JP2007207873A - Electronic equipment - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide electronic equipment which can take a wide structure depending on the use through a simplified process. <P>SOLUTION: The electronic equipment comprises an electronic device E, a protective portion 21e covering the electronic device E, and a housing 24 fusion molded of thermoplastic resin on the outside of the protective portion 21e wherein the protective portion 21e principally comprises resin having a heat-resistant temperature not lower than that of thermoplastic resin. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to an electronic device including an electronic device and a housing made of a melt-molded thermoplastic resin.

Generally, the heat resistance of an electronic device is determined by the physical properties of the material constituting the electronic device and the manufacturing conditions for manufacturing the electronic device.
For example, a capacitor with a lead wire including a capacitor main body (hereinafter referred to as a “capacitor main body”) having a dielectric and an electrode member, a lead wire, and a solder layer that connects the lead wire to the electrode member of the capacitor main body. In this case, the solid phase temperature of the solder layer is 246 ° C., and when this temperature is exceeded, the solder layer is melted, resulting in poor connection between the electrode member of the capacitor body and the lead wire. For this reason, the heat-resistant temperature of the above-mentioned capacitor is 246 ° C. or less at the highest. Depending on the physical properties of the materials constituting the electronic device and the manufacturing conditions for producing the electronic device, the heat-resistant temperature may be lower.

  On the other hand, when the housing for housing the electronic device is provided by melt-molding a thermoplastic resin, the temperature of the molten resin may be 250 ° C. or higher. For this reason, when a thermoplastic resin is melt-molded directly into an electronic device when the electronic device is housed in a housing to constitute an electronic device, the electronic device is damaged by heat, such as the aforementioned solder layer being melted. There is a case.

  Further, when a thermoplastic resin is melt-molded to provide a housing for housing the above-described electronic device, the pressure of the molten thermoplastic resin, that is, the molten resin pressure may be as high as 20 MPa or more. For this reason, when the electronic device is housed in the housing and the electronic apparatus is configured, if the thermoplastic resin is melt-molded directly on the electronic device, not only the solder layer described above is dissolved, but the molten solder layer The electronic device may be physically damaged by the molten resin pressure, such as being moved by the molten resin force.

  As an electronic apparatus using the electronic device as described above, a rotation sensor (see, for example, Patent Document 1) provided with a protection circuit composed of an electronic device such as a capacitor or a resistor in order to improve surge resistance is known. In this rotation sensor, a terminal of a sensor element for detecting rotation is extended and protruded from the housing, and a capacitor and a resistor provided in the protection circuit member are fitted into this terminal. By doing in this way, when melt-molding the housing of a rotation sensor with resin, it can prevent damaging electronic devices, such as a capacitor and a resistor.

JP 2004-309340 A (paragraph [0011] paragraph and FIG. 1).

However, in the above rotation sensor, it is necessary to provide a protective circuit member including an electronic device such as a capacitor or a resistor so that the sensor can be fitted to the terminal of the sensor element, which complicates the manufacturing process and increases the cost. There was a problem to do.
Further, when providing the protection circuit, the input / output portion of the rotation sensor is limited to a terminal structure or the like to which the protection circuit member can be fitted, and cannot have a wide structure according to the use such as a wire harness structure. There was a problem.
The present invention has been made in view of the above problems, and it is an object of the present invention to provide an electronic device that can take a wide range of structures in accordance with applications by a simplified process.

  A first characteristic configuration of an electronic device according to the present invention includes an electronic device, a protective part that covers the electronic device, and a housing made of a thermoplastic resin that is melt-molded outside the protective part, and the protective part Is based on a resin having a heat resistance temperature equal to or higher than the melting temperature of the thermoplastic resin.

  According to this configuration, since the electronic device is covered with the protective portion mainly composed of a resin having a heat resistant temperature equal to or higher than the melting temperature of the thermoplastic resin forming the housing, when the housing is melt-molded outside the electronic device, In addition, the electronic device can be prevented from being damaged by heat. As a result, there is no need to provide a structure for attaching an electronic device to the outside of the housing as in the prior art, or to form the housing separately and house the electronic device therein, so that the electronic device manufacturing process Can be simplified. Moreover, since the housing by melt molding can be formed in arbitrary shapes, it can take a wide structure according to a use. Furthermore, since the housing is formed directly on the electronic device via the protective part, the degree of adhesion between the housing and the electronic device can be increased.

