Method for predicting bonding strength of resin / metal bonded body, and method for manufacturing resin / metal bonded body

Abstract

To provide a method for predicting the bonding strength of a resin / metal bonded body capable of accurately predicting the bonding strength between a resin and metal in the resin / metal bonded body in which the resin and the metal are bonded to each other.SOLUTION: The method for predicting the bonding strength of the resin / metal bonded body includes: a metal compound identification step S01 of identifying metal compounds present on a bonding surface of metal; an interface model formation step S02 of forming an interface model of the metal and a resin and of the metal compound and the resin; a bonding strength calculation step S03 of calculating the bonding strength between the metal and the resin and of the metal compound and the resin by computer simulation; a peak intensity ratio calculation step S04 of calculating a ratio ICmin / ICmax of a minimum peak intensity ICmin of a metal or a metal compound with the lowest bonding strength to a maximum peak intensity ICmax of a metal or a metal compound with the highest bonding strength; and a bonding strength evaluation step S05 of evaluating the bonding strength between the resin and the metal using the peak intensity ratio ICmin / ICmax as an evaluation criterion.SELECTED DRAWING: Figure 2

Description

Technical Field

[0001] The present invention relates to a method for predicting the bonding strength of a resin / metal bonded body for predicting the bonding strength between a resin and a metal in a resin / metal bonded body in which the resin and the metal are bonded, and a method for manufacturing a resin / metal bonded body.

Background Art

[0002] For example, a circuit board having excellent insulation is bonded to a semiconductor element. However, as the semiconductor element is miniaturized and its performance is improved, a large amount of heat is generated, which may cause damage to the semiconductor element. Therefore, it is necessary to also have excellent high thermal conductivity. As a circuit board having high thermal conductivity and excellent insulation, for example, a metal / ceramics composite component in which ceramics such as AlN is sandwiched between metals having excellent conductivity is used.

[0003] When this metal / ceramics composite component is manufactured using a metal having excellent conductivity such as Cu, since the expansion coefficient of Cu is large with respect to ceramics, there is a problem that the ceramics cracks when the high temperature and low temperature states are repeated. Therefore, in Patent Document 1, an insulating heat dissipation substrate using high-purity Al having high mechanical strength has been proposed. This insulating heat dissipation substrate is used for the insulating heat dissipation substrate of the power module parts of hybrid vehicles and the inverter of industrial equipment due to its high reliability and high thermal conductivity. In addition, its application to the fields of electric vehicles, fuel cell vehicles, and trains / railways is also being promoted with keywords such as thermal cycle, heat cycle, and low thermal resistance.

[0004] However, with the spread and development of the above electric vehicles and electric railways, higher-performance semiconductor elements are being manufactured, and the number of scenarios where they are used in high-temperature and high-humidity environments is increasing. In conventional circuit boards, the problem of thermal stress generated with the temperature rise and temperature gradient has become apparent, and there has been a problem that the parts are warped. These problems must be overcome in order to ensure the reliability of the insulating heat dissipation circuit board. To solve this, the demand for a metal / resin bonded body in which the insulating layer is replaced with resin instead of ceramics is increasing.

[0005] In this metal / resin bonded body, it is required to improve the adhesive strength between the metal and the resin, and a uniaxial tensile shear test of the metal / resin bonded body is performed as its performance evaluation. In addition, with the increase in the speed of computers and the improvement of convenience, in the field of material development, a method of analyzing various physical properties and interfacial states at the molecular level using software developed based on the theory of computational science and performing physical property evaluation and behavior analysis of the target material has begun to be utilized.

[0006] Here, for example, in Patent Documents 1 and 2, in order to improve the bonding strength between the metal and the resin, after forming fine irregularities on the surface of the metal member by chemical treatment, machining, or laser processing, the resin layer is joined by an injection molding method to produce a metal / resin bonded body. In addition, in Patent Document 3, a technique has been proposed in which the bonding strength between a metal and a resin material is greatly improved by using a surface treatment agent containing a triazine compound having a specific structure.

[0007] Furthermore, in Patent Document 4, a method of calculating the interfacial binding energy between the metal surface and the organic film from molecular dynamics calculations has been proposed. In addition, in Patent Document 5, a method of predicting the bonding strength between a bonding strength improver added to the resin and the metal surface for improving the bonding strength by quantum chemical calculations and a new bonding strength improver calculated from this method have been proposed.

