TWI658766B - Corrosion-resistant electronic substrate and coating composition used therefor - Google Patents

Abstract

The present invention provides a corrosion-resistant electronic substrate having improved corrosion resistance by shielding corrosive gases such as hydrogen sulfide gas, and a coating composition for corrosive gas shielding for forming a coating layer of the corrosion-resistant electronic substrate. A corrosion-resistant electronic substrate is formed by forming a first coating layer on the whole or a part of a surface of a substrate body after constructing an electronic component, and then forming a second coating layer, and including the electronic component by the coating layer. The conductive metal part of the electrode is coated. The DMA after curing of the first coating layer at -20 ° C to 0 ° C and tanδ at 10 Hz is 0.10 or more, and the second coating layer is cured after hardening. In the distribution of the measured value of the free volume radius obtained by the positron lifetime extinction method, the distribution area of 0.32 nm or less (excluding 0) is set to 70% or more.

Description

Corrosion-resistant electronic substrate and coating composition used therefor

The present invention relates to an electronic substrate in which a coating composition is applied to a substrate body to improve corrosion resistance, and a coating composition for the electronic substrate.

In recent years, electronic substrates used in power supplies, temperature regulators, timers, and programmable logic controllers (PLCs) have been used in environments that require environmental resistance such as condensation prevention and corrosion-resistant gas resistance. The situation has increased. Therefore, in order to obtain such environmental resistance, a coating layer is formed on the surface of the substrate body in the electronic substrate by a coating composition that can block water vapor or corrosive gas, thereby improving the environmental resistance.

Conventionally, as such a coating layer, a multilayer barrier coating including an organic layer and a barrier layer alternately on a flexible substrate has been known. This multilayer barrier layer prevents the intrusion of liquids and gases, and is soft and prevents the occurrence of cracks and the like.

As a method for realizing the multilayer barrier coating, an inorganic material is formed to a thickness of 50 Å to 500 Å by evaporation to form a barrier layer. The organic layer is a polymerizable crosslinkable monomer, and is formed to a thickness of 0.1 μm to 1.0 μm by evaporation. In addition, in order to improve the adhesion between the organic layer and the barrier layer, the surface of the non-base layer is subjected to a plasma treatment before the organic layer is deposited by evaporation.

Such a multilayer barrier coating can achieve structural stress relaxation, and can improve crack resistance and flexibility (for example, refer to Patent Document 1). [Prior Art Literature] [Patent Literature]

[Patent Document 1] Japanese Patent Publication No. 2005-528250

[Problems to be Solved by the Invention] However, since the above-mentioned multilayer barrier coating has an organic layer or a barrier layer deposited on an electronic substrate on which a plurality of electronic components are mounted, there is a concern that the electronic components may be damaged.

In addition, flux residues are generated by using a flux during soldering. Therefore, when an organic layer or a barrier layer is applied to an electronic substrate on which the flux residues are generated, the electronic substrates are repeatedly applied. Warm heat shock or cold heat shock generates cracks starting from the flux residue, and the stress caused by the cracks is also propagated to the organic layers or barrier layers, whereby the multilayer barrier layer is damaged by cracks and the like. In this case, a gas component or a liquid component immerses into the crack along the crack of the organic layer or the barrier layer, thereby corroding the electronic substrate, and causing defects such as poor conduction or short circuit. This situation does not improve even if the overlap of the organic layer and the barrier layer is increased.

The present invention has been made in view of the above-mentioned actual situation, and an object thereof is to provide a corrosion-resistant electron that can shield a corrosive gas and improve the corrosion resistance even in a corrosive gas environment or an environment where warm or cold shock is repeatedly applied A coating composition for a substrate and a coating layer for forming the corrosion-resistant electronic substrate.

[Means for Solving the Problem] The corrosion-resistant electronic substrate of the present invention for solving the above-mentioned problems is an electronic substrate that is formed after the first coating layer is formed on the whole or a part of the surface of the substrate body after the electronic components are constructed, A second coating layer is formed, and the conductive metal part including the electrode of the electronic component is covered with the first coating layer and the second coating layer, and the first coating layer is hardened. The dynamic mechanical analyzer (DMA) after the tan δ at -20 ° C to 0 ° C and 10 Hz is 0.10 or more, and the second coating layer is obtained by a positron lifetime extinction method after hardening. In the distribution of the measured value of the free volume radius, the distribution area of 0.32 nm or less (excluding 0) is set to 70% or more.

