1. Field of the Invention
The disclosed embodiments relate to power conversion devices.
2. Discussion of the Background
For example, Japanese Unexamined Patent Application Publication No. 2008-103623 discloses a power conversion device. This power conversion device includes an IGBT (power conversion semiconductor element), lead frames electrically connected to the IGBT, and a resin mold that contains the IGBT and the lead frames. The lead frames protrude from a side face of the resin mold to be electrically connected to an external apparatus.
In this power conversion device, the lead frames protrude from the side face of the resin mold, and therefore, the space occupied by the lead frames increases the size of the device. This makes size reduction difficult.
A power conversion device according to one aspect of the present disclosure includes a power conversion device body unit. The power conversion device body unit includes a power conversion semiconductor element having an electrode; an electrode conductor electrically connected to the electrode of the power conversion semiconductor element, and including a side face and an upper end portion having a flat upper end face; and a seal material formed of resin to cover the power conversion semiconductor element and the side face of the electrode conductor. The flat upper end face of the electrode conductor is exposed from an upper surface of the seal material, and the upper end portion having the flat upper end face has a projecting portion projecting sideward. A wiring board is electrically connected to the flat upper end face of the electrode conductor exposed from the upper surface of the seal material so as to be electrically connected to the power conversion device body unit.
A more complete appreciation of the disclosure and many of the attendant advantages thereof will be readily obtained as the same becomes better understood by reference to the following detailed description when considered in connection with the accompanying drawings, wherein:
Embodiments will now be described with reference to the accompanying drawings, wherein like reference numerals designate corresponding or identical elements throughout the various drawings.
Embodiments will be described below with reference to the drawings.
A description will be given of a structure of a power module 100 according to a first embodiment. The power module 100 is an example of a disclosed “power conversion device body unit.”
Referring to
Preferably, the semiconductor element 2 is provided on a substrate that contains silicon carbide (SiC) as a major component, and is formed by an FET (field-effect transistor) capable of high-frequency switching. As illustrated in
The semiconductor element 3 includes a first recovery diode (FRD) having an anode electrode 3a and a cathode electrode 3b. Preferably, the cathode electrode 3b of the semiconductor element 3 is electrically connected to the drain electrode 2c of the semiconductor element 2, and the semiconductor element 3 preferably functions as a free wheeling diode (see
Referring to
When this type of semiconductor element is used, the temperature of a joint portion increases to about 200° C. For this reason, the joint material 8 is formed of solder having high heat resistance, for example, Au-20Sn, Zn-30Sn, or Pb-5Sn. When the temperature of the joint portion increases to about 400° C., the joint material 8 is formed of Ag nanoparticle paste having a higher heat resistance.
The gate terminal 4 is joined to a front surface of the semiconductor element 2 (on the control electrode 2a) by a joint material 8. As illustrated in
The source terminal 5 is joined to the front surface of the semiconductor element 2 (on the source electrode 2b) by a joint material 8. As illustrated in
In the source terminal 5, a dent portion 5e is provided on a semiconductor element 2 side of the columnar portion 5a. The dent portion 5e is narrowed in a manner such that the cross-sectional area of the columnar portion 5a increases toward the upper end portion 5b having the projecting portion 5d. This allows heat propagating from the source electrode 2b of the semiconductor element 2 to be easily diffused toward the upper end portion 5b. Further, when the source terminal 5 is joined to the source electrode 2b, a surplus part of the joint material 8 is pushed out into an area of the dent portion 5e, and stays in the area because of surface tension. Hence, even when the surplus part of the joint material 8 spreads out from the joint portion to the source electrode 2b, a short circuit with a neighboring electrode or the like is suppressed.
The drain terminals 6 are joined to the surface of the drain-electrode heat radiation plate 1 by joint materials 8. As illustrated in
As illustrated in
The drain terminals 6 are electrically connected to the cathode electrode 3b of the semiconductor element 3, and also function as cathode electrode terminals of the semiconductor element 3. The drain terminals 6 also correspond to an example of a disclosed “second diode electrode conductor.”