  A second characteristic configuration of the electronic device according to the present invention is that, at the melting temperature of the thermoplastic resin, a thermal decomposition rate of the resin, which is a main component of the protective portion, is 5% or less.

  According to this configuration, since the thermal decomposition rate of the resin that is the main component of the protective portion is 5% or less at the melting temperature of the thermoplastic resin, the electronic device can be reliably protected from heat.

  A third characteristic configuration of the electronic device according to the present invention is that the protective portion has pressure resistance against a molten resin pressure during the melt molding.

  According to this structure, since the protection part has pressure resistance against the molten resin pressure at the time of melt molding, it is possible to maintain the state where the electronic device is covered by the housing when the housing is molded. As a result, it is possible to prevent the electronic device from being damaged by stress from the housing forming resin when the housing is molded.

  A fourth characteristic configuration of the electronic device according to the present invention is that the protective portion has a compressive strength and a shear strength equal to or higher than a molten resin pressure in the melt molding.

  According to this configuration, since the protective part has a compressive strength and a shear strength equal to or higher than the molten resin pressure of the melt molding, when the housing is molded, the protective part is destroyed by the molding pressure, that is, the molten resin pressure. Can be prevented. As a result, since the electronic device can be maintained in the state covered with the protective portion, the electronic device can be prevented from being damaged by the molten resin pressure at the time of molding the housing.

  According to a fifth characteristic configuration of the electronic device according to the present invention, the protection unit attaches the resin solution, which is a main component of the protection unit, to the surface of the electronic device, and is the main component of the protection unit. The resin is solidified or cured.

  According to this configuration, since the protection part is formed by adhering the solution of the resin, which is the main component of the protection part, to the surface of the electronic device body and solidifying or curing it, the electronic device has a heat load. The protective part can be formed without applying the.

  According to a sixth characteristic configuration of the electronic device according to the present invention, the resin that is a main component of the protective part is selected from the group consisting of a polyamideimide resin, a polyethersulfone resin, a polyarylate resin, and a thermoplastic polyimide resin. At least one kind of resin.

  By using the above-mentioned resin as the main component of the protective part, the protective part having high heat resistance and pressure resistance can be formed, so that the electronic device body can be reliably protected.

Hereinafter, an electronic device according to the present invention will be described with reference to the drawings, taking a rotation sensor as an example.
[Configuration of electronic device]
FIG. 1 shows a rotation sensor 4 which is an example of the electronic apparatus S of the present invention. FIG. 2 shows the rotation sensor 4 before the housing 24 is formed. The rotation sensor 4 has two components as shown in FIG. One component is a main body portion 1 (hereinafter referred to as “main body portion 1”) that constitutes a detection unit that detects rotation, and the other component supplies an electric signal to the main body portion 1, and A transmission unit 2 (hereinafter referred to as “transmission unit 2”) having a function of transmitting a signal from the main body unit 1 to the outside. Each of them is covered with housings 13 and 24. In the housing 13 of the main body 1, a sensor element 10 such as a Hall IC that detects the rotation of the rotating body, a bias magnet 11 that applies a bias magnetic flux or a bias magnetic field to the sensor element 10 such as a Hall IC, and the transmission from the main body 1. The first terminal 12 and the like that extend to the part 2 and transmit the signal detected by the sensor element 11 to the transmission part 2 are accommodated. The transmission unit 2 is connected to the first terminal 12 of the main body unit 1 through the second terminal 22, and includes a cable 23 and the like for transmitting the signal to a control controller or the like. Moreover, the capacitor | condenser 21 (an example of the electronic device E) as a protection circuit is connected to the connection part of the 1st terminal 12 and the 2nd terminal 22 by welding etc., for example. On the surface of the capacitor 21, a protective portion 21 e mainly composed of a resin having a heat resistance temperature equal to or higher than the melting temperature of the thermoplastic resin forming the housing 24 (hereinafter referred to as “protective portion forming resin”) is formed. It is.

