US20170094771A1 - Printed circuit board and electronic apparatus - Google Patents
Printed circuit board and electronic apparatus Download PDFInfo
- Publication number
- US20170094771A1 US20170094771A1 US15/272,201 US201615272201A US2017094771A1 US 20170094771 A1 US20170094771 A1 US 20170094771A1 US 201615272201 A US201615272201 A US 201615272201A US 2017094771 A1 US2017094771 A1 US 2017094771A1
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- United States
- Prior art keywords
- electronic component
- conductor pattern
- conductor
- wiring board
- printed wiring
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- H—ELECTRICITY
- H05—ELECTRIC TECHNIQUES NOT OTHERWISE PROVIDED FOR
- H05K—PRINTED CIRCUITS; CASINGS OR CONSTRUCTIONAL DETAILS OF ELECTRIC APPARATUS; MANUFACTURE OF ASSEMBLAGES OF ELECTRICAL COMPONENTS
- H05K1/00—Printed circuits
- H05K1/02—Details
- H05K1/0201—Thermal arrangements, e.g. for cooling, heating or preventing overheating
- H05K1/0203—Cooling of mounted components
- H05K1/0209—External configuration of printed circuit board adapted for heat dissipation, e.g. lay-out of conductors, coatings
-
- H—ELECTRICITY
- H05—ELECTRIC TECHNIQUES NOT OTHERWISE PROVIDED FOR
- H05K—PRINTED CIRCUITS; CASINGS OR CONSTRUCTIONAL DETAILS OF ELECTRIC APPARATUS; MANUFACTURE OF ASSEMBLAGES OF ELECTRICAL COMPONENTS
- H05K1/00—Printed circuits
- H05K1/02—Details
- H05K1/0201—Thermal arrangements, e.g. for cooling, heating or preventing overheating
- H05K1/0203—Cooling of mounted components
-
- H—ELECTRICITY
- H05—ELECTRIC TECHNIQUES NOT OTHERWISE PROVIDED FOR
- H05K—PRINTED CIRCUITS; CASINGS OR CONSTRUCTIONAL DETAILS OF ELECTRIC APPARATUS; MANUFACTURE OF ASSEMBLAGES OF ELECTRICAL COMPONENTS
- H05K1/00—Printed circuits
- H05K1/18—Printed circuits structurally associated with non-printed electric components
- H05K1/181—Printed circuits structurally associated with non-printed electric components associated with surface mounted components
-
- H—ELECTRICITY
- H05—ELECTRIC TECHNIQUES NOT OTHERWISE PROVIDED FOR
- H05K—PRINTED CIRCUITS; CASINGS OR CONSTRUCTIONAL DETAILS OF ELECTRIC APPARATUS; MANUFACTURE OF ASSEMBLAGES OF ELECTRICAL COMPONENTS
- H05K1/00—Printed circuits
- H05K1/02—Details
- H05K1/0201—Thermal arrangements, e.g. for cooling, heating or preventing overheating
- H05K1/0203—Cooling of mounted components
- H05K1/0204—Cooling of mounted components using means for thermal conduction connection in the thickness direction of the substrate
- H05K1/0206—Cooling of mounted components using means for thermal conduction connection in the thickness direction of the substrate by printed thermal vias
-
- H—ELECTRICITY
- H05—ELECTRIC TECHNIQUES NOT OTHERWISE PROVIDED FOR
- H05K—PRINTED CIRCUITS; CASINGS OR CONSTRUCTIONAL DETAILS OF ELECTRIC APPARATUS; MANUFACTURE OF ASSEMBLAGES OF ELECTRICAL COMPONENTS
- H05K2201/00—Indexing scheme relating to printed circuits covered by H05K1/00
- H05K2201/06—Thermal details
-
- H—ELECTRICITY
- H05—ELECTRIC TECHNIQUES NOT OTHERWISE PROVIDED FOR
- H05K—PRINTED CIRCUITS; CASINGS OR CONSTRUCTIONAL DETAILS OF ELECTRIC APPARATUS; MANUFACTURE OF ASSEMBLAGES OF ELECTRICAL COMPONENTS
- H05K2201/00—Indexing scheme relating to printed circuits covered by H05K1/00
- H05K2201/09—Shape and layout
- H05K2201/09209—Shape and layout details of conductors
- H05K2201/09218—Conductive traces
- H05K2201/09227—Layout details of a plurality of traces, e.g. escape layout for Ball Grid Array [BGA] mounting
-
- H—ELECTRICITY
- H05—ELECTRIC TECHNIQUES NOT OTHERWISE PROVIDED FOR
- H05K—PRINTED CIRCUITS; CASINGS OR CONSTRUCTIONAL DETAILS OF ELECTRIC APPARATUS; MANUFACTURE OF ASSEMBLAGES OF ELECTRICAL COMPONENTS
- H05K2201/00—Indexing scheme relating to printed circuits covered by H05K1/00
- H05K2201/09—Shape and layout
- H05K2201/09209—Shape and layout details of conductors
- H05K2201/09372—Pads and lands
-
- H—ELECTRICITY
- H05—ELECTRIC TECHNIQUES NOT OTHERWISE PROVIDED FOR
- H05K—PRINTED CIRCUITS; CASINGS OR CONSTRUCTIONAL DETAILS OF ELECTRIC APPARATUS; MANUFACTURE OF ASSEMBLAGES OF ELECTRICAL COMPONENTS
- H05K2201/00—Indexing scheme relating to printed circuits covered by H05K1/00
- H05K2201/10—Details of components or other objects attached to or integrated in a printed circuit board
- H05K2201/10007—Types of components
- H05K2201/10015—Non-printed capacitor
-
- H—ELECTRICITY
- H05—ELECTRIC TECHNIQUES NOT OTHERWISE PROVIDED FOR
- H05K—PRINTED CIRCUITS; CASINGS OR CONSTRUCTIONAL DETAILS OF ELECTRIC APPARATUS; MANUFACTURE OF ASSEMBLAGES OF ELECTRICAL COMPONENTS
- H05K2201/00—Indexing scheme relating to printed circuits covered by H05K1/00
- H05K2201/10—Details of components or other objects attached to or integrated in a printed circuit board
- H05K2201/10431—Details of mounted components
- H05K2201/10507—Involving several components
- H05K2201/10545—Related components mounted on both sides of the PCB
Definitions
- Embodiments of the present invention relate to a printed circuit board having an electronic component which generates heat and an electronic apparatus including the printed circuit board.
- heat radiation pad heat sink
- the heat generated from such an electronic component is conducted from a heat radiation pad of the electronic component through a conductive jointing material of solder, for example, to heat radiation lands on a printed wiring board.
- the heat conducted to the heat radiation lands is then conducted to a plane-shaped conductor pattern on an opposite surface of a surface having an electronic component or in an inner layer through a via conductor placed in the heat radiation lands and is dissipated into the air.
- countermeasures against heat are provided such as attaching a heat sink thereto.
- thermal interference may occur among the plurality of electronic components.
- two electronic components having different heat values from each other are mounted on a printed wiring board, one having a higher heat value of the electronic components is influenced by heat generated from the other electronic component.
- the heat radiation is prevented, and the temperature increases.
- increasing the area of the conductor pattern thermally connected to the heat radiation pad may disadvantageously increase the size of the printed circuit board.
- heat from an electronic component can be effectively dissipated without adding a heat sink, and the size of a printed circuit board can be reduced.
- a printed circuit board includes a printed wiring board, a first electronic component having a first heat radiation pad, a first circuit component provided for the first electronic component and having a first terminal, a second electronic component having a second heat radiation pad and generating heat exhibiting a higher heat value than that of the first electronic component, a second circuit component provided for the second electronic component and having a second terminal; and a conductor provided on the printed wiring board and having a conductor pattern part.
- the first electronic component, the first circuit component, the second electronic component, and the second circuit component are mounted on the printed wiring board, the first heat radiation pad of the first electronic component, the first terminal of the first circuit component, the second heat radiation pad of the second electronic component, and the second terminal of the second circuit component are connected through the conductor, and a thermal resistance between the second heat radiation pad and the first terminal is lower than a thermal resistance between the first heat radiation pad and the first terminal.
- heat from an electronic component can be effectively dissipated without adding a heat sink, and the size of a printed circuit board can be reduced.
- FIG. 1 is a sectional view schematically illustrating a printed circuit board according to a first exemplary embodiment.
- FIG. 2 is an electric circuit diagram illustrating the printed circuit board according to the first exemplary embodiment.
- FIG. 3A is a bottom view of first and second electronic components viewed from a +Z direction according to the first exemplary embodiment.
- FIG. 3B is a plan view illustrating a first surface layer viewed from a ⁇ Z direction of the printed wiring board according to the first exemplary embodiment.
- FIG. 3C is a plan view of a second surface layer viewed from the ⁇ Z direction of the printed wiring board according to the first exemplary embodiment.
- FIG. 4 is an electric circuit diagram illustrating a heat conduction path in the printed circuit board according to the first exemplary embodiment.
- FIG. 5A is a plan view from a ⁇ Z direction of a first surface layer of a printed wiring board in a printed circuit board according to a second exemplary embodiment.
- FIG. 5B is a plan view from a ⁇ Z direction of a second surface layer of a printed wiring board in a printed circuit board according to the second exemplary embodiment.
- FIG. 6A is a plan view viewed from a ⁇ Z direction of a first surface layer of a printed wiring board in a printed circuit board according to a third exemplary embodiment.
- FIG. 6B is a plan view viewed from a ⁇ Z direction of a second surface layer of a printed wiring board in a printed circuit board according to the third exemplary embodiment.