Prior Art Documents

Patent Documents

[0008]

Patent Document 1

Patent Document 2

Patent Document 3

Patent Document 4

Patent Document 5

Summary of the Invention

Problems to be Solved by the Invention

[0009] By the way, as disclosed in Patent Documents 1 and 2, when fine irregularities are formed on the bonding interface, these fine irregularities are easily broken by a minute force. When this part is broken, there is a problem that the anchor effect is not sufficiently exhibited and the resin and the metal are easily peeled off. Further, as disclosed in Patent Document 3, when a surface treatment agent is used, there is a problem in the heat resistance of the surface treatment agent, and it is difficult to apply it to an insulating heat dissipation circuit board or the like used in a high-temperature environment.

[0010] Further, in Patent Document 4, although the interfacial bonding energy between the metal surface and the organic film is obtained, no specific method for improving the bonding strength between the metal surface and the organic film from this interfacial bonding energy is described. Furthermore, in Patent Document 5, a method for predicting the bonding strength between a bonding strength improver added to a resin for improving the bonding strength and a metal surface by quantum chemical calculation and a new bonding strength improver calculated from this method are proposed. However, when there is a problem in the heat resistance of this bonding strength improver, it is difficult to apply it to an insulating heat dissipation circuit board or the like used in a high-temperature environment.

[0011] This invention has been made in view of the above circumstances, and in a resin / metal bonded body in which a resin and a metal are bonded, a method for predicting the bonding strength of the resin / metal bonded body capable of accurately predicting the bonding strength between the resin and the metal, and a manufacturing method of a resin / metal bonded body using this method for predicting the bonding strength of the resin / metal bonded body.

Means for Solving the Problems

[0012] In order to solve the above problems, as a result of intensive studies by the present inventors, metals and metal compounds present on the bonding surface of metals were identified, the bonding strength between these metals and metal compounds and the resin was calculated, and metals and metal compounds that greatly affect the bonding strength between the metal and the resin were identified. By calculating the abundance ratios of these, the inventors obtained the knowledge that the bonding strength of the resin / metal bonded body can be predicted. And from this prediction result, by setting the bonding conditions so as to appropriately control the abundance ratios of the metals and metal compounds present on the bonding surface of the metal, a resin / metal bonded body excellent in bonding strength can be produced without using minute irregularities or a surface treatment agent.

[0013] The present invention has been made based on the above findings. The method for predicting the bonding strength of a resin / metal bonded body according to the first aspect of the present invention is a method for predicting the bonding strength between the resin and the metal in a resin / metal bonded body in which the resin and the metal are bonded, including: a metal compound specifying step of specifying the metal compound present on the bonding surface of the metal by Fourier transform infrared spectroscopy (FT-IR); an interface model forming step of forming an interface model between the metal and the resin and an interface model between the metal compound and the resin; a bonding strength calculating step of calculating, by computer simulation, the bonding strength between the metal and the resin and the bonding strength between the metal compound and the resin, and specifying the metal or metal compound having the highest bonding strength and the metal or metal compound having the lowest bonding strength among the calculated bonding strength between the metal and the resin and the bonding strength between the metal compound and the resin; a peak strength ratio calculating step of calculating the ratio I Cmax of the maximum peak strength I of the metal or metal compound having the lowest bonding strength to the maximum peak strength I of the metal or metal compound having the highest bonding strength when analyzing the bonding surface of the metal by Fourier transform infrared spectroscopy (FT-IR); and a bonding strength evaluating step of evaluating the bonding strength between the resin and the metal using the peak strength ratio I Cmin / I Cmin as an evaluation criterion. Cmax This is characterized by comprising the above steps. Cmin / I Cmax

[0014] According to the method for predicting the bonding strength of the resin / metal bonded body of the first aspect of the present invention, by calculating the metal compound present on the bonding surface of the metal and the bonding strength between the metal and the resin by computer simulation, the bonding strength in any combination of resin and metal or metal compound can be predicted without using an experimental method, factors that greatly affect the bonding strength at the resin-metal interface can be identified, and the bonding strength between the metal and the resin can be accurately predicted based on the abundance ratio on the bonding surface of the metal.

