JP2020107834A - Electronic unit - Google Patents

Abstract

SOLUTION: An electronic unit 1 includes: a first substrate 10 having a first electrode 14 arranged on the first surface and a second electrode 18 arranged on a second surface opposite to the first surface; a second substrate 20 that is disposed so as to face the first surface, has a coefficient of thermal expansion different from that of the first substrate, and has a third electrode 24 at a surface of the first substrate side; an electronic device 30 including an active element, arranged to face the second surface, and electrically connected to the second electrode; a connecting portion having elasticity (anisotropic conductive film 40) which includes conductive particles 41 and a binder 43 that electrically connect the first electrode and the third electrode; and a holding mechanism 50 for holding the connecting portion in an elastically deformed state by the first substrate and the second substrate.EFFECT: It is possible to suppress defects caused by thermal stress.SELECTED DRAWING: Figure 2

Description

The present disclosure relates to electronic units.

A semiconductor circuit board on which active elements and the like are formed is mounted on a printed wiring board via bumps. In recent years, due to the narrower pitch of bumps, an interposer is provided between a semiconductor circuit board and a printed wiring board. The interposer is formed of a glass substrate, a silicon substrate, a ceramic substrate, or the like. The printed wiring board is formed of a resin substrate called a laminated board. Non-Patent Document 1 discloses an interposer using a glass substrate.

Scott McCann, et al., "Board-Level Reliability of 3D Through Glass Via Filters During Thermal Cycling", IEEE 66th Electronic Components and Technology Conference, 2016, p.1575-1582

For example, according to the electronic unit 1Z having the conventional structure shown in FIG. 19, the interposer 10Z and the printed wiring board 20Z are connected via the solder 40Z. Due to the heat cycle caused by the heat generated by the electronic device 30Z and the like, cracks may occur particularly in the vicinity of the electrode 14Z on the interposer 10Z side among the electrodes to which the solder 40Z is connected. It is considered that this phenomenon is caused by a large difference between the coefficient of thermal expansion of the glass substrate forming the interposer 10Z and the coefficient of thermal expansion of the resin substrate forming the printed wiring board 20Z. That is, the amount of expansion and contraction between the interposer 10Z and the printed wiring board 20Z due to thermal cycles is different, and the resulting thermal stress concentrates on the solder 40Z, which is the connecting portion of both, and further the electrode 14Z to which the solder 40Z is connected. Cause cracks in the vicinity of. Since cracks that occur in the substrate when a brittle material such as glass or silicon is used cause electrical connection failure, it is desirable to reduce it as much as possible.

One of the purposes of the present disclosure is to suppress defects caused by thermal stress.

According to the present disclosure, a first substrate having a first electrode arranged on a first surface and a second electrode arranged on a second surface opposite to the first surface, and facing the first surface. A second substrate having a thermal expansion coefficient different from that of the first substrate, the second substrate having a third electrode on a surface on the first substrate side, and an active element, and a second substrate on the second surface. An electronic device electrically arranged to face each other and electrically connected to the second electrode; and an elastic connecting portion including a conductor electrically connecting the first electrode and the third electrode, and There is provided an electronic unit including: a holding portion for holding the connection portion in a state where the connection portion is elastically deformed by the first substrate and the second substrate.

The holder may include a structure arranged outside the first substrate.

The structure may include a portion connected to the second surface and a portion connected to the second substrate.

The electronic device may further include a temperature adjustment unit disposed on a side opposite to the first substrate, and the structure may include a portion connected to the temperature adjustment unit and a portion connected to the second substrate. Good.

The holding unit may include a structure that is bonded to the first substrate and the second substrate between the first substrate and the second substrate.

The distance between the structure and the end of the first substrate may be longer than the distance between the conductor and the end.

The connection portion includes a plurality of the conductors including a first conductor and a second conductor, and the holding portion includes a plurality of the structure bodies including a first structure and a second structure. The first structure may be arranged between one conductor and the second conductor, and the first conductor may be arranged between the first structure and the second structure.

The structure may have a shape in which a tangent line at each position of the outer edge in a cross section parallel to the first surface does not enter the inside of the outer edge.

The connecting portion may have a resin having elasticity and the conductor arranged in contact with the resin.

The conductor may include a portion arranged along the surface of the resin.

The conductor may include a portion disposed on the surface of the resin, and the resin may include conductive particles.

The connection portion may include conductive particles that are electrically connected to the first electrode and the third electrode and conductive particles that are not electrically connected to the first electrode and the third electrode.

The conductor may include a linear metal, and the connecting portion may further include a linear conductor that is not connected to either the first electrode or the third electrode.

The conductor may have elasticity due to a spring structure.

The coefficient of thermal expansion of the second substrate may be larger than the coefficient of thermal expansion of the first substrate.

The difference between the coefficient of thermal expansion of the second substrate and the coefficient of thermal expansion of the first substrate may be greater than the difference between the coefficient of thermal expansion of the electronic device and the coefficient of thermal expansion of the first substrate.

The first substrate may be a glass substrate and may include an electrode penetrating the glass substrate.

The second substrate may include a resin.

According to the present disclosure, defects caused by thermal stress can be suppressed.