In the corrosion-resistant electronic substrate, the first coating layer and the second coating layer may be integrated through an interface thereof.

In the corrosion-resistant electronic substrate, the first coating layer may be selected from the group consisting of styrene-based rubber, urethane-based rubber, silicone-based rubber, fluorine-based rubber, olefin-based elastomer, Any one or more of a styrene-based elastomer and a fluorine-based elastomer.

In the corrosion-resistant electronic substrate, the second coating layer may be selected from acrylic resin, polyester resin, polyurethane resin, silicone resin, fluororesin, and epoxy resin. More than one.

In the corrosion-resistant electronic substrate, the thickness of the first coating layer may be 10 μm to 500 μm, and the thickness of the second coating layer may be 5 μm to 200 μm.

The coating composition of the present invention for solving the problem is a coating composition for forming the first coating layer in the corrosion-resistant electronic substrate, and the coating composition includes: The resin composition containing tan δ at −20 ° C. to 0 ° C. and 10 Hz of the cured DMA of the first coating layer is 0.10 or more, and a solvent thereof.

The coating composition of the present invention for solving the problem is a coating composition for forming the second coating layer in the corrosion-resistant electronic substrate, and the coating composition includes: Resin composition having a distribution area of 0.32 nm or less (excluding 0) in the distribution of the measured value of the free volume radius obtained by the positron lifetime extinction method after hardening of the second coating layer is 70% or more, and a solvent thereof .

[Effects of the Invention] As described above, according to the present invention, the entire or a part of the surface of the substrate body after the electronic component is constructed forms a hardened DMA with a tan δ at -20 ° C to 0 ° C and 10 Hz of 0.10 or more. After the coating layer, a second coating layer having a distribution area of 0.32 nm or less (excluding 0) in the distribution of the measured value of the free volume radius obtained by the positron lifetime extinction method after hardening becomes 70% or more, The conductive metal part including the electrode of the electronic component is covered with the first coating layer and the second coating layer, thereby shielding corrosive gas and preventing corrosion of the electrode and the conductive metal part. In addition, since the first coating layer having a tan δ at -20 ° C to 0 ° C and 10 Hz of 0.10 or more at a temperature of 0.10 or more is formed in the cured DMA, even in an environment where repeated warm and cold shocks are applied, It is possible to prevent cracking of the solder residue on the surface of the electronic substrate, or propagation of cracks caused by the cracking toward the coating layer, and prevent corrosion of the electronic substrate.

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

FIGS. 1 (a) to 1 (c) and FIGS. 2 (a) and 2 (b) show the outline of the overall configuration of the corrosion-resistant electronic substrate 1, and FIG. 3 shows a second coating in the corrosion-resistant electronic substrate 1. The physical properties of the cladding layer 5. FIG. 4 shows the main part of the second coating layer 5 in the corrosion-resistant electronic substrate 1.

The corrosion-resistant electronic substrate 1 is formed by forming a first coating layer 4 on the whole or a part of the surface of the substrate body 3 after the electronic component 2 is constructed, and then forming a second coating layer 5 through the first coating layer 4 and The second coating layer 5 covers the conductive metal part 20 including the electrode 21 of the electronic component 2. The hardened DMA of the first coating layer 4 is -20 ° C to 0 ° C, 10 ° C. The tanδ at Hz is 0.10 or more, and the distribution of the measured value of the free volume radius obtained by the positron lifetime extinction method after hardening of the second coating layer 5 is 0.32 nm or less (excluding 0). The area is set to 70% or more.

The electronic component 2 is not particularly limited as long as it is a known one constructed on the corrosion-resistant electronic substrate 1. For example, it may be an integrated circuit (IC) or a large-scale integration (LSI). Such as semiconductor components, resistors, capacitors, inductors, etc.

The substrate body 3 is not particularly limited as long as it is a known one used for the corrosion-resistant electronic substrate 1, and examples thereof include a silicone substrate, a glass substrate, a ceramic substrate, a resin substrate, and a thin film substrate. In order to arrange and construct the electronic component 2 on the substrate body 3, it can be performed by electrically connecting a part of the electrode 21 of each electronic component 2 to a circuit formed on the substrate body 3 with solder 22 by soldering or the like. Patterned conductive metal portion 20. This connection method is not particularly limited, and a method known in the technical field can be used.