[0015] The method for predicting the bonding strength of the resin / metal bonded body of the second aspect of the present invention is the method for predicting the bonding strength of the resin / metal bonded body of the first aspect, wherein the interface model forming step includes a step of creating a monomer model of the resin and a surface model of the metal, and a global search using molecular dynamics calculation and a structural optimization calculation using the density functional method are performed on a composite model in which the monomer model is temporarily arranged on the metal surface model to create a resin-metal interface model with high reproducibility of the adsorption structure of the resin on the metal surface. As the bonding strength calculation step, a step of calculating the potential energy using the density functional method for the resin-metal interface model when the monomer model of the resin and the metal surface model are separated at regular intervals in the peeling direction of the resin-metal interface model, and a step of calculating the bonding strength of the resin-metal interface model from the relationship between the potential energy and the separation distance of the resin from the metal surface.

[0016] According to the method for predicting the bonding strength of the resin / metal bonded body of the second aspect of the present invention, since the interface model forming step and the bonding strength calculation step are configured as described above, by estimating the type of metal or metal compound present on the bonding surface of the metal, a stable surface of the metal compound or metal simple substance in each chemical state can be obtained, and by performing a structural optimization calculation using the density functional method, an appropriate metal surface model can be constructed, and further, the bonding strength between the metal and the resin can be predicted with high accuracy.

[0017] The method for manufacturing a resin / metal bonded body according to the third aspect of the present invention is a method for manufacturing a resin / metal bonded body in which a resin and a metal are bonded, and using the method for predicting the bonding strength of the resin / metal bonded body according to Aspect 1 or Aspect 2, the peak strength ratio I Cmin / I Cmax is determined for the state of the bonding surface of the metal when it is below a predetermined value, and the bonding conditions are adjusted so that the state of the bonding surface of the metal is such that the peak strength ratio I Cmin / I Cmax is below a predetermined value. This is characterized by the above.

[0018] According to the method for predicting the bonding strength of the resin / metal bonded body according to the third aspect of the present invention, using the method for predicting the bonding strength of the resin / metal bonded body according to Aspect 1 or Aspect 2, the peak strength ratio I Cmin / I Cmax is determined for the state of the bonding surface of the metal when it is below a predetermined value, and the bonding conditions are adjusted so that the state of the bonding surface of the metal is such that the peak strength ratio I Cmin / I Cmax is below a predetermined value. Since it is configured in this way, by adjusting the bonding conditions to appropriately control the state of the bonding surface of the metal, without adding a bonding strength improver to the resin, performing microfabrication on the metal surface, or performing surface treatment with chemicals, a resin / metal bonded body having excellent bonding strength between the resin and the metal can be manufactured.

Effects of the Invention

[0019] According to the present invention, in a resin / metal bonded body in which a resin and a metal are bonded, it is possible to provide a method for predicting the bonding strength of the resin / metal bonded body that can accurately predict the bonding strength between the resin and the metal, and a method for manufacturing a resin / metal bonded body using this method for predicting the bonding strength of the resin / metal bonded body.

Brief Description of the Drawings

[0020]

Figure 1

Figure 2

Figure 3

Figure 4

Figure 5

Embodiments for Carrying Out the Invention

[0021] Hereinafter, a method for predicting the bonding strength of a resin / metal bonded body, which is an embodiment of the present invention, and a method for manufacturing a resin / metal bonded body will be described with reference to the accompanying drawings. As shown in FIG. 1, the resin / metal bonded body according to this embodiment is an insulating heat dissipation substrate 10 formed by bonding an insulating resin layer 12, which is a resin member, a circuit layer 13, which is a metal member, and a metal substrate 11.

[0022] The metal substrate 11 has a function of improving heat dissipation characteristics by spreading the heat generated in electronic components such as semiconductor elements mounted on the insulating heat dissipation substrate 10 in the plane direction. For this reason, the metal substrate 11 is made of a metal having excellent thermal conductivity, such as copper or a copper alloy, aluminum or an aluminum alloy.

[0023] The circuit layer 13 has a circuit pattern formed thereon, and one surface (the upper surface in FIG. 1) thereof is a mounting surface on which electronic components such as semiconductor elements are mounted. Therefore, this circuit layer 13 is made of a metal having excellent electrical conductivity, such as copper or a copper alloy, aluminum or an aluminum alloy.

[0024] The insulating resin layer 12 prevents electrical connection between the circuit layer 13 and the metal substrate 11 and is made of a resin having insulating properties. In this embodiment, in order to ensure the strength of the insulating resin layer 12 and the thermal conductivity, a thermosetting resin containing a filler may be used. Here, as the filler, for example, alumina, boron nitride, aluminum nitride, etc. can be used. Further, as the thermosetting resin, an epoxy resin, a polyimide resin, etc. can be used.