As shown in FIG. 2, after the cable 23, the capacitor 21, and the like are provided in the transmission unit 2 described above, a thermoplastic resin is melt-molded and the housing 24 is provided in the transmission unit 2. The thermoplastic resin for housing formation (hereinafter referred to as “housing resin”) is not particularly limited, but from the viewpoint of heat resistance and chemical resistance, for example, polyphenylene sulfide (PPS) resin / polyamide resin ( For example, 66 nylon resin, polybutylene terephthalate (PBT) resin, polyacetal (POM) resin, or the like can be used.
In the case of a PPS resin having the highest heat resistance and chemical resistance among the above-mentioned resins, the melting temperature thereof is 283 ° C., which has the highest melting temperature among the above-mentioned resins, and the PPS resin at the time of melt molding The temperature is generally 300 to 320 ° C. Moreover, the molten resin pressure at the time of melt molding is generally 20 to 30 MPa.

[Method for forming protective part]
Next, as an electronic device E applicable to the present invention, an example of a method for forming the protective portion 21e will be described using the capacitor 21 as an example.
FIG. 3 shows a capacitor 21 which is an example of the electronic device E. Moreover, the capacitor | condenser 21 after forming the protection part 21e in FIG. 4 is shown. The capacitor 21 includes a capacitor body 21a that is a multilayer ceramic capacitor, a lead wire 21b, and a solder layer 21d that connects the lead wire 21b to the electrode portion of the capacitor body 21a. And the exterior resin layer 21c formed, for example with the epoxy resin is provided in the outer side of the capacitor | condenser main body 21a. The exterior resin layer 21c is provided as an external stress relaxation layer in order to avoid applying mechanical stress directly to the capacitor body 21a and the solder layer 21d. In the case of an epoxy resin, the heat resistant temperature is about 180 ° C. The solidus temperature of the solder layer 21d that joins the lead wire 21b and the terminal electrode of the capacitor 21 is 246 ° C.

The protection part 21e can be formed on the capacitor 21 by, for example, an immersion method. Capacitor 21 is immersed in a solution obtained by dissolving protective portion forming resin in an organic solvent, and this solution is attached to exterior resin layer 21 c of capacitor 21. Thereafter, the attached protective portion forming resin is solidified or cured to form a protective portion 21e that covers the junction between the capacitor body 21a and the lead wire 21b and the capacitor body 21a, as shown in FIG.
In addition, the formation method of a protection part is not restricted to the immersion method, You may make the resin for protection part formation adhere by other methods, such as application | coating and spraying.

  As the protective portion forming resin, a resin having a heat resistance temperature equal to or higher than the melting temperature of the thermoplastic resin forming the housing 24 is used. Here, the “resin having a heat resistant temperature equal to or higher than the melting temperature of the thermoplastic resin forming the housing 24” means that the protective portion 21e is interposed between the housing forming resin having the melting temperature and the electronic device E. Until the temperature of the resin for forming the housing is equal to or lower than the heat resistant temperature of the electronic device E (in this embodiment, for example, 246 ° C. which is the solidus temperature of the solder layer 21d), A resin capable of forming the protective portion 21e that can prevent direct contact with the resin.

  Preferably, a resin that does not substantially thermally decompose at the melting temperature of the housing forming resin is preferable. Specifically, a resin having a thermal decomposition rate of 5% or less at the melting temperature of the housing forming resin, that is, a temperature at which the thermal decomposition rate is 5% (hereinafter referred to as “5% thermal decomposition temperature”), A resin having a temperature equal to or higher than the melting temperature of the housing forming resin is preferable. More preferably, a resin having a thermal decomposition start temperature equal to or higher than the melting temperature of the housing forming resin is preferable. If such a resin is used as the protective portion forming resin, the electronic device E may be thermally deteriorated even if the molten housing forming resin contacts the protective portion 21e when the housing 24 is melt-molded. Can be prevented from being damaged.

  Further, when the housing 24 is melt-molded, the protective portion 21e receives a stress such as a compressive stress or a shear stress from the housing-forming resin. It is good to have pressure resistance with respect to the molten resin pressure of resin. In particular, it is preferable that the protective portion has a compressive strength and a shear strength that are equal to or higher than the molten resin pressure during the melt molding. If such a resin is used as the protective part forming resin, even when the melted housing molding resin comes into contact with the protective part 21e during the melt molding of the housing 24, the electronic device E may cause a stress breakdown. Damage can be prevented.

