Electronic unit and electronic apparatus

An electronic unit according to the present invention, the first support member has a first base body, and a first contact member extending from the first base body and making contact with the first main surface of the substrate. The second support member includes a second base body, and a second contact member extending from the second base body and making contact with the second main surface of the substrate. At least part of the area on the first main surface that corresponds to the region at which the second contact member is in contact with the substrate overlaps with the region at which the first contact member is in contact with the substrate. This electronic unit is capable of suppressing distortion in the substrate even when an impact is applied from the exterior. The electrical connection between the electronic component and the substrate can therefore be prevented from being disrupted.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The present invention relates to an electronic unit and electronic apparatus provided with a substrate that includes electronic components, and particularly relates to an electronic unit and electronic apparatus in which it is difficult to disrupt the electric connections between wires and electronic components mounted on the substrate even under the application of an external force.

2. Description of Related Art

Electronic apparatuses such as computers, television receivers, and recording/reproducing apparatuses that record to and play back from disks and the like are provided with substrates on which electronic components are mounted. As an example of such an electronic apparatus, JP 2006-120378A (referred to as “Patent Document 1” hereinafter) discloses the configuration of an intercom provided with a substrate on which electronic components are mounted.

FIG. 7illustrates a cross-sectional view of this conventional electronic apparatus. As shown inFIG. 7, an intercom101, which is an example of an electronic apparatus, includes an outer housing108that encloses the apparatus. A substrate102, on which an electronic component103is mounted, is contained within the housing108. Terminals104of the electronic component103are electrically connected to the wiring (not shown) of the substrate102. Bosses105are formed in the housing108, and the substrate102is anchored to the housing108by threading screws107through the substrate102and into the bosses105.

In recent years, weight reduction and miniaturization have been progressing in electronic devices, and the portability thereof is improving, as exemplified by laptop computers, mobile telephone terminals, portable game devices, and so on. Electronic devices that feature such portability are more likely to, for example, be dropped on the floor, collide with other objects, and so on, and thus it is necessary to shock-proof such devices.

FIG. 8illustrates a perspective view of a conventional electronic apparatus111that has been shock-proofed.FIG. 9illustrates a cross-sectional view taken along the C-C line shown inFIG. 8.FIG. 9is a cross-sectional view of a substrate116that has been cut vertically relative to its main surface.

As shown inFIG. 9, a housing112contains an intermediate chassis114. The intermediate chassis114is anchored to the housing112via support portions113. The intermediate chassis114is formed of metal, and bosses115are formed on the inner surface of the intermediate chassis114. The substrate116is anchored to the bosses115with screws117. An electronic component118is mounted on the substrate116. Terminals118aof the electronic component are connected to a wiring pattern116aprovided on the surface of the substrate116. Recently, taking into consideration high-density mounting and space conservation, components packaged as ball grid arrays (BGAs) are used as the electronic component118. Furthermore, the rear surface of the mounting surface of the electronic component118is in contact with the intermediate chassis114via a buffer member118bformed of a material that has a high degree of thermal conductivity, such as graphite.

According to the electronic apparatus shown inFIG. 9, heat generated by the electronic component118can be dissipated to the intermediate chassis114via the buffer member118bformed of a material that has a high degree of thermal conductivity, thereby improving the efficiency of heat dissipation of the electronic component118. Furthermore, electromagnetic waves emitted by the electronic component118are absorbed by the intermediate chassis114, making it possible to reduce electromagnetic waves leaking to the exterior of the electronic apparatus.

If an impact is applied to such a conventional electronic apparatus, such as when the apparatus is dropped accidentally, the impact on the housing112will pass through the support portion113and the intermediate chassis114to the substrate116. Because both ends of the substrate116are anchored to the bosses115using the screws117, when a force such as an impact is applied, the substrate116experiences a wave and distorts, as shown inFIG. 10. When the substrate116distorts, there is a high probability that the terminals118aof the electronic component118mounted upon the substrate116will separate from the wiring pattern116aformed on the surface of the substrate116, disrupting the electrical connection. Although such separation of terminals from the wiring pattern occurs more prominently in electronic components packaged as BGAs, there is also the chance for such a disconnection to occur in electronic components whose terminals are connected using connection wiring provided by QFPs (Quad Flat Packages).

SUMMARY OF THE INVENTION

Therefore, with the foregoing in mind, it is an object of the present invention to provide an electronic unit and electronic apparatus capable of preventing a substrate from distorting and disrupting connections even if a drop impact or the like is applied to the electronic apparatus.

The electronic unit of the present invention comprises a substrate including a first main surface and a second main surface opposite to the first main surface, on which an electronic component is mounted, and a support member that supports the substrate. The support member includes a first support member and a second support member, with the substrate being sandwiched between the support members. The first support member includes a first base body, and a first contact member capable of being in contact with the first main surface. The second support member includes a second base body, and a second contact member capable of being in contact with the second main surface; and at least part of the area on the substrate at which the first contact member is in contact with the substrate overlaps with a region at which the second contact member is in contact with the substrate.