[0025] Here, in this embodiment, the insulating heat dissipation substrate 10 is formed such that the metal substrate 11 is made of copper or a copper alloy and the insulating resin layer 12 is made of an epoxy resin, and the bonding strength between the metal substrate 11 (copper) and the insulating resin layer 12 (resin) is predicted. More specifically, it is assumed that the metal substrate 11 is composed of a copper plate of oxygen-free copper with a purity of 99.96 mass% or more. As the insulating resin layer 12, an epoxy resin containing 75 mass% or more of an epoxy component having two or more epoxy groups in one molecule as a binder is used.

[0026] And the bonding strength prediction method of the resin / metal joint in this embodiment, as shown in the flowchart of FIG. 2, a metal compound identification step S01 for identifying a metal compound present on the bonding surface of the metal by Fourier transform infrared spectroscopy (FT-IR), an interface model formation step S02 for forming an interface model between the metal and the resin and an interface model between the metal compound and the resin, and by computer simulation, the bonding strength between the metal and the resin and the bonding strength between the metal compound and the resin are calculated, and among the calculated bonding strength between the metal and the resin and the bonding strength between the metal compound and the resin, the metal or metal compound with the highest bonding strength and the metal or metal compound with the lowest bonding strength are identified in a bonding strength calculation step S03, and the maximum peak intensity I of the metal or metal compound with the highest bonding strength when analyzing the bonding surface of the metal by Fourier transform infrared spectroscopy (FT-IR) Cmax with respect to the maximum peak intensity I of the metal or metal compound with the lowest bonding strength Cmin and the ratio I Cmin / I Cmax is calculated in a peak intensity ratio calculation step S04, and the peak intensity ratio I Cmin / I CmaxAs an evaluation criterion, it includes a joint strength evaluation step S05 for evaluating the joint strength between the resin and the metal.

[0027] (Metal compound identification step S01) For Fourier transform infrared spectroscopy (FT-IR) to examine the types of surface products present on the metal surface, infrared light with an energy distribution represented by B(ν) in a Michelson interferometer is split into two optical paths by a beam splitter. One path is reflected by a fixed mirror and the other by a movable mirror, and then recombined and sent to a detector. By doing so, an interference pattern is obtained that reflects the absorption (reflection) pattern of the characteristic vibration (reference vibration) frequencies due to the vibrational and rotational motions of the molecules constituting the sample placed in the optical path. By performing a Fourier transform on this interference pattern, the energy distribution of infrared light, that is, the spectrum, which reflects the absorption (reflection) pattern of the characteristic vibration (reference vibration) frequencies due to the vibrational and rotational motions of the molecules constituting the sample, is measured. By analyzing the wavenumber of the peak positions and the absorption (reflection) pattern present in this absorbed (reflected) spectrum, the substances contained in the sample are analyzed. The sample can be placed either before or after the Michelson interferometer. Generally, as the light for irradiation, infrared light in the wavelength range corresponding to 4000 cm -1 to 400 cm -1 is used.

[0028] Here, in this embodiment, the metal is copper (oxygen-free copper), and it was confirmed by Fourier transform infrared spectroscopy (FT-IR) that on the surface (bonding surface) of this metal, phases of CuO, Cu2O, and basic copper carbonate (Malachite: Cu2(CO3)(OH)2) are mixed. Note that the infrared absorption peaks of metal oxides formed on the metal surface are in the range of 1400 cm -1 to 400 cm -1 where there is at least one infrared absorption peak of metal and oxygen for each compound, and the infrared absorption peak of basic copper carbonate formed on the metal surface is at 1900 cm -1 to 860 cm -1 are present. Therefore, Fourier transform infrared spectroscopy (FT-IR) is in the range of 1900 cm -1 to 400 cm -1It is desirable to carry out the process within the specified range and use polystyrene for wavelength calibration.

[0029] (Interface model formation step S02) As a step of creating an interface model between a metal or a metal compound present on a metal surface and a resin for computer simulation, for the creation of the resin model, monomers, which are the minimum constituent elements of the polymer contained in the resin, were adopted as the resin model in the computer simulation, and the monomer model of the resin was constructed by performing a structure optimization calculation using the density functional method. For the creation of the metal surface model, from the chemical state of the metal surface analyzed by Fourier transform infrared spectroscopy (FT-IR), the types of metals or metal compounds present on the metal surface were estimated, and the stable surfaces of the metal compounds or the metal alone in each chemical state were obtained. By performing a structure optimization calculation using the density functional method, an appropriate metal surface model was constructed. At this time, the construction of the metal surface model was carried out such that the number of atomic model layers was 3 or more in the stacking direction of the atomic models. By setting it to 3 or more layers, a simulation that accurately reproduces the characteristics of the actual metal surface can be performed.

