This application is based on and claims priority under 35 U.S.C. ยง 119 to Japanese Patent Applications 2003-153364, filed on May 29, 2003 and 2004-151945, filed on May 21, 2004, the entire content of which is incorporated herein by reference.
This invention generally relates to a method of forming a resin molding (a resin casting) by sealing a held member in resin. More particularly, this invention pertains to a holding structure for holding a held member inside a case and a molding (a casting) including the holding structure. The holding structure holds the held member located inside the case by injecting resin into a clearance between the held member and the case.
In a conventional semiconductor device, in order to protect a sensor IC and so on against an external environment such as dust, humidity, impact or the like, an injection molding is performed with ceramic material for air-tight sealing, with epoxy resin for resin sealing, or the like. Hereinafter, a vehicle speed sensor is taken as an example of resin moldings. Detecting precision of the vehicle speed sensor is largely influenced due to even slight fluctuation in a distance between a case surface and a detecting surface of the sensor IC. Therefore, requirements have lead to holding the sensor IC more accurately at a given position.
In general, if the sensor IC is sealed in resin under the condition that the sensor IC has been just located in the case, the sensor IC may be displaced from the given position. Therefore, performance of the semiconductor device may be deteriorated. In light of foregoing, a holding member has been conventionally applied for holding the sensor IC at an appropriate position inside the case, whereby the sensor IC is prevented from being displaced. The holding member is generally attached to a hole at a die surrounding the sensor IC, such that the holding member can hold the sensor IC at the given position. Resin is then injected into the die and molded therein. Accordingly, the sensor IC is sealed in the resin while the holding member retracts. In this case, the holding member should smoothly retracts from the case. For example, if the holding member is adjusted to move back from the case before charging a cavity with the molten resin, the sensor IC may displace due to flow of the molten resin. On the other hand, if the holding member is adjusted to move back from the case after charging the cavity with the molten resin, i.e., after the solidification of the resin, the resin does not reach holes at the holding member and a clearance between the resin and the holding member may be unnecessarily defined. This may cause deterioration of air tightness.
According to Japanese Patent Laid-Open Publication No. 1997-38982, resin is injected into a case while a held member is located inside the case and held by a holding member. The holding member can be moved back and forth relative to the case. This reference discloses a method of insert-molding the held member while the holding member is moved back from the case before charging the case with the resin or after thereof. According to the method of insert-molding the held member, a surface of the holding member in contact with the resin is heated by a heating device (a heating means). At least the holding member surface is heated up to a temperature higher than a surface of resin in contact with an inner surface of the case. Further, according to the method of insert-molding the held member, the resin only at the holding member is heated and molten by the heating device, and the holding member is moved back from the case. Therefore, it can effectively prevent the held member from displacing and avoid deterioration of airtightness.
However, the above-described method of insert-molding the held member requires the heating device and the holding device individually. Further, in order to heat the surface of the holding member in contact with the resin at a higher temperature than the surface of the resin in contact with the case, the heating device is required to be controlled appropriately.
Further, there may be a case that a main body and a flange portion are molded with a secondarily molding resin. The main body is molded for holding the case molded as described above. The flange portion is molded to laterally extend from the main body and is provided with an attaching hole.
A need exists for providing a holding structure capable of holding a held member such as a sensor IC at a given position when the held member is sealed in resin, and for providing a molding provided with the above-described holding structure. The holding structure can hold the held member at the given position with less manufacturing cost and power.
According to an aspect of the present invention, a holding structure includes a held member located in a case, and a guiding space defined between the held member and a predetermined inner surface of the case. A primary molding resin is guided into the guiding space upon injection of the primary molding resin such that the held member is held in the case.
It is preferable that the holding structure further includes a base surface defined in the case and being different from the predetermined inner surface of the case, and means for temporarily holding the held member relative to the base surface. The means for temporarily holding positions the held member relative to the base surface of the case and defines the guiding space between the held member and the predetermined inner surface of the case.
It is further preferable that the holding structure further includes an auxiliary member inserted into the case and to be connected to the held member. The means for temporarily holding is provided at the auxiliary member to push the held member on the base surface such that the held member is held by the means for temporarily holding. The means for temporarily holding in this case is an arm portion. The case can be provided with a contact portion defined at the case. The means for temporarily holding comes in contact with the contact portion and pushes the held member on the base surface.