The electronic apparatus of the present invention comprises a housing and an electronic unit that includes a substrate having a first main surface on which an electronic component is mounted and a second main surface opposite to the first main surface, and a support member that supports the substrate. The electronic unit is contained in the housing, and the support member includes a first support member and a second support member, with the substrate being sandwiched between the support members; the first support member includes a first base body, and a first contact member capable of being in contact with the first main surface. The second support member includes a second base body, and a second contact member capable of being in contact with the second main surface; and at least part of the area on the substrate at which the first contact member is in contact with the substrate overlaps with a region at which the second contact member is in contact with the substrate.

According to the present invention, an electronic unit and electronic apparatus capable of preventing a substrate from distorting and severing connections even if a drop impact or the like is applied to the electronic apparatus can be provided by supporting the substrate with a first contact member and a second contact member.

DETAILED DESCRIPTION OF THE INVENTION

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

The electronic unit of the present invention comprises a substrate including a first main surface and a second main surface opposite to the first main surface, on which an electronic component is mounted, and a support member that supports the substrate. The support member includes a first support member and a second support member, with the substrate being sandwiched between the support members. The first support member includes a first base body, and a first contact member capable of being in contact with the first main surface. The second support member includes a second base body, and a second contact member capable of being in contact with the second main surface; and at least part of the area on the substrate at which the first contact member is in contact with the substrate overlaps with a region at which the second contact member is in contact with the substrate.

The electronic unit of the present invention can take on various forms using the aforementioned configuration as a base.

In other words, the configuration of the electronic unit of the present invention can be such that either the first contact member and the first base body, the second contact member and the second base body, or both sets of contact members and base bodies are formed as a single body. With such a configuration, it is possible simultaneously to manufacture the first contact member and first base body and/or the second contact member and second base body, making it possible to eliminate a process for anchoring the contact members to their respective base bodies. Furthermore, the resistance to impact, due to disturbances, that shakes the substrate in the surface direction can be improved.

The configuration of the electronic unit of the present invention can be such that the first contact member and the second contact member are capable of making contact with the substrate at the region that experiences the largest amount of distortion. Through such a configuration, it is possible to suppress the overall substrate from distorting when an impact is applied to the electronic unit. Accordingly, it is possible to prevent breakage, such as cracks, from occurring in parts of the substrate, in the vicinity of the portions of the substrate anchored to the support members, the outer edges of the corners of the substrate, and so on.

The configuration of the electronic unit of the present invention can be such that the center line of the first contact member and the center line of the second contact member are matched, and the center lines are center on the surface of the contact members that is in contact with the substrate. Through such a configuration, it is possible to suppress the overall substrate from distorting when an impact is applied to the electronic unit. In addition, the first contact member and second contact member can be brought into contact with the substrate at right angles. Accordingly, it is possible to prevent breakage, such as cracks, from occurring in the vicinity of the portions of the substrate anchored to the support members. It is also possible to cause, for example, a rotation moment in the substrate, thereby suppressing the burden placed on the substrate.

The configuration of the electronic unit of the present invention can be such that the first contact member and the second contact member are capable of making contact with the substrate in the vicinity of the electronic component. By employing such a configuration, it is possible to suppress impacts on the substrate arising due to disturbances applied to the electronic unit, thereby making it possible to prevent the soldered connections between the substrate and the electronic component from separating.

The configuration of the electronic unit of the present invention can be such that the first contact member and the second contact member are plate-shaped. By employing such a configuration, the rigidity of the first base body and the second base body can be improved.

1. Configuration of Electronic Apparatus

FIG. 1is a perspective view of an electronic apparatus1according to Embodiment 1 of the present invention. The electronic apparatus1is an apparatus provided with a substrate on which electronic components are mounted, such as a personal computer, a terminal apparatus for an inventory management system, a mobile telephone terminal, or the like. In the present embodiment, a laptop computer shall be described as an example of the electronic apparatus1.

The electronic apparatus1includes a first housing4and a second housing5. The first housing4provides a display monitor2. The second housing5, meanwhile, includes an operational unit3. The first housing4and the second housing5are connected by a hinge mechanism configured of hinge portions10, enabling the two housings to pivot in the direction of or opposite to the arrow Z. The display monitor2can be implemented by, for example, a liquid-crystal display. The operational unit3accepts input operations made by a user. The operational unit3can be implemented using a keyboard, a touch panel, or the like.

Note that a state in which the first housing4of the electronic apparatus1has been rotated so that the display monitor2and the operational unit5are exposed, as shown inFIG. 1, is defined as an “open state”. Likewise, a state in which the first housing4has been rotated in the direction of the arrow Z from the state shown inFIG. 1, thereby placing the display monitor2and the operational unit3opposite to each other, is defined as a “closed state”. The direction of the second housing5when the electronic apparatus1is in the closed state and the second housing5is opposite to the first housing4is defined as “up”. The direction opposite to “up” with respect to the second housing5therefore is defined as “down”.