- FIG. 7 is a sectional view schematically illustrating a printed circuit board according to a fourth exemplary embodiment.
- FIG. 8A is a plan view illustrating a first surface layer viewed from a ⁇ Z direction of the printed wiring board in the printed circuit board according to the fourth exemplary embodiment.
- FIG. 8B is a plan view illustrating a second surface layer viewed from the ⁇ Z direction of the printed wiring board in the printed circuit board according to the fourth exemplary embodiment.
- FIG. 9 is a graph illustrating an area of a conductor pattern in printed circuit boards according to the first to third examples and a first comparison example.
- FIG. 10 is a schematic diagram illustrating a heat distribution of the opposite surface of a surface having an electronic component thereon of a printed wiring board in the printed circuit board according to a second example.
- FIG. 11A is a sectional view schematically illustrating a printed circuit board according to the first comparison example.
- FIG. 11B is a plan view illustrating a first surface layer viewed from the ⁇ Z direction of the printed wiring board in the printed circuit board according to the first comparison example.
- FIG. 11C is a plan view illustrating a second surface layer viewed from the ⁇ Z direction of the printed wiring board in the printed circuit board according to the second comparison example.
- FIG. 12 is a schematic diagram illustrating a heat distribution of a surface opposite against a surface having an electronic component thereon of a printed wiring board in the printed circuit board according to the first comparison example.
- FIG. 1 is a sectional view schematically illustrating a printed circuit board according to a first exemplary embodiment.
- FIG. 2 is an electric circuit diagram illustrating the printed circuit board according to the first exemplary embodiment.
- a printed circuit board 100 includes a printed wiring board 200 , a circuit module 301 being a first circuit module, and a circuit module 302 being a second circuit module.
- the circuit modules 301 and 302 are mounted on the printed wiring board 200 .
- FIG. 1 is a sectional view schematically illustrating a printed circuit board according to a first exemplary embodiment.
- FIG. 2 is an electric circuit diagram illustrating the printed circuit board according to the first exemplary embodiment.
- a printed circuit board 100 includes a printed wiring board 200 , a circuit module 301 being a first circuit module, and a circuit module 302 being a second circuit module.
- the circuit modules 301 and 302 are mounted on the printed wiring board 200 .
- FIG. 1 is a sectional view schematically illustrating a printed circuit board according to
- a direction horizontal to a surface of the printed wiring board 200 is an X direction
- a direction horizontal to a surface of the printed wiring board 200 perpendicular to the X direction is a Y direction
- a direction perpendicular to the surface of the printed wiring board 200 is a Z direction.
- the printed wiring board 200 is a substrate body on which an electronic component is not mounted
- the printed circuit board 100 has an electronic component and so on mounted on the printed wiring board 200 .
- the printed wiring board 200 has a signal line and so on, which are not illustrated.
- the printed wiring board 200 has a plurality of (two in the first exemplary embodiment) conductor layers including conductor layers 201 and 202 stacked through an insulator layer (dielectric layer) 203 .
- the printed wiring board 200 is a 2-layered printed wiring board.
- the number of layers in the printed wiring board is not limited to two but may be equal to or higher than three.
- Each of the conductor layers 201 and 202 mainly has a conductor pattern.
- Each of the conductor layers 201 and 202 being a surface layer has a solder resist 205 covering the conductor.
- An insulator layer 203 mainly has an insulator (dielectric).
- the surface layers are outermost conductor layers (mounting surface) having an electronic component and so on thereon. Between the pair of surface layers, one surface layer (second surface layer) on the opposite side of the other surface layer (first surface layer) will also be called a back layer.
- the surface layer of the printed wiring board 200 will also be called a front surface (first surface), and the back layer will also be called a back surface (second surface).
- the insulator layer 203 may contain an insulator having electrical isolation which may be a hardened resin such as an epoxy resin.
- the conductor layers 201 and 202 have conductors such as conductor patterns and via conductors (each being a conductor provided in a via) being highly electrically and thermally conductive substances that may be metal such as copper and gold.
- the circuit module 301 has an electronic component 311 being a first electronic component and an active element and an electrolytic capacitor 321 being a first circuit component and a passive element.
- the electronic component 311 and electrolytic capacitor 321 are mounted on the printed wiring board 200 .
- the electronic component 311 is a motor driver configured to drive a motor M 1 and supplies electric current to the motor M 1 based on an input command.
- the electrolytic capacitor 321 is provided for the electronic component 311 to reduce power supply noise (power potential variations) in the electronic component 311 .
- the circuit module 302 has an electronic component 312 being a second electronic component and an active element and an electrolytic capacitor 322 being a second circuit component and a passive element.
- the electronic component 312 and electrolytic capacitor 322 are mounted on the printed wiring board 200 .
- the electronic component 312 is a motor driver configured to drive a motor M 2 and supplies electric current to the motor M 2 based on an input command.
- the electrolytic capacitor 322 is provided for the electronic component 312 and may reduce power supply noise (power potential variations) in the electronic component 312 .
- FIG. 3A is a bottom view of the electronic components 311 and 312 viewed from a +Z direction.
- the electronic component 311 has a plurality of terminals 331 including, more specifically, a power supply terminal 331 E, a ground terminal 331 G, a signal terminal 331 S and an output terminal 331 I illustrated in FIG. 2 .
- the electronic component 312 has a plurality of terminals 332 including, more specifically, a power supply terminal 332 E, a ground terminal 332 G, a signal terminal 332 S and an output terminal 332 I illustrated in FIG. 2 .
- Each of terminals of the electronic components 311 and 312 is connected to a signal line, a power supply line, a ground line, and a drive signal line and outputs a drive signal (electric current) from the output terminals 331 I and 332 I to the motors M 1 and M 2 .
- the electronic component 311 is mounted on the surface layer 201 being the first surface layer
- the electrolytic capacitor 321 is mounted on the surface layer 202 being the second surface layer.
- the electronic component 311 and the electrolytic capacitor 321 are mounted on mutually different surfaces of the printed wiring board 200
- the electronic component 312 is mounted on the surface layer 201
- the electrolytic capacitor 322 is mounted on the surface layer 202 .
- the electronic component 312 and the electrolytic capacitor 322 are mounted on mutually different surfaces of the printed wiring board 200 .
- the electronic components 311 and 312 are mounted on an identical surface of the printed wiring board 200
- the electrolytic capacitors 321 and 322 are mounted on an identical surface of the printed wiring board 200 .
- the electronic components 311 and 312 may be configured by a semiconductor package such as an HQFN, an HSON, an HQFP, and an HSOP and include heat radiation pads (heat sinks) 341 and 342 , respectively, as illustrated in FIG. 3A .
- FIG. 3B is a plan view illustrating the first surface layer viewed from a ⁇ Z direction of the printed wiring board according to the first exemplary embodiment
- FIG. 3C is a plan view illustrating the second surface layer of the printed wiring board viewed from the ⁇ Z direction according to the first exemplary embodiment.
- the solid lines represent the electrolytic capacitors 321 and 322 for convenience of illustration.
- the electrolytic capacitor 321 has a power supply terminal 351 E and a ground terminal (first terminal) 351 G.
- the electrolytic capacitor 322 has a power supply terminal 352 E and a ground terminal (second terminal) 352 G.
- the ground terminal 331 G of the electronic component 311 and a heat radiation pad 341 being a first heat radiation pad of the electronic component 311 are electrically connected.
- the ground terminal 331 G and the heat radiation pad 341 are connected within the electronic component 311 or may be connected through the printed wiring board 200 .
- the ground terminal 332 G of the electronic component 312 and a heat radiation pad 342 being a second heat radiation pad of the electronic component 312 are electrically connected.
- the ground terminal 332 G and heat radiation pad 342 are connected within the electronic component 312 or may be connected through the printed wiring board 200 .
- the surface layer 201 of the printed wiring board 200 has a plurality of lands (conductor pattern) 231 to which a plurality of terminals 331 of the electronic component 311 is bonded by using an electrically conductive jointing material 431 .
- the surface layer 201 has heat radiation lands (conductor pattern) 241 to which a heat radiation pad 341 of the electronic component 311 is bonded by using an electrically conductive jointing material 441 of solder, for example.
- the surface layer 201 of the printed wiring board 200 has a plurality of lands (conductor pattern) 232 to which a plurality of terminals 332 of the electronic component 312 are bonded by using an electrically conductive jointing material 432 of solder, for example.
- the surface layer 201 has heat radiation lands (conductor pattern) 242 to which a heat radiation pad 342 of the electronic component 312 is bonded by using an electrically conductive jointing material 442 of solder, for example.
- the surface layer 202 of the printed wiring board 200 has a plane-shaped conductor pattern 250 being a conductor pattern part.
- the conductor pattern 250 is provided in a region including the electronic components 311 and 312 and the electrolytic capacitors 321 and 323 viewed from the arrow Z direction perpendicular to the surface of the printed wiring board 200 . More specifically, the conductor pattern 250 is provided so as to include a projected region acquired by projecting the heat radiation pads 341 and 342 of the electronic components 311 and 312 and the ground terminals 351 G and 352 G of the electrolytic capacitors 321 and 323 to the conductor layer 202 in the arrow Z direction.
- the conductor pattern 250 has a conductor present on a straight line connecting a connection point between the via conductor 261 and the conductor pattern 250 and a connection point between the ground terminal 351 G of the electrolytic capacitor 321 and the conductor pattern 250 viewed from the arrow Z direction. Also, the conductor pattern 250 has a conductor present on a straight line connecting between a connection point between the via conductor 262 and the conductor pattern 250 and a connection point between the ground terminal 351 G of the electrolytic capacitor 321 and the conductor pattern 250 viewed from the arrow Z direction.