The first coating layer 4 is provided on the entire surface of the substrate body 3 after the electronic component 2 is constructed on the substrate body 3 so as to cover the conductive metal portion 20 of the substrate body 3 including the electrodes 21 of the electronic component 2. . Alternatively, the first coating layer 4 is provided on a part of the substrate body 3 so as to cover the conductive metal portion 20 of the substrate body 3 including the electrodes 21 of the electronic component 2. Therefore, as shown in FIG. 2 (a), when the conductive metal portion 20 is located on the upper surface side of the electronic component 2 on which the substrate body 3 is constructed and soldered from the upper surface side or the like, the first coating is applied The layer 4 is provided on the upper surface side. In addition, as shown in FIG. 2 (b), when the electrode 21 of the electronic component 2 is passed from the upper surface side to the lower surface side of the substrate body 3 constituting the electronic component 2, the lower surface side is flow-welded ( In the case of welding or the like, the first coating layer 4 is provided on the lower surface side. Although the electrode 21 of the electronic component 2 is penetrated, the electrode 21 is exposed to some extent on the upper surface side of the substrate body 3. Therefore, the first coating layer 4 may be provided on both sides of the substrate body 3.

The first coating layer 4 may be a coating composition containing a resin composition containing DMA at -20 ° C. to 0 ° C. and a tan δ at 10 Hz of 0.10 or more, and a solvent thereof.

The resin composition with tan δ at -20 ° C to 0 ° C and 10 Hz of 0.10 or more as the cured DMA is styrene · acrylonitrile rubber, styrene · butadiene rubber, ethylene · propylene rubber, and nitrile rubber , Butyl rubber, butadiene rubber, chloroprene rubber, acrylic rubber, urethane rubber, silicone rubber, fluorine rubber, olefin elastomer, styrene elastomer, polyester Elastomers, urethane-based elastomers, vinyl chloride-based elastomers, fluorine-based elastomers, silicone resins, silicone-modified epoxy resins, and silicone-modified acrylic resins. It is made from solvents such as methyl ethyl ketone (MEK) or alcohols such as ethanol and isopropyl alcohol (IPA). As long as the requirements for tan δ measured by DMA after curing are satisfied, these resin compositions may be used alone or in combination.

The first coating composition may contain various additives such as pigments, dyes, flame retardants, viscosity modifiers, antioxidants, and fillers, which are well known in the technical field, in addition to the components. The content of the additive is not particularly limited as long as it is within a range that does not inhibit the effects of the present invention, and can be appropriately adjusted for use.

By applying the first coating composition configured as described above to the entire or a part of the surface of the substrate body 3 after the electronic component 2 is constructed, the first coating layer 4 can be formed on the entire or a part of the surface.

Although the example shown in FIG.1 (a)-FIG.1 (c) shows the example of spray coating, the method of apply | coating a 1st coating composition at this time is not specifically limited, You may use this Methods well known in the art. Specific examples of the coating method include bristle coating, brush coating, roll coating, spray coating, dipping, dripping, and the like. These methods may be performed alone or in combination of two or more methods.

The first coating layer 4 can be formed by applying a first coating composition and drying and hardening it. In this case, as the drying and curing method, it may be determined as appropriate in accordance with the type of the first coating composition to be used. Specific examples of the curing method include dry curing at room temperature and heat curing.

The thickness of the first coating layer 4 is 10 μm to 500 μm, and preferably 20 μm to 200 μm. If it is less than 10 μm, the stress relaxation property of the first coating layer 4 is insufficient, and it is difficult to absorb stress propagation caused by cracks in the flux residue 23. In addition, if it exceeds 500 μm, the thickness of the coating layer makes it difficult for the solvent to detach due to drying and hardening, or it is difficult or difficult to harden locally due to the heating effect, thereby causing uneven hardening.

As described above, the electronic substrate 1 on which the first coating layer 4 is formed on the entire or part of the surface of the substrate body 3 after the electronic component 2 is constructed is -20 ° C to 0 ° C, The tan δ at 10 Hz becomes the first coating layer 4 of 0.10 or more. Even if the flux residue 23 of the solder 22 is cracked in an environment where repeated warm or cold heat shocks are applied, it can absorb the crack originating from the crack. Stress propagation. As a result, when the second coating layer 5 having barrier properties against corrosive gases is formed on the first coating layer 4 later, the second coating layer caused by the crack stress propagation of the flux residue 23 can be prevented. 5 cracked.