FIG. 2is a cross-sectional view taken along the A-A line shown inFIG. 1. Note that inFIG. 2, elements unnecessary in the descriptions of the present embodiment have been omitted.

An electronic unit13is enclosed within an upper surface housing11and a lower surface housing12, which together make up the second housing5. The electronic unit13includes an upper chassis14and a lower chassis17. The upper chassis14and the lower chassis17are connected to each other, and within the inner space formed by the two chassis being connected, a substrate23is provided.

The upper chassis14includes an upper primary wall15and upper side walls16. Buffer members20are anchored between the upper primary wall15and the upper surface housing11. The buffer members20may be formed of an elastic material such as rubber.

The lower chassis17includes a lower primary wall18and lower side walls19. Buffer members21are anchored between the lower primary wall18and the lower surface housing12. The buffer members21may be also formed of an elastic material such as rubber. End portions19aof the lower side walls19are in contact with end portions16aof the upper side walls16.

Bosses22are formed in the inner surface of the lower primary wall18(that is, the surface opposite to the upper primary wall15) as a single body. End portions22aof the bosses22are end portions that are in contact with the substrate23. A screw hole22bis formed in each end portion22a. Through-holes23c, through which screws24can pass, are formed in the substrate23. The screws24are passed through the through-holes23cfrom the side of the upper surface23aof the substrate23, and are threaded into the screw holes22b, thereby anchoring the substrate23to the bosses22. This makes it possible to anchor the substrate23to the lower chassis17.

A wiring pattern23dis provided in the upper surface23aof the substrate23. Terminals25aof an electronic component25may be electrically connected to the wiring pattern23dof the substrate23with solder.

A through-hole15ais formed in the upper primary wall15. The inner surface15bof the upper primary wall15(the surface opposite to the lower primary wall18) is in contact with an upper column member26(contact member) via an end portion26a. The end portion26aof the upper column member26is the end portion on the side of the upper column member26that is in contact with the upper primary wall15. Meanwhile, the other end portion of the upper column member26, or an end portion26bopposite to the end portion26a, is in contact with the upper surface23aof the substrate23, or is opposite the upper surface23aof the substrate23with an extremely small amount of space provided therebetween. A screw hole26cis formed in the end portion26a. A screw27is threaded through the through-hole15aand into the screw hole26c, thereby anchoring the upper column member26to the upper primary wall15.

A through-hole18ais formed in the lower primary wall18. The inner surface18bof the lower primary wall18(the surface opposite to the upper primary wall15) is in contact with a lower column member28(contact member) via an end portion28a. The end portion28aof the lower column member28is the end portion on the side of the lower column member28that is in contact with the lower primary wall18. Meanwhile, the other end portion of the lower column member28, or an end portion28b, is in contact with the lower surface23bof the substrate23, or is opposite the lower surface23bof the substrate23with an extremely small amount of space provided therebetween. A screw hole28cis formed in the end portion28a. A screw29is threaded through the through-hole18aand into the screw hole28c, thereby anchoring the lower column member28to the lower primary wall18.

Although the end portion26bof the upper column member26and the upper surface23aof the substrate23may be in tight contact or are opposite each other with an extremely small amount of space provided therebetween, it should be noted that the present embodiment describes an example in which the two are in tight contact. Likewise, although the end portion28bof the lower column member28and the lower surface23bof the substrate23may be in tight contact or are opposite each other with an extremely small amount of space provided therebetween, it should be noted that the present embodiment describes an example in which the two are in tight contact. In the following descriptions, the term “contact” is intended to be taken as meaning “tight contact” unless otherwise specified. Note that an “extremely small amount of space” refers to a distance less than or equal to the amplitude of the distortion that is transmitted to the substrate23caused by the electronic unit13receiving a disturbance. This amplitude can be evaluated based on, for example, the surface area of the substrate23, the mounting state of electronic component25with respect to the substrate23(that is, the mounting density, size, mass, and so on of the electronic components25), the positioning in the substrate23of the screws24that anchor the substrate23to the lower chassis17, and so on. The distance of this extremely small amount of space therefore cannot be specified.

At least part of the area on the lower surface23bof the substrate23that corresponds to the region at which the end portion26bis in contact with the upper surface23aof the substrate23overlaps with the region at which the end portion28bis in contact with the lower surface23bof the substrate23. In other words, the substrate23is supported on both the top and bottom by the upper column member26and the lower column member28, respectively.