- the conductor pattern 250 has a conductor present on a straight line connecting a connection point between the via conductor 262 and the conductor pattern 250 and a connection point between the ground terminal 352 G of the electrolytic capacitor 322 and the conductor pattern 250 viewed from the arrow Z direction.
- the ground terminal 351 G of the electrolytic capacitor 321 is bonded to the conductor pattern 250 by using an electrically conductive jointing material 451 of solder, for example, and the ground terminal 352 G of the electrolytic capacitor 322 is bonded to the conductor pattern 250 by using an electrically conductive jointing material 452 of solder, for example.
- the conductor pattern 250 and the heat radiation lands 241 are connected by using a plurality of via conductors (each being a conductor provided in a via) 261 .
- the conductor pattern 250 and the heat radiation lands 242 are connected by using a plurality of via conductors 262 .
- the via conductors 261 are provided within a region of the heat radiation lands 241
- the via conductors 262 are provided within a region of the heat radiation lands 242 .
- the ground conductor 220 is provided across the surface layer 201 and the surface layer 202 .
- the heat radiation pad 341 of the electronic component 311 , the ground terminal 351 G of the electrolytic capacitor 321 , the heat radiation pad 342 of the electronic component 312 , and the ground terminal 352 G of the electrolytic capacitor 322 are electrically and thermally connected through the ground conductor 220 .
- the printed wiring board 200 has a power supply conductor 211 being a first power supply conductor configured to electrically connect the power supply terminal 351 E of the electronic component 311 and the power supply terminal 351 E of the electrolytic capacitor 321 across the surface layer 201 and the surface layer 202 .
- the printed wiring board 200 further has a power supply conductor 212 being a second power supply conductor configured to electrically connect the power supply terminal 352 E of the electronic component 312 and the power supply terminal 352 E of the electrolytic capacitor 322 across the surface layer 201 and the surface layer 202 .
- the power supply conductor 211 and the power supply conductor 212 may be connected through a power supply conductor, not illustrated. In a case where the electronic components 311 and 312 operate with mutually different voltages, the power supply conductor 211 and the power supply conductor 212 may be isolated.
- Direct current voltage is applied from a direct current power supply circuit, not illustrated, to between the power supply conductors 211 and 212 and the ground conductor 220 , electric power is supplied to the electronic components 311 and 312 so that the electronic components 311 and 312 can operate.
- the electronic component 311 and electronic component 312 generate heat due to an operation for driving the motor.
- the electronic component 312 then generates heat exhibiting a heat value higher than that of the electronic component 311 .
- the heat generated from the electronic components 311 and 312 is conducted to the electrolytic capacitors 321 and 322 through the ground conductor 220 .
- the heat conducted to the electrolytic capacitors 321 and 322 is dissipated to the outside air.
- the electrolytic capacitors 321 and 322 provided for countermeasures against power supply noise also function as heat radiation parts. Therefore, no heat sink may be necessary in the printed wiring board 200 for heat radiation for the electronic components 311 and 312 .
- the electrolytic capacitors 321 and 322 in the first and second circuit components may have higher heat capacities, and aluminum electrolytic capacitors having a higher heat capacity than those of the other electrolytic capacitors are provided according to the first exemplary embodiment.
- the electrolytic capacitor 321 is disposed more closely to the electronic component 312 than the electronic component 311 , as illustrated in FIG. 1 and FIGS. 3B and 3C .
- the electrolytic capacitor 322 is also disposed more closely to the electronic component 312 than the electronic component 311 as illustrated in FIG. 1 and FIGS. 3B and 3C .
- the heat conduction of the electronic components are mainly through a conductor, particularly, the ground conductor 220 because a conductor has a higher heat conductivity than that of an insulator.
- the thermal resistance between the heat radiation pad 342 and the ground terminal 351 G is lower than the thermal resistance between the heat radiation pad 341 and the ground terminal 351 G.
- the thermal resistance between the heat radiation pad 341 and the ground terminal 351 G is higher than the thermal resistance between the heat radiation pad 342 and the ground terminal 351 G.
- FIG. 4 is an electric circuit diagram illustrating a heat conduction path in the printed circuit board according to the first exemplary embodiment.
- a heat conduction path PA from the heat radiation pad 341 in the electronic component 311 to the ground terminal 351 G of the electrolytic capacitor 321 includes the jointing material 441 , the heat radiation lands 241 , the via conductor 261 , the conductor pattern 250 , and the jointing material 451 .
- a heat conduction path PB from the heat radiation pad 342 of the electronic component 312 to the ground terminal 352 G of the electrolytic capacitor 322 includes the jointing material 442 , the heat radiation lands 242 , the via conductor 262 , the conductor pattern 250 , and the jointing material 452 .
- a heat conduction path PC from the heat radiation pad 342 in the electronic component 312 to the ground terminal 351 G of the electrolytic capacitor 321 includes the jointing material 442 , the heat radiation lands 242 , the via conductor 262 , the conductor pattern 250 , and the jointing material 451 .
- the heat conduction paths PA to PC have thermal resistances dependent on the dimensions and heat conductivities of the materials.
- the conductor pattern 250 is shared. It can be regarded that the thermal resistances of the jointing material 441 and the jointing material 442 , the thermal resistances of the jointing material 451 and the jointing material 452 , the thermal resistances of the heat radiation lands 241 and the heat radiation lands 242 , and the thermal resistances of the via conductor 261 and the via conductor 262 are equal.
- the thermal resistances of the heat conduction paths PA to PC depend on the distances between the connection points of the via conductors 261 and 262 and the connection point of the ground terminal 351 G of the electrolytic capacitor 321 in the conductor pattern 250 illustrated in FIG. 3C .
- the electrolytic capacitor 321 is disposed more closely to the electronic component 312 between the electronic component 311 and the electronic component 312 . Therefore, in the conductor pattern 250 , the distance between the connection point of the via conductor 262 and the connection point of the ground terminal 351 G of the electrolytic capacitor 321 is shorter than the distance between the connection point of the via conductor 261 and the connection point of the ground terminal 351 G of the electrolytic capacitor 321 . As a result, in the ground conductor 220 , the thermal resistance between the heat radiation pad 342 and the ground terminal 351 G is lower than the thermal resistance between the heat radiation pad 341 and the ground terminal 351 G.
- the electrolytic capacitor 321 has an absorption of heat more in the heat conduction from the heat conduction path PC of the electronic component 312 than the heat conduction from the heat conduction path PA in the electronic component 311 .
- heat generated from the electronic component 312 is not only conducted to the electrolytic capacitor 322 through the heat conduction path PB but also is conducted to the electrolytic capacitor 321 through the heat conduction path PC so that the temperature of the electronic component 312 can be reduced.
- the thermal resistance of the heat conduction path PA is higher than the thermal resistance of the heat conduction path PC, the amount of heat radiation to the electrolytic capacitor 321 increases even when thermal interference from the electronic component 311 occurs in the electronic component 312 . Therefore, the area of the conductor pattern 250 can be reduced, and the size of the printed circuit board 100 having the circuit modules 301 and 302 can be reduced.
- the thermal resistance of a conductor satisfies the following expression (1).
- ⁇ (° C./W) is the thermal resistance
- L (mm) is a length
- K (W/m*° C.) is a heat conductivity
- W (mm) is a width
- a thickness is t (mm) of the conductor.
- L 1 and ⁇ 1 are a length and a thermal resistance, respectively, of the heat conduction path PA
- L 3 and ⁇ e are a length and a thermal resistance, respectively, of the heat conduction path PC
- K, W, and t are a heat conductivity, a width, and a thickness, respectively, of each of the conductors.
- the heat conductivities K, the thicknesses t, and the widths W of the heat conduction path PA and heat conduction path PC are equal. Therefore, from the magnitude relationship between the lengths L 1 and L 3 of the heat conduction paths, the values of the thermal resistances can be determined.
- the difference in value between the thermal resistance ⁇ 1 and the thermal resistance ⁇ 3 increases as the length of the heat conduction path PA increases and the length of the heat conduction path PC decreases.
- the temperature of the electronic component 312 can be reduced, and the required area of the conductor pattern 250 can be reduced.
- the thermal resistance between two arbitrary points on the electronic components 311 and 312 and the printed wiring board 200 can be calculated by measuring the lengths, thicknesses, and widths of conductors on the printed wiring board 200 and using Expression (1).
- the thermal resistance of a conductor is ⁇ (° C./W)
- the heat value of an electronic component is Q (W)
- a junction temperature of the electronic component is T 1 (° C.)
- the temperature of an arbitrary point on the printed wiring board is T 2 (° C.)
- the thermal resistance between two arbitrary points on the electronic components 311 and 312 and the printed wiring board 200 can be calculated by using Expression (3).
- the T 1 (° C.) that is a junction temperature of an electronic component and the T 2 (° C.) that is a temperature at an arbitrary point on a printed wiring board can be measured from a temperature distribution diagram of the printed circuit board by using an apparatus such as a thermograph.
- the thermal resistances of the heat conduction paths PA, PB, and PC do not impair the functionality of the circuit modules 301 and 302 .
- the inside of the vias having the via conductors 261 and 262 may be filled with a highly electrically conductive jointing material of solder, for example.
- FIG. 5A is a plan view from a ⁇ Z direction of a first surface layer of a printed wiring board in the printed circuit board according to the second exemplary embodiment.
- FIG. 5B is a plan view from a ⁇ Z direction of a second surface layer of the printed wiring board in the printed circuit board according to the second exemplary embodiment.
- the second exemplary embodiment is different from the first exemplary embodiment in the configuration of a conductor pattern part in the printed wiring board and is the same as the first exemplary embodiment in the other configuration.