However, if the tan δ at -20 ° C to 0 ° C and 10 Hz of the DMA becomes 1.0 or more, the first coating layer 4 is easily deformed and it is difficult to control the film thickness. As a result, the formation of the second coating layer 5 becomes Unstable. Therefore, the first coating layer 4 is preferably a coating composition using a cured DMA at -20 ° C to 0 ° C and a tan δ of less than 1.0 at 10 Hz.

Before the first coating layer 4 is formed, the substrate body 3 on which the electronic components 2 are mounted may be plasma-cleaned. By performing plasma cleaning, the surface of the substrate body 3 is modified, and foreign matter is removed, whereby the coating performance of the first coating composition is improved. In addition, since the excess flux residues 23 are reduced, the flux residues 23 that cause cracks to propagate can also be reduced when warm shock or cold shock is repeatedly applied. The plasma cleaning can be performed by a known method such as air, nitrogen, or argon. From the viewpoint of productivity, atmospheric piezoelectric slurry cleaning using air is preferred. In addition, the electronic component 2 mounted on the substrate body 3 may be damaged due to plasma cleaning. Therefore, when performing plasma cleaning, it is determined whether the application is possible or not.

As shown in FIG. 3, the second coating layer 5 can use a coating composition for corrosive gas shielding, the coating composition for corrosive gas shielding comprising: a hardened material obtained by a positron lifetime extinction method; The resin composition having a distribution area of 0.32 nm or less (excluding 0) in the distribution of the measured value of the free volume radius is 70% or more, and a solvent thereof.

Examples of the resin composition in which the distribution area of 0.32 nm or less (excluding 0) in the distribution of the measured value of the free volume radius obtained by the positron lifetime extinction method after curing is 70% or more, include acrylic resins, polymers, and polymers. Any one or more of an ester resin, a polyurethane resin, a silicone resin, a fluororesin, and an epoxy resin. These resin compositions are also acceptable as long as the distribution area of 0.32 nm or less (excluding 0) in the distribution of the measured value of the free volume radius obtained by the positron lifetime extinction method after curing is 70% or more. Use one type or multiple types in combination.

Examples of the acrylic resin include those obtained by subjecting a polyfunctional (meth) acrylate monomer to ultraviolet (UV) curing and electron beam curing.

Examples of the polyester resin include those in which a unsaturated polyester produced by polycondensation of a saturated dibasic acid or an unsaturated dibasic acid with a glycol is diluted and dissolved in a reactive monomer such as styrene with a hardener. Or, a vinyl monomer produced by the addition reaction of an epoxy resin and (meth) acrylic acid is diluted with a reactive monomer such as styrene and dissolved or hardened.

Examples of the polyurethane resin include a (meth) propylene terminal (NCO) of a urethane prepolymer obtained by reacting a polyisocyanate with a polyester polyol having an average molecular weight of 6,000 or less. Those who have been modified by fluorene base are those who have undergone UV curing.

Examples of the silicone resin include hard coating agents such as organic polysiloxane.

Examples of the fluororesin include perfluoroalkyl (meth) acrylates and (meth) acrylates such as perfluorohexylethyl (meth) acrylate and perfluorobutylethyl (meth) acrylate. Copolymer (copolymer). Examples of the coating agent include those obtained by dissolving 5% by weight of the copolymer in 95% by weight of a solvent such as ethyl acetate and toluene.

Examples of the epoxy resin include amine-based and acid anhydrides used as hardeners in bisphenol A epoxy resin, novolac epoxy resin, glycidyl ester epoxy resin, and glycidylamine epoxy resin. System, polyamine system and heat curing.

The second coating composition may contain various additives such as pigments, dyes, flame retardants, viscosity modifiers, antioxidants, and fillers, which are well known in the technical field, in addition to the components. The content of the additive is not particularly limited as long as it is within a range that does not inhibit the effects of the present invention, and can be appropriately adjusted for use.

After the first coating layer 4 is formed on the whole or a part of the surface of the substrate body 3 after the electronic component 2 is constructed, the first coating layer 4 covering the first coating layer 4 will cover the first structured layer as described above. The two coating compositions are applied to the whole or a part of the surface of the substrate body 3, whereby the second coating layer 5 can be formed on the whole or a part of the surface. Therefore, when the first coating layer 4 or the like is provided on any one side of the upper surface or the lower surface of the substrate body 3, the second coating layer is coated so as to cover the first coating layer 4. The cladding layer 5 is provided on the same single-sided side, and when the first coating layer 4 and the like are provided on both sides, the second coating layer 5 is similarly provided on both sides.