[0030] It is desirable to set the size of the cell in the XY direction of the metal surface model to about 1 to 3 times, preferably about 1 to 2 times, the size of the cell in the XY direction of the partial structure model of the resin to be combined. If it is too large, the calculation will take a long time, which is not preferable. Also, the size in the Z direction that defines the vacuum region of the cell needs to be a distance that allows the monomer model of the resin to move sufficiently from the metal surface. In addition to the original sizes of the metal surface model and the monomer model of the resin, a setting of about 10 to 30 Å, preferably about 15 to 25 Å, is required. If the distance of the vacuum region is small, the metal surface model and the monomer model of the resin will be affected by the interaction across the periodic boundary, which is not preferable. Taking a value larger than 30 Å will not affect the result of the required computer simulation, but the calculation will take a long time, which is not preferable.

[0031] For a composite model in which a monomer model is temporarily placed on a metal surface model, perform a global search using molecular dynamics calculations and a structural optimization calculation using the density functional method to create a resin-metal interface model with high reproducibility of the adsorption structure of the resin on the metal surface. At this time, when the composite model falls into a locally stable structure, during the global search simulation, it is necessary to escape from that state, and to prevent the molecular structure of the resin monomer model from being broken by high temperature. Therefore, the temperature setting in the molecular dynamics simulation needs to be set to about 400K to 1500K, preferably about 500K to 800K.

[0032] In this embodiment, for example, as shown in FIG. 3, the stable surface was selected for the crystal models of Cu, CuO, Cu2O, and basic copper carbonate (Malachite: Cu2(CO3)(OH)2) using "QuantumATK". For Cu, CuO, and Cu2O, a model of the surface structure with Miller index (111) was selected, and for basic copper carbonate (Malachite: Cu2(CO3)(OH)2), a model of the surface structure with Miller index (201) was selected. In the Z direction, the number of atomic model layers was set to 3, and the copper surface model was constructed. The size of the cell of each copper surface model was adjusted according to the size of the epoxy resin partial structure model in the XY direction, and the structural optimization calculation of the surface models of Cu, CuO, Cu2O, and basic copper carbonate (Malachite: Cu2(CO3)(OH)2) was performed using the software "Vienna Ab initio Simulation Package" to construct the most stable structure. In this way, a composite model was formed by combining the monomer model of the epoxy resin, the surface models of Cu, CuO, Cu2O, and basic copper carbonate (Malachite: Cu2(CO3)(OH)2), and the monomer model of the resin, respectively.

[0033] (Bond strength calculation step S03) As a step of calculating the bonding strength of the interface between a metal or a metal compound existing on a metal surface and a resin by computer simulation, as shown in FIG. 4, by calculating the potential energy for a resin-metal interface model when a monomer model of the resin and a metal surface model are separated at regular intervals in the peeling direction of the resin-metal interface model using the density functional method, a simulation that mimics a uniaxial tensile test of an actual resin-metal interface becomes possible. At this time, by changing the separation direction of the resin partial structure model with respect to the metal surface model, simulations that mimic shear tests and peel tests can be performed.

[0034] When separating the monomer model of the resin from the metal surface model, a certain displacement amount needs to be determined as an appropriate value according to the purpose of the simulation, but it is desirable to perform the separation at about 0.1 Å to 0.5 Å. By performing the simulation with this displacement amount, accurate numerical values of the minimum and maximum values of the potential energy can be obtained from the obtained adhesion energy curve, so that the bonding strength of the appropriate resin and metal can be calculated with a small number of calculation times. The relationship between the potential energy E and the separation distance of the resin from the metal surface is fitted with the Morse potential function of the following formula (I) to obtain the coefficients D and a. D is the depth of the potential, and a is the coefficient of the width of the potential. By performing fitting with the Morse potential function, comparison of the potential energy curves of each composite model calculated by computer simulation can be made with a unified index.

