JP4450175B2 - Method for forming sealed structure - Google Patents

Description

  The present invention relates to a method for forming a sealed structure in which a plurality of members are bonded and fixed with an adhesive to form a sealed structure having an internal space.

  Conventionally, as disclosed in Patent Document 1, for example, a sealed structure formed by bonding a plurality of members with an adhesive is known.

This sealed structure is formed by bonding a pair of box-shaped cap members that open to one side with an adhesive in a state where electronic components such as piezoelectric elements are mounted on the bottom surface of one cap member. . Therefore, the electronic component is hermetically sealed in a state of being disposed in the internal space constituted by the cap member, and is configured not to be affected by moisture or the like outside the internal space.
JP 2002-22761 A

  Here, in the formation of the above-described sealed structure, in order to simplify the configuration, for example, a room-temperature curable adhesive is applied to the entire surface of at least one of the opposing bonding portions of the pair of cap members, and the two are positioned in a positioned state. Assemble parts by overlapping and pressing. Specifically, the bonding portions of the pair of cap members are opposed to each other via an adhesive, and the cap member is pressurized in a direction in which the initial internal space formed at this time is reduced. At this time, since the internal space is reduced, the gas in the internal space is compressed and the internal pressure rises. Therefore, since the compressed gas tends to escape outside the internal space through the adhesive before curing, there is a problem that bubbles are generated in the adhesive. Such bubbles are unfavorable in appearance because they swell, for example, on the surface of the adhesive, and require reworking.

  An object of this invention is to provide the formation method of the sealing structure which can reduce the bubble which arises in an adhesive agent in view of the said problem.

In order to achieve the above object, a method for forming a sealed structure according to claim 1 is characterized in that the internal space is formed with respect to a plurality of members constituting the sealed structure having an internal space hermetically sealed in a completed state. Among the bonding parts of a plurality of members to be hermetically sealed, the application process of applying an adhesive to at least one of the opposing bonding parts and the bonding parts are opposed to each other through the adhesive before the adhesive is cured. And an assembly process for pressurizing and assembling a plurality of members in a direction in which the initial internal space formed at this time is reduced, and curing to fix the members to each other by curing the adhesive in the assembled state A process. Then, in the application process, a gap that is a non-application area of the adhesive for discharging a part of the gas in the initial internal space at the time of executing the assembly process is formed in a part of the adhesion part. is closed when the assembly is completed by the flow of the adhesive, the interior space of the sealed structure, characterized in that it is hermetically sealed.

As described above, according to the method for forming a sealed structure of the present invention, the non-application of the adhesive for discharging a part of the gas in the initial internal space at the time of performing the assembling process on a part of the bonding site in the applying process. A gap that is a region is positively formed. Accordingly, it is possible to mitigate an increase in internal pressure of the internal space when the initial internal space is reduced to become an internal space. That is, bubbles generated in the adhesive can be reduced. In addition, the adhesive flows due to the pressurization during assembly, the gap is gradually reduced, and the gap is closed when the assembly is completed, so that the internal space of the sealed structure can be hermetically sealed. it can.

  Since the adhesive part has an annular structure surrounding the internal space, the application start position and the application of the adhesive when applying the adhesive by, for example, a dispenser in the application process, as described in claim 2. By setting the end position to a different position, the gap can be easily formed.

  The plurality of members are not limited as long as they form a sealed structure by being bonded with an adhesive. For example, as described in claim 3, the plurality of members includes a pair of an upper case and a lower case. Configuration can be applied.

  The completed sealed structure has an airtightly sealed internal space. Therefore, as described in claim 4, by forming the initial internal space in a state where the electronic components such as the sensor chip are accommodated, the electronic components are placed in the internal space of the sealed structure so as not to be affected by moisture. It can be hermetically sealed.

In the case of a thermosetting adhesive , the gas in the inner space is thermally expanded by heating, which may cause bubbles in the adhesive again. Therefore, as the adhesive, it is preferable to apply a room temperature curable adhesive (for example, a moisture curable type or a UV curable type) as described in claim 5 .

Further, in the application step, as described in claim 6, when more adhesive is applied to the application positions adjacent to both ends of the gap than the other application positions, the gap is closed until the adhesive is cured. It becomes easy to do.

In addition, as described in claim 7 , the plurality of members have a configuration in which a convex portion is provided on one of the opposing adhesion portions, and a concave portion that accommodates the convex portion is provided on the other side. By applying the adhesive inside, it is possible to prevent unnecessary protrusion (overflow) of the adhesive to other than the bonding site.