Although the example shown in FIG.1 (a)-FIG.1 (c) shows the example of spray coating, the method of apply | coating a 2nd coating composition is not specifically limited at this time, You may use this Methods well known in the art. Specific examples of the coating method include bristle coating, brush coating, roll coating, spray coating, dipping, dripping, and the like. These methods may be performed alone or in combination of two or more methods.

The second coating layer 5 can be formed by applying and curing the second coating composition, but in this case, as the curing method, it may be determined appropriately according to the type of the second coating composition used. . Specific examples of the curing method include dry curing, room temperature curing, heat curing, or infrared curing, ultraviolet curing, and electron beam curing.

The thickness of the second coating layer is 5 μm to 200 μm, and preferably 10 μm to 100 μm. If it is less than 5 μm, the barrier property of the corrosive gas of the second coating layer is insufficient, and it is difficult to prevent corrosion of the electronic substrate 1. In addition, if it exceeds 200 μm, the curing shrinkage stress of the second coating layer during hardening becomes large, and peeling at the interface with the first coating layer or cracking of the second coating layer easily occurs.

After forming the first coating layer 4 on the entire or part of the surface of the substrate body 3 after the electronic component 2 is constructed as described above, a second coating layer is formed so as to cover the first coating layer 4. The electronic substrate 1 of 5 uses the second coating layer 5 having a distribution area of 0.32 nm or less (excluding 0) in the measured distribution of the free volume radius obtained by the positron lifetime extinction method after curing, which is 70% or more. When the conductive metal part including the electrode 21 of the electronic component 2 is covered, as shown in FIG. The free volume portion 50 passes. As a result, the second coating layer 5 can shield corrosive gases such as hydrogen sulfide gas. Thereby, the corrosion resistance of the electronic substrate 1 to corrosive gas is improved, and excellent environmental resistance performance can be obtained.

In addition, in the measured distribution of the free volume radius of the second coating layer 5 obtained by the positron lifetime extinction method after curing, the distribution area of 0.32 nm or less (excluding 0) is set to 70% or more. The above-mentioned barrier gas is excellent in gas barrier properties, but has a dense molecular structure and high rigidity. Therefore, if only the second coating layer 5 is used, stress relaxation properties are lacking. Therefore, in the case where the electronic substrate 1 is easily broken (for example, the electronic component 2 is mounted using the solder 22) by repeatedly applying a thermal shock or a thermal shock, there is a concern that the hardened flux residue 23 is subject to a thermal shock. Or cold and hot shock, and the crack propagates in the second coating layer 5 and breaks likewise, causing the gas barrier property to be lost due to warm or cold heat shock, but in the present invention, after the first coating layer 4 is formed A second coating layer 5 is formed. In addition, the tan δ of -20 ° C to 0 ° C and 10 Hz of the DMA in the cured state of the first coating layer 4 is set to 0.10 or more, and prevents the occurrence of flux residues 23 caused by warm shock or cold shock. Since cracks propagate through the function of the second coating layer 5, excellent gas barrier properties can be maintained even in an environment with large thermal changes.

Therefore, as shown in FIG. 2 (b), the electronic substrate 1 is used when the electronic component 2 is mounted on the substrate body 3 by flow soldering in which a large amount of flux residues 23 are generated, or when the electronic substrate 1 is used in an environment with large thermal changes. , Can obtain particularly significant gas barrier properties.

Example <Sample preparation> As a first coating composition, it is prepared to dilute Seal-glo (rubber-based coating agent resin composition) manufactured by Fuji Chemical Industries with a diluent (solvent). It is prepared so that the viscosity measured by an E-type viscometer becomes about 100 mPa · s to 300 mPa · s.