1 is a schematic plan view showing an electronic unit according to a first embodiment of the present disclosure. It is a schematic sectional drawing (A1-A2 line sectional view of Drawing 1) showing an electronic unit in a 1st embodiment of this indication. FIG. 5 is a diagram illustrating a method of manufacturing the electronic unit according to the first embodiment of the present disclosure. FIG. 5 is a diagram illustrating a method of manufacturing the electronic unit according to the first embodiment of the present disclosure. FIG. 5 is a diagram illustrating a method of manufacturing the electronic unit according to the first embodiment of the present disclosure. It is a schematic sectional drawing which shows the structure before fixing a printed wiring board and an interposer in the electronic unit in 2nd Embodiment of this indication. It is a schematic sectional drawing which shows the electronic unit in 2nd Embodiment of this indication. It is a schematic sectional drawing which shows the structure before fixing a printed wiring board and an interposer in the electronic unit in 3rd Embodiment of this indication. It is a schematic sectional drawing which shows the electronic unit in 3rd Embodiment of this indication. It is a schematic sectional drawing which shows the structure before fixing a printed wiring board and an interposer in the electronic unit in 4th Embodiment of this indication. It is a schematic sectional drawing which shows the electronic unit in 4th Embodiment of this indication. It is a schematic sectional drawing which shows the structure before fixing a printed wiring board and an interposer in the electronic unit in 5th Embodiment of this indication. It is a schematic sectional drawing which shows the electronic unit in 5th Embodiment of this indication. It is a figure which shows the example of arrangement|positioning of the columnar structure in 5th Embodiment of this indication. It is a figure which shows the shape (1st example) of the columnar structure in 5th Embodiment of this indication. It is a figure which shows the shape (2nd example) of the columnar structure in 5th Embodiment of this indication. It is a schematic sectional drawing which shows the electronic unit in 6th Embodiment of this indication. It is a figure explaining an example of an electronic device in a 7th embodiment of this indication. It is a schematic plan view which shows the electronic unit which concerns on a prior art example.

Hereinafter, an embodiment of the present disclosure will be described with reference to the drawings. Each embodiment described below is an example, and the present disclosure should not be construed as being limited to these embodiments. In the drawings referred to in the present embodiment, the same portions or portions having similar functions are designated by the same reference numerals or similar reference numerals (reference numerals having only A, B, etc. added after the numeral), and repetitive description thereof. May be omitted. In addition, the dimensional ratios in the drawings may differ from the actual ratios for convenience of description, and some of the configurations may be omitted from the drawings. In the drawings attached to the present specification, for convenience of illustration and understanding, the scale and the vertical-horizontal dimension ratio are appropriately changed from those of the actual product and exaggerated, or a part of the configuration is omitted from the drawings. There is a case.

<First Embodiment>
[1. Electronic unit structure]
FIG. 1 is a schematic plan view showing an electronic unit according to the first embodiment of the present disclosure. FIG. 2 is a schematic cross-sectional view (cross-sectional view taken along the line A1-A2 of FIG. 1) showing the electronic unit according to the first embodiment of the present disclosure. The electronic unit 1 according to the first embodiment includes an interposer 10 (first substrate), a printed wiring board 20 (second substrate), an electronic device 30, and a holding mechanism 50 (holding unit). In this example, the electronic unit 1 includes a plurality of electronic devices 30 (electronic devices 30-1, 30-2) and a plurality of holding mechanisms 50 (holding mechanisms 50-1, 50-2, 50-3, 50-4). )including. Unless otherwise specified, the electronic devices 30-1 and 30-2 are simply referred to as the electronic device 30. When the holding mechanisms 50-1, 50-2, 50-3, and 50-4 are not particularly distinguished, they are simply called the holding mechanism 50. The electronic device 30 and the printed wiring board 20 are connected via the interposer 10. The interposer 10 and the printed wiring board 20 are connected by an anisotropic conductive film 40 (connecting portion). The holding mechanism 50 includes a structure for holding the anisotropic conductive film 40 in an elastically deformed state by applying a force in a direction in which the interposer 10 and the printed wiring board 20 are brought close to each other. The number of holding mechanisms 50 is not limited to four as shown in FIG. 1, but is preferably three or more. Furthermore, at least three holding mechanisms 50 are arranged so as not to be aligned on a straight line. Preferably. By doing so, the distance and parallelism between the interposer 10 and the printed wiring board 20 can be adjusted, and the connection between each and the anisotropic conductive film 40 can also be stabilized. The number of holding mechanisms 50 may be three or less. For example, when only one holding mechanism 50 is provided, the holding mechanism 50 preferably surrounds the outer periphery of the interposer 10.

The interposer 10 uses glass, silicon, or the like as a substrate, but here, glass is used for description. The interposer 10 includes an electrode (hereinafter, referred to as a penetrating electrode) penetrating the glass substrate, a plurality of first electrodes 14 and a plurality of second electrodes 18. The coefficient of thermal expansion of the glass substrate is approximately 3 to 8 ppm/K. The through electrode is omitted in the figure. The first electrode 14 is arranged on the first surface 10a side of the interposer 10. The second electrode 18 is arranged on the second surface 10b side of the interposer 10. The second surface 10b is a surface opposite to the first surface 10a. At least one of the first electrodes 14 and at least one of the second electrodes 18 are electrically connected via a through electrode. In this way, the interposer 10 electrically connects the electrode arranged on the first surface 10a side and the electrode arranged on the second surface 10b side.

The electronic device 30 uses a semiconductor such as silicon, gallium arsenide, or silicon carbide as a substrate. The electronic device 30 includes an element that generates heat by driving, such as an active element formed on a substrate such as silicon, and the fourth electrode 38. The thermal expansion coefficient of the silicon substrate is approximately 2 to 3 ppm/K. The fourth electrode 38 is arranged on the first surface 30a side of the electronic device 30. The first surface 30a of the electronic device 30 is arranged to face the second surface 10b of the interposer 10. The second surface 30b of the electronic device 30 is a surface opposite to the first surface 30a. The fourth electrode 38 and the second electrode 18 are electrically connected via the bump 80.

