal part and the resin can be bonded relatively easily by the anchor effect. Problems, configurations, and effects other than those described above will be clarified by the following description of embodiments.

It is a flowchart which shows an example of the joining method of the metal component which concerns on this invention, and resin. FIG. 2 is an enlarged view of a portion X in FIG. 1. It is an enlarged view of the Y part of FIG. It is a photograph of the surface of a porous plating film. It is a cross-sectional photograph of a metal part, a base film, and a porous plating film. It is the elements on larger scale of FIG. It is the elements on larger scale of FIG. It is the elements on larger scale of FIG. It is the elements on larger scale of FIG. It is the elements on larger scale of FIG. It is the elements on larger scale of FIG. It is a conceptual diagram for demonstrating communication of the micropores in a porous plating film. It is sectional drawing which shows typically the example of a shape of the recessed part formed with the joining method of the metal component which concerns on this invention, and resin. It is a figure which shows typically the cross section (after porous film formation) at the time of forming a porous plating film in a rectangular recessed part. It is a figure which shows typically the cross section (after resin formation) at the time of forming a porous plating film in a rectangular recessed part. It is a flowchart which shows another example of the joining method of the metal component which concerns on this invention, and resin. It is a perspective view which shows typically an example of the integrally molded product of a metal component and resin. It is a perspective view which shows typically another example of the integrally molded product of a metal component and resin. 2 is a perspective view schematically showing a first example of a part of a recess formed in a metal part 1. FIG. It is a perspective view which shows typically the 2nd example of a part of recessed part formed in the metal component. It is a perspective view which shows typically the 3rd example of a part of recessed part formed in the metal component. It is a perspective view which shows typically an example of the aspect which formed the groove | channel in some metal components. It is a perspective view which shows typically the aspect which formed resin in the metal component of FIG. 21A.

  Embodiments of the present invention will be described below with reference to the drawings.

[Method of joining metal parts and resin]
First, a method for joining a metal part and a resin according to the present invention will be described. FIG. 1 is a flowchart showing an example of a method for joining a metal part and a resin according to the present invention. FIG. 1 shows a cross section of the metal part 1, the porous plating film 3 and the resin 4. As shown in FIG. 1, the metal part and resin joining method according to the present invention forms a recess 2 on the surface of the metal part 1 (step (a)), and micropores on the surface of the metal part 1 including the recess 2. (Detailed in FIGS. 2 to 11A described later) is formed (step (b)), the resin 4 is poured into the micropores of the recess 2 and the porous plating film 3, and the metal part 1 And the resin 4 are joined to produce an integrally molded product 5 of the metal part and the resin (step (c)).

  2 is an enlarged view of a portion X in FIG. 1, and FIG. 3 is an enlarged view of a portion Y in FIG. As shown in FIGS. 2 and 3, the porous plating film 3 has a large number of fine holes 8 extending in the film thickness direction of the porous plating film 3, and the resin 4 is poured into the fine holes 8. That is, in the method for joining a metal part and a resin according to the present invention, a relatively macro uneven structure (depth: several tens μm to several mm, hereinafter referred to as “macro uneven structure”) on the surface of the metal part 1 formed by the recess 2. And a relatively micro uneven structure (pore diameter: about 1 to 10 μm, depth: about 3 to 5 times the hole diameter, hereinafter referred to as “micro uneven structure”. 2), and the high adhesion between the metal part and the resin is realized by the anchor effect of the two types of uneven structure. The macro concavo-convex structure generates resistance against peeling in the direction perpendicular to the peeling direction (x direction shown in FIG. 3), and the micro concavo-convex structure is mainly used in the peeling direction (y direction shown in FIG. 3). ) Resistance to peeling. Further, in the case of using an engineering plastic containing a glass filler (diameter: several μm to several tens μm) as a resin, the fine hole is generally held in the fine hole of the porous plating film 3 to improve the bonding force. Is possible.

  The “porous plating film” of the present invention means a film having innumerable micropores produced by plating treatment, and a porous film (porous film) in which micropores are produced by chemical etching or the like after film formation. Are different.

  In a normal plating process, fine holes are not formed. In the plating treatment in the present invention, a porous plating film having fine pores is formed. The formation of such a porous plating film is described in, for example, JP 2010-121194 A, JP 2008-50673 A, JP 2009-74147 A, and the like.

An example of the structure of the porous plating film 3 will be described in detail. Steps (a) and (b) in FIG. 1 were performed to form a porous plating film on the metal part, and the microstructure was observed with a laser microscope. FIG. 4 is a photograph of the surface of the porous plating film. 5 is a cross-sectional photograph of the metal part, the base film and the porous plating film, and FIGS. 6 to 11A are partially enlarged views of FIG. The porous plating film 3 (porous nickel plating film) was produced by electroplating described in JP 2010-121194 A and the like. The composition of the plating bath is nickel sulfate (NiSO ₄ .6H ₂ O): 200 to 380 g / L, nickel chloride (NiCl ₂ .6H ₂ O): 30 to 70 g / L, boric acid: (H ₃ BO ₃ ): 30 to 45 g / L and dodecyldimethylbenzylammonium chloride: 0.03 mol / L. The plating conditions were pH: 3.0 to 4.8, bath temperature: 40 to 70 ° C., and cathode current density: 0.5 to 10 A / dm ^2. Porous plating film so as to have a plating thickness of 2 μm. 3 was produced. Even if the plating conditions are adjusted so that the plating thickness is 2 μm, a large number of micropores are formed, so that a porous plating film having a thickness of about 5 μm is evident from FIGS. 7 to 11A described later. It is formed. The cross section was observed by cutting the sample and then polishing the surface. Note that the polishing agent may have entered the fine holes during the surface polishing, and it is assumed that more fine holes are actually formed. FIGS. 5 to 11A are photographs in the case where a base film (undercoat film) described later is formed between the metal part and the porous plating film. The structure of the porous plating film changes depending on the presence or absence of the underlayer. is not.

  As shown to FIGS. 7-11A, the porous plating film 3 has the micropore 8 extended in the film thickness direction, and it can confirm that the resin 4 is filled in the micropore 8 (FIG. 10 and). FIG. 11A). Thus, the micropores extending in the film thickness direction are unique to the porous plating film. Even if micropores are created on the metal surface by chemical etching, chemical etching inherently increases the length (depth) of the micropores so that the micropores disappear and become flat. Such long fine holes (for example, fine holes of 5 μm or more) cannot be obtained.