Similarly, as the second coating composition, HumiSeal (acrylic coating resin composition) manufactured by AR Brown was prepared to be diluted with a diluent (solvent), It is prepared so that the viscosity measured by an E-type viscometer may be about 100 mPa · s to 300 mPa · s. <Preparation of a coating sample for physical property evaluation> The coating agent was applied on a release paper using a bar coater (No. 75 manufactured by AS ONE), and a vacuum dryer (300 Torr) was dried for 24 hours to obtain a first coating layer and a second coating layer having a cured film thickness of 100 μm to 200 μm. <Measurement of tanδ by DMA> For the first coating layer, a dynamic viscoelasticity measuring device (type Rheogel-E4000) manufactured by UBM was used in the range of -20 ° C to 0 ° C. The measurement frequency was 10 Hz for tanδ measurement after hardening. <Measurement of Free Volume Radius> For the second coating layer, a small positron beam generating device Pals (PALS) -200A (thin film corresponding positron extinction life measuring device) manufactured by Fuji Imvac was used. Using a 22Na base positron as the positron source, using BaF ₂ scintillator + photomultiplier tube as the γ-ray detector, device constants: 243 ps to 246 ps, 24.55 ps / ch, beam intensity : 5 keV, measurement depth: 0 μm to 2 μm (estimated), measurement temperature: room temperature, measurement environment: vacuum, total number of counts: about 5000000 counts, sample pretreatment: under vacuum degassing at room temperature, After confirming the free volume radius by the positron lifetime extinction method after hardening, a distribution area of 0.32 nm or less (excluding 0) was measured. <Calculate distribution area based on free volume measurement result> As a method of calculating a distribution area of 0.32 nm or less (excluding 0) based on the measurement result of free volume radius, for example, referring to FIG. 3, based on the intersection of the distribution curve and the baseline The histogram was divided into 100 parts, and the area ratio of 0.32 nm or less was calculated.

For the first coating composition and the second coating composition shown in Table 1, the tan δ and distribution area by DMA were measured by the same method, respectively. The results are shown in Table 1.

[Table 1] No. Resin species Product name tanδ Distribution area 1 Rubber system 1 Fuji Chemical Industry Seal-glo 0.22 50% 2 Silicone 1 Toray Dow Corning Pelgan 0.20 72% 3 Silicone 2 Momentive TSE 0.20 - 4 Rubber system 2 Nittoshinko Elepcoat 0.12 - 5 Polyolefin AR Brown HumiSeal 0.10 - 6 Urethane series 1 AR Brown HumiSeal 0.07 60% 7 Acrylic 1 Hitachi becomes Tuffy 0.05 - 8 Ester Fuji Chemical Industry Seal-glo - 97% 9 Fluoride 2 Fluoro technology FluoroSurf - 90% 10 Acrylic 2 AR Brown HumiSeal - 75% 11 Fluoride 1 Noda Screen PCH - 74% 12 Urethane series 2 Ryoden Chemical to MELQUID - 70%

Example 1 to Example 12, Comparative Example 1 to Comparative Example 9 <Preparation of test piece> As an electronic substrate, a substrate of a switching power supply S8VK-S manufactured by Omron was prepared. In addition, the mounting of the electronic component on the substrate body of the electronic substrate has undergone the steps of flux coating and flow solder coating, and the solder cleaning is not particularly performed.

A coating valve (CV-10) manufactured by Musashi Engineering was used to apply the first coating composition to the substrate body of the electronic substrate so as to have a film thickness of 30 μm. Thereafter, it was dried for 24 hours by a reduced pressure dryer (300 torr) to form a first coating layer. Thereafter, using the valve again, the second coating composition was superimposed on the first coating layer so as to have a thickness of 30 μm, and dried for 24 hours by a vacuum dryer (300 torr). This forms a second coating layer, thereby obtaining an electronic substrate covered with two kinds of coating layers. The film thickness of the coating layer was adjusted by measuring with a micrometer. The film thickness of the first coating layer and the film thickness of the second coating layer were both 30 μm.

For the first coating layer and the second coating layer, the combinations shown in Table 2 were used as shown in Table 1. <Conditions of environmental resistance test> The electronic substrate on which the coating layer was formed was repeatedly subjected to cold and thermal shocks and warm and thermal shocks at a low temperature side of -40 ° C × 30 minutes and a high temperature side of 85 ° C × 30 minutes.

Thereafter, it was left to stand in a test tank which became an environment of a sulfur-based gas (mixed gas of H ₂ S, SO ₂ ) in accordance with Japanese Industrial Standards (JIS) C0048: 1999.

After standing, the appearance of the surface of the coating layer was checked visually. As the observation portion, a portion including a material including silver and copper components such as solder, a wafer terminal, and a through hole is mainly observed. <Evaluation> The case where the first coating layer and the second coating layer on the electronic substrate were free of cracks, and the appearance of the metal part on the electronic substrate was not changed at all was ◎, and the case where only the metal part was not changed was 设为.