The active element, which is not shown in the figure, is formed on the first surface 30a side and generates heat by being driven by being supplied with electric power via the fourth electrode 38. The heat generated from the active element is mainly radiated from the first surface 30a and the second surface 30b, and is also radiated from the fourth electrode 38 through the bump 80 to heat the interposer 10 and the printed wiring board 20.

In this example, the printed wiring board 20 uses a resin such as glass epoxy as a substrate. The printed wiring board 20 is a substrate on which copper wiring is formed using a copper clad laminate. The thermal expansion coefficient of this laminated plate (glass epoxy substrate) is larger than the thermal expansion coefficient of the glass substrate, and is approximately 15 to 25 ppm/K. As described above, the thermal expansion coefficients of the interposer 10 and the electronic device 30 are almost the same, but the interposer 10 and the printed wiring board 20 are greatly different depending on the combination. Further, in general, the printed wiring board 20 is sufficiently thick as compared with the interposer 10 and the electronic device 30, so that the stress derived from the printed wiring board 20 has a great influence.

The printed wiring board 20 includes a third electrode 24. The third electrode 24 is arranged on the second surface 20b side of the printed wiring board 20. The second surface 20b of the printed wiring board 20 is arranged so as to face the first surface 10a of the interposer 10. The first surface 20a of the printed wiring board 20 is a surface opposite to the second surface 20b.

The anisotropic conductive film 40 includes conductive particles 41 and a binder 43. The conductive particles 41 have a structure in which resin particles are coated with a conductive material (for example, nickel and gold). Therefore, the conductive particles 41 have elasticity. The conductive particles 41 may be formed of a conductive material (eg, gold, silver, copper, nickel) instead of the resin particles as long as it has elasticity.

The binder 43 is a thermosetting resin such as epoxy or acrylic, and has elasticity even after being cured. The anisotropic conductive film 40 is an example of a connecting portion that electrically connects the first electrode 14 and the third electrode 24. The anisotropic conductive film 40 has conductivity in the thickness direction by pressure bonding, but does not have conductivity in the in-plane direction. In the figure, the first electrode 14 and the third electrode 24 are shown to be electrically connected via one conductive particle 41, but via a plurality of conductive particles 41 arranged in series. May be electrically connected. An anisotropic conductive paste may be used instead of the anisotropic conductive film 40. When the resin is evenly present on the interposer 10 and the printed wiring board 20 like the binder 43, the resin may have adhesiveness. In that case, in order to improve connection reliability, The resin preferably has tensile stress. Since the interposer 10 receives stress so as to be recessed inward from the outer periphery, peeling is less likely to occur, and the stress applied by the holding mechanism 50 applies uniform pressure to the entire anisotropic conductive film 40 to maintain connection reliability. Can be added.

The holding mechanism 50 is an example of a holding unit for holding the anisotropic conductive film 40 in an elastically deformed state via the interposer 10 and the printed wiring board 20. The holding mechanism 50 is formed of, for example, metal such as stainless steel, resin, or ceramic. In particular, the resin can be designed according to the coefficient of thermal expansion of the printed wiring board 20. Therefore, even when expansion or contraction occurs due to heat, it is possible to maintain the elastic conductive film 40 with a constant force without largely changing the force that elastically deforms the anisotropic conductive film 40. Therefore, the coefficient of thermal expansion is preferably 10 to 30 ppm/K, more preferably 15 to 25 ppm/K. Further, since the interposer 10 is made of glass, it is preferable that the holding mechanism 50 is made of resin in order to prevent the occurrence of chipping at a portion contacting the interposer 10. For example, even when the holding mechanism 50 is formed of metal or ceramic, it is preferable that the contact portion with the interposer 10 be formed of resin. The holding mechanism 50 includes a shaft portion 51 and a support portion 55. A support portion 55 is coupled to one end of the shaft portion 51. In this example, the holding mechanism 50 is a screw-shaped structure, and the shaft portion 51 is formed with a screw thread. The support 55 corresponds to the head of the screw. A part of the shaft portion 51 is connected to the printed wiring board 20 by being screwed. As a result, the axial movement of the shaft portion 51 with respect to the printed wiring board 20 is restricted. The support 55 contacts the second surface 10b of the interposer 10. A member such as a washer that indirectly makes contact between the support portion 55 and the interposer 10 may be disposed between the support portion 55 and the interposer 10, or may be bonded to the interposer surface with an adhesive. Good. Alternatively, the printed wiring board 20 may be penetrated, and a fixing tool such as a nut may be attached to the penetrated portion so as not to be easily peeled off.

By controlling the screwing amount of the shaft portion 51 to the printed wiring board 20, the distance between the support portion 55 and the printed wiring board 20 is controlled. As a result, since the distance between the interposer 10 and the printed wiring board 20 is controlled, the pressure applied from the interposer 10 and the printed wiring board 20 to the anisotropic conductive film 40 can be controlled by changing the distance. it can. In this example, the holding mechanism 50 controls the distance between the interposer 10 and the printed wiring board 20 so that the anisotropic conductive film 40 is held in a state of being compressed and elastically deformed. In this state, the elastic force of the anisotropic conductive film 40 acts in the direction of restoring the shape, that is, in the direction of increasing the distance between the interposer 10 and the printed wiring board 20.