- Like numbers refer to like parts in descriptions and illustrations according to the first and second exemplary embodiments, and repetitive description will be omitted.
- FIG. 5B illustrates electrolytic capacitors 321 and 322 by using solid lines for convenience of illustration.
- a printed wiring board 200 A in the printed circuit board according to the second exemplary embodiment has a plurality of (two in the second exemplary embodiment) conductor layers including conductor layers 201 and 202 A stacked through an insulator layer (dielectric layer).
- the wiring of a power supply line and so on, not illustrated, has the same configuration as that of the conductor layer 201 illustrated in FIG. 3B .
- the printed wiring board 200 A is a 2-layered printed wiring board.
- the number of layers in the printed wiring board is not limited to two but may be equal to or higher than three.
- the electronic component 311 is mounted on the surface layer 201 being a first conductor layer, and the electrolytic capacitor 321 is mounted on a surface layer 202 A being a second conductor layer.
- the electronic component 311 and the electrolytic capacitor 321 are mounted on mutually different surfaces of the printed wiring board 200 A.
- the electronic component 312 is mounted on the surface layer 201
- the electrolytic capacitor 322 is mounted on the surface layer 202 A.
- the electronic component 312 and the electrolytic capacitor 322 are mounted on mutually different surfaces of the printed wiring board 200 A.
- the electronic components 311 and 312 are mounted on an identical surface of the printed wiring board 200 A, and the electrolytic capacitors 321 and 322 are mounted on an identical surface of the printed wiring board 200 A.
- the electrolytic capacitor 321 is disposed more closely to the electronic component 312 than the electronic component 311 .
- the electrolytic capacitor 322 is also disposed more closely to the electronic component 312 than the electronic component 311 .
- the printed wiring board 200 A has a conductor pattern part 250 A.
- the conductor pattern part 250 A has plane-shaped conductor patterns 251 A, 252 A, and 253 A.
- the conductor patterns 251 A, 252 A, and 253 A are provided on the identical surface layer 202 A.
- a projected region (first projected region) R 1 is a region acquired by projecting the heat radiation pad 341 in the electronic component 311 to the conductor layer 202 A in an arrow Z direction perpendicular to the surface of the printed wiring board 200 A.
- a projected region (second projected region) R 2 is a region acquired by projecting the heat radiation pad 342 in the electronic component 312 to the conductor layer 202 A in an arrow Z direction perpendicular to the surface of the printed wiring board 200 A.
- a projected region (third projected region) R 3 is a region acquired by projecting the ground terminal 351 G of the electrolytic capacitor 321 to the conductor layer 202 A in the arrow Z direction perpendicular to the surface of the printed wiring board 200 A.
- a projected region (fourth projected region) R 4 is a region acquired by projecting the ground terminal 352 G of the electrolytic capacitor 322 to the conductor layer 202 A in the arrow Z direction perpendicular to the surface of the printed wiring board 200 A.
- a conductor pattern 251 A being a first conductor pattern is provided so as to include the projected region R 1 .
- a conductor pattern 252 A being a second conductor pattern is provided so as to include the projected regions R 2 and R 3 (or projected regions R 2 , R 3 , and R 4 more specifically).
- the conductor pattern 251 A and the conductor pattern 252 A are spaced from each other.
- a conductor pattern 253 A being a connection conductor is a third conductor pattern configured to connect the conductor pattern 251 A and the conductor pattern 252 A.
- a conductor pattern 253 A is provided such that the thermal resistance between the heat radiation pad 341 and the ground terminal 351 G can be higher than the thermal resistance between the heat radiation pad 342 and the ground terminal 351 G. More specifically, the conductor pattern 253 A is narrower than the conductor patterns 251 A and 252 A.
- a slit-shaped notch 260 A is provided between the conductor pattern 251 A and the conductor pattern 252 A so that the conductor pattern 251 A and the conductor pattern 252 A can be connected through the conductor pattern 253 A.
- the notch 260 A is provided between the conductor pattern 251 A and the conductor pattern 252 A such that the conductor pattern 251 A and the conductor pattern 252 A can be connected through the narrow conductor pattern 253 A.
- the conductor pattern 253 A formed with the notch 260 A can bring the conductor pattern 251 A and the conductor pattern 252 A into conduction and can increase the thermal resistance therein.
- the notch 260 A is provided between the electronic component 311 and the electronic capacitor 321 , viewed from the Z direction.
- the conductor pattern 253 A is not present on a straight line LA connecting the connection point between the via conductor 261 and the conductor pattern 251 A and the connection point between the ground terminal 351 G of the electrolytic capacitor 321 and the conductor pattern 252 A, viewed from the arrow Z direction.
- This means that the conductor pattern 253 A is provided by avoiding the straight line LA.
- the notch 260 A is present on the straight line LA.
- the ground terminal 351 G of the electrolytic capacitor 321 is disposed at a position facing the heat radiation pad 341 of the electronic component 311 with the notch 260 A interposed therebetween and is provided closely to the electronic component 312 .
- the thermal resistance between the heat radiation pad 341 and the heat radiation pad 342 can be higher than that in the first exemplary embodiment. This can reduce the influence of thermal interference from the electronic component 311 to the electronic component 312 .
- the temperature of the electronic component 312 can be reduced more than the first exemplary embodiment, and the size of the printed circuit board can further be reduced.
- the thus further increased thermal resistance between the ground terminal 351 G of the electrolytic capacitor 321 and the heat radiation pad 341 (via conductor 261 ) can reduce the heat of the electronic component 311 conducted to the electrolytic capacitor 321 .
- the heat of the electronic component 312 can be conducted effectively to the electrolytic capacitor 321 . Therefore, the temperature of the electronic component 312 can effectively be reduced, and the size of the printed circuit board can further be reduced.
- the heat conduction path between the ground terminal 351 G of the electrolytic capacitor 321 and the via conductor 261 can be redundant because of the notch 260 A, the length of the heat conduction path PA ( FIG. 4 ) can be longer than that in the first exemplary embodiment, and the thermal resistance can further be increased than that of the heat conduction path PC. Therefore, the influence of thermal interference from the electronic component 311 to the electronic component 312 can further be reduced, and the temperature of the electronic component 312 can be reduced more effectively. Then, the size of the printed circuit board can further be reduced.
- FIG. 6A is a plan view from a ⁇ Z direction of a first surface layer of a printed wiring board in the printed circuit board according to the third exemplary embodiment.
- FIG. 6B is a plan view from a ⁇ Z direction of a second surface layer of the printed wiring board in the printed circuit board according to the third exemplary embodiment.
- the third exemplary embodiment is different from the first and second exemplary embodiments in the configuration of a conductor pattern component and mounted states of electronic components in the printed wiring board and is the same as the first and second exemplary embodiments in the other configuration.
- Like numbers refer to like parts in descriptions and illustrations according to the first, second and third exemplary embodiments, and repetitive description will be omitted.
- FIG. 6B illustrates electrolytic capacitors 321 and 322 by using solid lines for convenience of illustration.
- a printed wiring board 200 B in the printed circuit board according to the third exemplary embodiment has a plurality of (two in the third exemplary embodiment) conductor layers including conductor layers 201 B and 202 B stacked through an insulator layer (dielectric layer).
- the printed wiring board 200 B is a 2-layered printed wiring board.
- the number of layers in the printed wiring board is not limited to two but may be equal to or higher than three.
- the electronic component 311 and the electrolytic capacitor 321 are mounted on a surface layer 202 B being a second conductor layer.
- the electronic component 311 and the electrolytic capacitor 321 are mounted on a same surface of the printed wiring board 200 B, unlike the first and second exemplary embodiments.
- the electronic component 312 is mounted on a surface layer 201 B
- the electrolytic capacitor 322 is mounted on a surface layer 202 B.
- the electronic component 312 and the electrolytic capacitor 322 are mounted on mutually different surfaces of the printed wiring board 200 B.
- the electronic component 311 and the electronic component 312 is mounted on mutually different surfaces of the printed wiring board 200 B, and the electrolytic capacitors 321 and 322 are mounted on a same surface of the printed wiring board 200 B, unlike the first and second exemplary embodiments.
- the electrolytic capacitor 321 is disposed more closely to the electronic component 312 than the electronic component 311 .
- the electrolytic capacitor 322 is also disposed more closely to the electronic component 312 than the electronic component 311 .
- the printed wiring board 200 B has a conductor pattern part 250 B.
- the conductor pattern part 250 B has plane-shaped conductor patterns 251 B and 252 B.
- a conductor pattern 251 B is provided on a conductor layer (surface layer) 201 B, and a conductor pattern 252 B is provided on a conductor layer (surface layer) 202 B different from the surface layer 201 B.
- the conductor pattern 251 B is disposed on the opposite surface of the surface having the electronic component 311
- the conductor pattern 252 B is disposed on the opposite surface of the surface having the electronic component 312 .
- the conductor pattern 251 B and the conductor pattern 252 B are connected through a via conductor 253 B.
- a projected region (first projected region) R 1 is a region acquired by projecting the heat radiation pad 341 in the electronic component 311 to the conductor layer 201 B in an arrow Z direction perpendicular to the surface of the printed wiring board 200 B.
- a projected region (second projected region) R 2 is a region acquired by projecting the heat radiation pad 342 in the electronic component 312 to the conductor layer 202 B in an arrow Z direction perpendicular to the surface of the printed wiring board 200 B.
- a projected region (third projected region) R 3 is a region acquired by projecting the ground terminal 351 G of the electrolytic capacitor 321 to the conductor layer 202 B in the arrow Z direction perpendicular to the surface of the printed wiring board 200 B.