  Further, at the bottom of the porous plating film 3 (interface portion with the base film 6), there is a portion having a communication hole in which a plurality of fine holes 8 are formed in communication (FIGS. 9 to 11A). This will be described with reference to the conceptual diagram shown in FIG. 11B. The arrow in FIG. 11B indicates the direction in which the poured resin flows. One of the adjacent fine holes becomes the outlet 8A, and the other becomes the outlet 8B. A communication hole 8 </ b> C is formed at the bottom of the porous plating film 3. The communication hole 8C is formed when the porous plating film is formed. For example, the temperature of the thermoplastic molten resin injected by the injection cylinder pressure is usually 200 ° C. or higher, and when injected onto the surface of the porous plating film, it enters the surface of the porous plating film while receiving interfacial shear stress. . Since this shear stress is partially different on the surface of the porous plating film, the molten resin flows quickly at the interface where the shear stress is small, and the penetration of the molten resin is delayed at the interface where the shear stress is large. Due to this time delay, an outlet 8B and an inlet 8A for the molten resin are generated. The air in the fine holes pushed out by the molten resin flowing from the inlet 8A can be released from the outlet 8B through the communication holes 8C. As a result, the molten resin can uniformly enter the fine holes 8. Thus, in the porous plating film 3 according to the present invention, when the resin 4 is poured (press-fitted) into the fine holes 8, the air is removed from the communication holes 8C, so that the resin is deep inside the fine holes (the base film 6). Side) and the bonding strength between the metal part (base film) and the resin is improved. Such communication holes 8C are also unique to the porous plating film and are not formed in the porous film formed by chemical etching.

  Hereinafter, steps (a) to (c) in FIG. 1 will be described in detail. First, in the step (a), the recess 2 is formed on the surface of the metal part 1. The material of the metal part 1 is not particularly limited and can be selected according to the use of the integrally molded product of the metal part and the resin. For example, copper (Cu), iron (Fe), aluminum (Al), etc. Can be used. FIG. 12 is a cross-sectional view schematically showing an example of the shape of a recess formed by the method for joining a metal part and a resin according to the present invention. As shown in FIG. 12, the cross-sectional shape of the recess is not particularly limited, and besides the wedge shape (2 a) shown in FIG. 1, a simple rectangular shape (2 b) has a width toward the center of the metal part 1. Various shapes can be applied, such as a narrower mortar shape (2c) or a hemispherical shape (crater shape) (2d). 13 and 14 are diagrams schematically showing a cross section when a porous plating film is formed in a rectangular recess. As shown in FIGS. 13 and 14, even if the recess is rectangular, the fine holes 8 generate a resistance against peeling in the peeling direction (y direction in FIG. 14), and are shown in FIGS. As in the case of the wedge shape, high adhesion between the metal part and the resin can be realized.

  Moreover, the recessed part 2 may be a groove | channel extended in the length direction or width direction of a metal component, as shown to FIGS. 16-21B mentioned later. As a formation mode of the grooves, a plurality of parallel grooves may be formed on the surface of the metal part, or the grooves may be formed so as to be orthogonal to each other. Furthermore, a large number of grooves may be formed so as to extend in an irregular direction. As the arrangement of the grooves is more complicated, resistance is generated in multiple directions, and high adhesion between the metal part and the resin can be realized.

  The method for forming the recess 2 is not particularly limited, and the recess 2 can be formed by cutting, plastic working (such as pressing), or surface roughening by laser light irradiation. Among these, press working is particularly preferable. In the case of press working, the concave portion can be formed by using the vertical movement of the die of the press machine. The progressive die can be incorporated as a step in the progressive step, which can contribute to cost reduction. Further, when the wedge-shaped groove is formed by pressing, an overhang portion 7 having an overhang amount O is formed as shown in FIG. A large anchor effect can be obtained by the overhang portion 7. Furthermore, it is preferable to perform press work so that the overhang portion 7 of the press groove formed on the surface of the metal part is pushed downward from above. By performing press working in this way, a bag-like space is formed in the press groove, and a higher anchor effect can be obtained.

  The depth of the recess 2 is not particularly limited, but when formed on one side of the metal part, it is preferably 10 to 50% of the thickness of the metal part. For example, when an example of the size in the case of forming a press groove using a connector terminal (thickness: 0.2 mm) as the metal part 1, the depth of the recess 2: 30 μm, width: 30 μm, length: 0. 5 to 5 mm.

  Although there is no limitation in particular as a preparation method of the porous plating film 3 in a process (b), electroplating is suitable. The composition of the porous film is preferably nickel (Ni). Otherwise, when the metal part 1 is Cu, a Cu-based alloy is preferable, when it is Fe, an Fe-based alloy is preferable, and when it is Al. Is preferably an Al-based alloy. As the composition of the electroplating bath, a compound containing a metal constituting the porous film is used, and additives are appropriately used. Known types of plating baths can be used. Examples of the Ni plating bath include a Watt bath, a sulfamic acid bath, a citric acid bath, and a wood bath. Examples of the Cu plating bath include a copper pyrophosphate bath. As plating conditions, general conditions for forming a porous film can be used. An example of the plating bath and the plating conditions are as described above. The film thickness of the porous plating film 3 depends on how large the pore diameter is. That is, the depth of the fine holes is preferably 5 times or less the diameter of the fine holes, although it depends on the viscosity of the resin, considering the penetration of the resin into the fine holes. This is because if it is deeper than that, the resin may not sufficiently enter. Moreover, the depth of the deepest hole is the same as the thickness of the porous plating film. For these reasons, the thickness of the porous plating film is set depending on the diameter of the micropores. On the other hand, the hole diameter of the fine holes can be changed depending on the plating conditions and the thickness of the porous plating film 3.

  Although there is no limitation in particular as the filling method of the resin 4 in a process (c), injection molding of molten resin is preferable. The resin can be poured by inserting the metal part 1 in which the concave portion 2 and the porous plating film 3 are formed in a mold and injecting the resin into the mold in the same manner as in normal injection molding. As the resin 4, a thermoplastic resin, a thermosetting resin, a thermoplastic elastomer, or the like applicable to normal injection molding can be used. More specifically, general-purpose plastics, engineering plastics and super engineering plastics used in general injection molding, polymer alloys mixed with these, inorganic fibers such as glass fibers as fillers, organic fibers such as aramid fibers, carbon fibers Metal fibers, or materials containing inorganic materials such as silica and talc can also be used. As the thermoplastic resin, polyphenylene sulfide resin (PPS resin) and the like are preferable.

  FIG. 15 is a flowchart showing an example of a method for joining a metal part and a resin according to the present invention. 15 is different from the method shown in FIG. 1 in that a step of forming a base film 6 (base film) (b1) is provided before the step (b2) of forming a porous plating film. . If the surface of the metal part is plated directly with the porous plating film, the porous plating film cannot protect the surface of the metal part if the metal part is placed in a corrosive environment. It is desirable to form a formation. For this reason, in this embodiment, the base film is a plating film having no fine holes. That is, a plating film formed by a normal electroplating process is formed as a base film on the metal front. In addition, by providing the base film 6 between the recess 2 and the porous plating film 3 in this way, the adhesion between the metal part 1 and the porous plating film 3 is improved, and the metal part and the resin are integrally formed. The corrosion resistance of the product 5 ′ can be improved. Although there is no limitation in particular as a base film, Cu-type alloy, Fe-type alloy, or Al-type alloy may be used according to the composition of the metal component 1 like a porous plating film, and it is also preferable to use Ni. . The film thickness of the base film 6 is preferably 1 to 6 μm.