Thus, according to the electronic unit 1 of the first embodiment, the interposer 10 and the printed wiring board 20 are connected by the anisotropic conductive film 40 having elasticity. Thereby, even if the thermal expansion coefficients of the interposer 10 and the printed wiring board 20 are significantly different, the thermal stress caused by the difference in expansion between the two can be dispersed by elastic deformation of the anisotropic conductive film 40. Therefore, defects due to thermal stress can be suppressed.

On the other hand, if the distance between the interposer 10 and the printed wiring board 20 is increased due to the elastic deformation of the anisotropic conductive film 40 when the thermal stress is relaxed, the electrical connection may be defective. This connection failure may be caused by, for example, blocking conduction by the conductive particles 41, conducting the anisotropic conductive film 40 with the first electrode 14 of the interposer 10 or with the third electrode 24 of the printed wiring board 20. This is because conduction is obstructed. According to the electronic unit 1 in the first embodiment, the holding mechanism 50 holds the distance between the interposer 10 and the printed wiring board 20 so that the anisotropic conductive film 40 is elastically deformed.

This will be described in more detail. Deformation and the like of the interposer 10 and the printed wiring board 20 due to thermal expansion occur, and at this time, the direction in which the elastic deformation of the anisotropic conductive film 40 is restored (the distance between the interposer 10 and the printed wiring board 20 increases. ) Is assumed. Even in such a situation, the position of the support portion 55 in the holding mechanism 50 (the amount screwed to the printed wiring board 20 in advance) is maintained so that the elastically deformed state (the state where the elastic deformation is not completely restored) is maintained. ) Is set. Thus, the interposer 10 and the printed wiring board 20 can be kept narrower than when the interposer 10 and the printed wiring board 20 were connected by the anisotropic conductive film 40 (before the holding mechanism 50 was provided). it can. As a result, the conductive particles 41 are pressed against the first electrode 14 and the third electrode 24 together with the binder 43, and the electrical continuity between the first electrode 14 and the third electrode 24 can be maintained.

[2. Electronic unit manufacturing method]
Subsequently, a method of manufacturing the electronic unit 1 will be described.

3 to 5 are diagrams illustrating a method of manufacturing the electronic unit according to the first embodiment of the present disclosure. First, as shown in FIG. 3, the interposer 10 is prepared. The interposer 10 includes the first electrode 14 arranged as an electrode pad on the first surface 10a and the second electrode 18 arranged as an electrode pad on the second surface 10b, as described above.

Subsequently, as shown in FIG. 4, the fourth electrode 38 and the second electrode 18 arranged on the first surface 30 a of the electronic device 30 are electrically connected via the bumps 80. For this connection method, for example, a reflow method is used.

Subsequently, as shown in FIG. 5, the anisotropic conductive film 40 is sandwiched between the third electrode 24 and the first electrode 14 arranged on the second surface 20b of the printed wiring board 20. After that, the first electrode 14 and the third electrode 24 are electrically connected by thermocompression bonding. Thereafter, as shown in FIG. 1, the distance between the interposer 10 and the printed wiring board 20 is further reduced by the holding mechanism 50, and the anisotropic conductive film 40 is held in a state of being elastically deformed. The above is the description of the method for manufacturing the electronic unit 1.

<Second Embodiment>
In the second embodiment, an electronic unit 1A in which the interposer 10 and the printed wiring board 20 are connected by elastic bumps will be described.

FIG. 6 is a schematic cross-sectional view showing the configuration before fixing the printed wiring board and the interposer in the electronic unit according to the second embodiment of the present disclosure. FIG. 7 is a schematic sectional view showing an electronic unit according to the second embodiment of the present disclosure. Of the electronic unit 1A, the description of the same parts as those described in the first embodiment will be omitted.

The first electrode 14A is arranged on the first surface 10a of the interposer 10. An elastic bump 40A is arranged between the printed wiring board 20 and the interposer 10. The elastic bump 40A includes a conductor 41A and a resin 42A. The resin 42A has elasticity and is formed in a substantially hemispherical shape on the interposer 10. The conductor 41A covers the surface of the resin 42A and is electrically connected to the first electrode 14A. The conductor 41A covers, for example, the resin 42A in the order of nickel and gold. A method of manufacturing such an elastic bump 40A and the like are exemplified in Japanese Patent Laid-Open No. 2009-111107.

When connecting the interposer 10 and the printed wiring board 20, first, as shown in FIG. 6, a conductor 41A is brought into contact with the third electrode 24. Thereafter, as shown in FIG. 7, the resin 42A is elastically deformed by reducing the distance between the interposer 10 and the printed wiring board 20 by the holding mechanism 50. At this time, the conductor 41A deforms following the elastic deformation of the resin 42A. Even if the conductor 41A itself is plastically deformed, the elastic bump 40A can be elastically deformed by following the elastic deformation of the resin 42A.

As a result, the elastic bumps 40A between the interposer 10 and the printed wiring board 20 are elastically deformed so as to be crushed as a whole, and the conductor 41A is pressed against the third electrode 24, so that the first electrode 14A and the third electrode 14A. 24 is electrically connected with the conductor 41A. Even if the elastic deformation of the elastic bumps 40A is changed to a direction in which the elastic deformation is restored (a state in which the distance between the interposer 10 and the printed wiring board 20 is expanded), the elastically deformed state (a state that is not completely restored) is the holding mechanism. Maintained by 50. Therefore, even with such a configuration, the stress is dispersed by the elasticity of the resin 42A, and the holding mechanism 50 can prevent the third electrode 24 and the conductor 41A from separating from each other.