- a projected region (fourth projected region) R 4 is a region acquired by projecting the ground terminal 352 G of the electrolytic capacitor 322 to the conductor layer 202 B in the arrow Z direction perpendicular to the surface of the printed wiring board 200 B.
- a conductor pattern 251 B being a first conductor pattern is provided so as to include the projected region R 1 .
- a conductor pattern 252 B being a second conductor pattern is provided so as to include the projected regions R 2 and R 3 (or projected regions R 2 , R 3 , and R 4 more specifically).
- the via conductor 253 B is a connection conductor configured to connect the conductor pattern 251 B and the conductor pattern 252 B.
- the via conductor 253 B is provided such that the thermal resistance between the heat radiation pad 341 and the ground terminal 351 G can be higher than the thermal resistance between the heat radiation pad 342 and the ground terminal 351 G.
- the thermal resistance between the heat radiation pad 341 and the heat radiation pad 342 can be higher than that in the first exemplary embodiment. This can reduce the influence of thermal interference from the electronic component 311 to the electronic component 312 . Thus, the temperature of the electronic component 312 can be reduced more than the first exemplary embodiment, and the size of the printed circuit board can further be reduced.
- the electronic component 311 and the electronic component 312 are mounted on mutually different surfaces.
- the path from the ground terminal 351 G of the electrolytic capacitor 321 to the via conductor 261 through the via conductor 253 B is longer than that in first exemplary embodiment.
- the thermal resistance of the heat conduction path PA ( FIG. 4 ) between the heat radiation pad 341 and the ground terminal 351 G is higher than the thermal resistance of the heat conduction path PC ( FIG. 4 ) between the heat radiation pad 342 and the ground terminal 351 G.
- the via conductor 253 B has a higher thermal resistance than those of the conductor patterns 251 B and 252 B, the heat conduction path PA ( FIG. 4 ) can have a further higher thermal resistance.
- the temperature of the electronic component 312 can effectively be reduced, and the size of the printed circuit board can further be reduced.
- FIG. 7 is a sectional view schematically illustrating a printed circuit board according to the fourth exemplary embodiment.
- FIG. 8A is a plan view illustrating a first surface layer viewed from a ⁇ Z direction of the printed wiring board in the printed circuit board according to the fourth exemplary embodiment.
- FIG. 8B is a plan view illustrating a second surface layer viewed from the ⁇ Z direction of the printed wiring board in the printed circuit board according to the fourth exemplary embodiment.
- the fourth exemplary embodiment is different from the first to third exemplary embodiments in the configuration of a conductor pattern part in the printed wiring board and the mounting of electrolytic capacitors and is the same as the first to third exemplary embodiments in the other configuration.
- Like numbers refer to like parts in descriptions and illustrations according to the first to fourth exemplary embodiments, and repetitive description will be omitted.
- FIG. 8B illustrates the electrolytic capacitors 321 and 322 mounted on the printed wiring board 200 C for convenience of illustration.
- a printed wiring board 200 C in a printed circuit board 100 C according to the fourth exemplary embodiment has a plurality of (two in the fourth exemplary embodiment) conductor layers including conductor layers 201 C and 202 C stacked through an insulator layer (dielectric layer).
- the printed wiring board 200 C is a 2-layered printed wiring board.
- the number of layers in the printed wiring board is not limited to two but may be equal to or higher than three.
- the electronic components 311 and 312 and electrolytic capacitors 321 and 322 are mounted on a surface layer 201 C being a first conductor layer.
- the electronic components 311 and 312 and electrolytic capacitors 321 and 322 are mounted on a same surface of the printed wiring board 200 C.
- the electrolytic capacitor 321 is disposed more closely to the electronic component 312 than the electronic component 311 .
- the electrolytic capacitor 322 is also disposed more closely to the electronic component 312 than the electronic component 311 .
- the printed wiring board 200 C has plane-shaped conductor patterns 251 C and 252 C. These conductor patterns 251 C and 252 C are included in a conductor pattern part 250 C.
- a conductor pattern 251 C is provided on a surface layer 202 C, and a conductor pattern 252 C is provided on a surface layer 201 C.
- the conductor pattern 251 C is provided in a region including the electronic components 311 and 312 and electrolytic capacitor 231 , 232 viewed from an arrow Z direction perpendicular to the surface of the printed wiring board 200 C. More specifically, the conductor pattern 251 C is provided so as to include a projected region acquired by projecting the heat radiation pads 341 and 342 of the electronic components 311 and 312 and the ground terminals 351 G and 352 G of the electrolytic capacitors 231 and 232 to the conductor layer 202 C in the arrow Z direction.
- the ground terminals 351 G and 352 G of the electrolytic capacitors 321 and 322 are bonded to the conductor pattern 252 C by using jointing materials 451 and 452 of solder, for example.
- the heat radiation land 241 and the conductor pattern 251 C are connected by using a plurality of via conductors 261 , and the heat radiation land 242 and the conductor pattern 251 C are connected by using a plurality of via conductors 262 .
- a plurality of (such as three) via conductors 271 is disposed which connects the conductor pattern 251 C and the conductor pattern 252 C.
- a plurality of (such as three) via conductors 272 is disposed which connects the conductor pattern 251 C and the conductor pattern 252 C.
- the ground conductor 220 C is provided across the surface layer 201 C and the surface layer 202 C.
- the temperature of the electronic component 312 can be reduced, and the size of the printed circuit board 100 C can be reduced, like the first exemplary embodiment.
- the components 311 , 312 , 321 , and 322 provided on a same surface can improve the degree of freedom in designing the opposite surface of the surface having the components.
- An electronic apparatus having the printed circuit board according to an embodiment of the present invention exhibited the excellent performance of heat radiation.
- a printed circuit board according to a first example will be described.
- conditions were defined for the printed wiring board 200 , electronic component 311 , electronic component 312 , electrolytic capacitor 321 , electrolytic capacitor 322 and jointing materials 441 , 442 , 451 , 452 as follows.
- the printed wiring board 200 was a 1.6 [mm]-thick two-layered substrate having a size of 60 ⁇ 60 [mm].
- the heat radiation lands 241 and 242 facing the heat radiation pads 341 and 342 of the electronic components 311 and 312 were disposed on the surface having the electronic components 311 and 312 .
- the heat radiation lands 241 and 242 had a size of 2.7 [mm] ⁇ 2.7 [mm] and a thickness of 0.043 [mm] and was made of Cu.
- the plurality of via conductors 261 ( 262 ) were formed by forming a total of nine ⁇ 0.3 [mm] vias in a 3 ⁇ 3 matrix on the heat radiation lands 241 ( 242 ) and were plated within corresponding via holes.
- the plating was 20 [ ⁇ m] thick and was made of Cu.
- the vias were disposed at pitches of 0.7 [mm].
- the conductor pattern 250 was disposed on the opposite surface of the surface having the electronic components 311 and 312 , had a size of 41 [mm] ⁇ 14 [mm] (X [mm] ⁇ Y [mm]) and was made of Cu.
- the electronic components 311 and 312 had package specifications of HQFN, had a size of 4.0 [mm] ⁇ 4.0 [mm] and was 0.75 [mm] thick.
- the heat radiation pads 341 and 342 in a central area of the bottom faces of the electronic components 311 and 312 had a size of 2.7 [mm] ⁇ 2.7 [mm] and were 0.22 [mm] thick.
- the chip within each of the electronic components 311 and 312 had a size of 2.3 [mm] ⁇ 1.8 [mm] and was 0.20 [mm] thick.
- the electrolytic capacitors 321 and 322 were aluminum electrolytic capacitors and had a cylindrical shape of 3 [mm] radius and were 5.8 [mm] high.
- the ground terminals 351 G and 352 G of the electrolytic capacitors 321 and 322 were 0.6 [mm] ⁇ 2.7 [mm] ⁇ 0.3 [mm] rectangular parallelepipeds and were provided on the bottom surfaces of the main bodies of the electrolytic capacitors 321 and 322 .
- the central positions of the ground terminals 351 G and 352 G were disposed at a position at 2.5 [mm] in the Y direction and a position at ⁇ 2.5 [mm] from the central positions of the main bodies of the electrolytic capacitors 321 and 322 , respectively.
- the jointing materials 441 and 442 had a size of 2.7 [mm] ⁇ 2.7 [mm], where 0.05 [mm] thick and were made of Sn—Ag—Cu.
- the jointing materials 451 and 452 had a size of 0.6 [mm] ⁇ 2.7 [mm] ⁇ 0.050 [mm].
- the positional conditions for the electronic components 311 and 312 and electrolytic capacitors 321 and 322 will be described. Setting the central positions of the printed wiring board 200 as a point of origin, the central position of the electronic component 311 was disposed at a position at ⁇ 10.5 [mm] in the X direction from the point of origin, and the electronic component 312 was disposed at a position at 10.5 [mm] in the X direction from the point of origin. The center distance between the electronic component 311 and the electronic component 312 was equal to 21 [mm].
- the electrolytic capacitors 321 and 322 were mounted on the opposite surface of the surface having the electronic components 311 and 312 .
- the electrolytic capacitor 321 is disposed at a position at ⁇ 4 [mm] in the Y direction from the central position of the electronic component 312
- the electrolytic capacitor 322 is disposed at a position at 4 [mm] in the Y direction from the central position of the electronic component 312 .
- the central position of the conductor pattern 250 was equal to the central position of the printed wiring board 200 .
- Thermal analysis conditions in the configuration of the first example as described above will be described.
- the power consumption in the electronic component 311 was assumed as 0.3 [W]
- the power consumption in the electronic component 312 was assumed as 0.6 [W].
- the center of the upper surface of a silicon chip within the electronic component 312 is analyzed with respect to the junction temperature of the electronic component 312 .