At that time, as described in claim 8 , when the width of the convex portion is provided narrower than the width of the concave portion, and the convex portion is disposed in the concave portion, at least a part of the side surface together with the front end surface of the convex portion. When the adhesive is in contact with the adhesive, the bonding area can be increased, and the strength of the sealed structure can be improved.

Hereinafter, embodiments of the present invention will be described with reference to the drawings.
(First embodiment)
FIG. 1 is a partial cross-sectional view showing a schematic configuration of a sealed structure in the present embodiment.

  As shown in FIG. 1, the sealed structure 100 according to the present embodiment is disposed in an internal space 30 constituted by a pair of an upper case 10 and a lower case 20 as a plurality of members, and the upper case 10 and the lower case 20. And a circuit board 40 as an electronic component.

  As a material constituting the upper case 10 and the lower case 20, a resin such as polyphenylene sulfide, ceramic, or the like can be applied. In this embodiment, polybutylene terephthalate (PBT) is applied. The upper case 10 and the lower case 20 may be made of different materials.

  Moreover, at least one has the concave structure so that the upper case 10 and the lower case 20 may comprise the internal space 30 in the state assembled | attached mutually. In the present embodiment, the upper case 10 has a box-type structure opened on one side, and the lower case 20 also has a box-type structure where a part corresponding to the upper case 10 is opened on one side. And the adhesion | attachment site | part is provided in the peripheral part which protrudes substantially perpendicularly from each bottom face part.

  As shown in FIG. 1, the bonding portion of the upper case 10 is a protruding tip 11 (a tip surface and a side surface within a predetermined range from the tip surface) of the peripheral portion, and the bonding portion of the lower case 20 is formed on the tip surface of the peripheral portion. It is the groove part 21. And both the protrusion front-end | tip 11 and the groove part 21 are cyclically | annularly provided corresponding to the cyclic | annular peripheral part. Moreover, the groove part 21 is provided in the said groove part 21 so that the protrusion front-end | tip 11 can be arrange | positioned. In the present embodiment, the width of the protruding tip 11 is provided narrower than the width of the groove 21, and when the protruding tip 11 is disposed in the groove 21, it adheres to at least a part of the side surface together with the tip surface of the protruding tip 11. The composition is in contact with the agent 50. With such a configuration, the bonding area can be increased, so that the strength of the sealed structure 100 can be improved. Moreover, since the lower case 20 has the groove part 21 as an adhesion part, the adhesive agent 50 is apply | coated in the said groove part 21, and the assembly | attachment is implemented, and the adhesive agent 50 other than an adhesion part is unnecessary. Protrusion can be prevented.

  The protruding tip 11 is disposed in the adhesive 50 in a state where the adhesive 50 is applied (filled) in the groove portion 21, and the upper case 10 and the lower case 20 are bonded and fixed. Therefore, the internal space 30 constituted by the upper case 10 and the lower case 20 is hermetically sealed by the upper case 10, the lower case 20, and the adhesive 50, and the circuit board 40 disposed in the internal space 30 is sealed. Prevent from moisture, oil, etc.

  As the adhesive 50, it is preferable to apply a normal temperature curable adhesive such as a moisture curable adhesive or a UV curable adhesive instead of a thermosetting adhesive. In the case of a thermosetting adhesive, the gas in the internal space 30 that is hermetically sealed by heating may thermally expand, and bubbles may be generated in the adhesive 50 again. Therefore, in this embodiment, a two-component mixed epoxy adhesive that is a room temperature curing adhesive is applied as the adhesive 50.

  In FIG. 1, reference numeral 12 denotes a positioning concave portion formed on the upper case 10, and reference numeral 22 denotes a positioning convex portion formed on the circuit board 40 fixed to the inner surface of the bottom surface portion of the lower case 20. Then, by inserting and fixing the positioning convex portion 22 to a predetermined position of the positioning concave portion 12 (for example, a so-called snap fit structure), the assembling direction of the upper case 10 and the lower case 20 (extending direction of the peripheral portion) and the bottom surface portion. The position in the plane direction is determined. In the present embodiment, the positioning recess 12 is formed integrally with the upper case 10, and the positioning protrusion 22 is bonded and fixed to the circuit board 40. Details of the assembly will be described later.

  The circuit board 40 is formed with a signal processing circuit and the like, and a sensor chip (for example, an acceleration sensor), a discrete component, etc. (not shown) are mounted on the surface thereof. And it is electrically joined to the terminal part which is not illustrated formed in the bottom face part of the lower case 20 via solder etc., and it has the composition which can output a detection signal outside via the terminal 23. The terminal 23 is insert-molded in the lower case 20, protrudes from an opening 24 formed in the lower case 20, and constitutes a connector portion 25 together with the lower case 20.

