JP4971617B2 - Coil device - Google Patents

Description

  The present invention relates to a coil device.

  A conventional coil device generally has a structure in which a conductive wire is wound around a support member such as a core or a bobbin and the whole is covered with an exterior insulating resin (see Patent Document 1). As the conductive wire, a urethane wire in which a copper wire is coated with urethane is used. The exterior insulating resin is molded by injection molding or the like.

Further, in order to prevent the winding state of the conductive wire from being disturbed during the molding of the exterior insulating resin, an undercoat material serving as a buffer layer between the winding portion formed by winding the conductive wire and the exterior insulating resin It is also known to apply resin.
JP-A-6-325938

  In recent years, coil devices are being used for automobile control devices, and in this case, reliability under considerably severe conditions such as PCT test (pressure cooker test) has been required. Therefore, it is very useful if the undercoat material can be adapted to the PCT test.

  Conventionally, a silicon acrylate insulating resin has been used as the undercoat material. However, when the present applicant examined, since the silicon acrylate insulating resin contains an acrylic ester group in the molecular structure, it is hydrolyzed and decomposed into carboxylic acid in the PCT test. May cause damage. For example, when a urethane film is used as the insulating film of the conductive wire, the urethane film is very likely to be damaged such as erosion.

  The present invention has been made in view of the above problems, and an object thereof is to provide a coil device with higher reliability.

  In order to solve the above-described problem, the coil device according to the present invention includes a support member, a winding portion, an exterior body, and a buffer layer.

  The winding portion is configured by winding a conductive wire around the support member. The exterior body is a resin molded body and covers at least the winding part.

  The said buffer layer is interposed between the said exterior body and the said coil | winding part, and consists of an imide silicon resin.

  In the coil device according to the present invention, the winding portion is configured by winding a conductive wire around a support member. The exterior body is made of a resin molded body and covers at least the winding part. Therefore, the basic structure of the coil device can be obtained.

  Further, a buffer layer is interposed between the exterior body and the winding part. The buffer layer has a function of preventing the winding state of the conductive wire from being disturbed during resin molding of the exterior body.

  As an important feature of the present invention, the buffer layer is made of imidosilicon resin. The imidosilicon resin does not contain an ester group in the molecular structure and does not cause hydrolysis. Therefore, the conductive wire is not damaged.

  Furthermore, since the imide silicone resin is a solvent type, after the imide silicone resin is applied to the winding portion, the solvent is volatilized, and the thickness of the buffer layer made of the coating film can be reduced. Therefore, during the reflow process of the coil device, internal stress on the exterior body can be reduced, and cracks in the exterior body can be suppressed.

  Furthermore, by employing an imide silicon resin, it is possible to suppress the change in inductance over time in the reliability test, for example, the inductance change rate (ΔL / L) over a certain period of time.

  Next, a preferred embodiment will be described.

  As the imide silicon resin, one having a weight composition ratio of silicon and imide of 70:30 to 80:20 can be used. According to such a composition ratio, the low temperature curability, the strength of the coating film and the heat resistance can be improved in comparison with a resin of 100% silicon.

  Moreover, in the case of application | coating of an imide silicone resin, a solvent type can be used which added a solvent and made weight composition ratio of solid content and a solvent 50: 50-20: 80.

  The conductive wire may have an insulating film made of urethane around the conductive core wire. In this case, the urethane insulating film of the conductive wire is not eroded by adopting imide silicon resin as the constituent material of the buffer layer.

  Examples of the constituent material of the exterior body include a thermosetting resin and a thermoplastic resin. In the case of a thermoplastic resin, it is excellent in flexibility in comparison with a thermosetting resin, and the possibility of occurrence of cracks can be reduced. In particular, the liquid crystal polymer is supple and soft, and is suitable as a constituent material of the outer package.

  As described above, according to the present invention, a highly reliable coil device can be provided.

  1 is a partially cutaway perspective view showing an embodiment of a coil device according to the present invention, and FIG. 2 is a front sectional view of the coil device shown in FIG. As illustrated, the coil device according to the present invention includes a winding portion 1, a support member 2, a buffer layer 3, and an exterior body 4. The support member 2 is a core, a bobbin, or a combination thereof, and can take any shape and structure. The support member 2 shown in the embodiment is a core molded using a ferrite magnetic material or the like, and has a rod-like shape in which the intermediate portion 20 is thinned and the flange portions 21 and 22 are provided at both ends thereof.