Here, FIG. 5 shows changes over time in the molten resin temperature and the molten resin pressure at the position of the capacitor 21 when the housing 24 is injection-molded using PPS resin as an example of the housing forming resin. The temperature of the PPS molten resin at the time of injection molding is 320 ° C., and the molten resin pressure is 27 MPa.
At a position corresponding to the substantially central portion of the capacitor 21, the temperature is raised to 270 ° C. and the molten resin pressure is raised to 23 MPa after the injection of the PPS resin.
Thereafter, the PPS resin is cooled from 270 ° C. to a temperature lower than 246 ° C. which is the solidus temperature of the solder within 3 seconds, and the molten resin pressure at the time when the temperature is lowered to the solidus temperature of the solder is 13 MPa. It is falling.

  As described above, the housing forming resin is in a high temperature state near the melting temperature in a very short time. For this reason, as described above, the protective portion forming resin does not necessarily have a thermal decomposition start temperature equal to or higher than the melting temperature of the housing forming resin.

  Specifically, although not particularly limited, for example, the protective portion 21e can be formed using a resin such as a polyamideimide resin, a polyethersulfone resin, a polyarylate resin, or a thermoplastic polyimide resin as a main component. These resins may be used alone, or a plurality of types of resins may be mixed and used.

  The 5% thermal decomposition temperature of the polyamideimide resin is 440 ° C. or higher, which is higher than the melting temperature of the housing forming resin such as PPS resin. Further, at 300 to 320 ° C. which is the temperature of the housing forming resin such as PPS resin at the time of melt molding, the compressive strength of the polyamideimide resin is 100 MPa or more, and 20 at the melt resin pressure at the time of molding the housing 24. Greater than ~ 30 MPa.

  The 5% thermal decomposition temperature of the polyethersulfone resin is 480 ° C. or higher, which is higher than the melting temperature of the housing forming resin such as PPS resin. Further, at 300 to 320 ° C. which is the temperature of the PPS resin at the time of melt molding, the compressive strength of the polyethersulfone resin is 85 MPa, which is larger than 20 to 30 MPa which is the molten resin pressure at the time of molding the housing 24.

  The 5% thermal decomposition temperature of the polyarylate resin is 480 ° C. or higher, which is higher than the melting temperature of the housing forming resin such as PPS resin. Further, at 300 to 320 ° C. which is the temperature of the PPS resin at the time of melt molding, the compressive strength of the polyarylate resin is 82 MPa, which is larger than 20 to 30 MPa which is the molten resin pressure at the time of molding the housing 24.

  The 5% thermal decomposition temperature of the thermoplastic polyimide resin is 520 ° C. or higher, which is higher than the melting temperature of the housing forming resin such as PPS resin. Further, at 300 to 320 ° C. which is the temperature of the PPS resin at the time of melt molding, the compressive strength of the thermoplastic polyimide resin is 120 MPa, which is larger than 20 to 30 MPa which is the molten resin pressure at the time of molding the housing 24.

  Since the 5% thermal decomposition temperature of these resins is higher than the melting temperature of the housing forming resin as described above, the thermal decomposition rate of these resins is 5% or less at the melting temperature of the housing forming resin. . Further, when the housing 24 is melt-molded, it has a compressive strength equal to or higher than the molten resin pressure at the time of melt-molding. For this reason, even if housing forming resin such as PPS resin is discharged to the protective portion 21e, the protective portion 21e is not destroyed, and the housing 24 molding resin is prevented from coming into direct contact with the electronic device E. Can do.

  The organic solvent for dissolving the protective portion forming resin is not particularly limited as long as the protective portion forming resin can be dissolved. However, it is easy to attach the solution when the capacitor 21 is immersed in the solution. From the viewpoint, it is preferable to use an organic solvent in which the viscosity of the protective part-forming resin solution is 10 to 20 Pa · s. Further, an organic solvent capable of solidifying or curing the protective portion forming resin at a temperature equal to or lower than the heat resistant temperature of the electronic device E (in this embodiment, for example, 246 ° C., which is the solid phase line temperature of the solder layer) is used. Is preferred.