  In the above-described embodiment, the metal part and the resin are integrated by the anchor effect by the macro uneven structure and the micro uneven structure. Hereinafter, the improvement in the connectivity between the metal part and the resin will be described by paying attention to the relationship between the filler filled in the resin and the macro uneven structure or the micro uneven structure.

In the integral molding of the metal part and the resin, the adhesion between the metal and the resin is particularly important. However, in fact, many thermoplastic resins for injection molding do not have chemical bondability with the metal. In thermosetting resins such as epoxy resins, uncured epoxy resin functional groups and metals are chemically bonded during injection molding, and heated and cured after injection molding to improve the adhesion between the metal and resin and the mechanical strength of the resin. A technique for achieving both is used. However, a thermoplastic resin is basically a resin that does not have a chemical functional group, melts when the temperature is raised, and solidifies when the temperature is lowered. For this reason, in the thermoplastic resin, no bond between the chemical metal and the molten resin can be obtained in the process. Therefore, the actual situation is that there is no method other than increasing the adhesion between the metal and the resin interface by mechanical locking called the anchor effect. The inventors have found that the structural control of the metal-resin interface is the most important in making the most of this mechanical locking. In insert molding in which a metal and a thermoplastic resin are integrally molded, the thermoplastic resin is filled with several kinds of fillers. In order to reduce the thermal stress in the temperature cycle, glass fiber is frequently used as a filler for controlling the linear expansion coefficient that brings the linear expansion coefficient of the thermoplastic resin close to that of the metal.
Glass fiber has the effect | action which reduces the linear expansion coefficient of the arrangement direction of a fiber. On the other hand, there is quartz powder as a filler that matches the linear expansion coefficient of the resin with the metal without orientation. As the glass fiber filler, one having a thickness of 5 to 10 μm is usually used. Usually, the length is about 10 times the thickness of the glass fiber. However, since only the glass fiber filler has a direction of linear expansion coefficient, the powdery filler is also filled into the thermoplastic resin together. In the case of a powder filler, for example, a quartz filler has a diameter (average particle diameter) of 1 to 3 μm. Since this powdery filler can also enter into the metal irregularities, the linear expansion coefficient at the interface between the metal and the thermoplastic resin can also be reduced. Other fillers for resin include ferrite fillers for absorbing electromagnetic waves, fillers such as Al2O3 (alumina), AlN (aluminum nitride) and BN (boron nitride) for imparting thermal conductivity, carbon fillers for imparting conductivity, There are many antibacterial zeolite fillers, slidable molybdenum sulfide fillers, etc., and these are powder fillers having a diameter (average particle diameter) of 1 to 10 μm. For this reason, it is preferable that these fine powder fillers also enter the interface between the metal and the thermoplastic resin.

  In other words, it is desirable that the recess has a dimension that allows a filler such as glass fiber to enter, and that the micropore has a dimension that allows the powder filler to enter. By configuring the recesses and micropores in this way, the powder filler also enters the micropores, so that the linear expansion coefficient of the thermoplastic resin that has entered the micropores is maintained at a value close to that of the metal, while the recesses are made of glass. With the invasion of the fiber filler, the linear expansion coefficient matched with the metal can be obtained. Molten resin generally has high viscosity, and the viscosity is lowered by adding a powder filler. In particular, as for the discharge pressure of the injection cylinder of the injection molding machine, thixotropy is generated by inserting a filler, and dynamic viscoelasticity is lowered. By mixing the filler, the thixo index increases significantly, so that the dynamic viscoelasticity is lowered and the molten resin easily flows into the micropores. The inventors focused on this point and found that it is desirable to make the size and shape of the micropores easy to enter the powder filler. Specifically, the diameter of the fine holes is preferably 1 to 10 μm. Further, the depth of the fine holes is preferably 5 times or less the diameter of the fine holes in consideration of the penetration of the resin, and the fine holes are preferably communicated with each other. By communicating, the inlet and outlet of the molten resin are naturally generated, so that the thermoplastic resin is more likely to enter the micropores. As shown in FIG. 10 and the like, the inventors have found that the molten resin easily enters by connecting the fine holes. As shown in the enlarged image of FIG. 11A in which the molten resin has entered, it can be seen that the adjacent micropores communicate with each other and form an inlet / outlet for the molten resin. A model of the communication hole is shown in FIG. 11B. The arrows in the figure indicate the molten resin inlet and outlet. The temperature of the thermoplastic molten resin injected by the injection cylinder pressure is usually 200 ° C. or higher, and when injected onto the surface of the metal part, it enters the metal surface while receiving interfacial shear stress. Since this shear stress is partially different on the metal surface, the molten resin flows quickly at the interface where the shear stress is small, and the penetration of the molten resin is delayed at the interface where the shear stress is large. Due to this time delay, an outlet and an inlet of the molten resin are generated, and the molten resin can uniformly enter the fine holes. Moreover, in a recessed part, a glass fiber filler can enter a recessed part by setting it as the dimension which a glass fiber filler can also enter. The width dimension of the recess is preferably about 100 μm into which the glass fiber can enter.

  In Patent Document 2, fine irregularities having a period of 5 to 500 nm are formed on the metal surface. However, since the powder filler cannot penetrate into such fine irregularities, the thermoplastic resin or adhesive that has entered the fine irregularities in the temperature cycle is used. Since the linear expansion coefficient is larger than that of metal, peeling occurs due to shrinkage of the resin, particularly under temperature cycle test conditions where the low temperature side is minus 20 to minus 65 ° C. This is the reason why Patent Document 2 cannot be used for metal resin integrated products such as automobile parts.

  As described above, by setting the size of the recesses and the fine holes so that the filler filled in the resin can enter, it is possible to realize the bonding between the metal component and the resin that is resistant to heat shock. If this feature pays attention to a fine hole, it is not always necessary to form a recess in a metal part. In other words, by forming a porous plating film on a metal part with a flat surface and forming fine pores in a size that allows the powder filler filled in the resin to enter, the connectivity between the metal part and the resin can be improved. it can. For example, the diameter of the micropores of the porous plating film formed under predetermined plating conditions is confirmed with a laser microscope or the like, and a resin filled with a filler having an average particle size smaller than the pore diameter of the confirmed micropores is used. . For example, if the fine pore diameter is about 1 μm, a filler having an average particle diameter of 1 μm is used. A filler smaller than 1 μm in the particle size distribution of the filler can enter the micropores, and the difference in linear expansion coefficient between the resin in the micropores and the metal part can be reduced.