  V-shaped grooves 211 and 221 are formed in the collar portions 21 and 22. Terminals 71 and 72 are engaged with the grooves 211 and 221, and are fixed by adhesives 61 and 62. The terminals 71 and 72 are metal plate-like members curved in a substantially U shape. More specifically, a nonmagnetic and springy material such as a phosphor bronze plate or a stainless metal plate such as SUS 304-CSP can be used.

  The winding part 1 is configured by winding a conductive wire 5 around an intermediate part 20 of the support member 2. The conductive wire 5 is led from the winding portion 1 through the surfaces of the flange portions 21 and 22 to the terminals 71 and 72, and the terminals 51 and 52 of the conductive wire 5 are joined to the terminals 71 and 72 by means such as soldering. Is done. The conductive wire 5 has a structure in which a conductive core wire is covered with an insulating film. The conductive core wire is, for example, a copper wire. An example of the constituent material of the insulating film is polyurethane.

  The exterior body 4 covers the winding portion 1, the buffer layer 3, and the support member 2. The exterior body 4 can be formed by injection molding or the like using a thermoplastic insulating resin or a thermosetting resin. A liquid crystal polymer can be mentioned as an example of a thermoplastic insulating resin. The liquid crystal polymer has a high melting temperature and excellent heat resistance. Examples of thermosetting resins include diallyl phthalate.

  The buffer layer 3 is made of an imide silicon resin. The buffer layer 3 is interposed between the exterior body 4 and the winding part 1 and covers the winding part 1. In the case of the illustrated embodiment, the buffer layer 3 fills a gap formed between the conductive wires 5 of the winding part 1, and the winding part 1 is integrated with the buffer layer 3 made of imide silicon resin. Further, the buffer layer 3 covers the conductive wire 5 in a region from the winding portion 1 to the terminals 71 and 72. Such a buffer layer 3 can be formed by applying an imide silicon resin to the corresponding portions of the winding portion 1 and the conductive wire 5 before the outer body 4 is resin-molded.

  In the coil device described above, the buffer layer 3 is interposed between the exterior body 4 and the winding part 1. The buffer layer 3 has a function of preventing the winding state of the conductive wire 5 from being disturbed during the resin molding of the exterior body 4.

  If the buffer layer 3 is composed of a silicon acrylate insulating resin, since the silicon acrylate insulating resin contains an ester group in the molecular structure, it is hydrolyzed and decomposed into a carboxylic acid in the PCT test. There is a risk of damaging the insulating film of the conductive wire 5. For example, the insulating film of the conductive wire may be eroded and the conductor core wire may be corroded.

  On the other hand, in this invention, the buffer layer 3 is comprised from an imide silicon resin. The imidosilicon resin does not contain an ester group in the molecular structure and does not cause hydrolysis. Therefore, the conductive wire 5 is not damaged.

  Furthermore, since the imide silicone resin is a solvent type, after the imide silicone resin is applied to the winding part 1, the solvent is volatilized, and the thickness of the buffer layer 3 made of the coating film can be reduced. Therefore, the internal stress with respect to the exterior body 4 can be reduced during the reflow process of the coil device, and the occurrence of cracks can be suppressed.

  Furthermore, by employing an imide silicon resin, it is possible to suppress the change in inductance over time in the reliability test, for example, the inductance change rate (ΔL / L) over a certain period of time.

  In the case of the illustrated embodiment, since the winding part 1 is integrated with the buffer layer 3 made of imide silicon resin, the conductive wire 5 does not move during the resin molding of the exterior body 4. For this reason, the winding state of the winding part 1 can be kept good and a stable inductance value can be secured.

  Furthermore, the coil device of the illustrated embodiment has a configuration that does not include other circuit elements, such as a capacitor and a resistor, but the present invention is not limited to such a configuration, and the capacitor and the resistor It is applicable also to the coil apparatus provided with.

  Next, experimental data will be given and explained.

<Experiment 1>
The durability of the various constituent materials of the buffer layer in the PCT test was examined. Actually, considering the interaction between the buffer layer constituting material and the insulating film of the conductive wire, a sample in a state close to the actual specification was prepared. Details are as follows.