FIG. 3Ais a plan view of the upper surface23aof the substrate23. Contact regions31represent regions in which upper column members26is in contact with the upper surface23aof the substrate23. It is preferable for the contact regions31to be present in the regions of the substrate23that distort the most when an impact is applied to the electronic apparatus1. For example, in the case where the vicinity of the external edge of the substrate23is anchored and supported by screws and/or in the case where electronic components25are mounted almost uniformly across the entire surface of the substrate23, the vicinity of the center of the substrate23distorts the most; positioning a contact region31in the vicinity of the center of the substrate23therefore makes it possible to reduce distortion of the substrate23. It is thus possible to prevent cracks from forming in the substrate23in the vicinity of the through-holes23c.

In the substrate23shown inFIG. 3A, the electronic components25are disposed in the vicinity of the center of the substrate23, and thus it is preferable for the contact regions31to be surrounding or in the vicinity of the electronic components25. Positioning the contact regions31surrounding or in the vicinity of the electronic components25makes it possible to prevent the soldered portions of the electronic components25from separating due to distortion of the substrate23.

Note that a configuration in which the upper column member26is in contact with the top of an electronic component25mounted on the substrate23also can prevent the soldered portions of the electronic component25that the upper column member26is in contact with from separating. However, distortion in the substrate23is transmitted directly to the electronic component25. There is a high likelihood that the electronic component25will be damaged, and thus the configuration in which the electronic component25is in contact with the upper column member26offers no practical advantages.

2. Behavior When Impact is Applied to Electronic Apparatus

Next, states occurring when an impact, such as an impact resulting from being dropped, is applied to the electronic apparatus1having the abovementioned configuration shall be described with reference toFIGS. 2 and 3A.

When a user accidentally drops the electronic apparatus1onto to floor or the like, a large impact is applied to the electronic apparatus1when the electronic apparatus1collides with the floor or the like. For example, when an impact is applied to the lower surface housing12(seeFIG. 2), that impact is transmitted to the electronic unit13via the buffer member21. Because the buffer member21is formed of an elastic body, the impact transmitted from the lower surface housing12can be softened. Meanwhile, in the case where an impact is applied to the upper surface housing11, that impact is softened by the buffer member20before being transmitted to the electronic unit13.

The impact that is transmitted to the electronic unit13attempts to reach the substrate23via the upper column member26or the lower column member28.

Here, because the upper column member26and the lower column member28are formed in a column shape, the durability with respect to the directions indicated by the arrows Y1and Y2inFIG. 2is high. For this reason, even if an impact is transmitted from the upper surface housing11and the lower surface housing12, the upper column member26and the lower column member28experience very little distortion in the directions indicated by the arrow Y1or Y2shown inFIG. 2. Therefore, the substrate23is supported from the top and the bottom by the upper column member26and the lower column member28, and as a result, regions supported by the upper column member26and the lower column member28experience almost no distortion. In addition, because the region of the substrate23that experiences the most distortion is supported by the upper column member26and the lower column member28, the substrate experiences little distortion as a whole.

Therefore, as shown inFIG. 3A, disposing the electronic components25in the vicinity of the contact regions31makes it possible to prevent the terminals25aof the electronic component25from separating from the wiring pattern23d(seeFIG. 2), thereby preventing disruption of the electrical connection between the terminals25aand the wiring pattern23d. This effect is particularly evident in BGA-packaged electronic components, whose adhesion to the substrate23is relatively weak.

3. Effects of the Embodiment, etc.

According to the present embodiment, the substrate23can be prevented from being damaged when an impact is applied to the electronic apparatus1. In other words, with a configuration such as that shown inFIG. 7, in which the region of the substrate102that distorts the most (for example, the vicinity of the center) is not supported, the substrate102distorts extensively when an impact is applied to the electronic apparatus101. If the substrate102distorts extensively, there is a heightened chance for damage such as cracking to occur in the vicinity of the portions that are anchored by the screws107. As opposed to this, in the configuration of the present embodiment, the regions of the substrate23that experience the most distortion are supported by the upper column member26and the lower column member28, making it possible to reduce the amount by which the substrate23distorts when an impact is applied to the electronic apparatus1. It is therefore possible to prevent damage such as cracks from occurring in the portions of the substrate23that are anchored to the lower chassis17(the vicinity of the through-holes23c).

Note that the “regions that distort the most” in the substrate23generally indicates the regions that are the furthest (inFIG. 3A, a line central and perpendicular to a line spanning between the two through-holes23c) from the portions of the substrate23that are anchored (inFIG. 3A, the through-holes23c). However, as mentioned earlier, the “regions that distort the most” change depending on the state in which the electronic components25are mounted on the substrate23. Practically speaking, the “region that distorts the most” tends to be in the vicinity of the center of the substrate23.

In addition, with the electronic apparatus1according to the present embodiment, the top and bottom of the substrate23are supported by the upper column member26and the lower column member28, respectively, thereby reducing the amount of distortion of the substrate23, and making it possible to prevent disruption of the electrical connection between the terminals25aof the electronic component25and the wiring pattern23dof the substrate23.