  Thus, in the sealed structure 100 according to the present embodiment, the circuit board 40 as an electronic component is disposed in the internal space 30 constituted by the upper case 10 and the lower case 20, and the circuit board 40 is placed in the upper case. 10, a sensor device hermetically sealed with a lower case 20 and an adhesive 50. Therefore, such a sensor device can be disposed in the engine room as an impact detection sensor, for example.

  Next, a method for forming the sealed structure 100 will be described with reference to FIGS. 2 (a) and 2 (b) and FIGS. 3 (a) and 3 (b). In the description of the forming method, the application of the adhesive 50, which is a characteristic part of the present embodiment, will be particularly described. 2A and 2B are diagrams for explaining the application process and the assembly process. FIG. 2A is a plan view for explaining the application range of the adhesive 50 before the assembly, and FIG. 2B shows the assembly process. It is a schematic sectional drawing for doing. FIG. 3 is a diagram for explaining after the assembly process is completed (curing process), (a) is a plan view for explaining the application range of the adhesive 50 after the assembly is completed, and (b). FIG. 3 is a schematic sectional view after assembly is completed. In FIG. 2A and FIG. 3A, for convenience, only the box-shaped structure portion of the lower case 20 to which the upper case 10 is assembled is illustrated, and the circuit board 40 is omitted.

  First, a preparation process for preparing the upper case 10 and the lower case 20 is performed. Both the upper case 10 and the lower case 20 in this embodiment are made of PBT as a constituent material and are processed into a predetermined shape by injection molding. At that time, the terminal 23 and the like are also inserted and integrated with the lower case 20. Then, the circuit board 40 is fixed on the bottom surface of the lower case 20 so as to be electrically connected to the terminal 23.

  After completion of the preparation process, an application process for applying the adhesive 50 is performed before the assembly process.

  Here, it is possible to prevent an increase in internal pressure of the internal space 30 (that is, to prevent generation of bubbles in the adhesive 50) by adopting a configuration in which the application step is performed after the assembly step. However, since the adhesive 50 must be applied to the bonding site in the state where the upper case 10 is assembled to the lower case 20, the bonding site becomes large, and it is difficult to reduce the size of the sealed structure 100. Become. Therefore, as shown in the present embodiment, when the coating process is performed first, the size of the sealed structure 100 can be reduced.

  Specifically, a two-component mixed epoxy adhesive is used as the adhesive 50, the viscosity is adjusted (for example, the viscosity is 50 to 100 poise at 40 ° C.), and applied to the groove portion 21 of the lower case 20 by a dispenser (not shown) ( Discharge). And the dispenser side was fixed, the lower case 20 side was moved, for example with the robot, and it apply | coated to the predetermined range of the groove part 21 provided in cyclic | annular form. In addition, it is good also as a structure which moves the dispenser side and performs application | coating.

  Here, the present embodiment is characterized in that the adhesive 50 is applied so that a gap 51 that is a non-application region is formed in a part of the groove portion 21 that is an adhesion portion provided in an annular shape. Specifically, as shown in FIG. 2A, by setting the application start position 52a and the application end position 52b to different positions, there is a non-application area between the application start position 51a and the application end position 51b. A gap 51 is formed.

  The gap 51 makes the internal pressure in the internal space 30 compressed at the time of assembly substantially equal to the external pressure outside the internal space 30 (normal atmospheric pressure), and the upper case 10 is pressurized to reduce the internal space 30. Needed while changing. Further, the gap 51 needs to be closed before the curing of the adhesive 50 is completed in order to hermetically seal the internal space 30. Accordingly, the gap 51 discharges the gas in the internal space 30 that is compressed at the time of assembly based on the viscosity of the adhesive 50, the curing time, the application amount of the adhesive 50, and the like, and cures. It is formed with a predetermined range so that the internal space 30 is hermetically sealed by the flow of the adhesive 50 by the time.

  In the present embodiment, as shown in FIG. 2A, more adhesives 50 are applied to the application positions adjacent to both ends of the gap 51, that is, the application start position 52a and the application end position 52b than other application positions. Is applied (that is, a liquid reservoir is provided). With such a configuration, the gap 51 is easily closed before the adhesive 50 is cured.

  Next, after the application process is completed, an assembly process is performed. In the present embodiment, the upper case 10 is assembled to the lower case 20. The upper case is positioned so that the positioning concave portion 12 formed in the upper case 10 is positioned with respect to the positioning convex portion 22 formed in advance on the circuit board 40, and the positioning convex portion 22 is inserted into the positioning concave portion 12. 10 is pressed in the direction of the white arrow in FIG.