First, after sticking a polyimide double-sided adhesive tape on the surface of the slide glass plate, five ferrite substrates were arranged in a row on the adhesive tape, and two conductive wires were placed on the ferrite substrate. Five such slide glass plates were prepared and used as samples 1 to 5. The following were used for the ferrite substrate and the conductive wire.
(1) Ferrite substrate Material: Ni—Cu—Zn material Dimensions: 2.9 × 2.9 × 1.0 mm
(2) UEW with a conductive wire diameter of 0.050 mm

Next, for each of Samples 1 to 5, a resin was applied in a state where two conductive wires were placed on the ferrite substrate, and cured according to predetermined curing conditions. The resin and curing conditions were as follows.

For sample 1, as the imide silicon resin, one having a weight composition ratio of silicon and imide of 80:20 was used. Furthermore, the when a coating solvent was added, and solid matter, the weight composition ratio of the solvent 43: using solvent type was 5 7.

  Next, each sample 1-5 was exposed to PCT conditions (121 degreeC, humidity 98%, 2 atmospheres), and the sample was evaluated. As an evaluation method, the discoloration of the conductive wire was examined according to the appearance. The evaluation results are as follows.

  In sample 4, the conductive wire changed to brown or black. This means that the insulating film of the conductive wire is corroded and the conductive core wire is corroded.

  In sample 5, the white turbidity of the epoxy resin occurred.

  On the other hand, in samples 1 to 3, there was no discoloration of the conductive wires. Therefore, it is estimated that there is no erosion of the insulating film and corrosion of the conductive core wire.

  Next, the film thickness of the coating film was examined for samples 1 to 3.

  In the silicon resins used in Samples 2 and 3, it was difficult to reduce the viscosity due to their physical properties, and the thickness of the coating film could not be reduced. When the thickness of the coating film is large, the internal stress on the exterior body of the coil device increases, and there is a risk that a crack may occur in the exterior body.

  On the other hand, with the imide silicon resin used in Sample 1, the thickness of the coating film could be reduced. When the thickness of the coating film is small, the internal stress on the exterior body of the coil device can be reduced, and the occurrence of cracks in the exterior body can be suppressed.

  Therefore, the inventors determined that the imidosilicon resin is compatible with the PCT test.

<Experiment 2>
Next, in accordance with the configuration shown in FIGS. 1 and 2, a coil device having a buffer layer made of imide silicon resin was prepared, and the rate of change with time in the PCT test was examined.

  FIG. 3 is data showing the rate of change with time in the PCT test. In FIG. 3, the horizontal axis represents the charging time (hour), and the vertical axis represents the inductance change rate (%). However, the number of measurements n is 30. Referring to FIG. 3, it can be seen that in the coil device in which the buffer layer is made of imide silicon resin, the inductance change rate ΔL / L can be suppressed within a range of ± 0.5%.

It is a partial fracture perspective view showing one embodiment of a coil device concerning the present invention. It is front sectional drawing of the coil apparatus shown in FIG. It is data which shows the time-dependent change rate of the inductance in a PCT test.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Winding part 2 Support member 3 Buffer layer 4 Exterior body 5 Conductive wire

Claims (3)

A coil device including a support member, a winding portion, an exterior body, and a buffer layer, and used in an automobile ,
The winding portion is configured by winding a conductive wire around the support member,
The conductive wire has an insulating film made of urethane around the conductive core wire,
The exterior body is a resin molded body and covers at least the winding part,
The buffer layer is interposed between the exterior body and the winding portion, and is made of imide silicon resin,
The imide silicone resin is a coating film obtained by volatilizing a solvent in a solvent type having a weight composition ratio of silicon and imide of 70:30 to 80:20, and is cured at 80 ° C./30 minutes + 160 ° C./60 minutes. Have
The rate of change with time ΔL / L of the inductance in the PCT test (pressure cooker test) performed under the test conditions of 121 ° C., humidity 98%, and 2 atm is within a range of ± 0.5% at least for 380 hours.
Coil device.   The coil device according to claim 1, wherein the exterior body is made of a thermoplastic resin.   The coil device according to claim 2, wherein the thermoplastic resin is a liquid crystal polymer.