  Specifically, for example, N-methyl-2-pyrrolidone, N, N-dimethylformamide, N, N-dimethylacetamide, methyl ethyl ketone, gamma-butyrolactone, xylene, N-methylpyrrolidone, methylene chloride, tetrahydrofuran, 1,4-dioxane An organic solvent such as cyclohexane, ethanol, or toluene can be used. These organic solvents may be used alone or as a mixture of a plurality of types of organic solvents.

  When a polyamideimide resin is used as the protective part forming resin, organic solvents include N-methyl-2-pyrrolidone, N, N-dimethylformamide, N, N-dimethylacetamide, methyl ethyl ketone, gamma-butyrolactone, xylene, ethanol, Toluene or the like may be used. If these organic solvents are used, the polyamide-imide resin solution can be prepared by dissolving the polyamide-imide resin.

In particular, N-methyl-2-pyrrolidone is 70 to 80 wt%, dimethylformamide is 30 to 20 wt% to constitute an organic solvent, and a polyamideimide resin is dissolved in this organic solvent to obtain a 35 to 40 wt% polyamideimide resin solution. May be prepared.
Alternatively, N-methyl-2-pyrrolidone is 70 to 75 wt%, xylene is 25 to 30 wt% to constitute an organic solvent, and polyamideimide resin is dissolved in this organic solvent to obtain a 35 to 40 wt% polyamideimide resin solution. It may be prepared.
By preparing the polyamide-imide resin solution in this way, a solution having a viscosity of 10 to 20 Pa · s can be obtained. For example, the number necessary for forming the protective portion 21e in one immersion is generally required. One hundred micron coating can be formed.
Furthermore, polyamideimide can be cured at a temperature of 240 ° C. or lower, and the solder layer 21d can be prevented from melting during curing.

  When a polyethersulfone resin is used as the protective part-forming resin, N-methylpyrrolidone / N, N-dimethylformamide / N, N-dimethylacetamide or the like may be used as the organic solvent. With these organic solvents, the polyethersulfone resin can be dissolved to prepare a polyethersulfone resin solution.

In particular, a 20 to 25 Wt% polyethersulfone resin solution may be prepared using N, N-dimethylformamide as the organic solvent. By preparing the polyethersulfone resin solution in this way, a solution having a viscosity of 10 to 20 Pa · s can be obtained. For example, it is generally necessary for forming the protective portion 21e by one immersion. A coating film of several hundred microns can be formed.
Furthermore, the polyethersulfone resin can be cured at a temperature of 240 ° C. or lower, and the solder layer 21d can be prevented from melting during curing.

  When a polyarylate resin is used as the protective part forming resin, the organic solvent is methylene chloride, tetrahydrofuran, 1,4-dioxane, N-methyl-2-pyrrolidone, N, N-dimethylformamide, N, N- Dimethylacetamide / cyclohexane or the like may be used. With these organic solvents, the polyarylate resin can be dissolved to prepare a polyarylate resin solution.

In particular, a 15-20 wt% polyarylate resin solution may be prepared using methylene chloride or N-methyl-2-pyrrolidone as the organic solvent. By doing in this way, the solution which has a viscosity of 10-20 Pa * s can be obtained, for example, the coating film of several hundred microns can be formed by one immersion.
Furthermore, the polyarylate resin can be solidified at a temperature of 204 ° C. or lower, and the solder layer 21d can be prevented from melting during solidification.

  When a thermoplastic polyimide resin is used as the protective part forming resin, N-methyl-2-pyrrolidone, N, N-dimethylformamide, xylene, methyl ethyl ketone, N, N-dimethylacetamide, etc. may be used as the organic solvent. . If it is these organic solvents, a thermoplastic polyimide resin can be melt | dissolved and a thermoplastic polyimide resin solution can be prepared.