- the same was also applied to the electronic component 311 .
- the ambient temperature of the printed circuit board 100 was defined as 25[° C.], and the ambient environment was defined as natural convection.
- a thermal analysis was performed to evaluate the area (14 [mm] ⁇ 41 [mm]) of the conductor pattern 250 necessary for the junction temperature of the electronic component 312 to be equal to or lower than 80[° C.], for example.
- the thermal resistance of the heat conduction path PA was 59[° C./W]
- the thermal resistance of the heat conduction path PC was 15[° C./W].
- the area of the conductor pattern 250 necessary for the junction temperature of the electronic component 312 to be equal to or lower than 80[° C.] was also acquired.
- FIG. 9 is a graph illustrating an area of a conductor pattern in printed circuit boards according to the first to third examples and a first comparison example. As illustrated in FIG. 9 , the area of the conductor pattern 250 was 570 [mm 2 ] (14 [mm] ⁇ 41 [mm]).
- FIG. 11A is a sectional view schematically illustrating a printed circuit board according to the first comparison example.
- FIG. 11B is a plan view illustrating a first surface layer (surface layer 201 X) viewed from the ⁇ Z direction of the printed wiring board in the printed circuit board according to the first comparison example.
- FIG. 11C is a plan view illustrating a first surface layer (surface layer 202 X) viewed from the ⁇ Z direction of the printed wiring board in the printed circuit board according to the second comparison example.
- the central position of the electrolytic capacitor 321 is the same as the central position of the electronic component 311
- the central position of the electrolytic capacitor 322 is the same as the central position of the electronic component 312 , unlike the first example.
- the first comparison example is also different from the first example in that the conductor pattern 250 X of the first comparison example has a size of 44 [mm] ⁇ 14 [mm] (X [mm] ⁇ Y [mm]).
- the other configuration of the first comparison example is the same as that of the first example.
- the thermal resistance of the heat conduction path PA between the heat radiation pad 341 and the ground terminal 351 G of the electrolytic capacitor 321 in the first comparison example was 10.8[° C./W].
- the thermal resistance of the heat conduction path PC between the heat radiation pad 342 and the ground terminal 351 G of the electrolytic capacitor 321 in the first comparison example was 50.2[° C./W].
- the area of the conductor pattern 250 X necessary for the junction temperature of the electronic component 312 of the printed circuit board 100 X to be equal to or lower than 80[° C.] was acquired.
- the area of the conductor pattern 250 X was 620 [mm 2 ] (44 [mm] ⁇ 14 [mm]) as illustrated in FIG. 9 .
- FIG. 12 is a schematic diagram illustrating a heat distribution of a surface opposite against a surface having an electronic component thereon of a printed wiring board in the printed circuit board according to the first comparison example.
- FIG. 12 illustrates regions A, B, and C of a heat distribution representing isotherms of the heat distribution and that the temperatures decrease in order of the regions A, B, and C.
- the heats generated from the electronic component 311 and the electronic component 312 are conducted to the printed wiring board 200 X and interfere with each other.
- the heats generated from the electronic component 311 and the electronic component 312 interfere with each other.
- the heat radiation from the electronic component 312 to the conductor pattern 250 X is prevented by the thermal interference from the electronic component 311 .
- the electronic component 312 has a higher temperature than that of the electronic component 311 .
- a printed circuit board according to a second example will be described.
- the printed circuit board according to the second example corresponds to the printed circuit board of the second exemplary embodiment illustrated in FIGS. 5A and 5B .
- a conductor pattern part 250 A is provided which has a notch 260 A on a 37 [mm] ⁇ 14 [mm] (X [mm] ⁇ Y [mm]) conductor pattern.
- the electrolytic capacitor 321 faces the electronic component 311 with the notch 260 A interposed therebetween.
- the configuration other than the conductor pattern part 250 A in the second example is the same as that of the first example.
- the notch 260 A had a size of 1 [mm] ⁇ 13.5 [mm] (X [mm] ⁇ Y [mm]).
- the notch 260 A was provided at a position at 2 [mm] in the X direction from the central position of the electronic component 311 .
- the thermal resistance of the heat conduction path PA between the heat radiation pad 341 and the ground terminal 351 G in the printed circuit board of the second example was 187[° C./W]
- the thermal resistance of the heat conduction path PC between the heat radiation pad 342 and the ground terminal 351 G was 15[° C./W].
- the area of the conductor pattern part 250 A was 515 [mm 2 ] (14 [mm] ⁇ 37 [mm]) as illustrated in FIG. 9 .
- FIG. 10 is a schematic diagram illustrating a heat distribution of the opposite surface of a surface having an electronic component thereon of a printed wiring board in the printed circuit board according to the second example.
- FIG. 10 illustrates regions A, B, and C of a heat distribution representing isotherms of the heat distribution and that the temperatures decrease in order of the regions A, B, and C.
- the notch 260 A provided between the electronic component 311 and the electronic component 312 can prevent mutual interferences between heat distributions of the electronic component 311 and the electronic component 312 . In other words, because the heats generated from the electronic component 311 and the electronic component 312 do not interfere with each other, the heat radiation from the electronic component 312 can efficiently be performed.
- a printed circuit board according to a third example will be described.
- the printed circuit board according to the third example corresponds to the printed circuit board of the third exemplary embodiment illustrated in FIGS. 6A and 6B .
- the printed circuit board of the third example is different from the printed circuit board of the first example in position of the electronic component 311 and configuration of a conductor pattern part.
- a conductor pattern 251 B is disposed on the opposite surface of a surface having the electronic component 311 .
- the conductor pattern 251 B had a size of 12.5 [mm] ⁇ 14 [mm] (X [mm] ⁇ Y [mm]) and was made of Cu.
- the central position of the conductor pattern 251 B was equal to the central position of the electronic component 311 .
- a conductor pattern 252 B is disposed on the opposite surface of the surface having the electronic component 312 .
- the conductor pattern 252 B had a size of 27 [mm] ⁇ 14 [mm] (X [mm] ⁇ Y [mm]) and was made of Cu.
- the central position of the conductor pattern 252 B was equal to the central position of the electronic component 312 .
- the via conductor 253 B was provided at a position at ⁇ 6.5 [mm] in the X direction and ⁇ 6 [mm] in the Y direction from the central position of the printed wiring board as the point of origin.
- the hole diameter of the via having the via conductor 253 B was 0.3 [mm].
- the thickness of plating provided within the via hole was 20 [ ⁇ m], and the plating was made of Cu.
- the via conductor 253 B electrically connects the conductor pattern 251 B and the conductor pattern 252 B.
- the other configuration of the third example illustrated in FIGS. 6A and 6B is the same as that of the first example.
- a thermal analysis was performed to evaluate the area of the conductor pattern part 250 B necessary for the junction temperature of the electronic component 312 to be equal to or lower than 80[° C.], for example, in the printed circuit board of the third example.
- the area of the conductor pattern part 250 B was equal to a sum total of the conductor pattern 251 B (12.5 [mm] ⁇ 14 [mm]) and the conductor pattern 252 B (27 [mm] ⁇ 14 [mm]).
- the thermal resistance of the heat conduction path PA between the heat radiation pad 341 and the ground terminal 351 G was 77[° C./W]
- the thermal resistance of the heat conduction path PC between the heat radiation pad 342 and the ground terminal 351 G was 15[° C./W].
- the area of the conductor pattern part 250 B necessary for the junction temperature of the electronic component 312 to be equal to or lower than 80[° C.] was also acquired. As illustrated in FIG. 9 , the area of the conductor pattern part 250 B was equal to 553 [mm 2 ] ((12.51 [mm] ⁇ 14 [mm])+(27 [mm] ⁇ 14 [mm])).
- a printed circuit board according to a fourth example will be described.
- the printed circuit board according to the fourth example corresponds to the printed circuit board illustrated in FIG. 7 .
- the printed circuit board of the fourth example is different from the printed circuit board of the first example in positions of the electrolytic capacitors 321 and 322 .
- the electrolytic capacitors 321 and 322 are mounted on the same surface as the surface having the electronic components 311 and 312 .
- the electrolytic capacitor 321 was mounted at a position at 4 [mm] in the Y direction from the central position of the electronic component 312
- the electrolytic capacitor 322 was mounted at a position at ⁇ 4 [mm] in the Y direction from the central position of the electronic component 312 .
- Three via conductors 271 were disposed in vicinity of the ground terminal 351 G of the electrolytic capacitor 321 .
- the three via conductors 271 electrically connect the ground terminal 351 G of the electrolytic capacitor 321 and a conductor pattern part 250 C.
- the hole diameters of vias having the via conductors 271 are all equal to 0.3 [mm], and the vias are arranged at pitches of 0.8 [mm].
- Three via conductors 272 are disposed in vicinity of the ground terminal 352 G of the electrolytic capacitor 322 .
- the three via conductors 272 electrically connect the ground terminal 352 G of the electrolytic capacitor 322 and the conductor pattern part 250 C.
- the hole diameters of vias having the via conductors 272 are all equal to 0.3 [mm], and the vias are arranged at pitches of 0.8 [mm].
- the other configuration of the fourth example illustrated in FIG. 7 is the same as that of the first example.
- the thermal resistance of the heat conduction path PA between the heat radiation pad 341 and the ground terminal 351 G was 73[° C./W]
- the thermal resistance of the heat conduction path PC between the heat radiation pad 342 and the ground terminal 351 G was 30[° C./W].
- the area of a conductor pattern of copper foil necessary for the junction temperature of the electronic component 312 of the first example to be equal to or lower than 80[° C.] was 570 [mm 2 ] (41 [mm] ⁇ 14 [mm]).