The anode terminal 7 is arranged and fixed on the front surface of the semiconductor element 3 (on the anode electrode 3a) with a joint material 8 being disposed therebetween. As illustrated in
A dent portion 7e is provided on a semiconductor element 3 side of the columnar portion 7a of the anode terminal 7, similarly to the source terminal 5. This structure allows heat propagating from the anode electrode 3a of the semiconductor element 3 to be easily diffused toward the upper end portion 7b. When the anode terminal 7 is joined to the anode electrode 3a, a surplus part of the joint material 8 is pushed out into an area of the dent portion 7e, and stays in the area because of surface tension. Hence, even when the surplus part of the joint material 8 spreads out from the anode electrode 3a, a short circuit with a neighboring electrode or the like is suppressed.
As illustrated in
In a typical power module, a semiconductor element and an electrode are joined by wiring such as wire bonding. However, since the wiring inductance becomes relatively high in wiring such as wire bonding, switching of the power module at a high frequency is difficult. In contrast, in the power module 100 of the first embodiment, the gate terminal 4, the source terminal 5, and the drain terminals 6 (anode terminal 7) are directly joined to the semiconductor element 2 (semiconductor element 3) by the joint material 8. For this reason, the power module 100 of the first embodiment provides a wiring inductance lower than that of the typical power module using wire bonding. This allows high-frequency switching.
In
As illustrated in
With this structure, the power module 100 of the first embodiment may radiate heat generated by the semiconductor element 2 and the semiconductor element 3 from both the upper end faces 4c, 5c, 6c, and 7c of the gate terminal 4, the source terminal 5, of the drain terminals 6, and the anode terminal 7 that are located on the upper surface (main surface) side of the semiconductor element 2 and the semiconductor element 3 and the drain-electrode heat radiation plate 1 located on the lower surface (back surface) side of the semiconductor element 2 and the semiconductor element 3.
The substantially flat upper end face 4c (upper end face 5c, upper end faces 6c, upper end face 7c) of the gate terminal 4 (source terminal 5, drain terminals 6, anode terminal 7) is exposed from the upper surface of the resin material 10. The upper end portion 4b (upper end portion 5b, upper end portions 6b, upper end portion 7b) having the exposed substantially flat upper end face 4c (upper end face 5c, upper end faces 6c, upper end face 7c) is provided with the projecting portion 4d (projecting portion 5d, projecting portions 6d, projecting portion 7d) projecting sideward. Thus, heat generated by the semiconductor element 2 and the semiconductor element 3 is radiated upward via the gate terminal 4 (source terminal 5, drain terminals 6, anode terminal 7). The projecting portion 4d (projecting portion 5d, projecting portions 6d, projecting portion 7d) projecting sideward increases the area of the upper end face 4c (upper end face 5c, upper end faces 6c, upper end face 7c, that is, a heat radiation surface) of the gate terminal 4 (source terminal 5, drain terminals 6, anode terminal 7). This enhances heat radiation performance in radiating heat generated by the semiconductor element 2 and the semiconductor element 3 upward. Further, the upper end face 4c (upper end face 5c, upper end faces 6c, upper end face 7c) of the gate terminal 4 (source terminal 5, drain terminals 6, anode terminal 7) exposed from the upper surface of the resin material 10 can be electrically connected to an external apparatus. According to this structure adopted in the first embodiment, the size of the device can be further reduced, compared with the power module of the related art in which the electrodes protrude from the side face of the resin material.