Here, when a predetermined amount of the positioning convex portion 22 is inserted into the positioning concave portion 12, the protruding tip 11 of the upper case 10 comes into contact with the surface of the adhesive 50 filled in the groove portion 21 of the lower case 20. An internal space 30 (volume V ₀ : initial internal space shown in claims) is formed. Conventionally, the gap 51 which is a non-application area is not formed, and the adhesive 50 is applied to the entire surface of the groove portion 21. Therefore, when the initial internal space 30 is formed, the internal space 30 is hermetically sealed. It will be in the state.

  Then, when the upper case 10 is further pressurized and the positioning convex portion 22 is inserted into the positioning concave portion 12 to a predetermined position where the positioning convex portion 22 is fixed with respect to the positioning concave portion 12, the protruding tip 11 is also in the groove portion 21 accordingly. It is buried deeply by the adhesive 50, and the contact area with the adhesive 50 increases. Accordingly, the upper case 10 and the lower case 20 are firmly connected via the adhesive 50 in a state where the adhesive 50 is cured.

At this time, as the contact area of the protruding tip 11 with the adhesive 50 increases, the internal space 30 is also reduced (volume V ₁ : V ₁ is smaller than V ₀ ), so that the gas in the internal space 30 is compressed. The internal pressure increases. Therefore, the compressed gas tends to escape to the outside of the internal space 30 through the adhesive 50 that is weakest in strength in the sealed internal space 30, so that bubbles are generated in the adhesive 50. There was a problem that occurred. In particular, when the adhesive 50 is cured, it is not preferable in appearance if the surface of the adhesive 50 on the side in contact with the external space is swollen or swollen by bubbles. In this case, reworking (for example, scraping the bubble surface) It was necessary to prepare and inject the filler.

  However, in the present embodiment, as shown in FIG. 2B, there is a gap 51 that is a non-application region between the protruding tip 11 and the groove portion 21 at least until the assembly is completed. Therefore, even if the upper case 10 is further pressurized and the internal space 30 is further reduced from the state in which the initial internal space 30 is formed, the gas in the internal space 30 flows from the gap 51 into the interior according to the pressurization. It is discharged out of the space 30. As described above, by actively providing the gap 50, the contact area between the protruding tip 11 and the groove 21 and the adhesive 50, which are adhesion sites, is increased (that is, the strength of the sealed structure is improved), while the internal space is increased. The increase in the internal pressure of the space 30 can be mitigated (that is, bubbles generated in the adhesive 50 can be reduced).

  Further, the gap 51 in the present embodiment is a point in time when the adhesive 50 flows due to pressurization at the time of assembly, the gap 51 is gradually reduced, and the assembly is completed (the reduction in the reduction of the internal space 30 is stopped). Thus, as shown in FIGS. 3A and 3B, they are closed (that is, the application start position 52a coincides with the application end position 52b). Therefore, after the assembly process, the internal space 30 is hermetically sealed by the upper case 10, the lower case 20, and the adhesive 50 when the adhesive 50 is cured by being left at room temperature for a predetermined time in the curing process. . Note that the gap 51 may exist at the time when the assembly is completed, and may be blocked by the flow of the adhesive 50 at least until the adhesive 50 is cured.

  As described above, according to the method for forming the sealed structure 100 shown in the present embodiment, in the coating process, the adhesive for discharging a part of the gas in the internal space 30 in the assembling process is applied to a part of the groove portion 21. Since the gap 51 which is a non-application area of the agent 50 is formed, bubbles generated in the adhesive 50 can be reduced. Therefore, it is possible to form the sealed structure 100 having a clean appearance without performing a reworking operation. Further, since the reworking work is reduced or unnecessary, the manufacturing cost can be reduced.

  Further, the gap 51 is closed by the flow of the adhesive 50 by the time of curing, and the internal space 30 of the sealed structure 100 is hermetically sealed, so that the circuit board 40 disposed in the internal space 30 is protected from moisture or the like. Can be protected.

  Although the preferred embodiments of the present invention have been described above, the present invention is not limited to the above-described embodiments, and can be implemented with various modifications.

  In this embodiment, the example which the some member which comprises the sealing structure 100 consists of a pair of upper case 10 and the lower case 20 showed. However, the plurality of members are not limited to a pair, and may be composed of three or more members.

  Moreover, in this embodiment, the example in which the circuit board 40 is arrange | positioned in the internal space 30 of the sealed structure 100 as an electronic component was shown. However, the feature of the present embodiment is not that the circuit board 40 is provided in the internal space 30, but the method of forming the sealed structure 100 itself. Therefore, what is arranged in the internal space 30 is not particularly limited.