According to another aspect of the present invention, a molding with the holding structure molded with the primary molding resin includes a main body molded with a secondary molding resin to hold the case, a flange portion molded with the secondary, molding resin laterally extending from the main body and having an attaching hole, and at least one hole defined at a flange base portion side of the flange portion rather than at the attaching hole side thereof.
It is preferable that the with the holding structure molded with the primary molding resin further includes a holder portion molded with the primary molding resin, and at least a holder contact portion provided at the holder portion and being in contact with an inner surface of a secondary molding die so as to position the holder portion relative to the main body. The primary molding resin can correspond to the secondary molding resin.
The foregoing and additional features and characteristics of the present invention will become more apparent from the following detailed description considered with reference to the accompanying drawings, wherein:
a), 1(b), and 1(c) are cross sectional views illustrating a case housing a sensor IC therein according to a first embodiment of the present invention;
a) and 3(b) are cross sectional views illustrating the sensor components sealed in the resin according to the first embodiment of the present invention;
a), 5(b), and 5(c) are cross sectional views illustrating a case housing the sensor IC therein according to a second embodiment of the present invention;
a) and 7(b) are cross sectional views illustrating the sensor components sealed in the resin according to the second embodiment of the present invention;
a), 11(b), and 11(c) are cross sectional views illustrating a secondary molding process for a molding according to the embodiments of the present invention;
a), 13(b), and 13(c) are sectional views illustrating a schematic view of the molding;
a) and 14(b) are a different mode of a hole of the molding; and
a) and 15(b) are a further different mode of the hole of the molding.
A holding structure according to embodiments of the present invention is applied to a vehicle sensor for detecting a vehicle speed based upon fluctuation of magnetic force of a pulsar ring. A held member in the holding structure is a sensor IC 2. The sensor IC 2 can detects the fluctuation of the magnetic force of the pulsar ring, on a peripheral edge portion of which South Pole and North Pole are alternatively arranged, or can detect the presence and absence of a gear rotor tooth.
The vehicle speed sensor as the molding includes sensor components such as a case 1 housed inside a die 10, the sensor IC 2, and an output terminal 6. The case 1, the sensor IC 2, and the output terminal 6 are substantially integrally sealed in resin. Polyamide resin can be applied as the resin injected into the case 1 as a non-limiting example. The injected resin can be, hereinafter, referred to as a primary molding resin.
Next, the holding structure according to a first embodiment of the present invention is described hereinbelow with reference to
As illustrated in
As illustrated in
Next, following explanation will be given for explaining resin-sealing according to the first embodiment of the present invention with reference to
As illustrated in
For example, when a holding member is used for sealing the held member such as the sensor IC 2 in the resin, the held member may be displaced due to the resin flow if the holding member is moved back from the case before solidification of the resin. On the other hand, the resin may not flow into a hole of the holding member if the holding member is moved back from the case after the resin solidification. In this case, the air-tightness in the resin may be deteriorated. As another example, when the resin only around the holding member is molten by a heating device and the holding member is moved back from the case, the displacement of the held member or the deterioration of the air-tightness may be able to be reduced. However, the manufacturing cost and hours may be increased.
In light of foregoing, according to the first embodiment of the present invention, the held member is positioned relative to the predetermined surface in the case 1, with the above-described structure. Further, the resin injected into the guiding space 4 pushes the held member such that there is substantially no clearance between the held member and the base surface 3. Therefore, the held member car be more accurately positioned in the case 1. According to the first embodiment of the present invention, the holding member is not required additionally. The sensor IC 2 can be hence sealed in the resin and positioned at an appropriate position without increasing manufacturing cost. Further, since the holding member is not required, the air-tightness in the resin can be highly achieved.
In the vehicle speed sensor as a non-limiting example, it is necessary to equally maintain a distance between the detecting surface of the sensor IC 2 and the base surface 3 of the case 1 in order to preferably assure the detecting precision and the sensor response. According to the first embodiment of the present invention, the means for temporarily holding is provided for positioning the sensor IC 2 by bringing the sensor IC 2 in contact with the base surface 3 of the case 1 and for defining the guiding space 4 for guiding the resin between the sensor IC 2 and the surface opposed to the base surface 3. Therefore, the distance between the sensor IC 2 and the base surface 3 can be equally assured with less loss of gap. Further, the held member such as the sensor IC 2 can be sealed in the resin with a simple Structure without deteriorating the detecting precision.