The power module 100 of the first embodiment is provided such that the projecting portion 4d (projecting portion 5d, projecting portions 6d, projecting portion 7d) at the upper end portion 4b (upper end portion 5b, upper end portions 6b, upper end portion 7b) of the gate terminal 4 (source terminal 5, drain terminals 6, anode terminal 7) shaped like an upward extending column protrudes peripherally from the outer peripheral surface of the columnar gate terminal 4 (source terminal 5, drain terminals 6, anode terminal 7). This increases the area of the upper end face 4c (upper end face 5c, upper end faces 6c, upper end face 7c) of the gate terminal 4 (source terminal 5, drain terminals 6, anode terminal 7) serving as the heat radiation surface.
The substantially flat upper end faces 4c, 5c, 6c, and 7c having the projecting portions 4d, 5d, 6d, and 7d in the gate terminal 4, the source terminal 5, the drain terminals 6, and the anode terminal 7 are substantially equal in height. Thus, when the upper end faces of the gate terminal 4, the source terminal 5, the drain terminals 6, and the anode terminal 7 are electrically connected to an external apparatus, arrangement of a wiring board and an electrode and electrical connection with the external apparatus can be performed easily.
The substantially flat upper end faces 4c, 5c, 6c, and 7c having the projecting portions 4d, 5d, 6d, and 7d in the terminals 4, 5, 6, and 7 are substantially equal in height to the upper surface of the resin material 10. The upper end faces 4c, 5c, 6c, and 7c are flush with the upper surface of the resin material 10. Thus, a wiring board or the like can be easily set on the upper end faces 4c, 5c, 6c, and 7c and the resin material 10 for electrical connection.
The upper end faces 4c, 5c, 6c, and 7c of the gate terminal 4, the source terminal 5, the drain terminals 6, and the anode terminal 7, which are exposed from the upper surface of the resin material 10, can be electrically connected to an external apparatus. The upper end faced 4c 5c, 6c, and 7c exposed from the upper surface of the resin material 10 each function both for heat radiation and electrical connection with the external apparatus.
The gate terminal 4 (source terminal 5) is connected to the control electrode 2a (source electrode 2b) on the main surface of the semiconductor element 2 by the joint material 8, and extends upward. Further, the gate terminal 4 (source terminal 5) has the substantially flat upper end face 4c (upper end face 5c) and the projecting portion 4d (projecting portion 5d) exposed from the upper surface of the resin material 10. The drain terminals 6 are electrically connected to the drain electrode 2c on the back surface of the semiconductor element 2, and extend upward from positions apart from the semiconductor element 2. Also, the drain terminals 6 have the substantially flat upper end faces 6c and the projecting portions 6d exposed from the upper surface of the resin material 10. The anode terminal 7 is connected to the anode electrode 3a on the main surface of the semiconductor element 3 by the joint material 8, and extends upward. Also, the anode terminal 7 has the substantially flat upper end face 7c and the projecting portion 7d exposed from the upper surface of the resin material 10. Further, the drain terminals 6 are electrically connected to the cathode electrode 3b on the back surface of the semiconductor element 3, and extend upward from positions apart from the semiconductor element 3. Also, the drain terminals 6 have the substantially flat upper end faces 6c and the projecting portions 6d exposed from the upper surface of the resin material 10. The upper end face 4c of the gate terminal 4, the upper end face 5c of the source terminal 5, the upper end faces 6c of the drain terminals 6, and the upper end face 7c of the anode terminal 7 are arranged on the upper side of the power module 100. This structure allows easy electrical connection with an external apparatus. The upper end face 4c of the gate terminal 4, the upper end face 5c of the source terminal 5, the upper end faces 6c of the drain terminals 6, and the upper end face 7c of the anode terminal 7 serve as the heat radiation surfaces, and the areas thereof are increased by the projecting portion 4d, the projecting portion 5d, the projecting portions 6d, and the projecting portion 7d. This further enhances heat radiation performance in radiating heat generated by the semiconductor element 2 and the gate terminal 4 upward.