Equation

[0035] As shown in the following formula (II), the maximum value of the gradient of the obtained adhesion energy curve dE / dr is calculated as the bonding strength F ad Since the adhesion energy curve is plotted against the displacement amount from the metal surface model, the obtained bonding strength corresponds to the tensile bonding strength.

Equation

[0036] As elements of computer simulation, the density functional theory (DFT) is used for the structural optimization calculation to obtain the most stable structures of the monomer model of the resin and multiple metal surface models with different oxidation states. The molecular dynamics method and the density functional theory (DFT) are used to construct the most stable structure of the composite model of the resin and the metal. The density functional theory (DFT) is used to calculate the potential energy of the composite model. The density functional theory (DFT) is preferably used considering the balance between calculation time and accuracy. Examples of the basis include plane wave basis, atomic orbital basis, real space basis, atomic localization basis, etc., and the plane wave basis is preferred. Examples of the functional include PW91, PBE, RPBE, B3LYP, ωB97XD, M06-2x, etc., and PBE is preferred for dealing with the interface between the resin and the metal. The potential energy E DFT obtained by the density functional theory (DFT) is subtracted from the minimum value of the potential energy E DFT as shown in the following formula (III) to calculate the adhesion energy E ad between the metal surface model and the monomer model of the resin.

Equation

[0037] In performing a global search for the adsorption structure of the monomer model of the resin temporarily arranged on the metal surface model using the molecular dynamics method, first, the bonds of each atom are set, and the non-bonding potential, bond stretching potential, angle potential, bond dihedral angle potential, and out-of-plane angle potential are set using a force field. By evolving in time by the Verlet method, candidate structures necessary for constructing a composite model combining the resin partial structure model and the metal surface model are calculated. Examples of the force field include COMPASS, CHARMM, Dreiding, OPLS, GROMACS, Amber, CVFF, etc., and COMPASS is preferred considering the balance between accuracy and corresponding elements. The potential energy E MD by the molecular dynamics method actually conforms to and is preferably shown by the following formula (IV). In the formula, E vdwlis the non-bonded van der Waals energy, E coul is the electrostatic interaction energy, E long is the long-range interaction energy, E bond is the bond stretching energy acting between two bonded atoms, E angle is the bond angle energy, E dihed is the torsional angle energy, E imp represents the out-of-plane angle energy of the bond.

Number

[0038] In this embodiment, for the composite model obtained by combining the monomer model of the epoxy resin constructed in the interface model formation step S02 with the surface models of Cu, CuO, Cu2O, and basic copper carbonate (Malachite: Cu2(CO3)(OH)2), fitting to the potential energy calculated by the density functional theory (DFT) was performed using the above formula (I), and the maximum value of the slope was calculated according to the above formula (II) for the adhesion energy curve obtained by fitting. As shown in Table 1 below, the maximum bonding strength of the copper / epoxy resin composite model was calculated. As a result, it was calculated that the combination of basic copper carbonate (Malachite: Cu2(CO3)(OH)2) and epoxy resin had the lowest bonding strength, and the combination of Cu2O and epoxy resin had the highest bonding strength. In addition, when the above molecular dynamics simulation was performed on the surface models of Cu, CuO, and Cu2O to calculate the formation process of basic copper carbonate (Malachite: Cu2(CO3)(OH)2), it was found that basic copper carbonate (Malachite: Cu2(CO3)(OH)2) was formed on the metal surface due to the presence of Cu2O on the metal (copper) surface.

[0039]

Table 1

[0040] (Peak intensity ratio calculation step S04) By analyzing the results of Fourier transform infrared spectroscopy (FT-IR) on the metal surface, the maximum peak intensity I of the metal or metal compound with the highest bonding strength Cmax to the maximum peak intensity I of the metal or metal compound with the lowest bonding strength Cmin and the ratio I Cmin / I Cmax is calculated. It is determined to be effective to utilize the absorption bands (I M2C03·MOH , I MaOb_ ) obtained by Fourier transform infrared spectroscopy (FT-IR). That is, the wave number at which the peak of the infrared absorption spectrum of the target metal surface product appears is obtained from the absorption band, and the baseline (I M2C03·MOH base , I MaOb base ) connecting the bottoms of the valleys of the spectra on both sides is set, and by using the ratio of the peaks of the infrared absorption spectra of the target metal surface products as shown by the following formula (V) based on the baseline, the abundance ratio X of the products on the metal surface can be analyzed.