Although the shape of the contact members that support the substrate23are described as being columns (column members) in the present embodiment, it should be noted that the contact members may instead be plate-shaped (plate members).FIG. 3Bis a plan view illustrating a substrate23provided with plate-shaped contact members (called “plate members” hereinafter). As shown inFIG. 3B, plate contact regions31b, with which the plate members is in contact, are present in the substrate23in the vicinity of the electronic components25, or regions where the substrate23distorts the most when an impact is applied to the electronic apparatus1. Because the plate contact regions31bhave an area that is larger than that of the contact regions31with which the column members is in contact (seeFIG. 3A), the resilience against impact can be improved. In addition, disposing the plate contact regions31balong the lengthwise direction of the substrate23makes it possible to reduce the amount by which the substrate23distorts in the lengthwise direction, which experiences a comparatively higher amount of distortion. It is therefore possible to prevent damage such as cracks from occurring in the portions of the substrate23that are anchored to the lower chassis17(the vicinity of the through-holes23c).

However, in the case where the electronic component25is a component that emits a high amount of heat, such as, for example, a CPU (central processing unit), and the electronic component25is surrounded by plate members, there is the chance that the plate members will obstruct the flow of air to the space in which the electronic component25is disposed. Therefore, there are cases where the heat dissipation efficiency of the electronic component25is reduced. In this case, it is preferable to provide column-shaped contact members, as illustrated by the contact regions31inFIG. 3A.

In addition, the plate members may be configured so as to be in contact only with either the upper surface23aor the lower surface23bof the substrate23. In other words, even if the configuration is such that the plate contact regions31bare present on the upper surface23aor the lower surface23bof the substrate23, and contact regions31are present on the lower surface23bor the upper surface23a, the same effect as the present embodiment can be achieved. That is, a configuration that employs both column members and plate members can be used in accordance with the shape and heat dissipation properties of the electronic components25.

In addition, although the upper column member26and the lower column member28are described as making tight contact with the substrate23in the present embodiment, the configuration may have these members positioned opposite to the substrate23with an extremely small amount of space provided therebetween. That is, the same effect as the present embodiment can be achieved even if the configuration is such that the upper column member26and lower column member28are separated from the substrate23in a state where an impact is not applied to the electronic apparatus1, and the upper column member26or lower column member28is in contact with the substrate23when an impact is applied to the electronic apparatus1and the substrate23distorts.

In addition, it is preferable for the configuration to be such that the surface of the electronic component25that is opposite to the surface that is mounted on the substrate23is opposite the upper primary wall15with the buffer member29disposed therebetween, as shown inFIG. 2. It is preferable for the buffer member29to be formed of a material that has a high thermal conductivity. For example, it is preferable for the buffer member29to be implemented by a graphite sheet. BGA-packaged semiconductor elements, capacitors, and the like are included as examples of the electronic component25.

In addition, although the upper column member26and the lower column member28are described as having a cylindrical shape in the present embodiment, they may have a rectangular shape instead.

Finally, the substrate23of Embodiment 1 is an example of the substrate of the present invention, and the upper chassis14of Embodiment 1 is an example of the first support member of the present invention. The lower chassis17of Embodiment 1 is an example of the second support member of the present invention. The upper column member26of Embodiment 1 is an example of the first contact member of the present invention. The upper primary wall15of Embodiment 1 is an example of the first base body of the present invention. The lower column member28of Embodiment 1 is an example of the second contact member of the present invention. The lower primary wall18of Embodiment 1 is an example of the second base body of the present invention. The contact region31of Embodiment 1 is an example of the contact region of the present invention.

1. Configuration of Electronic Apparatus

FIG. 4is a perspective view of an electronic apparatus according to Embodiment 2 of the present invention. An electronic apparatus6includes signal processing circuits and the like within a single housing. A display7and an operational unit8are disposed on the main surface of the housing of the electronic apparatus6. The display7can be implemented by, for example, a liquid-crystal display. The operational unit8can be implemented using, for example, a keyboard. The electronic apparatus6is often operated while the user holds it with one or both hands, and thus is likely to be dropped on the floor or the like, and thus requires a higher resilience against impact. In the electronic apparatus6, the side on which the display7and the operational unit8are disposed is defined as “top”. Meanwhile, in the electronic apparatus6, the side opposite to the side on which the display7and the operational unit8are disposed is defined as “bottom”.

FIG. 5is a cross-sectional view taken along the B-B line of the electronic apparatus6according to Embodiment 2, as shown inFIG. 4. In the electronic apparatus6according to the present embodiment, constituent elements that are identical to those of the electronic apparatus1according to Embodiment 1 shall be given the same reference numerals, and descriptions thereof shall be omitted.