- the area in the second example was 515 [mm 2 ] (37 [mm] ⁇ 14 [mm]).
- the area in the third example was 553 [mm 2 ] (12.5 [mm] ⁇ 14 [mm]+27 [mm] ⁇ 14 [mm]).
- the area in the fourth example was 559 [mm 2 ] (40 [mm] ⁇ 14 [mm]).
- the area in the first comparison example was 620 [mm 2 ] (44 [mm] ⁇ 14 [mm]).
- the necessary area of the conductor pattern 250 is reduced by about 9.0% of that of the first comparison example.
- the thermal resistance of the heat conduction path PA higher than the thermal resistance of the heat conduction path PC allow efficient heat radiation of heat generated from the electronic component 312 , the area of the conductor pattern 250 necessary for the heat radiation decreases. In other words, it can reduce the size of the printed circuit board having a plurality of circuit modules having electronic components.
- the notch 260 A provided in the conductor pattern part 250 A can further increase the thermal resistance of the heat conduction path PA so that the necessary area of the conductor pattern part 250 A decreases.
- the heat distributions of the electronic component 311 and the electronic component 312 do not interfere with each other because of the notch 260 A.
- heat generated from the electronic component 312 can efficiently be dissipated more, and the necessary area of the conductor pattern part 250 A can be reduced, which thus can reduce the size of the printed circuit board.
- the necessary area of the conductor pattern part 250 B decreases more than that in the first comparison example, and the size of the printed circuit board can further be reduced.
- the necessary area of the conductor pattern part 250 C decreases more than that of the first comparison example, and the size of the printed circuit board can further be reduced.
- the electrolytic capacitors 321 and 322 being the first and second circuit components are aluminum electrolytic capacitors according to the aforementioned exemplary embodiments and examples, the invention is not limited thereto, but other types of electrolytic capacitor are also applicable.
- the first and second circuit components may be ceramic capacitors without limiting to electrolytic capacitors.
- the first and second circuit components may be any of other passive elements such as a resistive element and coil, without limiting to capacitors.
- the first and second circuit components may be active elements without limiting to passive elements. In all of the cases, first and second circuit components having higher heat capacities may be more applicable.
- ground conductors are used to form the heat conduction paths PA to PC
- the invention is not limited thereto.
- Power supply conductors may be used to form the heat conduction paths PA to PC, for example. Because a ground conductor has a wider area than those of other conductors (such as a power supply conductor), ground conductors may be used to form the heat conduction paths PA to PC.
- each pair of the heat radiation lands 241 and the second heat radiation lands 242 , the via conductor 261 and the via conductor 262 , the jointing material 441 and the jointing material 442 , and the jointing material 451 and the jointing material 452 has an identical configuration. However, they may have different configurations.
Abstract
A printed wiring board has thereon an electronic component having a heat radiation pad, and an electrolytic capacitor provided for the electronic component. The printed wiring board further has thereon another electronic component having another heat radiation pad and exhibiting a higher heat value than that of the electronic component, and another electrolytic capacitor provided for the other electronic component. The heat radiation pad of the electronic component, a ground terminal of the electrolytic capacitor, the other heat radiation pad for the other electronic component, and another ground terminal of the other electrolytic capacitor are connected by using a ground conductor. In the ground conductor, a thermal resistance between the other heat radiation pad and other ground terminal is lower than the thermal resistance between the heat radiation pad and the ground terminal.
Description
- Field of the Invention
- Embodiments of the present invention relate to a printed circuit board having an electronic component which generates heat and an electronic apparatus including the printed circuit board.
- Description of the Related Art
- In order to avoid performance degradation due to temperature increases, countermeasures against heat may be required in an electronic component which generates heat, such as a driver IC configured to drive a motor. As such countermeasures against heat, an increased number of electronic components have a heat radiation pad (heat sink) in recent years.
- The heat generated from such an electronic component is conducted from a heat radiation pad of the electronic component through a conductive jointing material of solder, for example, to heat radiation lands on a printed wiring board. The heat conducted to the heat radiation lands is then conducted to a plane-shaped conductor pattern on an opposite surface of a surface having an electronic component or in an inner layer through a via conductor placed in the heat radiation lands and is dissipated into the air. When the heat radiation only with such a conductor pattern is not sufficient, countermeasures against heat are provided such as attaching a heat sink thereto. On the other hand, because of increased needs for downsizing and cost reduction of products, it has been desired not only to refrain from use of a heat sink but also to reduce the size of the printed circuit board.
- Accordingly, a technology has been proposed (as in Japanese Patent No. 4396005) in the past which includes a circuit component different from an electronic component on the opposite surface of a surface having the electronic component thereon so that heat generated from the electronic component is absorbed by the circuit component and is dissipated from the circuit component, without using a heat sink.
- However, in a case where a plurality of electronic components which generate heat is mounted on a printed wiring board, thermal interference may occur among the plurality of electronic components. For example, in a case where two electronic components having different heat values from each other are mounted on a printed wiring board, one having a higher heat value of the electronic components is influenced by heat generated from the other electronic component. As a result, the heat radiation is prevented, and the temperature increases. In order to reduce the increase in temperature, increasing the area of the conductor pattern thermally connected to the heat radiation pad may disadvantageously increase the size of the printed circuit board.
- According to an aspect of the present invention, heat from an electronic component can be effectively dissipated without adding a heat sink, and the size of a printed circuit board can be reduced.
- A printed circuit board according to an embodiment of the present invention includes a printed wiring board, a first electronic component having a first heat radiation pad, a first circuit component provided for the first electronic component and having a first terminal, a second electronic component having a second heat radiation pad and generating heat exhibiting a higher heat value than that of the first electronic component, a second circuit component provided for the second electronic component and having a second terminal; and a conductor provided on the printed wiring board and having a conductor pattern part. In this case, the first electronic component, the first circuit component, the second electronic component, and the second circuit component are mounted on the printed wiring board, the first heat radiation pad of the first electronic component, the first terminal of the first circuit component, the second heat radiation pad of the second electronic component, and the second terminal of the second circuit component are connected through the conductor, and a thermal resistance between the second heat radiation pad and the first terminal is lower than a thermal resistance between the first heat radiation pad and the first terminal.
- According to the invention, heat from an electronic component can be effectively dissipated without adding a heat sink, and the size of a printed circuit board can be reduced.
- Further features of the invention will become apparent from the following description of exemplary embodiments with reference to the attached drawings.
-
FIG. 1 is a sectional view schematically illustrating a printed circuit board according to a first exemplary embodiment. -
FIG. 2 is an electric circuit diagram illustrating the printed circuit board according to the first exemplary embodiment. -
FIG. 3A is a bottom view of first and second electronic components viewed from a +Z direction according to the first exemplary embodiment. -
FIG. 3B is a plan view illustrating a first surface layer viewed from a −Z direction of the printed wiring board according to the first exemplary embodiment. -
FIG. 3C is a plan view of a second surface layer viewed from the −Z direction of the printed wiring board according to the first exemplary embodiment. -
FIG. 4 is an electric circuit diagram illustrating a heat conduction path in the printed circuit board according to the first exemplary embodiment. -
FIG. 5A is a plan view from a −Z direction of a first surface layer of a printed wiring board in a printed circuit board according to a second exemplary embodiment. -
FIG. 5B is a plan view from a −Z direction of a second surface layer of a printed wiring board in a printed circuit board according to the second exemplary embodiment. -
FIG. 6A is a plan view viewed from a −Z direction of a first surface layer of a printed wiring board in a printed circuit board according to a third exemplary embodiment. -
FIG. 6B is a plan view viewed from a −Z direction of a second surface layer of a printed wiring board in a printed circuit board according to the third exemplary embodiment. -
FIG. 7 is a sectional view schematically illustrating a printed circuit board according to a fourth exemplary embodiment. -
FIG. 8A is a plan view illustrating a first surface layer viewed from a −Z direction of the printed wiring board in the printed circuit board according to the fourth exemplary embodiment. -
FIG. 8B is a plan view illustrating a second surface layer viewed from the −Z direction of the printed wiring board in the printed circuit board according to the fourth exemplary embodiment. -
FIG. 9 is a graph illustrating an area of a conductor pattern in printed circuit boards according to the first to third examples and a first comparison example. -
FIG. 10 is a schematic diagram illustrating a heat distribution of the opposite surface of a surface having an electronic component thereon of a printed wiring board in the printed circuit board according to a second example. -
FIG. 11A is a sectional view schematically illustrating a printed circuit board according to the first comparison example. -
FIG. 11B is a plan view illustrating a first surface layer viewed from the −Z direction of the printed wiring board in the printed circuit board according to the first comparison example. -
FIG. 11C is a plan view illustrating a second surface layer viewed from the −Z direction of the printed wiring board in the printed circuit board according to the second comparison example. -
FIG. 12 is a schematic diagram illustrating a heat distribution of a surface opposite against a surface having an electronic component thereon of a printed wiring board in the printed circuit board according to the first comparison example. - Exemplary embodiments of the present invention will be described in detail with reference to drawings.