[Metal parts and resin integrated molding]
Next, an integrally molded product of a metal part and a resin manufactured using the above-described method for joining a metal part and a resin according to the present invention will be described. 16 and 17 are perspective views schematically showing an example of an integrally molded product of a metal part and a resin. In FIG. 16 and FIG. 17, the illustration of the porous plating film is omitted in consideration of the visibility of the drawings. FIG. 16 shows a case where a groove having a wedge-shaped cross section is formed as the recess 2 in the metal part 1, and FIG. 17 shows a case where a groove having a rectangular cross section is formed as the recess 2 in the metal part 1.

  18 to 20 are perspective views schematically showing an example of a part of the recess 2 formed in the metal part 1. As shown in FIG. 18, the recessed part 2 may be formed in the single side | surface of the metal component 1, and may be formed in both surfaces, as shown in FIG. Further, as shown in FIG. 20, a plurality of wedge-shaped grooves may be formed so as to be orthogonal to each other.

  FIG. 21A is a perspective view schematically showing an example in which a groove is formed in a part of a metal part, and FIG. 21B is a perspective view schematically showing an aspect in which a resin is formed on the metal part in FIG. 21A. Thus, a recess may be formed only in a part of the metal part, and the resin 4 may be formed on the recess.

  The present invention can be applied to metal parts and resin integrated molded products having various uses and shapes, and can be used for various applications such as industrial equipment, automobiles, aircraft equipment, consumer products, and household appliances. It is applicable to typical mechanical parts. For example, a resin-made electronic circuit protective case member having a metal conductive terminal therein, a resin-made cover partially having a metal electromagnetic shield, a heat radiating plate, and the like.

  As described above, according to the present invention, even when subjected to a heat shock, the bonding strength between the metal part and the resin is hardly deteriorated, and the metal part and the resin are bonded relatively easily by the anchor effect. It has been shown that it is possible to provide a metal part-resin joining method and a metal part-resin integral molding product.

In addition, this invention is not limited to an above-described Example, Various modifications are included.
For example, the above-described embodiments have been described in detail for easy understanding of the present invention, and are not necessarily limited to those having all the configurations described. Further, a part of the configuration of one embodiment can be replaced with the configuration of another embodiment, and the configuration of another embodiment can be added to the configuration of one embodiment. Moreover, it is possible to add, delete, and replace other configurations for a part of the configuration of each embodiment.

  DESCRIPTION OF SYMBOLS 1 ... Metal component, 2 ... Recessed part, 3 ... Porous plating film, 4 ... Resin, 5 ... Integrated molding of metal component and resin, 6 ... Base film, 7 ... Overhang part, 8 ... Micropore.

  The present invention relates to a method for joining a metal part and a resin and an integrally molded product of the metal part and the resin.

  An integrally molded product of a metal part and a resin is manufactured, for example, by injecting a molten resin onto the surface of the metal part. In order to strengthen the bonding between the metal part and the resin, a method of forming fine irregularities on the surface of the metal part prior to the injection of the molten resin has been proposed. In Patent Document 1, micron-level irregularities are formed on a metal surface by pressing using a mold having fine irregularities formed thereon. In Patent Document 2, nano-level micropores are formed on a metal surface by chemical treatment (chemical etching). In Patent Document 3, a metal surface is laser-scanned to form a large number of protrusions (uneven portions). By filling molten resin into fine recesses formed by these methods, the adhesion at the metal / resin interface can be enhanced by the anchor effect (throwing effect).

  In Patent Document 4, in order to obtain a desired bonding strength with little variation in the bonding strength between the metal and the resin due to the anchor effect, the axis of the metal substrate surface is inclined at a predetermined angle with respect to the normal of the metal substrate surface. A method of forming a plurality of inclined holes and filling the inclined holes with a resin composition has been proposed.

JP 2012-64880 A Japanese Patent No. 4903881 Japanese Patent No. 4020957 JP 2009-51131 A

  In Patent Document 1, the metal surface is roughened by pressing, the contact area between the resin and the contact angle is increased, and the contact angle is randomized to increase the bite between the metal and the resin. Since it is not mechanical joining by the anchor effect like 3, the joining force in the peeling direction becomes a problem. Furthermore, it is necessary to form microscopic irregularities on the press mold, which complicates the manufacture of the mold, makes it difficult to duplicate, and deteriorates and determines the mold.

  As described in Patent Documents 2 and 3, when micron-level fine irregularities and nano-level micropores are formed on the metal surface and have an anchor effect, the initial adhesive strength is high, The anchor effect due to these fine irregularities and fine holes is that when an integrally molded product of metal parts and resin is subjected to thermal and mechanical repeated stress such as heat cycle, the fine anchor due to breakage of the fine resin part or resin creep It is assumed that it will deteriorate due to loss of function of the part. For example, since a metal and a resin have different linear expansion coefficients, a large thermal stress is generated at the interface between the two due to a temperature change. In general, since a resin has a larger linear expansion coefficient than that of a metal, thermal stress resulting from a difference in the linear expansion coefficient between the resin and the metal increases in an environment with a temperature change. For this reason, there is a possibility that interface peeling between the surface of the metal part and the resin occurs due to heat shock.

  In addition, when the molten resin does not sufficiently flow into fine irregularities and fine holes during insert molding, it is assumed that the bonding force is reduced or deteriorated. Therefore, special molding conditions are required such as increasing the temperature of the molten resin and increasing the injection pressure during insert molding in order to facilitate the flow of the resin into fine irregularities and fine holes. As a result, an increase in manufacturing cost, addition of device functions, generation of resin burrs, deterioration of shape accuracy, and the like can be problems.

  Furthermore, in patent document 2, a chemical wet process (etching process) and its pre-processing process are required with respect to a metal surface, and cost, lead time, environmental impact, etc. become a subject. In addition, there is a problem that the storage period from the etching process to the resin molding is limited.

  In Patent Document 4, an inclined hole having an opening diameter of about 0.05 to 1 mm and a depth of about 0.5 to 5 mm is formed. In Patent Document 4, when subjected to a heat cycle, thermal stress is generated between the resin and the metal due to the difference in linear expansion coefficient. Unlikely, it is considered that the anchoring effect by the resin filled in the inclined hole and the inclined hole on the surface of the metal part is hardly deteriorated.

  However, in Patent Document 4, since the anchor effect is obtained by the holes, it is necessary to form a large number of inclined holes in order to obtain a desired bonding strength between the metal and the resin. In Patent Document 4, in order to obtain stable bonding, a large number of inclined holes having different inclination directions are formed. For example, inclined holes having different inclination directions are formed in an annular shape on the surface of the metal part. It is difficult to easily form a large number of inclined holes having different inclination directions. Further, since the inclined hole is a closed hole, it is difficult to reliably fill the resin. Due to the air layer remaining in the blocking hole, there is a concern about the occurrence of peeling due to temperature change.