Equation

[0041] In this embodiment, as the abundance ratio of malachite (Cu2(CO3)(OH)2) with the lowest bonding strength and Cu2O with the highest bonding strength, for malachite (Cu2(CO3)(OH)2), the peak intensity at 1440 cm -1 is taken as I Cmin , and for Cu2O, the peak intensity at 650 cm -1 is taken as I Cmax , and the peak intensity ratio I Cmin / I Cmax is calculated. 1440 cm -1 and 650 cm -1 With the peaks of the infrared absorption spectra appearing in between, a baseline connecting the bottoms of the valleys of the spectra on both sides is set, and based on this baseline, 1440 cm -1 and 650 cm -1The ratio of the absorption peaks can be used to analyze the abundance ratio of basic copper carbonate (Malachite: Cu2(CO3)(OH)2) / Cu2O on the metal surface with copper or a copper alloy as the base material. The 1440 cm -1 and 650 cm -1 infrared absorption peaks can be regarded as the infrared absorption peaks for the purpose of use in the present invention as long as they can be regarded as the infrared absorption peaks of the 1440 cm -1 and the 650 cm -1 respectively. Similarly, the same applies to the valleys of the spectra on both sides sandwiching the peak, and there is no limitation as long as the method of the present embodiment can be substantially applied to the wavenumbers near the absorption peak.

[0042] (Bonding strength evaluation step S05) Then, using the peak intensity ratio I Cmin / I Cmax obtained as described above as an evaluation criterion, the bonding strength is predicted. In the present embodiment, in the abundance ratio of basic copper carbonate (Malachite: Cu2(CO3)(OH)2) and Cu2O calculated from the infrared absorption peaks of 1440 cm -1 and 650 cm -1 , using a test piece as shown in FIG. 5, a tensile shear adhesion strength test in a uniaxial tensile shear test defined by JIS K6850:1999 was conducted. From this test result, it was confirmed that sufficient bonding strength can be obtained if the peak intensity ratio I Cmin / I Cmax is 53% or less, and the reference value of the peak intensity ratio I Cmin / I Cmax was set to 53%.

[0043] And in the method for manufacturing a resin / metal bonded body according to the present embodiment, using the method for predicting the bonding strength of the resin / metal bonded body described above, the bonding conditions are adjusted so that the state of the bonding surface of the metal is such that the peak intensity ratio I Cmin / I Cmax is below a predetermined value. In this embodiment, the bonding conditions are set so that the surface concentration of Cu2O with the highest bonding strength is high and the surface concentration of basic copper carbonate with the lowest bonding strength is low on the surface of the metal (copper).

[0044] Specific methods include the following. (1) The bonding process of the resin and the metal is carried out under an inert gas. At this time, it is preferable to select an appropriate inert gas such as nitrogen or argon. (2) Since the formation of basic carbonate proceeds due to the presence of water, bonding is carried out under low-humidity air. This low humidity is desirably 25% or less in relative humidity, and most desirably 10% or less.

[0045] By setting the bonding conditions in this way, a resin / metal bonded body excellent in the bonding strength between the resin and the metal can be manufactured without adding a bonding strength improver to the resin, performing fine processing on the metal surface, or surface treatment with chemicals.

[0046] According to the bonding strength prediction method of the resin / metal bonded body of this embodiment configured as described above, by calculating the metal compound existing on the bonding surface of the metal and the bonding strength between the metal and the resin by computer simulation, the bonding strength of any combination of resin and metal or metal compound can be predicted without using an experimental method, the factors that greatly affect the bonding strength at the resin-metal interface can be specified, and the bonding strength between the metal and the resin can be accurately predicted based on the abundance ratio at the bonding surface of the metal.

[0047] In this embodiment, the interface model formation step S02 includes a step of creating a monomer model of the resin and a surface model of the metal, and a global search using molecular dynamics calculation and a structural optimization calculation using the density functional method for a composite model in which the monomer model is temporarily placed on the metal surface model to create a resin-metal interface model with high reproducibility of the adsorption structure of the resin on the metal surface. As the bonding strength calculation step S03, a step of calculating the potential energy for the resin-metal interface model when the monomer model of the resin and the metal surface model are separated at regular intervals in the peeling direction of the resin-metal interface model using the density functional method, and a step of calculating the bonding strength of the resin-metal interface model from the relationship between the potential energy and the separation distance of the resin from the metal surface. When configured to include these steps, by estimating the types of metals or metal compounds present on the bonding surface of the metal, obtaining the stable surfaces of metal compounds or elemental metals in each chemical state, and performing a structural optimization calculation using the density functional method, an appropriate metal surface model can be constructed, and furthermore, the bonding strength between the metal and the resin can be predicted with high accuracy.