The electronic apparatus6is enclosed within an upper surface housing11and a lower surface housing12. An electronic unit41is provided within the inner space formed by connecting the upper surface housing11and the lower surface housing12. The electronic unit41is enclosed within an upper chassis42and a lower chassis47. A substrate23is supported on the top and bottom by the upper chassis42and the lower chassis47. Part of the substrate23is disposed within the space formed by the upper chassis42and the lower chassis47.

The upper chassis42, which may be considered a first support member, is formed of a magnesium alloy. The upper chassis42includes an upper primary wall43, upper column portions44, upper side walls45, and side wall end portions46. The upper primary wall43, upper column portions44, upper side walls45, and side wall end portions46are formed as a single body. The upper primary wall43is in contact with and is anchored to the inner surface of the upper surface housing11(the surface opposite to the lower surface housing12) with buffer members20therebetween. The buffer members20may be formed of an elastic material such as rubber.

The lower chassis47, which may be considered a second support member, also is formed of a magnesium alloy. The lower chassis42has a lower primary wall48, lower column portions49, lower side walls50, and side wall end portions51. The lower primary wall48, lower column portions49, lower side walls50, and side wall end portions51are formed as a single body. The lower primary wall48is in contact with and is anchored to the inner surface of the lower surface housing12(the surface opposite to the upper surface housing11) with buffer members21therebetween. The buffer members21also may be formed of an elastic material such as rubber.

End portions44aof the upper column portions44, which may be considered first contact members, may be in contact with the upper surface23aof the substrate23, or may be opposite the upper surface23aof the substrate23with an extremely small amount of space provided therebetween. Meanwhile, end portions49aof the lower column portions49, which may be considered second contact members, may be in contact with the lower surface23bof the substrate23, or may be opposite the lower surface23bof the substrate23with an extremely small amount of space provided therebetween.

Although the end portions44aof the upper column portions44and the upper surface23aof the substrate23may be in tight contact or are opposite each other with an extremely small amount of space provided therebetween, it should be noted that the present embodiment describes an example in which the two are in tight contact. Likewise, although the end portions49bof the lower column portions49and the lower surface23bof the substrate23may be in tight contact or are opposite each other with an extremely small amount of space provided therebetween, it should be noted that the present embodiment describes an example in which the two are in tight contact. In the following descriptions, the term “contact” is intended to be taken as meaning “tight contact” unless otherwise specified. Note that an “extremely small amount of space” refers to a distance less than or equal to the amplitude of the distortion that is transmitted to the substrate23caused by the electronic unit41receiving a disturbance. This amplitude can be evaluated based on, for example, the surface area of the substrate23, the mounting state of electronic component25with respect to the substrate23(that is, the mounting density, size, mass, and so on of the electronic components25), the positioning in the substrate23of the screws24that anchor the substrate23to the lower chassis17, and so on. The distance of this extremely small amount of space therefore cannot be specified.

At least part of the areas on the lower surface23bthat correspond to the regions at which the end portions44aare in contact with the upper surface23aoverlap with the regions at which the end portions49aare in contact with the lower surface23b. In other words, the substrate23is supported both on the top and bottom by the upper column portions44and the lower column portions49, respectively.

The side wall end portions46are formed in the end portions of the upper side walls45so as to be approximately perpendicular to the upper side walls45. End surfaces46aof the side wall end portions46is in contact with the upper surface23aof the substrate23. Through-holes46bare formed in the side wall end portions46.

The side wall end portions51are formed in the end portions of the lower side walls50so as to be approximately perpendicular to the lower side walls50. End surfaces51aof the side wall end portions51are in contact with the lower surface23bof the substrate23. Screw holes51bare formed in each side wall end portion51.

Through-holes23care formed in the portions of the substrate23that are sandwiched between the side wall end portions46and the side wall end portions51. The substrate23is held between the upper side wall45and the lower side wall50by passing screws52through the through-holes46band the through-holes23cand threading them into the screw holes51b.

FIG. 6Ais a plan view of the upper surface23aof the substrate23according to Embodiment 2. As shown inFIG. 6A, contact regions61are present around or in the vicinity of an electronic component25. The contact regions61are regions in the upper surface23awhere the upper column portions44(seeFIG. 5) is in contact. It is preferable for the contact regions61to be present in the regions of the substrate23that distort the most when an impact is applied to the electronic apparatus6. For example, in the case where the vicinity of the external edge of the substrate23is anchored and supported by screws and/or in the case where electronic components25are mounted almost uniformly across the entire surface of the substrate23, the vicinity of the center of the substrate23distorts the most. Positioning the contact regions61in the vicinity of the center of the substrate23therefore makes it possible to reduce distortion of the substrate23. It is thus possible to prevent cracks from forming in the substrate23in the vicinity of the through-holes23c.

In the substrate23shown inFIG. 6A, the electronic component25is disposed in the vicinity of the center of the substrate23, and thus it is preferable for the contact regions61to be surrounding or in the vicinity of the electronic component25. Positioning the contact regions61surrounding or in the vicinity of the electronic component25makes it possible to prevent the soldered portions of the electronic components25from separating due to distortion of the substrate23.