In particular, a 15 to 20 wt% thermoplastic polyimide resin solution may be prepared using N-methyl-2-pyrrolidone as the organic solvent. By doing so, a solution having a viscosity of 10 to 20 Pa · s can be obtained. For example, a coating film of several hundred microns generally required for forming the protective portion 21e can be obtained by one immersion. Can be formed.
Furthermore, the thermoplastic polyimide resin can be solidified at a temperature of 204 ° C. or lower, and the solder layer 21d can be prevented from melting during solidification.

When the protective part 21e is provided on the surface of the exterior resin layer 21c of the electronic device E such as the capacitor 21 as described above, a coupling agent may be mixed with the protective part forming resin solution. Examples of the coupling agent include a silane coupling agent.
In this way, when the capacitor 21 is immersed in the resin solution by mixing the coupling agent into the solution for the protective part forming resin, the protective part forming resin and the resin of the exterior resin layer 21c change the coupling agent. Will be combined. For this reason, the resin solution can be reliably attached to the surface of the exterior resin layer 21c.

  Moreover, although the example which forms the protection part 21e in the surface of the exterior resin layer 21c of the capacitor | condenser 21 was shown in the above-mentioned embodiment, you may form the protection part 21e in the surface of the ceramic capacitor 21 directly. In this case, it is not necessary to mix a coupling agent with the solution of the protective part forming resin.

Hereinafter, the formation of the protection part 21e will be specifically described by taking the above-described capacitor 21 as an example of the electronic device E.
[Example 1]
Polyamideimide resin was used as the protective part forming resin.
In addition, a polyamideimide resin was dissolved in an organic solvent composed of 70 wt% organic N-methyl-2-pyrrolidone and 30 wt% dimethylformamide to prepare a 35 wt% polyamideimide resin solution. The capacitor 21 was immersed in this polyamideimide resin solution, and the polyamideimide resin solution was adhered to the surface of the capacitor 21. Thereafter, the attached polyamideimide resin solution was cured at 240 ° C. for 30 minutes, and a protective portion 21 e made of polyamideimide resin was formed on the surface of the capacitor 21.

[Example 2]
Polyamideimide resin was used as the protective part forming resin.
In addition, a polyamideimide resin was dissolved in an organic solvent composed of 73 wt% N-methyl-2-pyrrolidone and 27 wt% xylene to prepare a 35 wt% polyamideimide resin solution. The capacitor 21 was immersed in the polyamideimide resin solution, and the polyamideimide resin solution was adhered to the surface of the capacitor 21. Thereafter, the attached polyamideimide resin solution was cured at 230 ° C. for 30 minutes, and a protective portion 21 e made of polyamideimide resin was formed on the surface of the capacitor 21.

[Example 3]
Polyether sulfone resin was used as the protective part forming resin.
Further, N, N-dimethylformamide was used as an organic solvent, and a polyethersulfone resin was dissolved in the organic solvent to prepare a 25 wt% polyethersulfone resin solution. The capacitor 21 was immersed in this polyethersulfone resin solution, and the polyethersulfone resin solution was adhered to the surface of the capacitor 21. Thereafter, the attached polyethersulfone resin solution was cured at 240 ° C. for 30 minutes, and a protective portion 21 e made of polyethersulfone resin was formed on the surface of the capacitor 21.

[Example 4]
Polyarylate resin was used as the protective part forming resin.
Further, N-methyl-2-pyrrolidone was used as an organic solvent, and a polyarylate resin was dissolved in the organic solvent to prepare an 18 wt% polyarylate resin solution. The capacitor 21 was immersed in this polyarylate solution, and the polyethersulfone resin solution was adhered to the surface of the capacitor 21. Thereafter, the adhered polyarylate solution was cured at 210 ° C. for 30 minutes, and a protective portion 21 e made of polyamideimide resin was formed on the surface of the capacitor 21.

[Example 5]
A thermoplastic polyimide resin was used as the protective part forming resin.
Further, N-methyl-2-pyrrolidone was used as an organic solvent, and a thermoplastic polyimide resin was dissolved in the organic solvent to prepare an 18 wt% thermoplastic polyimide resin solution. The capacitor 21 was immersed in this thermoplastic polyimide resin solution, and the polyethersulfone resin solution was adhered to the surface of the capacitor 21. Thereafter, the adhered thermoplastic polyimide resin solution was cured at 210 ° C. for 30 minutes, and a protective portion 21 e made of polyamideimide resin was formed on the surface of the capacitor 21.