  An object of the present invention is to make it difficult for the bonding strength between a metal part and a resin to deteriorate even when subjected to a heat shock, and to relatively easily bond the metal part and the resin by an anchor effect. An object of the present invention is to provide a method for joining resin and resin and an integrally molded product of metal part and resin.

  The metal part and resin joining method according to the present invention is a metal part and resin joining method that integrates a metal part and a resin, and a porous plating film having micropores is formed on the surface of the metal part, A resin filled with a filler having a pore diameter equal to or smaller than the pore size is used as the resin, and the resin is poured onto a porous plating film to join the metal part and the resin.

  In addition, an integrally molded product of a metal part and a resin according to the present invention includes a porous plating film having micropores formed on the surface of the metal part, and a resin formed on the surface of the porous plating film. The resin is filled in the micropores of the porous plating film and bonded.

  According to the present invention, even when subjected to a heat shock, the bonding strength between the metal part and the resin is not easily deteriorated, and the metal part and the resin can be bonded relatively easily by the anchor effect. Problems, configurations, and effects other than those described above will be clarified by the following description of embodiments.

It is a flowchart which shows an example of the joining method of the metal component which concerns on this invention, and resin. FIG. 2 is an enlarged view of a portion X in FIG. 1. It is an enlarged view of the Y part of FIG. It is a photograph of the surface of a porous plating film. It is a cross-sectional photograph of a metal part, a base film, and a porous plating film. It is the elements on larger scale of FIG. It is the elements on larger scale of FIG. It is the elements on larger scale of FIG. It is the elements on larger scale of FIG. It is the elements on larger scale of FIG. It is the elements on larger scale of FIG. It is a conceptual diagram for demonstrating communication of the micropores in a porous plating film. It is sectional drawing which shows typically the example of a shape of the recessed part formed with the joining method of the metal component which concerns on this invention, and resin. It is a figure which shows typically the cross section (after porous film formation) at the time of forming a porous plating film in a rectangular recessed part. It is a figure which shows typically the cross section (after resin formation) at the time of forming a porous plating film in a rectangular recessed part. It is a flowchart which shows another example of the joining method of the metal component which concerns on this invention, and resin. It is a perspective view which shows typically an example of the integrally molded product of a metal component and resin. It is a perspective view which shows typically another example of the integrally molded product of a metal component and resin. 2 is a perspective view schematically showing a first example of a part of a recess formed in a metal part 1. FIG. It is a perspective view which shows typically the 2nd example of a part of recessed part formed in the metal component. It is a perspective view which shows typically the 3rd example of a part of recessed part formed in the metal component. It is a perspective view which shows typically an example of the aspect which formed the groove | channel in some metal components. It is a perspective view which shows typically the aspect which formed resin in the metal component of FIG. 21A.

  Embodiments of the present invention will be described below with reference to the drawings.

[Method of joining metal parts and resin]
As described above, the metal part-resin joining method of the present invention forms a porous plating film having fine pores on the surface of the metal part. As the resin to be joined to the metal part, a resin filled with a filler having a pore diameter equal to or smaller than the fine pores of the porous plating film is used. By adopting such a configuration, the filler in the resin is held in the fine pores of the porous plating film, the resin and the porous plating film are firmly connected, and high adhesion between the resin and the metal part can be realized. it can. The method for joining a metal part and a resin according to the present invention will be described more specifically. FIG. 1 is a flowchart showing an example of a method for joining a metal part and a resin according to the present invention. FIG. 1 shows a cross section of the metal part 1, the porous plating film 3 and the resin 4. In FIG. 1, the recess 2 is formed on the surface of the metal part 1 (step (a)), and the surface of the metal part 1 including the recess 2 has a fine hole (described in detail in FIGS. 2 to 11A described later). The metal plating film 3 is formed (step (b)), the resin 4 is poured into the micropores of the recess 2 and the porous plating film 3, the metal part 1 and the resin 4 are joined, and the metal part and the resin are integrally formed. 5 is produced (step (c)). As will be described later, in the present invention, it is not essential to form the recess 2 on the surface of the metal part 1.

  2 is an enlarged view of a portion X in FIG. 1, and FIG. 3 is an enlarged view of a portion Y in FIG. As shown in FIGS. 2 and 3, the porous plating film 3 has a large number of fine holes 8 extending in the film thickness direction of the porous plating film 3, and the resin 4 is poured into the fine holes 8. That is, in the method for joining a metal part and a resin shown in FIG. 1, a relatively macro uneven structure (depth: several tens μm to several mm, hereinafter referred to as “macro uneven structure”) on the surface of the metal part 1 formed by the recess 2. And a relatively micro uneven structure (pore diameter: about 1 to 10 μm, depth: about 3 to 5 times the hole diameter, hereinafter referred to as “micro uneven structure”. 2), and the high adhesion between the metal part and the resin is realized by the anchor effect of the two types of uneven structure. The macro concavo-convex structure generates resistance against peeling in the direction perpendicular to the peeling direction (x direction shown in FIG. 3), and the micro concavo-convex structure is mainly used in the peeling direction (y direction shown in FIG. 3). ) Resistance to peeling. Further, in the case of using an engineering plastic containing a glass filler (diameter: several μm to several tens μm) as a resin, the fine hole is generally held in the fine hole of the porous plating film 3 to improve the bonding force. Is possible.

  The “porous plating film” of the present invention means a film having innumerable micropores produced by plating treatment, and a porous film (porous film) in which micropores are produced by chemical etching or the like after film formation. Are different.

  In a normal plating process, fine holes are not formed. In the plating treatment in the present invention, a porous plating film having fine pores is formed. The formation of such a porous plating film is described in, for example, JP 2010-121194 A, JP 2008-50673 A, JP 2009-74147 A, and the like.

An example of the structure of the porous plating film 3 will be described in detail. Steps (a) and (b) in FIG. 1 were performed to form a porous plating film on the metal part, and the microstructure was observed with a laser microscope. FIG. 4 is a photograph of the surface of the porous plating film. 5 is a cross-sectional photograph of the metal part, the base film and the porous plating film, and FIGS. 6 to 11A are partially enlarged views of FIG. The porous plating film 3 (porous nickel plating film) was produced by electroplating described in JP 2010-121194 A and the like. The composition of the plating bath is nickel sulfate (NiSO ₄ .6H ₂ O): 200 to 380 g / L, nickel chloride (NiCl ₂ .6H ₂ O): 30 to 70 g / L, boric acid: (H ₃ BO ₃ ): 30 to 45 g / L and dodecyldimethylbenzylammonium chloride: 0.03 mol / L. The plating conditions were pH: 3.0 to 4.8, bath temperature: 40 to 70 ° C., and cathode current density: 0.5 to 10 A / dm ^2. Porous plating film so as to have a plating thickness of 2 μm. 3 was produced. Even if the plating conditions are adjusted so that the plating thickness is 2 μm, a large number of micropores are formed, so that a porous plating film having a thickness of about 5 μm is evident from FIGS. 7 to 11A described later. It is formed. The cross section was observed by cutting the sample and then polishing the surface. Note that the polishing agent may have entered the fine holes during the surface polishing, and it is assumed that more fine holes are actually formed. FIGS. 5 to 11A are photographs in the case where a base film (undercoat film) described later is formed between the metal part and the porous plating film. The structure of the porous plating film varies depending on the presence or absence of the underlayer. is not.