Note that a configuration in which the upper column portions44are in contact with the top of an electronic component25mounted on the substrate23can also prevent the soldered portions of the electronic component25that the upper column portions44are in contact with from separating. However, distortion in the substrate23is transmitted directly to the electronic component25. There is a high likelihood that the electronic component25will be damaged, and thus the configuration in which the electronic component25is in contact with the upper column portions44offers no practical advantages.

Furthermore, side wall contact regions62are present in the vicinity of the edges of the upper surface23aof the substrate23. The side wall contact regions62are regions in the upper surface23awhere the upper side walls45(seeFIG. 5) are in contact.

It is preferable to dispose grounding metallic portions63on the substrate23so as to overlap with at least part of the side wall contact regions62. The grounding metallic portions63can be formed of, for example, layered copper. The grounding metallic portions63are grounding patterns that set the 0 level of voltage for the substrate23. Although the grounding metallic portions63are formed of copper in the present embodiment, it should be noted that these portions may be formed of any conductive material.

Bringing the upper side walls45into contact with the grounding metallic portions63enables the upper chassis42to be used as a grounding metal in the same manner as the grounding metallic portions63. For this reason, the grounding capacity can be increased and EMI (electromagnetic interference) can be reduced or eliminated, as compared to the case where only the grounding metallic portions63are used as the grounding metal. EMI also can be reduced or eliminated by disposing grounding metal on the lower surface23bof the substrate23and bringing the grounding metal and the lower side walls50into contact with each other.

2. Behavior When Impact is Applied to Electronic Apparatus

Next, states occurring when an impact, such as an impact resulting from being dropped, is applied to the electronic apparatus6having the abovementioned configuration shall be described with reference toFIG. 5.

When a user accidentally drops the electronic apparatus6onto the floor or the like, a large impact is applied to the electronic apparatus6when the electronic apparatus6collides with the floor or the like. For example, when an impact is applied to the lower surface housing12(seeFIG. 5), that impact is transmitted to the electronic unit41via the buffer members21. Because the buffer members21are formed of elastic bodies, the impact transmitted from the lower surface housing12can be softened. Meanwhile, in the case where an impact is applied to the upper surface housing11, that impact is softened by the buffer members20before being transmitted to the electronic unit41.

The impact that is transmitted to the electronic unit41attempts to reach the substrate23via the upper column portions44or the lower column portions49.

Here, because the upper column portions44and the lower column portions49are formed in a column shape, the durability with respect to the directions indicated by the arrows Y3and Y4inFIG. 5is high. For this reason, even if an impact is transmitted from the upper surface housing11and the lower surface housing12, the upper column portions44and the lower column portions49experience very little distortion in the directions indicated by the arrows Y3and Y4. Thus, even if the electronic apparatus6is accidentally dropped onto a floor or the like, the substrate23is supported on the top and bottom by the upper column portions44and the lower column portions49, and thus the regions that are supported by the upper column portions44and the lower column portions49experience little distortion. In addition, because the region of the substrate23that experiences the most distortion is supported by the upper column portions44and the lower column portions49, the substrate experiences little distortion as a whole. Furthermore, sandwiching the substrate23between the upper side walls45and the lower side walls50makes it possible further to reduce distortion occurring in the substrate23when the electronic apparatus6accidentally is dropped on the floor or the like.

3. Effects of the Embodiment, etc.

According to the present embodiment, the substrate23can be prevented from being damaged when an impact is applied to the electronic apparatus6. In other words, with a configuration such as that shown inFIG. 7, in which the region of the substrate102that distorts the most (for example, the vicinity of the center) is not supported, the substrate102distorts extensively when an impact is applied to the electronic apparatus101. If the substrate102distorts extensively, there is a heightened chance for damage such as cracking to occur in the vicinity of the portions that are anchored by the screws107. As opposed to this, in the configuration of the present embodiment, the regions of the substrate23that experience the most distortion are supported by the upper column portions44and the lower column portions49, making it possible to reduce the amount by which the substrate23distorts when an impact is applied to the electronic apparatus6. It is therefore possible to prevent damage such as cracks from occurring in the portions of the substrate23that are anchored by the screws52to the upper chassis42and the lower chassis47(the vicinity of the through-holes23c).

Note that the “regions that distort the most” in the substrate23generally indicates the regions that are the furthest (inFIG. 6A, a line central and perpendicular to a line spanning between the two through-holes23c) from the portions of the substrate23that are anchored (inFIG. 6A, the through-holes23c). However, as mentioned earlier, the “regions that distort the most” change depending on the state in which the electronic components25are mounted on the substrate23or the like. Practically speaking, the “region that distorts the most” is in the vicinity of the center of the substrate23.