The elastic bumps 40A are not limited to being formed on the interposer 10 and may be formed on the printed wiring board 20. The elastic bumps 40A may be formed separately from both the interposer 10 and the printed wiring board 20. In this case, the elastic bump 40A is fixed in position by being sandwiched between the interposer 10 (first electrode 14) and the printed wiring board 20 (third electrode 24).

As another example of the elastic bump 40A, a material containing particles having conductivity may be used as the resin 42A. In this case, when the elastic bumps 40A are deformed by being sandwiched between the interposer 10 and the printed wiring board 20, the conductive particles contained in the resin 42A come into contact with each other, and the conductive particles and the first electrode 14A of the interposer 10 are included. The contact between the conductive particles and the third electrode 24 of the printed wiring board 20 is realized. As a result, electrical connection between the electrode 14A and the electrode 24 via the elastic bump 40A can be realized.

The elastic bumps 40A preferably have a repulsive force so that the reliability of the electrical connection can be ensured, that is, the electrodes can be kept in pressure contact with the electrodes of the interposer 10 and the printed wiring board 20. .. Further, the elastic bump 40A may have plasticity. However, a coating film is provided on the surface of the elastic bumps 40A having plasticity so that the conductive bumps and the resin containing the conductive bumps and the resin containing the interposer 10 and the printed wiring board 20 do not break down and spread to unintended locations. May be. It is preferable that the coating film is formed of, for example, a metal film of gold, nickel, platinum, or the like, or a laminated film formed of a combination of these metal films because electrical connection can be ensured.

<Third Embodiment>
In the third embodiment, an electronic unit 1B in which the interposer 10 and the printed wiring board 20 are connected by a resin film provided with through electrodes (hereinafter referred to as a through electrode film) will be described.

FIG. 8 is a schematic cross-sectional view showing a configuration before fixing the printed wiring board and the interposer in the electronic unit according to the third embodiment of the present disclosure. FIG. 9 is a schematic sectional view showing an electronic unit according to the third embodiment of the present disclosure. A description of the same parts of the electronic unit 1B as those of the first embodiment will be omitted.

As shown in FIG. 8, a through electrode film 40B is arranged between the interposer 10 and the printed wiring board 20. The through electrode film 40B includes a film 43B and a conductor 41B penetrating the film 43B. The film 43B is a resin such as polyimide or silicone and has elasticity at least in the thickness direction. The conductor 41B is a linear metal surrounded by the film 43B. In the state before the through electrode film 40B is elastically deformed, the conductor 41B has a linear shape (columnar shape).

When connecting the interposer 10 and the printed wiring board 20, first, as shown in FIG. 8, a through electrode film 40B is arranged between the interposer 10 and the printed wiring board 20. A part of the conductor 41B contacts the first electrode 14 and the third electrode 24. Hereinafter, among the conductors 41B, those that do not contact both the first electrode 14 and the third electrode 24 will be referred to as conductors 41Ba by changing the reference numerals.

Thereafter, as shown in FIG. 9, the film 43B is elastically deformed by reducing the distance between the interposer 10 and the printed wiring board 20 by the holding mechanism 50. At this time, the conductor 41B bends while following the elastic deformation of the film 43B. Even if the conductor 41B itself is plastically deformed, by following the elastic deformation of the film 43B, the through electrode film 40B can be elastically deformed. Further, since the conductor 41B is surrounded by the film 40B, even if the conductor 41B bends while following the elastic deformation of the film 43B, the adjacent conductors 41B do not short-circuit.

As a result, of the through electrode film 40B between the interposer 10 and the printed wiring board 20, the portion sandwiched between the first electrode 14 and the third electrode 24 elastically deforms so as to be crushed as a whole, and the conductor 41B. Is pressed against the first electrode 14 and the third electrode 24, and the first electrode 14 and the third electrode 24 are electrically connected via the conductor 41B. When the elastic deformation of the through electrode film 40B is released, the film 43B returns to the original shape, and the conductor 41B also tries to return to the pillar shape following the original shape.

Even if the elastic deformation of the through electrode film 40B is changed to a direction in which the elastic deformation is restored (a state in which the distance between the interposer 10 and the printed wiring board 20 is expanded), the elastically deformed state (a state that is not completely restored) is retained. Maintained by mechanism 50. Therefore, even with such a configuration, the stress is dispersed by the elasticity of the film 43B, and the holding mechanism 50 maintains the electrical continuity between the first electrode 14 and the third electrode 24 via the conductor 41B. You can

Even when a material that does not easily elastically deform is selected as the material of the film 43B, the conductor 40B may be plastically deformed to obtain and maintain the electrical continuity between the first electrode 14 and the third electrode 24 after the pressure contact. It is possible. Even at this time, the film 43B is positioned so as to maintain the insulation between the conductors 40B as in the other cases and to keep the position of the conductor 40B accurately with respect to the first electrode 14 and the third electrode 24. Function is required.

<Fourth Embodiment>
In the fourth embodiment, an electronic unit 1C in which the interposer 10 and the printed wiring board 20 are connected by a spring-shaped conductor having elasticity (hereinafter, referred to as a conductive spring) will be described.

FIG. 10 is a schematic cross-sectional view showing the configuration before fixing the printed wiring board and the interposer in the electronic unit according to the fourth embodiment of the present disclosure. FIG. 11 is a schematic sectional view showing an electronic unit according to the fourth embodiment of the present disclosure. Of the electronic unit 1C, the description of the same parts as those described in the first embodiment will be omitted.