  As shown to FIGS. 7-11A, the porous plating film 3 has the micropore 8 extended in the film thickness direction, and it can confirm that the resin 4 is filled in the micropore 8 (FIG. 10 and). FIG. 11A). Thus, the micropores extending in the film thickness direction are unique to the porous plating film. Even if micropores are created on the metal surface by chemical etching, chemical etching inherently increases the length (depth) of the micropores so that the micropores disappear and become flat. Such long fine holes (for example, fine holes of 5 μm or more) cannot be obtained.

  Further, at the bottom of the porous plating film 3 (interface portion with the base film 6), there is a portion having a communication hole in which a plurality of fine holes 8 are formed in communication (FIGS. 9 to 11A). This will be described with reference to the conceptual diagram shown in FIG. 11B. The arrow in FIG. 11B indicates the direction in which the poured resin flows. One of the adjacent fine holes becomes the inlet 8A, and the other becomes the outlet 8B. A communication hole 8 </ b> C is formed at the bottom of the porous plating film 3. The communication hole 8C is formed when the porous plating film is formed. For example, the temperature of the thermoplastic molten resin injected by the injection cylinder pressure is usually 200 ° C. or higher, and when injected onto the surface of the porous plating film, it enters the surface of the porous plating film while receiving interfacial shear stress. . Since this shear stress is partially different on the surface of the porous plating film, the molten resin flows quickly at the interface where the shear stress is small, and the penetration of the molten resin is delayed at the interface where the shear stress is large. Due to this time delay, an outlet 8B and an inlet 8A for the molten resin are generated. The air in the fine holes pushed out by the molten resin flowing from the inlet 8A can be released from the outlet 8B through the communication holes 8C. As a result, the molten resin can uniformly enter the fine holes 8. Thus, in the porous plating film 3 according to the present invention, when the resin 4 is poured (press-fitted) into the fine holes 8, the air is removed from the communication holes 8C, so that the resin is deep inside the fine holes (the base film 6). Side) and the bonding strength between the metal part (base film) and the resin is improved. Such communication holes 8C are also unique to the porous plating film, and are not formed in the porous film formed by chemical etching.

  Hereinafter, steps (a) to (c) in FIG. 1 will be described in detail. First, in the step (a), the recess 2 is formed on the surface of the metal part 1. The material of the metal part 1 is not particularly limited and can be selected according to the use of the integrally molded product of the metal part and the resin. For example, copper (Cu), iron (Fe), aluminum (Al), etc. Can be used. FIG. 12 is a cross-sectional view schematically showing an example of the shape of a recess formed by the method for joining a metal part and resin according to the present invention. As shown in FIG. 12, the cross-sectional shape of the recess is not particularly limited, and besides the wedge shape (2 a) shown in FIG. 1, a simple rectangular shape (2 b) has a width toward the center of the metal part 1. Various shapes can be applied, such as a narrower mortar shape (2c) or a hemispherical shape (crater shape) (2d). 13 and 14 are diagrams schematically showing a cross section when a porous plating film is formed in a rectangular recess. As shown in FIGS. 13 and 14, even if the recess is rectangular, the fine holes 8 generate a resistance against peeling in the peeling direction (y direction in FIG. 14), and are shown in FIGS. As in the case of the wedge shape, high adhesion between the metal part and the resin can be realized.

  Moreover, the recessed part 2 may be a groove | channel extended in the length direction or width direction of a metal component, as shown to FIGS. 16-21B mentioned later. As a formation mode of the grooves, a plurality of parallel grooves may be formed on the surface of the metal part, or the grooves may be formed so as to be orthogonal to each other. Furthermore, a large number of grooves may be formed so as to extend in an irregular direction. As the arrangement of the grooves is more complicated, resistance is generated in multiple directions, and high adhesion between the metal part and the resin can be realized.

  The method for forming the recess 2 is not particularly limited, and the recess 2 can be formed by cutting, plastic working (such as pressing), or surface roughening by laser light irradiation. Among these, press working is particularly preferable. In the case of press working, the concave portion can be formed by using the vertical movement of the die of the press machine. The progressive die can be incorporated as a step in the progressive step, which can contribute to cost reduction. Further, when the wedge-shaped groove is formed by pressing, an overhang portion 7 having an overhang amount O is formed as shown in FIG. A large anchor effect can be obtained by the overhang portion 7. Furthermore, it is preferable to perform press work so that the overhang portion 7 of the press groove formed on the surface of the metal part is pushed downward from above. By performing press working in this way, a bag-like space is formed in the press groove, and a higher anchor effect can be obtained.

  The depth of the recess 2 is not particularly limited, but when formed on one side of the metal part, it is preferably 10 to 50% of the thickness of the metal part. For example, when an example of the size in the case of forming a press groove using a connector terminal (thickness: 0.2 mm) as the metal part 1, the depth of the recess 2: 30 μm, width: 30 μm, length: 0. 5 to 5 mm.

  Although there is no limitation in particular as a preparation method of the porous plating film 3 in a process (b), electroplating is suitable. The composition of the porous film is preferably nickel (Ni). In addition, when the metal part 1 is Cu, a Cu-based alloy is preferable, when it is Fe, an Fe-based alloy is preferable, and when it is Al. Is preferably an Al-based alloy. As the composition of the electroplating bath, a compound containing a metal constituting the porous film is used, and additives are appropriately used. Known types of plating baths can be used. Examples of the Ni plating bath include a Watt bath, a sulfamic acid bath, a citric acid bath, and a wood bath. Examples of the Cu plating bath include a copper pyrophosphate bath. As plating conditions, general conditions for forming a porous film can be used. An example of the plating bath and the plating conditions are as described above. The film thickness of the porous plating film 3 depends on how large the pore diameter is. That is, the depth of the fine holes is preferably 5 times or less the diameter of the fine holes, although it depends on the viscosity of the resin, considering the penetration of the resin into the fine holes. This is because if it is deeper than that, the resin may not sufficiently enter. Moreover, the depth of the deepest hole is the same as the thickness of the porous plating film. For these reasons, the thickness of the porous plating film is set depending on the diameter of the micropores. On the other hand, the hole diameter of the fine holes can be changed depending on the plating conditions and the thickness of the porous plating film 3.