  As shown in FIG. 3, the capacitor 21 of the above-described five examples was fixed to the connection portion between the first terminal 12 and the second terminal 22 by electric welding. Thereafter, the melted PPS resin was injection molded as shown in FIG. The temperature of the PPS molten resin during melt molding was 320 ° C., and the molten resin pressure was 27 MPa.

After the formation of the housing 24, the housing 24 was broken and the solder layer 21d of the capacitor 21 was observed. In any of the examples, no change was seen in the solder layer 21d.
Furthermore, when the exterior coating of the epoxy resin was broken and the inside was observed, Example 1 and Example 4 were slightly discolored to a blackish color. This is because thermal degradation of the exterior resin layer 21c made of an epoxy resin slightly progressed at 240 ° C., which is the curing temperature of the protective portion forming resin. However, unlike the conventional case, the outer resin layer 21c is not broken and the solder layer 21d of the capacitor 21 is not melted, as in the case where the PPS resin is melt-molded into a capacitor that does not have the protective portion 21e.

  As described above, the surface of the capacitor 21 is covered with the protective portion forming resin having heat resistance equal to or higher than the melting temperature of the housing forming resin, so that the heat of the housing forming resin can be applied during the melt molding of the housing. The capacitor 21 can be prevented from being damaged by heat, for example, the solder layer 21d is dissolved.

[Comparative example]
As a comparative example, the housing 24 was formed by injection molding of a melted PPS resin in the same manner as in the example using the capacitor 21 having no protective part 21e. After the housing 24 was formed, the housing 24 was broken and the state of the capacitor 21 was observed.
The exterior resin layer 21c made of epoxy resin was melted by the high-temperature housing forming resin, and the housing forming resin reached the surface of the capacitor body 21a. As a result, the housing forming resin having a temperature equal to or higher than the solid phase of the solder layer 21d comes into direct contact with the solder layer 21d, and the solder layer 21d is dissolved by the heat of the dissolved resin, and the solder layer is dissolved by the pressure of the dissolved resin. 21d moved and the terminal electrodes of the capacitor 21 were short-circuited.

[Another embodiment]
In the above-described embodiment, the rotation sensor 4 is described as an example of the electronic device E. However, the electronic device E is not limited to the rotation sensor 4.
Although the capacitor 21 has been described as an example of the electronic device E, the electronic device E may be other than the capacitor 21 such as a resistor and a diode.
Moreover, although the example which provides a protection part in the electronic device E which is one electronic component like the capacitor | condenser 21 was demonstrated, the electronic device may be a printed circuit board etc. which attached several or several electronic components, for example .

The figure which shows the rotation sensor which is an example of the electronic device which concerns on this invention The figure which shows the electronic device before housing formation The figure which shows the capacitor which is an example of the electronic device The figure which shows the capacitor which has the protection part The figure which shows the time-dependent change of temperature and pressure of resin for housing molding

Explanation of symbols

21e Protection part 24 Housing E Electronic device S Electronic device

Claims (6)

An electronic device, a protective part covering the electronic device, and a housing made of a thermoplastic resin melt-molded outside the protective part,
The protection unit is an electronic device whose main component is a resin having a heat resistant temperature equal to or higher than the melting temperature of the thermoplastic resin.   2. The electronic device according to claim 1, wherein, at a melting temperature of the thermoplastic resin, a thermal decomposition rate of the resin that is a main component of the protective portion is 5% or less.   The electronic device according to claim 1, wherein the protection unit has pressure resistance against a molten resin pressure during the melt molding.   The electronic device according to claim 3, wherein the protection unit has a compressive strength and a shear strength equal to or higher than a molten resin pressure in the melt molding.   2. The protective part is formed by adhering a solution of the resin, which is a main component of the protective part, to the surface of the electronic device, and solidifying or curing the resin, which is a main component of the protective part. The electronic device as described in any one of -4.   The resin as the main component of the protective part is at least one resin selected from the group consisting of a polyamideimide resin, a polyethersulfone resin, a polyarylate resin, and a thermoplastic polyimide resin. The electronic device according to one item.

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