Next, a holding structure according to a second embodiment of the present invention is described hereinbelow with reference to
As illustrated in
As illustrated in
Next, following explanation will be given for explaining resin-sealing according to the second embodiment of the present invention with reference to
As illustrated in
According to the second embodiment, some other effects can be generated in addition to the above-described effects according to the first embodiment of the present invention. For example, the case 2 is provided with the two ribs 7. The ribs 7 can effectively increase the intensity of the case 1.
Next, the holding structure according to a third embodiment of the present invention is described hereinbelow with reference to
According to the first embodiment, the case 1 is provided with the convex portion 5 as the means for temporarily holding at the predetermined position of the case 1. According to the second embodiment, the case 1 is provided with the ribs 7 as the means for temporarily holding at the predetermined position of the case 1. According to the third embodiment, a portion of an auxiliary member 11 is applied as the means for temporarily holding.
As illustrated in
As illustrated in
The primary molding resin is then injected into the case 1 having the above-described structure. The resin injection is performed substantially in the same manner as the first and second embodiments. Therefore, the sensor IC 2 can be sealed in the resin while the pushing force of the arm portion 8 has been subjected to the sensor IC 2, thereby enabling to effectively avoid displacement of the sensor IC 2.
Further, the means for temporarily holding corresponds to the arm portion 8 that has a simple structure. Therefore, the sensor IC 2 can be positioned at the appropriate position with the simple structure. Further, the held member such as the sensor IC 2 is positioned by the auxiliary member 11. Therefore, the case 1 can be a conventional case.
According to the first and second embodiments of the present invention, the sensor IC 2 is sealed in the resin while already being engaged with the output terminal 6. Alternatively, the present invention is not limited to the above-described structures. More particularly, the output terminal 6 is not necessarily required, and any other member can be provided.
According to the first, second, and third embodiments, the case 1 houses the single sensor IC 2. Alternatively, the case 1 can house plural sensors IC, and the shape of the case 1 can be different from the above-described rectangular shape.
According to the third embodiment, the arm portion 8 is the leaf spring member. Alternatively, the arm portion 8 can be a rigid body. In this case, the contact portion 9 can include elastic force and push the arm portion 8 on the sensor IC 2.
Further, according to the third embodiment, the auxiliary member 11 is provided with the connecting terminal to be connected with the output terminal of the sensor IC 2. Alternatively, the connecting terminal is not necessarily provided in the auxiliary member 11. In this case, any other member can be provided and be sealed in the resin with the sensor IC 2.
In whichever alternatives described above, the present invention can be effectively achieved.
Next, a molding according to the embodiments of the present invention is described hereinbelow with reference to
The vehicle speed sensor as the molding according to the first, second and third embodiments of the present invention is provided with the sensor components such as the case 1, the output terminal 6, and the sensor IC 2. These sensor components are sealed in the holder portion 12 and are integrated therein. The vehicle sensor is formed by insert-molding the sensor components with a secondary molding resin.
More particularly, as illustrated in
Die projecting portions 20a are defined at an inner surface of the die 20 at a flange base portion 14a. The flange base portion 14a is near the main body 13 rather than the attaching hole 16. With the secondary molding resin flowing in a cavity of the die 20, a secondary molding is cut along the die projecting portions 20a so as to define holes 18. Each of the holes 18 is a concave shape or a: hole without a bottom. Further, a thick portion 12b integrally surrounds an outer peripheral surface of the holder portion 12 substantially at a height of the flange portion 14. In this case, the thickness of the secondary molding resin at the flange base portion 14a becomes substantially equal. Therefore, the secondary molding resin at the flange base portion 14a can substantially equally cooled. Further, the flange base portion 14a and the other portions of the main body 13 can be substantially equally cooled. In this case, the flange base portion 14a can be effectively prevented from being deformed or cambered. Further, occurrence of a surface sink on the flange base portion 14a can be effectively prevented. Therefore, the detecting precision and response of the vehicle sensor can be prevented from being deteriorated due to the displacement of the attaching hole 16 of the flange portion 14 relative to the sensor IC 2.