The upper end face 4c of the gate terminal 4, the upper end face 5c of the source terminal 5, and the upper end faces 6c of the drain terminals 6, which are substantially flat, are exposed from the upper surface of the resin material 10. That is, the upper end faces 4c, 5c, and 6c for the semiconductor element 2 are arranged on the upper side of the power module 100. Also, the upper end face 4c, 5c, and 6c have the projecting portions 4d, 5d, and 6d, whereby the areas thereof are increased. This allows easy electrical connection with the external apparatus.
The drain terminals 6 are electrically connected to the drain electrode 2c on the back surface of the semiconductor element 2, and extend upward from the positions apart from the semiconductor element 2. Also, the drain terminals 6 have the substantially flat upper end faces 6c and the projecting portions 6d. Since the drain terminals 6 are located apart from the semiconductor element 2, a short circuit between the side faces of the drain terminals 6 and the semiconductor element 2 is avoided.
In the first embodiment, the drain terminals 6 are preferably arranged near the end portions of the power module 100, and the gate terminal 4 and the source terminal 5 are arranged near the center of the power module 100. This arrangement ensures a sufficient insulation distance between the drain terminals 6, and the gate terminal 4 and the source terminal 5, and avoids a short circuit therebetween.
The side faces of the semiconductor element 3 and the anode terminal 7 are covered with the resin material 10, and the substantially flat upper end face 7c of the anode terminal 7 is exposed from the upper surface of the resin material 10. This allows heat generated by the semiconductor element 3 to be radiated upward from the substantially flat upper end face 7c of the anode terminal 7. Further, since the upper end face 7c (heat radiation surface) of the anode terminal 7 is provided with the projecting portion 7d projecting sideward, the area thereof can be increased. This structure enhances heat radiation performance in radiating heat generated by the semiconductor element 3 upward.
According to the first embodiment, the outer surface of the power module 100 is formed by the resin material 10. The semiconductor element 2, the semiconductor element 3, the gate terminal 4, the source terminal 5, the drain terminals 6, and the anode terminal 7 are covered with the resin material 10. Since this structure allows an external impact to be absorbed by the resin material 10, the semiconductor elements 2 and 3 can be protected from the impact, and reliability is enhanced. Further, since the resin material 10 ensures a sufficient insulation distance, a short circuit among the gate terminal 4, the source terminal 5, the drain terminals 6, and the anode terminal 7 can be avoided.
According to the first embodiment, heat generated by the semiconductor element 2 and the semiconductor element 3 is radiated from both the upper end faces 4c, 5c, 6, and 7c of the gate terminal 4, the source terminal 5, the drain terminal 6, and the anode terminal 7 arranged on the upper surface (main surface) side of the semiconductor element 2 and the semiconductor element 3, and the drain-electrode heat radiation plate 1 arranged on the lower surface (back surface) side of the semiconductor element 2 and the semiconductor element 3. Since heat can thus be radiated from both the upper and lower surface sides of the semiconductor element 2 and the semiconductor element 3, heat radiation performance of the power module 100 is enhanced greatly.
Preferably, the drain-electrode heat radiation plate 1 is joined to the back surfaces of the semiconductor element 2 and the semiconductor element 3 by the joint materials 8. Since there is no insulator between the drain-electrode heat radiation plate 1 and the semiconductor elements 2 and 3, the performance of heat radiation from the drain-electrode heat radiation plate 1 is enhanced. Since the surface of the drain-electrode heat radiation plate 1 is exposed from the resin material 10, heat radiation performance is obviously higher than in the case in which the surface of the drain-electrode heat radiation plate 1 is covered with the resin material 10.
Since SiC is used in the semiconductor element 2 (semiconductor element 3) in the first embodiment, higher speed switching can be performed in a high-temperature environment, than in the case in which Si is used.
Next, a second embodiment will be described. In the second embodiment, the power module 100 (power module body units 100a and 100b) of the above-described first embodiment is attached to a wiring board 21. The power module body units 100a and 100b correspond to an example of the disclosed “power conversion device body unit.”