  Although there is no limitation in particular as the filling method of the resin 4 in a process (c), injection molding of molten resin is preferable. The resin can be poured by inserting the metal part 1 in which the concave portion 2 and the porous plating film 3 are formed in a mold and injecting the resin into the mold in the same manner as in normal injection molding. As the resin 4, a thermoplastic resin, a thermosetting resin, a thermoplastic elastomer, or the like applicable to normal injection molding can be used. More specifically, general-purpose plastics, engineering plastics and super engineering plastics used in general injection molding, polymer alloys mixed with these, inorganic fibers such as glass fibers as fillers, organic fibers such as aramid fibers, carbon fibers Metal fibers, or materials containing inorganic materials such as silica and talc can also be used. As the thermoplastic resin, polyphenylene sulfide resin (PPS resin) and the like are preferable.

  FIG. 15 is a flowchart showing an example of a method for joining a metal part and a resin according to the present invention. 15 is different from the method shown in FIG. 1 in that a step of forming a base film 6 (base film) (b1) is provided before the step (b2) of forming a porous plating film. . If the surface of the metal part is plated directly with the porous plating film, the porous plating film cannot protect the surface of the metal part if the metal part is placed in a corrosive environment. It is desirable to form a formation. For this reason, in this embodiment, the base film is a plating film having no fine holes. That is, a plating film formed by a normal electroplating process is formed as a base film on the metal front. In addition, by providing the base film 6 between the recess 2 and the porous plating film 3 in this way, the adhesion between the metal part 1 and the porous plating film 3 is improved, and the metal part and the resin are integrally formed. The corrosion resistance of the product 5 ′ can be improved. Although there is no limitation in particular as a base film, Cu-type alloy, Fe-type alloy, or Al-type alloy may be used according to the composition of the metal component 1 like a porous plating film, and it is also preferable to use Ni. . The film thickness of the base film 6 is preferably 1 to 6 μm.

  In the above-described embodiment, the metal part and the resin are integrated by the anchor effect by the macro uneven structure and the micro uneven structure. Hereinafter, the improvement in the connectivity between the metal part and the resin will be described by paying attention to the relationship between the filler filled in the resin and the macro uneven structure or the micro uneven structure.

In the integral molding of the metal part and the resin, the adhesion between the metal and the resin is particularly important. However, in fact, many thermoplastic resins for injection molding do not have chemical bondability with the metal. In thermosetting resins such as epoxy resins, uncured epoxy resin functional groups and metals are chemically bonded during injection molding, and heated and cured after injection molding to improve the adhesion between the metal and resin and the mechanical strength of the resin. A technique for achieving both is used. However, a thermoplastic resin is basically a resin that does not have a chemical functional group, melts when the temperature is raised, and solidifies when the temperature is lowered. For this reason, in the thermoplastic resin, no bond between the chemical metal and the molten resin can be obtained in the process. Therefore, the actual situation is that there is no method other than increasing the adhesion between the metal and the resin interface by mechanical locking called the anchor effect. The inventors have found that the structural control of the metal-resin interface is the most important in making the most of this mechanical locking. In insert molding in which a metal and a thermoplastic resin are integrally molded, the thermoplastic resin is filled with several kinds of fillers. In order to reduce the thermal stress in the temperature cycle, glass fiber is frequently used as a filler for controlling the linear expansion coefficient that brings the linear expansion coefficient of the thermoplastic resin close to that of the metal.
Glass fiber has the effect | action which reduces the linear expansion coefficient of the arrangement direction of a fiber. On the other hand, there is quartz powder as a filler that matches the linear expansion coefficient of the resin with the metal without orientation. As the glass fiber filler, one having a thickness of 5 to 10 μm is usually used. Usually, the length is about 10 times the thickness of the glass fiber. However, since only the glass fiber filler has a direction of linear expansion coefficient, the powdery filler is also filled into the thermoplastic resin together. In the case of a powder filler, for example, a quartz filler has a diameter (average particle diameter) of 1 to 3 μm. Since this powdery filler can also enter into the metal irregularities, the linear expansion coefficient at the interface between the metal and the thermoplastic resin can also be reduced. In addition, resin fillers include ferrite fillers for absorbing electromagnetic waves, fillers such as Al ₂ O ₃ (alumina), AlN (aluminum nitride) and BN (boron nitride) for imparting thermal conductivity, and conductivity imparting agents. There are many carbon fillers, antibacterial zeolite fillers, slidable molybdenum sulfide fillers, etc., and these are powder fillers having a diameter (average particle diameter) of 1 to 10 μm. For this reason, it is preferable that these fine powder fillers also enter the interface between the metal and the thermoplastic resin.

  In other words, it is desirable that the recess has a dimension that allows a filler such as glass fiber to enter, and that the micropore has a dimension that allows the powder filler to enter. By configuring the recesses and micropores in this way, the powder filler also enters the micropores, so that the linear expansion coefficient of the thermoplastic resin that has entered the micropores is maintained at a value close to that of the metal, while the recesses are made of glass. With the invasion of the fiber filler, the linear expansion coefficient matched with the metal can be obtained. Molten resin generally has high viscosity, and the viscosity is lowered by adding a powder filler. In particular, as for the discharge pressure of the injection cylinder of the injection molding machine, thixotropy is generated by inserting a filler, and dynamic viscoelasticity is lowered. By mixing the filler, the thixo index increases significantly, so that the dynamic viscoelasticity is lowered and the molten resin easily flows into the micropores. The inventors focused on this point and found that it is desirable to make the size and shape of the micropores easy to enter the powder filler. Specifically, the diameter of the fine holes is preferably 1 to 10 μm. Further, the depth of the fine holes is preferably 5 times or less the diameter of the fine holes in consideration of the penetration of the resin, and the fine holes are preferably communicated with each other. By communicating, the inlet and outlet of the molten resin are naturally generated, so that the thermoplastic resin is more likely to enter the micropores. As shown in FIG. 10 and the like, the inventors have found that the molten resin easily enters by connecting the fine holes. As shown in the enlarged image of FIG. 11A in which the molten resin has entered, it can be seen that the adjacent micropores communicate with each other and form an inlet / outlet for the molten resin. A model of the communication hole is shown in FIG. 11B. The arrows in the figure indicate the molten resin inlet and outlet. The temperature of the thermoplastic molten resin injected by the injection cylinder pressure is usually 200 ° C. or higher, and when injected onto the surface of the metal part, it enters the metal surface while receiving interfacial shear stress. Since this shear stress is partially different on the metal surface, the molten resin flows quickly at the interface where the shear stress is small, and the penetration of the molten resin is delayed at the interface where the shear stress is large. Due to this time delay, an outlet and an inlet of the molten resin are generated, and the molten resin can uniformly enter the fine holes. Moreover, in a recessed part, a glass fiber filler can enter a recessed part by setting it as the dimension which a glass fiber filler can also enter. The width dimension of the recess is preferably about 100 μm into which the glass fiber can enter.