As shown in FIG. 10, a conductor spring 40C is connected to the third electrode 24 arranged on the second surface 20b of the printed wiring board 20. The conductor spring 40C is a metal having elasticity in a direction perpendicular to the second surface 20b. A method of manufacturing such a conductor spring 40C and the like are exemplified in Japanese Patent Laid-Open No. 2004-259530.

When connecting the interposer 10 and the printed wiring board 20, first, the tip of the conductor spring 40C is brought into contact with the first electrode 14 from the state shown in FIG. After that, as shown in FIG. 11, the holding mechanism 50 narrows the distance between the interposer 10 and the printed wiring board 20, whereby the conductor spring 40C elastically deforms so as to contract. As a result, the conductor spring 40C is pressed against the first electrode 14, and the first electrode 14 and the third electrode 24 are electrically connected via the conductor spring 40C.

Even if the elastic deformation of the conductor spring 40C is changed to a direction in which the elastic deformation is restored (a state in which the distance between the interposer 10 and the printed wiring board 20 is increased), the elastically deformed state (a state where the elastic deformation is not completely restored) is maintained. Maintained by 50. Therefore, even with such a configuration, the stress can be dispersed by the elasticity of the conductor spring 40C, and the holding mechanism 50 can prevent the first electrode 14 and the conductor spring 40C from separating from each other. The conductor spring 40C is not limited to the coil spring-shaped electrode, and may be a plate spring-shaped (cantilever or the like) electrode. Further, the conductor spring 40C is not limited to being provided on the third electrode 24 of the printed wiring board 20, but may be provided on the first electrode 14 of the interposer 10.

<Fifth Embodiment>
In the fifth embodiment, an electronic unit 1D in which the holding function of the holding mechanism 50 is realized by a columnar structure 50D arranged between the interposer 10 and the printed wiring board 20 will be described. Since the columnar structure 50D is arranged between the interposer 10 and the printed wiring board 20, it is applicable when a space is formed between the interposer 10 and the printed wiring board 20. For example, of the above-described embodiments, the columnar structure 50D is applied when the elastic bumps 40A are connected as in the second embodiment or when the conductor springs 40C are connected as in the fourth embodiment. It is possible. In the fifth embodiment, an electronic unit 1D to which the columnar structure 50D is applied in the second embodiment will be described.

FIG. 12 is a schematic cross-sectional view showing the configuration before fixing the printed wiring board and the interposer in the electronic unit according to the fifth embodiment of the present disclosure. FIG. 13 is a schematic sectional view showing an electronic unit according to the fifth embodiment of the present disclosure. Of the electronic unit 1D, the description of the same parts as those described in the first embodiment and the second embodiment will be omitted.

A plurality of columnar structures 50D are arranged between the interposer 10 and the printed wiring board 20. The columnar structure 50D is bonded to the first surface 10a of the interposer 10 and the second surface 20b of the printed wiring board 20, and applies a force in a direction to bring the interposer 10 and the printed wiring board 20 closer to each other. The columnar structure 50D is preferably made of, for example, resin or the like, and has a smaller coefficient of thermal expansion and a higher rigidity than at least the elastic bump 40A. When the coefficient of thermal expansion is made small, the action of widening the gap between the interposer 10 and the printed wiring board 20 when heat is applied is suppressed. Further, when the rigidity is increased, it is possible to prevent the gap between the interposer 10 and the printed wiring board 20 from being widened due to the stress caused by the elastic bumps 40A. At this time, the difference in coefficient of thermal expansion is preferably 5 pppm/K or more. Further, the difference in rigidity is preferably 3 GPa or more.

By holding the elastic bumps 40A (resin 42A) in an elastically deformed state, the distance (positional relationship) between the interposer 10 and the printed wiring board 20 is fixed. That is, the columnar structure 50D generates a force (tensile stress) in a direction to pull the interposer 10 and the printed wiring board 20 against the elastic force of the elastic bump 40A. Alternatively, in order to obtain the same effect as the tensile stress, the height of the columnar structure 50D and the height of the elastic bump 40A may be different in advance, or the material of the columnar structure 50D may be different depending on the place. .. For example, when the heights are made different, it is preferable to lower the columnar structure 50D toward the center of the interposer 10. When the material is changed depending on the place, it is preferable to select the material of the columnar structure 50D so that the thermal expansion coefficient becomes lower toward the center of the interposer 10.

When connecting the interposer 10 and the printed wiring board 20, first, as shown in FIG. 12, a conductor 41A is brought into contact with the third electrode 24. At this time, the columnar structure 50D is adhered to the printed wiring board 20, but is separated from the interposer 10. The columnar structure 50D may be adhered to the interposer 10 side. In this case, the columnar structure 50D is separated from the printed wiring board 20.

Then, as shown in FIG. 13, by narrowing the distance between the interposer 10 and the printed wiring board 20, the elastic bumps 40A are crushed and elastically deformed, and the columnar structure 50D and the interposer 10 are bonded. The adhesive strength is required to be stronger than the stress that restores the elastic deformation of the elastic bump 40A. As a result, the conductor 41A is pressed against the third electrode 24, and the first electrode 14A and the third electrode 24 are electrically connected via the conductor 41A.

Even if the elastic deformation of the elastic bump 40A is changed to a direction in which the elastic deformation is restored (a state in which the distance between the interposer 10 and the printed wiring board 20 is expanded), the elastically deformed state (a state where the elastic bump 40A is not completely restored) has a columnar structure. Maintained by body 50D. Therefore, even with such a configuration, it is possible to suppress the stress from being dispersed due to the elasticity of the resin 42A, and to prevent the third electrode 24 and the conductor 41A from being separated by the columnar structure 50D.