[0048] According to the method for manufacturing a resin / metal bonded body according to this embodiment, using the method for predicting the bonding strength of the resin / metal bonded body according to this embodiment, the state of the bonding surface of the metal where the peak intensity ratio I Cmin / I Cmax is equal to or less than a predetermined value is obtained, and the bonding conditions are adjusted so that the state of the bonding surface of the metal where the peak intensity ratio I Cmin / I Cmax is equal to or less than a predetermined value. Therefore, by adjusting the bonding conditions and appropriately controlling the state of the bonding surface of the metal, a resin / metal bonded body excellent in the bonding strength between the resin and the metal can be manufactured without adding a bonding strength improver to the resin, performing microfabrication on the metal surface, or performing surface treatment with chemicals.

[0049] As described above, the embodiments of the present invention have been described, but the present invention is not limited thereto, and can be appropriately modified without departing from the technical idea of the invention. In this embodiment, the metal is described as copper and the resin as epoxy resin, but it is not limited thereto, and there is no particular limitation on the combination of the metal and the resin.

Explanation of Signs

[0050] S01 Metal compound identification step S02 Interface model formation step S03 Bond strength calculation step S04 Peak intensity ratio calculation step S05 Bond strength evaluation step

Claims

1. A method for predicting the bonding strength of a resin / metal bonded body, which predicts the bonding strength between the resin and the metal in the resin / metal bonded body where the resin and the metal are bonded, comprising: a metal compound identification step of identifying the metal compound present on the bonding surface of the metal by Fourier transform infrared spectroscopy (FT-IR); an interface model formation step of forming an interface model between the metal and the resin and an interface model between the metal compound and the resin; a bonding strength calculation step of calculating the bonding strength between the metal and the resin and the bonding strength between the metal compound and the resin by computer simulation, and identifying the metal or metal compound with the highest bonding strength and the metal or metal compound with the lowest bonding strength among the calculated bonding strength between the metal and the resin and the bonding strength between the metal compound and the resin; The maximum peak intensity I of the metal or metal compound with the highest bonding strength when analyzing the bonding surface of the metal by Fourier transform infrared spectroscopy (FT-IR) Ｃｍａｘ to the maximum peak intensity I of the metal or metal compound with the lowest bonding strength Ｃｍｉｎ and the ratio I Ｃｍｉｎ / I Ｃｍａｘ A peak intensity ratio calculation step for calculating; Peak intensity ratio I Ｃｍｉｎ / I Ｃｍａｘ Using the peak intensity ratio I Ｃｍｉｎ / I Ｃｍａｘ as an evaluation criterion, a joint strength evaluation step for evaluating the joint strength between the resin and the metal is performed. A method for predicting the bonding strength of a resin / metal bonded body, characterized by comprising the above steps.

2. The interface model formation step includes a step of creating a monomer model of the resin and a surface model of the metal, and a global search using molecular dynamics calculation and a structural optimization calculation using the density functional method for a composite model in which the monomer model is temporarily placed on the metal surface model, to create a resin-metal interface model with high reproducibility of the adsorption structure of the resin on the metal surface. As the bonding strength calculation step, a step of calculating the potential energy using the density functional method for the resin-metal interface model when the monomer model of the resin and the metal surface model are separated at regular intervals in the peeling direction of the resin-metal interface model, and a step of calculating the bonding strength of the resin-metal interface model from the relationship between the potential energy and the separation distance of the resin from the metal surface. The method for predicting the bonding strength of a resin / metal bonded body according to Claim 1, characterized by comprising the above steps.

3. A method for manufacturing a resin / metal bonded body in which a resin and a metal are bonded, comprising: Using the method for predicting the bonding strength of the resin / metal bonded body according to claim 1 or claim 2, the state of the bonding surface of the metal when the peak strength ratio I Ｃｍｉｎ / I Ｃｍａｘ becomes equal to or less than a predetermined value is determined, The peak intensity ratio I Ｃｍｉｎ / I Ｃｍａｘ A method for manufacturing a resin / metal bonded body, characterized in that the bonding conditions are adjusted so that the state of the bonding surface of the metal becomes a state where the ratio is equal to or less than a predetermined value.

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