In addition, those in which the first coating layer and the second coating layer on the surface of the electronic substrate had cracks, or those in which the appearance of the metal portion on the electronic substrate in the vicinity of the cracks was changed, were set to ×. As the visual inspection method, in addition to visual inspection, magnification, magnification (loupe), microscope, etc. are used to magnify 1 to 20 times for inspection.

The results are shown in Table 2.

[Table 2] First coating layer Second coating Evaluation Composition No. tanδ Composition No. Distribution area Examples 1 1 0.22 10 75% ◎ 2 1 0.22 12 70% ◎ 3 3 0.20 10 75% ◎ 4 3 0.20 12 70% ◎ 5 4 0.12 8 97% ◎ 6 4 0.12 9 90% ◎ 7 4 0.12 10 75% ◎ 8 4 0.12 2 70% ◎ 9 5 0.10 8 97% ○ 10 5 0.10 9 90% ○ 11 5 0.10 10 75% ○ 12 5 0.10 2 72% ○ Comparative example 1 4 0.12 6 60% X 2 4 0.12 1 50% X 3 5 0.10 6 60% X 4 5 0.10 1 50% X 5 6 0.07 11 74% X 6 6 0.07 12 70% X 7 7 0.05 11 74% X 8 7 0.05 12 70% X 9 7 0.05 6 60% X

Based on the above results, the electronic substrates conforming to Examples 1 to 12 of the present invention neither cracked, and good results were confirmed in subsequent operation confirmation.

In addition, the present invention can be implemented in various other forms without departing from the spirit or main characteristics thereof. Therefore, the embodiments are merely examples in all aspects and cannot be interpreted in a limited manner. The scope of the present invention is expressed by the scope of patent application, and is not limited at all by the text of the specification. Furthermore, all the deformation | transformation and change which belong to the scope of patent application are the scope of the present invention.

1: Corrosion-resistant electronic substrate 2: Electronic component 20: Conductive metal portion 21: Electrode 22: Solder 23: Flux residue 3: Substrate body 4: First coating layer 5: Second coating layer 50: Free volume portion 51 : Molecular chain 6: Gas molecules of corrosive gas

FIGS. 1 (a) to 1 (c) are schematic perspective views showing the overall configuration in the manufacturing steps of the corrosion-resistant electronic substrate of the present invention. Fig. 2 (a) is a sectional view taken along the line I-I in Fig. 1 (c), and Fig. 2 (b) is a sectional view of a corrosion-resistant electronic substrate in another embodiment. 3 is a graph showing physical properties of a second coating layer of a corrosion-resistant electronic substrate of the present invention. FIG. 4 is a schematic view showing a main part of a second coating layer of a corrosion-resistant electronic substrate of the present invention.

Claims (4)

A corrosion-resistant electronic substrate is formed by forming a first coating layer on the whole or a part of a surface of a substrate body after constructing an electronic component, and then forming a second coating layer, and using the first coating layer and the first coating layer. The two coating layers cover the conductive metal part including the electrode of the electronic component, and the corrosion-resistant electronic substrate is characterized in that the thickness of the first coating layer is 10 μm to 500 μm, and the first coating layer is The tan δ at -20 ° C to 0 ° C and 10Hz of the hardened dynamic mechanical analyzer of the coating layer is 0.10 or more and 0.22 or less, and the thickness of the second coating layer is 5 μm to 200 μm, and the second In the distribution of the measured value of the free volume radius of the coating layer after hardening by the positron lifetime extinction method, the distribution area of 0.32 nm or less (excluding 0) is set to 70% or more and 97% or less. The corrosion-resistant electronic substrate according to item 1 of the scope of patent application, wherein the first coating layer and the second coating layer are integrated through an interface thereof. The corrosion-resistant electronic substrate according to item 1 of the scope of patent application, wherein the first coating layer is selected from the group consisting of styrene-based rubber, urethane-based rubber, silicone-based rubber, fluorine-based rubber, and olefin Any one or more of a system-based elastomer, a styrene-based elastomer, and a fluorine-based elastomer. The corrosion-resistant electronic substrate according to item 1 of the patent application scope, wherein the second coating layer is selected from the group consisting of an acrylic resin, a polyester resin, a polyurethane resin, a silicone resin, a fluororesin, and a ring. One or more of the oxygen resins.