Here, the positional relationship between the columnar structure 50D and the elastic bumps 40A will be described.

FIG. 14 is a diagram showing an arrangement example of columnar structures in the fifth embodiment of the present disclosure. More specifically, FIG. 14 is a diagram showing the positional relationship between the columnar structure 50D and the elastic bumps 40A, taken along a direction perpendicular to the second surface 20b of the printed wiring board 20. In the example shown in FIG. 14, a plurality of elastic bumps 40A and a plurality of columnar structures 50D are alternately arranged. For example, the columnar structure 50D-1 is arranged between the elastic bump 40A-1 and the elastic bump 40A-2 adjacent thereto. Further, the elastic bump 40A-2 is arranged between the columnar structure 50D-1 and the columnar structure 50D-2 adjacent thereto.

In other words, the arrangement example shown in FIG. 14 can also be shown as follows. For example, the distance to the columnar structure 50D adjacent to the elastic bump 40A is shorter than the distance between two adjacent elastic bumps 40A. In addition, the distance to the elastic bumps 40A adjacent to the columnar structure 50D is shorter than the distance between two adjacent columnar structures 50D.

Further, in this example, the distance between at least one of the columnar structures 50D (for example, the columnar structure 50D-1) and the end of the interposer 10 is at least one of the elastic bumps 40A (for example, the elastic bumps 40A-1). ) Is greater than the distance between the end.

The arrangement example shown in FIG. 14 is an example, and another arrangement may be used. For example, of the elastic bumps 40A and the columnar structure 50D, the one closest to the end of the interposer 10 may be the elastic bump 40A as shown in FIG. 14 or the columnar structure 50D. With the arrangement shown in FIG. 14, the elastic bumps 40A can be efficiently arranged up to the vicinity of the end portion of the interposer 10. On the other hand, if the columnar structure 50D is arranged at a position close to the end of the interposer 10, the columnar structure 50D can be arranged so as to surround the periphery of the elastic bump 40A. Elastic deformation can be realized.

Next, the shape when the columnar structure 50D is viewed as a cross section parallel to the first surface 10a will be described. The cross-sectional shape is a circle in the example shown in FIG.

FIG. 15 is a diagram showing the shape (first example) of the columnar structure according to the fifth embodiment of the present disclosure. FIG. 16 is a diagram showing the shape (second example) of the columnar structure according to the fifth embodiment of the present disclosure. The cross-sectional shape of the columnar structure 50D can take various shapes such as the shape shown in FIGS. 15B and 15C and the shape shown in FIG. 16 in addition to the circle shown in FIGS. 14 and 15A. The group shown in FIG. 15 and the group shown in FIG. 16 are classified as follows.

In the group (columnar structures 50D, 50DA, 50DB) shown in FIG. 15, the tangent line T at the outer edge of the cross-sectional shape does not cross the outer edge regardless of the position of the tangent line T, that is, the inside where the tangent line T is surrounded by the outer edge. It has a shape that does not penetrate into the (columnar structure itself). On the other hand, in the group (columnar structures 50DC, 50DD, 50DE) shown in FIG. 16, the tangent line T at the outer edge of the cross-sectional shape crosses the outer edge at the tangent line T at any position (for example, the position shown in FIG. 16), that is, The tangent line T has a shape that penetrates into the inside (columnar structure itself) surrounded by the outer edge.

Although any structure can be used as the columnar structure 50D, the group structure shown in FIG. 15 is preferable. With such a structure, the stress tends to act in the tensile direction, so that it is possible to efficiently increase the distance between the interposer 10 and the printed wiring board 20 that are bonded to both ends of the columnar structure 50D. Can be suppressed.

<Sixth Embodiment>
In the sixth embodiment, an electronic unit 1E in which a heat sink (temperature adjusting unit) for heat dissipation of the electronic device 30 is further arranged will be described.

FIG. 17 is a schematic sectional view showing an electronic unit according to the sixth embodiment of the present disclosure. Of the electronic unit 1E, the description of the same parts as those described in the first embodiment will be omitted.

A heat sink 70 is arranged on the second surface 30b of the electronic device 30 with a heat dissipation grease 37 interposed therebetween. As described above, in this example, the holding mechanism 50E can contact the heat sink 70 and the printed wiring board 20, and control the distance between the heat sink 70 and the printed wiring board 20. This also controls the distance between the interposer 10 and the printed wiring board 20 via the heat sink 70. Therefore, the holding mechanism 50E in the sixth embodiment can also hold the anisotropic conductive film 40 in an elastically deformed state. Further, according to this configuration, the degree of adhesion between the heat sink 70 and the electronic device 30 is improved more than the degree of adhesion in which the heat dissipation grease 37 is merely in contact, so that the heat dissipation effect is also improved.

<Seventh Embodiment>
In the seventh embodiment, an electronic device using the electronic unit in each of the above-described embodiments will be described. Examples of electronic devices include mobile terminals, information processing devices, home appliances, and the like. Specific examples of the mobile terminal include a mobile phone, a smartphone, a digital still camera, a digital video camera, and a notebook personal computer. More specifically, the information processing device may be a desktop personal computer, a server, a car navigation, a communication device, or the like.

FIG. 18 is a diagram illustrating an example of the electronic device according to the seventh embodiment of the present disclosure. As an example, the smartphone 500 and the notebook personal computer 600 are shown as examples of the electronic device in which the electronic unit 1 according to the first embodiment is mounted. These electronic devices include a control unit 1100 including a CPU that executes an application program to realize various functions. At least one of the various functions includes a function of using the output signal from the electronic unit 1. The electronic unit 1 may have the function of the control unit 1100.