  In Patent Document 2, fine irregularities having a period of 5 to 500 nm are formed on the metal surface. However, since the powder filler cannot penetrate into such fine irregularities, the thermoplastic resin or adhesive that has entered the fine irregularities in the temperature cycle is used. Since the linear expansion coefficient is larger than that of metal, peeling occurs due to shrinkage of the resin, particularly under temperature cycle test conditions where the low temperature side is minus 20 to minus 65 ° C. This is the reason why Patent Document 2 cannot be used for metal resin integrated products such as automobile parts.

  As described above, by setting the size of the recesses and the fine holes so that the filler filled in the resin can enter, it is possible to realize the bonding between the metal component and the resin that is resistant to heat shock. If this feature pays attention to a fine hole, it is not always necessary to form a recess in a metal part. In other words, by forming a porous plating film on a metal part with a flat surface and forming fine pores in a size that allows the powder filler filled in the resin to enter, the connectivity between the metal part and the resin can be improved. it can. For example, the diameter of the micropores of the porous plating film formed under predetermined plating conditions is confirmed with a laser microscope or the like, and a resin filled with a filler having an average particle size smaller than the pore diameter of the confirmed micropores is used. . For example, if the fine pore diameter is about 1 μm, a filler having an average particle diameter of 1 μm is used. A filler smaller than 1 μm in the particle size distribution of the filler can enter the micropores, and the difference in linear expansion coefficient between the resin in the micropores and the metal part can be reduced.

[Metal parts and resin integrated molding]
Next, an integrally molded product of a metal part and a resin manufactured using the above-described method for joining a metal part and a resin according to the present invention will be described. 16 and 17 are perspective views schematically showing an example of an integrally molded product of a metal part and a resin. In FIG. 16 and FIG. 17, the illustration of the porous plating film is omitted in consideration of the visibility of the drawings. FIG. 16 shows a case where a groove having a wedge-shaped cross section is formed as the recess 2 in the metal part 1, and FIG. 17 shows a case where a groove having a rectangular cross section is formed as the recess 2 in the metal part 1.

  18 to 20 are perspective views schematically showing an example of a part of the recess 2 formed in the metal part 1. As shown in FIG. 18, the recessed part 2 may be formed in the single side | surface of the metal component 1, and may be formed in both surfaces, as shown in FIG. Further, as shown in FIG. 20, a plurality of wedge-shaped grooves may be formed so as to be orthogonal to each other.

  FIG. 21A is a perspective view schematically showing an example in which a groove is formed in a part of a metal part, and FIG. 21B is a perspective view schematically showing an aspect in which a resin is formed on the metal part in FIG. 21A. Thus, a recess may be formed only in a part of the metal part, and the resin 4 may be formed on the recess.

  The present invention can be applied to metal parts and resin integrated molded products having various uses and shapes, and can be used for various applications such as industrial equipment, automobiles, aircraft equipment, consumer products, and household appliances. It is applicable to typical mechanical parts. For example, a resin-made electronic circuit protective case member having a metal conductive terminal therein, a resin-made cover partially having a metal electromagnetic shield, a heat radiating plate, and the like.

  As described above, according to the present invention, even when subjected to a heat shock, the bonding strength between the metal part and the resin is hardly deteriorated, and the metal part and the resin are bonded relatively easily by the anchor effect. It has been shown that it is possible to provide a metal part-resin joining method and a metal part-resin integral molding product.

  In addition, this invention is not limited to an above-described Example, Various modifications are included. For example, the above-described embodiments have been described in detail for easy understanding of the present invention, and are not necessarily limited to those having all the configurations described. Further, a part of the configuration of one embodiment can be replaced with the configuration of another embodiment, and the configuration of another embodiment can be added to the configuration of one embodiment. Moreover, it is possible to add, delete, and replace other configurations for a part of the configuration of each embodiment.

  DESCRIPTION OF SYMBOLS 1 ... Metal component, 2 ... Recessed part, 3 ... Porous plating film, 4 ... Resin, 5 ... Integrated molding of metal component and resin, 6 ... Base film, 7 ... Overhang part, 8 ... Micropore.

Claims (11)

A metal part-resin joining method that integrates a metal part and resin,
Forming a recess in the surface of the metal part;
Forming a porous plating film having micropores on the surface of the metal part including the recess,
A method of joining a metal part and a resin, wherein the resin is poured into the recesses and the fine holes of the porous plating film, and the metal part and the resin are joined. In the joining method of the metal component and resin of Claim 1,
Forming a base film on the surface of the metal part including the recess,
A method for joining a metal part and a resin, comprising forming the porous plating film on a surface of the metal part on which the base film is formed. In the joining method of the metal component and resin of Claim 1 or 2,
The method for joining a metal part and a resin, wherein the porous plating film has a communication hole that communicates a plurality of the fine holes at the bottom of the porous plating film. In the metal part and resin joining method according to any one of claims 1 to 3,
A method of joining a metal part and a resin, wherein the recess is formed by cutting, plastic working or laser light irradiation. In the joining method of the metal component and resin of Claim 4,
The metal part and resin joining method, wherein the plastic working is press working. In the joining method of the metal component and resin of Claim 5,
On the surface of the metal part, as the concave part, a press groove inclined with respect to a perpendicular to the surface of the metal part is formed by pressing,
A method of joining a metal part and a resin, wherein the press working is performed so as to push in an overhang portion of the press groove. An integrally molded product of metal parts and resin,
A recess formed on the surface of the metal part; a porous plating film having micropores formed on the surface of the metal part including the recess; and the resin formed on the surface of the porous plating film; Have
An integrally molded article of a metal part and a resin, wherein the resin is filled and joined to the concave portion and the micropores of the porous plating film. In the integrally molded product of the metal part and the resin according to claim 7,
An integrally molded product of a metal part and a resin, wherein the resin is bonded to the metal part by an anchor effect by the concave portion and the fine hole. In the integrally molded product of the metal part and the resin according to claim 7 or 8,
A metal part and resin integral molded product, wherein the recess is a groove having a wedge-shaped cross section. In the integrally molded product of the metal part and the resin according to any one of claims 7 to 9,
Furthermore, the metal part and the resin integrally molded product characterized by having a base film between the metal part and the porous plating film. A metal part-resin joining method that integrates a metal part and resin,
Forming a porous plating film having micropores on the surface of the metal part;
A resin filled with a filler having a pore diameter equal to or smaller than the pore size is used as the resin, the resin is poured onto the porous plating film, and the metal component and the resin are joined. Joining method.

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