  In the present embodiment, the bonding portion of the lower case 20 is the groove portion 21, and the protruding tip 11 of the upper case 10 is disposed in the groove portion 21 in a state where the adhesive agent 50 is applied to the groove portion 21. The example of the structure which connects each other via was shown. However, the connection structure is not limited to the above example. For example, as shown in FIGS. 4 (a) and 4 (b), the tip surfaces of the peripheral portions having a box-shaped structure are at least bonded to each other, and the tip surfaces are connected to each other via an adhesive 50. The invention of this embodiment is applicable. However, in this case, if the amount of application to the front end surface is large, the adhesive 50 protrudes (overflows) beyond the front end surface as shown in FIG. Further, if the application amount on the tip surface is reduced, the adhesive 50 can be prevented from protruding beyond the tip surface, but the increase in the contact area of the bonded portion with respect to the adhesive 50 is small. Therefore, it is preferable to have a configuration having a convex portion on one side and a concave portion that accommodates the convex portion on the other side of the facing adhesive portions.

  Moreover, in this embodiment, the upper case 10 has the positioning recessed part 12, and the lower case 20 showed the example which has the positioning convex part 22 in the circuit board 40 fixed on the bottom face part. However, the positioning of the upper case 10 and the lower case 20 is not limited to the above configuration.

It is a fragmentary sectional view which shows schematic structure of the sealing structure in the 1st Embodiment of this invention. It is a figure for demonstrating an application | coating process and an assembly | attachment process, (a) is a top view for demonstrating the application | coating range of the adhesive agent 50 before an assembly | attachment, (b) is the outline for demonstrating an assembly | attachment process. It is sectional drawing. It is a figure for demonstrating after an assembly | attachment process (hardening process), (a) is a top view for demonstrating the application | coating range of the adhesive 50 after completion | finish of an assembly | attachment, (b) is after completion | finish of an assembly | attachment. It is a schematic sectional drawing. It is a figure which shows the modification of this embodiment, (a) has shown the assembly | attachment process, (b) has shown the assembly process completion (hardening process).

Explanation of symbols

10 ... Upper case 11 ... Projection tip (adhesion site)
20 ... Lower case 21 ... Groove (adhesion site)
30 ... Internal space 40 ... Circuit board 50 ... Adhesive 51 ... Gap (non-application area)
52a ... coating start position 52b ... coating end position 100 ... sealed structure (sensor device)

Claims (8)

The plurality of members constituting a hermetic structure having an internal space hermetically sealed in a completed state, the bonding sites facing each other among the bonding sites of the plurality of members surrounding and sealing the internal space An application step of applying an adhesive to at least one of
Before the adhesive is cured, the assembling step of assembling by pressing the plurality of members in a direction in which the adhesive portions are opposed to each other via the adhesive and the initial internal space formed at this time is reduced. When,
A method of forming a sealed structure comprising: a curing step of curing the adhesive in the assembled state and fixing the plurality of members to each other;
In the application step, a gap that is a non-application region of the adhesive for discharging a part of the gas in the initial internal space at the time of execution of the assembly step is formed in a part of the adhesion site,
The gap, the are closed when the assembling is completed by the flow of the adhesive, the method of forming the sealing structure in which the internal space of the sealed structure, characterized in that it is hermetically sealed.   2. The method for forming a sealed structure according to claim 1, wherein, in the application step, the gap is formed between an application start position and an application end position of the adhesive.   The method for forming a sealed structure according to claim 2, wherein the plurality of members includes a pair of an upper case and a lower case.   The method for forming a sealed structure according to claim 1, wherein the initial internal space is formed in a state in which an electronic component is stored. The method for forming a sealed structure according to any one of claims 1 to 4 , wherein a normal temperature curable adhesive is used as the adhesive . 6. The sealed structure according to claim 1 , wherein, in the application step, more adhesive is applied to application positions adjacent to both ends of the gap than to other application positions . Forming method. The plurality of members have a convex portion on one of the opposing adhesion portions, and a concave portion that houses the convex portion on the other side,
In the said application | coating process, the said adhesive agent is apply | coated in the said recessed part, The formation method of the sealing structure of any one of Claims 1-6 characterized by the above-mentioned. The width of the convex portion is provided narrower than the width of the concave portion, and when the convex portion is disposed in the concave portion, the adhesive contacts at least a part of the side surface together with the front end surface of the convex portion. The method for forming a sealed structure according to claim 7 .

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