Furthermore, according to the present embodiment, as shown inFIG. 6A, disposing the electronic component25in the vicinity of the contact regions61is it possible to prevent the terminals25aof the electronic component25from separating from the wiring pattern23d(seeFIG. 5), thereby preventing the electrical connection therebetween from being severed. This effect is particularly evident in BGA-packaged electronic components, whose adhesion to the substrate23is relatively weak.

In addition, because the upper column portions44and the upper primary wall43are formed as a single body, the upper column portions44and the upper primary wall43can be manufactured at the same time, making it possible to reduce the number of manufacturing steps. Likewise, because the lower column portions49and the lower primary wall48are formed as a single body, the lower column portions49and the lower primary wall48can be manufactured at the same time, making it possible to reduce the number of manufacturing steps.

Although the shape of the contact members that support the substrate23(the upper column portions44and lower column portions49) are described as being columns in the present embodiment, it should be noted that the contact members may be plate-shaped instead.FIG. 6Bis a plan view illustrating a substrate23provided with plate-shaped contact members (called “plate members” hereinafter). As shown inFIG. 6B, plate contact regions61b, with which the plate members is in contact, are present in the substrate25in the vicinity of the electronic component25, or regions where the substrate23distorts the most when an impact is applied to the electronic apparatus6. Because the plate contact regions61bhave an area that is larger than that of the contact regions61with which the column members is in contact, the resilience against impact can be improved. In addition, disposing the plate contact regions61balong the lengthwise direction of the substrate23makes it possible to reduce the amount by which the substrate23distorts in the lengthwise direction, which experiences a comparatively higher amount of distortion. It is therefore possible to prevent damage such as cracks from occurring in the portions of the substrate23that are anchored by the screws52to the upper chassis42and the lower chassis47(the vicinity of the through-holes23c).

However, in the case where the electronic component25is a component that emits a high amount of heat, such as, for example, a CPU (central processing unit), and the electronic component25is surrounded by plate members, there is the chance that the plate members will obstruct the flow of air to the space in which the electronic component25is disposed. Therefore, there are cases where the heat dissipation efficiency of the electronic component25is reduced. In this case, a configuration that combines column members with plate members, such as the contact regions61and plate contact regions61bshown inFIG. 6C, is preferable.

In addition, the plate members may be configured so as to is in contact only with either the upper surface23aor the lower surface23bof the substrate23. In other words, even if the configuration is such that the plate contact regions61bare present on the upper surface23aor the lower surface23bof the substrate23, and contact regions61are present on the lower surface23bor the upper surface23a, the same effects as the present embodiment can be achieved. That is, a configuration that employs both column members and plate members can be used in accordance with the shape and heat dissipation properties of the electronic components25.

In addition, although the upper column portions44and the lower column portions49are described as making tight contact with the substrate23in the present embodiment, the configuration may have these portions positioned opposite to the substrate23with an extremely small amount of space provided therebetween. That is, the same effects as the present embodiment can be achieved even if the configuration is such that the upper column portions44and lower column portions49are separated from the substrate23in a state where an impact is not applied to the electronic apparatus1, and the upper column portions44or lower column portions49is in contact with the substrate23when an impact is applied to the electronic apparatus1and the substrate23distorts.

In addition, although the upper column portions44and the lower column portions49are described as having a cylindrical shape in the present embodiment, they may have a rectangular shape instead.

Note that Embodiment 1 illustrated an example in which the upper chassis14and the lower chassis17are formed of a magnesium alloy. Embodiment 2 also illustrates an example in which the upper chassis42and the lower chassis47are formed of a magnesium alloy. Magnesium alloy is preferable due to its light weight and high durability. However, the upper chassis14and42and the lower chassis17and47may be formed of another metal material.

In addition, it is not completely necessary to provide the buffer member29. However, because the buffer member29can transfer heat generated by the electronic component25to the upper primary wall15, thereby improving the heat dissipation properties, it is preferable to provide the buffer member29between the electronic component25and the upper primary wall15. In addition, because the buffer member29can absorb impacts transmitted from the upper primary wall15to the electronic component25, thereby improving the resilience against impact, it is preferable to provide the buffer member29between the electronic component25and the upper primary wall15.

Finally, the substrate23of Embodiment 2 is an example of the substrate of the present invention, and the upper chassis42of Embodiment 2 is an example of the first support member of the present invention. The lower chassis47of Embodiment 2 is an example of the second support member of the present invention. The upper column portions44of Embodiment 2 are examples of the first contact member of the present invention. The upper primary wall43of Embodiment 2 is an example of the first base body of the present invention. The lower column portions49of Embodiment 2 are examples of the second contact member of the present invention. The lower primary wall48of Embodiment 2 is an example of the second base body of the present invention. The contact regions61and61bof Embodiment 2 are examples of the contact region of the present invention.

The electronic unit and electronic apparatus of the present invention are useful in various electronic units and electronic apparatuses, such as personal computers.