Referring to
The power module body unit 100a is attached to the wiring board 21 with bump electrodes 41 being disposed therebetween. In the second embodiment, a substantially flat upper end face 4c (upper end face 5c, upper end faces 6c, and upper end face 7c) of a gate terminal 4 (source terminal 5, drain terminals 6, anode terminal 7) exposed from a surface of a resin material 10 (see
The power module body unit 100b is attached to the wiring board 21 with bump electrodes 41 being disposed therebetween. In the second embodiment, a substantially flat upper end face 4c (upper end face 5c, upper end faces 6c, upper end face 7c) of a gate terminal 4 (source terminal 5, drain terminals 6, and anode terminal 7) exposed from a surface of a resin material 10 (see
A P-side metal terminal 32 and an N-side metal terminal 33 are provided at one end of the wiring board 21. The P-side metal terminal 32 is connected to the P-side drain metal terminals 26 of the power module body unit 100a by a bus-bar-like wire 34 formed by a conductive metal plate in the wiring board 21. The P-side source metal terminal 25 and the P-side anode metal terminal 27 of the power module body unit 100a are connected to the N-side drain metal terminal 30 of the power module body unit 100b by bus-bar-like wires 34 provided in the wiring board 21. The N-side source metal terminal 29 and the N-side anode metal terminal 31 of the power module body unit 100b are connected to the N-side metal terminal 33 at the one end of the wiring board 21 by wires 34 provided in the wiring board 21.
The P-side gate driver IC 22 is located near the power module body unit 100a. The P-side gate driver IC 22 is also connected to a P-side control signal terminal 35 provided at the one end of the wiring board 21.
The N-side gate driver IC 23 is located near the power module body unit 100b. The N-side gate driver IC 23 is also connected to an N-side control signal terminal 36 provided at the one end of the wiring board 21.
Since the P-side gate driver IC 22 and the N-side gate driver IC 23 are located near the power module body unit 100a and the power module body unit 100b, respectively, wiring inductance can be decreased. This allows high-frequency switching of the power module body unit 100a and the power module body unit 100b.
The wiring board 21 is located at a slight distance from the power module body unit 100a and the power module body unit 100b. A space in the distance is filled with an insulating resin material 37. This fixes the wiring board 21 to the power module body units 100a and 100b, and suppresses promotion of corrosion of the bump electrodes 41 that electrically connect the wiring board 21 to the power module body units 100a and 100b. The material of the resin material 37 is appropriately selected, for example, according to the temperature of heat generated by semiconductor elements 2 and 3. The resin material 37 is an example of the disclosed “seal material.”
According to the second embodiment, the substantially flat upper end face 4c (upper end faces 5c, upper end faces 6c, upper end face 7c) of the gate terminal 4 (source terminal 5, drain terminals 6, anode terminal 7) exposed from the upper surface of the resin material 10 is electrically connected to the wiring board 21. Such a simple structure allows power to be supplied to the gate terminal 4 (source terminal 5, drain terminals 6, anode terminal 7) via the wiring board 21.
According to the second embodiment, the substantially flat upper end face 4c (upper end face 5c, upper end faces 6c, upper end face 7c) of the gate terminal 4 (source terminal 5, drain terminals 6, anode terminal 7) exposed from the upper surface of the resin material 10 may be electrically connected to the wiring board 21 by the bump electrode 41. Hence, the substantially flat upper end face 4 (upper end face 5c, upper end faces 6c, and upper end face 7c) of the gate terminal 4 (source terminal 5, drain terminals 6, anode terminal 7) and the wiring board 21 are spaced tightly. This structure suppresses the contact of the gate terminal 4 (source terminal 5, drain terminals 6, anode terminal 7) and the wiring board 21 with the outside air. This suppresses promotion of corrosion.