The holes 18 are defined to have concave shapes at a surface of the flange portion 14, respectively. Alternatively, the holes 18 can be holes without a bottom as illustrated in
Further, as illustrated in
Further, as illustrated in
More particularly, the case 1 housing the sensor IC 2 therein is fit into the inner surface of the die 20 such that an outer surface of the case 1 surrounding the sensor IC 2 is not covered with the secondary molding resin. As illustrated in the drawings, when the holder portion 12 extends and projects at a relatively long distance from the opening portion of the case 1, there may a case that the holder portion 12 rattles in the die 20 due to the injection pressure of the secondary molding resin. In light of foregoing, the holder contact portion 12a of the holding portion 12 can accurately determine the position of the holder portion 12 in the die 20 and can effectively prevent the holder portion 12 from rattling therein. Therefore, in the vehicle speed sensor after the secondary molding process, the displacement between the attaching hole 16 and the sensor IC 2 can be more effectively prevented.
As illustrated in
As illustrated in
As illustrated in
Alternatively, the holder portion 12 can be individually formed by another primary molding process. In this case, the sensor components molded as described above and the holder portion 12 can be insert-molded together with the secondary molding resin. The main body 13, the flange portion 14, the flange base portion 14a, and the holes 18 can be molded in the same manner as described above. In this case, the flange base portion 14a can be effectively prevented from the camber or surface sink thereon. Further, the holder contact portions 12a in contact with the inner surface of the die 20 for determining the position of the holder portion 12 can be arranged in the same manner as described above. The holder contact portions 12a can effectively prevent the holder portion 12 from rattling in the metal made die 20 due to the injection pressure of the secondary molding resin.
According to the embodiments of the present invention, the vehicle speed sensor is formed through the plural molding processes as described above: Alternatively, the vehicle speed sensor can be formed through a single molding process as described below. The holder portion 12 is assembled with the output terminal 6 or is integrated therewith. The sensor IC 2 is connected to the output terminal 6. The holder portion 12 with the sensor IC 2 is then housed in the case 1. At this point, the guiding space 4 is defined between the sensor IC 2 and the case 1. The main body 13 is then integrally molded around the holder portion 12 through the single resin molding process. The resin is guided into the guiding space such that the sensor IC 2 is pushed on the base surface 3.
According to this alternative molding process, it is preferable that the thickness of the holder portion 12 has been pre-designed to be substantially equal relative to each portion of the main body 13. It is further preferable that the thickness of the flange portion 14 is formed to be substantially equal at any portion thereof. Therefore, the time required for cooling the resin can be substantially equal at portions of the molding, thereby enabling to effectively prevent chamber or surface sinks from occurring around the flange portion 14. It is still further preferable that the holder portion 12 is provided with the holder contact portion 12a beforehand, thereby enabling to prevent the holder portion 12 from declining or displacing during the single resin molding process.
The principles, embodiments, and modes of operation of the present invention have been described in the foregoing specification and drawings. However, the invention which is intended to be protected is not to be construed as limited to the particular embodiments disclosed. Further, the embodiments described herein are to be regarded as illustrative rather than restrictive. Plural objectives are achieved by the present invention, and yet there is usefulness in the present invention as far as one of the objectives are achieved. Variations and changes may be made by others, and equivalents employed, without departing from the spirit of the present invention. Accordingly, it is expressly intended that all such variations, changes, and equivalents which fall within the spirit and scope of the present invention as defined in the claims, be embraced thereby.
Number | Date | Country | Kind |
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2003-153364 | May 2003 | JP | national |
2004-151945 | May 2004 | JP | national |
Number | Name | Date | Kind |
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3806766 | Fanning | Apr 1974 | A |
3838316 | Brown et al. | Sep 1974 | A |
4213106 | Egawa et al. | Jul 1980 | A |
5412532 | Nishimori et al. | May 1995 | A |
20030001566 | Tsuge et al. | Jan 2003 | A1 |
Number | Date | Country |
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60-260138 | Dec 1985 | JP |
9-38928 | Feb 1997 | JP |
2002-141240 | May 2002 | JP |
2003-14498 | Jan 2003 | JP |
Number | Date | Country | |
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20040241358 A1 | Dec 2004 | US |