<Modification>
The present disclosure is not limited to the above-described embodiment, and various other modifications are included. For example, the above-described embodiments have been described in detail in order to explain the present disclosure in an easy-to-understand manner, and are not necessarily limited to those including all the configurations described. Further, a part of the configuration of a certain embodiment may be replaced with the configuration of another embodiment, and the configuration of a certain embodiment may be added to the configuration of another embodiment. Further, it is possible to add/delete/replace other configurations with respect to a part of the configurations of the respective embodiments. Hereinafter, some modified examples will be described. Note that the modified example of the first embodiment can be applied as an modified example of the other embodiments.

(1) The printed wiring board 20 is not limited to the glass epoxy substrate, and may be any substrate as long as it has a different thermal expansion coefficient from that of the interposer 10.

(2) Although the holding mechanism 50 is screwed to the printed wiring board 20, the movement of the shaft portion 51 in the axial direction is restricted, but the movement may be restricted by another means such as an adhesive. ..

(3) In the holding mechanism 50, the portion that connects the support portion 55 and the printed wiring board 20 is the shaft portion 51. However, the holding mechanism 50 is not limited to the shaft shape (for example, a cylinder), and may be a plate shape. .. In the case of a plate shape, the plate portion and the printed wiring board 20 may be fixed with an adhesive or the like.

1, 1A, 1B, 1C, 1D, 1E, 114Z... Electronic unit, 10, 10Z... Interposer, 14, 14A... First electrode, 14Z... Electrode, 18... Second electrode, 20, 20Z... Printed wiring board, 24 ...Third electrode, 30, 30Z... Electronic device, 37... Heat dissipation grease, 38... Fourth electrode, 40... Anisotropic conductive film, 40A... Elastic bump, 40B... Penetrating electrode film, 40C... Conductor spring, 40Z... Solder , 41... Conductive particles, 41A, 41B... Conductor, 41Ba... Conductor, 42A... Resin, 43... Binder, 43A... Resin, 43B... Film, 50... Holding mechanism, 50-1... Holding mechanism, 50-2 ... Holding mechanism, 50-3... Holding mechanism, 50-4... Holding mechanism, 50D, 50DA, 50DB, 50DC, 50DD, 50DE... Columnar structure, 50E... Holding mechanism, 51... Shaft section, 55... Support section, 70 ... heat sink, 80... bump, 500... smartphone, 600... notebook type personal computer, 1100... control unit

Claims (18)

A first substrate having a first electrode arranged on a first surface and a second electrode arranged on a second surface opposite to the first surface;
A second substrate which is arranged so as to face the first surface and has a coefficient of thermal expansion different from that of the first substrate, and which has a third electrode on the surface on the first substrate side;
An electronic device including an active element, arranged to face the second surface, and electrically connected to the second electrode;
An elastic connecting portion that includes a conductor that electrically connects the first electrode and the third electrode;
A holding portion for holding the connecting portion in an elastically deformed state by the first substrate and the second substrate;
An electronic unit comprising. The electronic unit according to claim 1, wherein the holder includes a structure arranged outside the first substrate. The electronic unit according to claim 2, wherein the structure includes a portion connected to the second surface and a portion connected to the second substrate. Further comprising a temperature adjustment unit arranged on the side opposite to the first substrate with respect to the electronic device,
The electronic unit according to claim 2, wherein the structure includes a portion connected to the temperature adjustment unit and a portion connected to the second substrate. The electronic unit according to claim 1, wherein the holding unit includes a structure that is bonded to the first substrate and the second substrate between the first substrate and the second substrate. The electronic unit according to claim 5, wherein a distance between the structure and an end portion of the first substrate is longer than a distance between the conductor and the end portion. The connection portion includes a plurality of the conductors including a first conductor and a second conductor,
The holding part includes a plurality of the structures including a first structure and a second structure,
The first structure is disposed between the first conductor and the second conductor,
The electronic unit according to claim 5, wherein the first conductor is arranged between the first structure and the second structure. The electronic unit according to claim 5, wherein the structure has a shape in which a tangent line at each position of an outer edge in a cross section parallel to the first surface does not enter the inside of the outer edge. The electronic unit according to claim 1, wherein the connecting portion has a resin having elasticity and the conductor arranged in contact with the resin. The electronic unit according to claim 9, wherein the conductor includes a portion arranged along a surface of the resin. The conductor includes a portion disposed on the surface of the resin,
The electronic unit according to claim 9, wherein the resin contains conductive particles. The connection portion includes conductive particles electrically connected to the first electrode and the third electrode and conductive particles not electrically connected to the first electrode and the third electrode. 9. The electronic unit according to item 9. The conductor includes a linear metal,
The electronic unit according to claim 9, wherein the connection portion further includes a linear conductor that is not connected to either the first electrode or the third electrode. The electronic unit according to claim 1, wherein the conductor has elasticity due to a spring structure. The electronic unit according to claim 1, wherein a coefficient of thermal expansion of the second substrate is larger than a coefficient of thermal expansion of the first substrate. The electron according to claim 15, wherein a difference between a coefficient of thermal expansion of the second substrate and a coefficient of thermal expansion of the first substrate is larger than a difference between a coefficient of thermal expansion of the electronic device and a coefficient of thermal expansion of the first substrate. unit. The electronic unit according to claim 1, wherein the first substrate is a glass substrate and includes an electrode penetrating the glass substrate. The electronic unit according to claim 1, wherein the second substrate includes a resin.

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