Next, a third embodiment will be described. Referring to
A space between the power module body units 100a and 100b and the wiring board 21 is filled with an insulating resin material 37a. The resin material 37a covers an area from surfaces of the wiring board 21 to center portions of side faces of the power module body units 100a and 100b. The power module body units 100a and 100b are electrically connected to the wiring board 21 (P-side gate metal terminal 24, P-side source metal terminal 25, P-side drain metal terminals 26, P-side anode metal terminal 27, N-side gate metal terminal 28, N-side source metal terminal 29, N-side drain metal terminals 30, and N-side anode metal terminal 31) with bump electrodes 41 being disposed therebetween. Hence, the power module body units 100a and 100b and the wiring board 21 are spaced tightly. This structure suppresses the contact of the terminals and the like with the outside air, and suppresses promotion of corrosion. Therefore, the resin material 37a may sometimes be omitted. The resin material 37a is an example of the disclosed “seal material.”
Advantages obtained by the third embodiment are similar to those of the second embodiment.
Next, a fourth embodiment will be described. Referring to
Next, a fifth embodiment will be described. Referring to
Next, a sixth embodiment will be described. Referring to
Next, a seventh embodiment will be described. Referring to
Next, an eighth embodiment will be described. Referring to
Next, a ninth embodiment will be described. Referring to
Next, a tenth embodiment will be described. Referring to
Next, an eleventh embodiment will be described. Referring to
A lower heat spreader 109b having a heat radiation function is provided on a lower surface of the insulating circuit board 109a. The lower heat spreader 109b is shaped like a box (case) having a bottom face and a side face. An upper heat spreader 109a is provided on the lower heat spreader 109b with a joint material being disposed therebetween. The upper heat spreader 109c is shaped like a box (case) having an upper face and a side face. The upper face of the upper heat spreader 109c has an opening 109d, as illustrated in
As illustrated in
In the eleventh embodiment, preferably, the side faces of the semiconductor element 2, the semiconductor element 3, the gate terminal 4, the source terminal 5, the drain terminal 6, and the anode terminal 7 are covered with the filled resin material 10f, and the upper end face 4c of the gate terminal 4, the upper end face 5c of the source terminal 5, the upper end face 6c of the drain terminal 6, and the upper end face 7c of the anode terminal 7 are exposed from the upper surface of the resin material 10f. With this structure, external impact is absorbed by the lower heat spreader 109b, the upper heat spreader 109c, and the resin material 10f. Hence, it is possible to protect the semiconductor elements 2 and 3 from the impact and to thereby enhance reliability.
The embodiments disclosed herein are to be considered as illustrative and not restrictive, and the following changes are intended to be embraced therein.
For example, while the substantially flat upper end faces of the gate terminal, the source terminal, the drain terminal, and the anode terminal (cathode terminal) are exposed from the resin material in the above first to eleventh embodiments, the disclosure is not limited thereto. For example, the substantially flat upper end face of at least one of the gate terminal, the source terminal, the drain terminal, and the anode terminal (cathode terminal) may be exposed from the resin material.
While the substantially flat upper end faces of the gate terminal, the source terminal, the drain terminal, and the anode terminal (cathode terminal) are equal in height in the above first to eleventh embodiments, the disclosure is not limited thereto. For example, the substantially flat upper end faces may be different in height.
While the gate terminal, the source terminal, the drain terminal, and the anode terminal (cathode terminal) have the columnar portions in the above first to eleventh embodiments, the disclosure is not limited thereto. For example, the gate terminal, the source terminal, the drain terminal, and the anode terminal (cathode terminal) may have shapes different from the shapes adopted in the first to eleventh embodiments.
While the substantially flat upper end faces of the gate terminal, the source terminal, the drain terminal, and the anode terminal (cathode terminal) are substantially rectangular in plan view in the first to eleventh embodiments, the disclosure is not limited thereto. In the disclosure, the substantially flat upper end faces may have shapes other than the substantially rectangular shape in plan view.
While the substantially flat upper end faces of the gate terminal, the source terminal, the drain terminal, and the anode terminal (cathode terminal) are substantially equal in height to the upper surface of the resin material in the above first to eleventh embodiments, the disclosure is not limited thereto. For example, the substantially flat upper end faces may protrude from the upper surface of the resin material.
While the drain terminals are located apart from the gate terminal, the source terminal, and the anode terminal in the above first to eleventh embodiments, the disclosure is not limited thereto. For example, the gate terminal, the source terminal, the drain terminals, and the anode terminal may be located close to one another.
While the projecting portions of the upper end portions of the drain terminals, the gate terminal, the source terminal, and the anode terminal protrude peripherally from the outer peripheral surfaces of the columnar portions in the above first to eleventh embodiments, the disclosure is not limited thereto. For example, each of the projecting portions may protrude to one side from the corresponding columnar portion. Further, the projecting portion may be formed around a part of the outer peripheral surface of the columnar portion, instead of being formed all around the outer peripheral surface of the columnar portion.
While the upper end portions of the drain terminals, the gate terminal, the source terminal, and the anode terminal have the projecting portions in the above first to eleventh embodiments, the disclosure is not limited thereto. For example, the upper end portion of any one of the drain terminals, the gate terminal, the source terminal, and the anode terminal may have a projecting portion.
While each of the semiconductor elements is formed by the FET provided on the SiC substrate containing silicon carbide (SiC) as a major component and capable of high-frequency switching in the above first to eleventh embodiments, the disclosure is not limited thereto. For example, the semiconductor element may be formed by an FET provided on a GaN substrate containing gallium nitride (GaN) as a major component and capable of high-frequency switching. Alternatively, the semiconductor element may be formed by a MOSFET (metal-oxide semiconductor field-effect transistor) provided on a Si substrate containing silicon (Si) as a major component. Further alternatively, the semiconductor element may be formed by an IGBT (insulated gate bipolar transistor).
While the first recovery diode (FRD) is used as the free wheeling diode element in the above first to eleventh embodiments, the disclosure is not limited thereto. For example, a schottky barrier diode (SBD) may be used as the free wheeling diode. Diode elements other than the first recovery diode (FRD) and the schottky barrier diode (SBD) may be used as long as they can function as a free wheeling diode.
While the joint material is formed of solder of Au-20Sn, Zn-30Sn, or Pb-5Sn or the Ag nanoparticle paste in the above first to eleventh embodiment, the disclosure is not limited thereto. For example, the joint material may be formed of solder foil or solder cream.
It is noted that the modifier “substantially” used in the specification, for example, as in “substantially flat” and “substantially equal in height”, includes not only the range of dimensional tolerance but also the acceptable range of error caused during industrial production.
Obviously, numerous modifications and variations of the present disclosure are possible in light of the above teachings. It is therefore to be understood that within the scope of the appended claims, the disclosure may be practiced otherwise than as specifically described herein.
Number | Date | Country | Kind |
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2009-146952 | Jun 2009 | JP | national |
The present application is a continuation application of the U.S. patent application Ser. No. 13/565,802, filed Aug. 3, 2012, which in turn is a continuation application of the U.S. patent application Ser. No. 13/329,379, filed Dec. 19, 2011, which in turn is a continuation application of International Application No. PCT/JP2010/060335, filed Jun. 18, 2010, which claims priority under 35 U.S.C. §119 to Japanese Patent Application No. 2009-146952, filed Jun. 19, 2009. The contents of these applications are incorporated herein by reference in their entirety.
Number | Date | Country | |
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Parent | 13565802 | Aug 2012 | US |
Child | 13851208 | US | |
Parent | 13329379 | Dec 2011 | US |
Child | 13565802 | US | |
Parent | PCT/JP2010/060335 | Jun 2010 | US |
Child | 13329379 | US |