-
FIG. 1 is a sectional view schematically illustrating a printed circuit board according to a first exemplary embodiment.FIG. 2 is an electric circuit diagram illustrating the printed circuit board according to the first exemplary embodiment. As illustrated inFIG. 1 , aprinted circuit board 100 includes a printedwiring board 200, acircuit module 301 being a first circuit module, and acircuit module 302 being a second circuit module. Thecircuit modules wiring board 200. InFIG. 1 , a direction horizontal to a surface of the printedwiring board 200 is an X direction, a direction horizontal to a surface of the printedwiring board 200 perpendicular to the X direction is a Y direction, and a direction perpendicular to the surface of the printedwiring board 200 is a Z direction. The printedwiring board 200 is a substrate body on which an electronic component is not mounted, and the printedcircuit board 100 has an electronic component and so on mounted on the printedwiring board 200. The printedwiring board 200 has a signal line and so on, which are not illustrated. - The printed
wiring board 200 has a plurality of (two in the first exemplary embodiment) conductor layers includingconductor layers wiring board 200 is a 2-layered printed wiring board. However, the number of layers in the printed wiring board is not limited to two but may be equal to or higher than three. - Each of the conductor layers 201 and 202 mainly has a conductor pattern. Each of the conductor layers 201 and 202 being a surface layer has a solder resist 205 covering the conductor. An
insulator layer 203 mainly has an insulator (dielectric). - Here, in the printed
wiring board 200, the surface layers are outermost conductor layers (mounting surface) having an electronic component and so on thereon. Between the pair of surface layers, one surface layer (second surface layer) on the opposite side of the other surface layer (first surface layer) will also be called a back layer. The surface layer of the printedwiring board 200 will also be called a front surface (first surface), and the back layer will also be called a back surface (second surface). - The
insulator layer 203 may contain an insulator having electrical isolation which may be a hardened resin such as an epoxy resin. The conductor layers 201 and 202 have conductors such as conductor patterns and via conductors (each being a conductor provided in a via) being highly electrically and thermally conductive substances that may be metal such as copper and gold. - As illustrated in
FIGS. 1 and 2 , thecircuit module 301 has anelectronic component 311 being a first electronic component and an active element and anelectrolytic capacitor 321 being a first circuit component and a passive element. Theelectronic component 311 andelectrolytic capacitor 321 are mounted on the printedwiring board 200. Theelectronic component 311 is a motor driver configured to drive a motor M1 and supplies electric current to the motor M1 based on an input command. Theelectrolytic capacitor 321 is provided for theelectronic component 311 to reduce power supply noise (power potential variations) in theelectronic component 311. - The
circuit module 302 has anelectronic component 312 being a second electronic component and an active element and anelectrolytic capacitor 322 being a second circuit component and a passive element. Theelectronic component 312 andelectrolytic capacitor 322 are mounted on the printedwiring board 200. Theelectronic component 312 is a motor driver configured to drive a motor M2 and supplies electric current to the motor M2 based on an input command. Theelectrolytic capacitor 322 is provided for theelectronic component 312 and may reduce power supply noise (power potential variations) in theelectronic component 312. -
FIG. 3A is a bottom view of theelectronic components electronic component 311 has a plurality ofterminals 331 including, more specifically, apower supply terminal 331E, aground terminal 331G, asignal terminal 331S and an output terminal 331I illustrated inFIG. 2 . Theelectronic component 312 has a plurality ofterminals 332 including, more specifically, apower supply terminal 332E, aground terminal 332G, asignal terminal 332S and an output terminal 332I illustrated inFIG. 2 . Each of terminals of theelectronic components - According to the first exemplary embodiment, the
electronic component 311 is mounted on thesurface layer 201 being the first surface layer, and theelectrolytic capacitor 321 is mounted on thesurface layer 202 being the second surface layer. In other words, theelectronic component 311 and theelectrolytic capacitor 321 are mounted on mutually different surfaces of the printedwiring board 200. Theelectronic component 312 is mounted on thesurface layer 201, and theelectrolytic capacitor 322 is mounted on thesurface layer 202. In other words, theelectronic component 312 and theelectrolytic capacitor 322 are mounted on mutually different surfaces of the printedwiring board 200. Theelectronic components wiring board 200, and theelectrolytic capacitors wiring board 200. - The
electronic components FIG. 3A . -
FIG. 3B is a plan view illustrating the first surface layer viewed from a −Z direction of the printed wiring board according to the first exemplary embodiment, andFIG. 3C is a plan view illustrating the second surface layer of the printed wiring board viewed from the −Z direction according to the first exemplary embodiment. InFIG. 3C , the solid lines represent theelectrolytic capacitors - The
electrolytic capacitor 321 has apower supply terminal 351E and a ground terminal (first terminal) 351G. Theelectrolytic capacitor 322 has apower supply terminal 352E and a ground terminal (second terminal) 352G. - The
ground terminal 331G of theelectronic component 311 and aheat radiation pad 341 being a first heat radiation pad of theelectronic component 311 are electrically connected. For example, theground terminal 331G and theheat radiation pad 341 are connected within theelectronic component 311 or may be connected through the printedwiring board 200. Theground terminal 332G of theelectronic component 312 and aheat radiation pad 342 being a second heat radiation pad of theelectronic component 312 are electrically connected. For example, theground terminal 332G andheat radiation pad 342 are connected within theelectronic component 312 or may be connected through the printedwiring board 200. - The
surface layer 201 of the printedwiring board 200 has a plurality of lands (conductor pattern) 231 to which a plurality ofterminals 331 of theelectronic component 311 is bonded by using an electricallyconductive jointing material 431. Thesurface layer 201 has heat radiation lands (conductor pattern) 241 to which aheat radiation pad 341 of theelectronic component 311 is bonded by using an electricallyconductive jointing material 441 of solder, for example. Thesurface layer 201 of the printedwiring board 200 has a plurality of lands (conductor pattern) 232 to which a plurality ofterminals 332 of theelectronic component 312 are bonded by using an electricallyconductive jointing material 432 of solder, for example. Furthermore, thesurface layer 201 has heat radiation lands (conductor pattern) 242 to which aheat radiation pad 342 of theelectronic component 312 is bonded by using an electricallyconductive jointing material 442 of solder, for example. - The
surface layer 202 of the printedwiring board 200 has a plane-shapedconductor pattern 250 being a conductor pattern part. Theconductor pattern 250 is provided in a region including theelectronic components electrolytic capacitors 321 and 323 viewed from the arrow Z direction perpendicular to the surface of the printedwiring board 200. More specifically, theconductor pattern 250 is provided so as to include a projected region acquired by projecting theheat radiation pads electronic components ground terminals electrolytic capacitors 321 and 323 to theconductor layer 202 in the arrow Z direction. - The
conductor pattern 250 has a conductor present on a straight line connecting a connection point between the viaconductor 261 and theconductor pattern 250 and a connection point between theground terminal 351G of theelectrolytic capacitor 321 and theconductor pattern 250 viewed from the arrow Z direction. Also, theconductor pattern 250 has a conductor present on a straight line connecting between a connection point between the viaconductor 262 and theconductor pattern 250 and a connection point between theground terminal 351G of theelectrolytic capacitor 321 and theconductor pattern 250 viewed from the arrow Z direction. Theconductor pattern 250 has a conductor present on a straight line connecting a connection point between the viaconductor 262 and theconductor pattern 250 and a connection point between theground terminal 352G of theelectrolytic capacitor 322 and theconductor pattern 250 viewed from the arrow Z direction. - The
ground terminal 351G of theelectrolytic capacitor 321 is bonded to theconductor pattern 250 by using an electricallyconductive jointing material 451 of solder, for example, and theground terminal 352G of theelectrolytic capacitor 322 is bonded to theconductor pattern 250 by using an electricallyconductive jointing material 452 of solder, for example. - The
conductor pattern 250 and the heat radiation lands 241 are connected by using a plurality of via conductors (each being a conductor provided in a via) 261. Theconductor pattern 250 and the heat radiation lands 242 are connected by using a plurality of viaconductors 262. Viewed from the arrow Z direction, the viaconductors 261 are provided within a region of the heat radiation lands 241, and the viaconductors 262 are provided within a region of the heat radiation lands 242. - According to the first exemplary embodiment, by using the heat radiation lands 241 and 242, the
conductor pattern 250 and viaconductors ground conductor 220 is provided across thesurface layer 201 and thesurface layer 202. - In other words, the
heat radiation pad 341 of theelectronic component 311, theground terminal 351G of theelectrolytic capacitor 321, theheat radiation pad 342 of theelectronic component 312, and theground terminal 352G of theelectrolytic capacitor 322 are electrically and thermally connected through theground conductor 220. - According to the first exemplary embodiment, the printed
wiring board 200 has apower supply conductor 211 being a first power supply conductor configured to electrically connect thepower supply terminal 351E of theelectronic component 311 and thepower supply terminal 351E of theelectrolytic capacitor 321 across thesurface layer 201 and thesurface layer 202. - The printed
wiring board 200 further has apower supply conductor 212 being a second power supply conductor configured to electrically connect thepower supply terminal 352E of theelectronic component 312 and thepower supply terminal 352E of theelectrolytic capacitor 322 across thesurface layer 201 and thesurface layer 202. - In a case where the
electronic components power supply conductor 211 and thepower supply conductor 212 may be connected through a power supply conductor, not illustrated. In a case where theelectronic components power supply conductor 211 and thepower supply conductor 212 may be isolated. - Direct current voltage is applied from a direct current power supply circuit, not illustrated, to between the
power supply conductors ground conductor 220, electric power is supplied to theelectronic components electronic components - According to the first exemplary embodiment, the
electronic component 311 andelectronic component 312 generate heat due to an operation for driving the motor. Theelectronic component 312 then generates heat exhibiting a heat value higher than that of theelectronic component 311. - The heat generated from the
electronic components electrolytic capacitors ground conductor 220. The heat conducted to theelectrolytic capacitors electrolytic capacitors wiring board 200 for heat radiation for theelectronic components - The
electrolytic capacitors - The
electrolytic capacitor 321 is disposed more closely to theelectronic component 312 than theelectronic component 311, as illustrated inFIG. 1 andFIGS. 3B and 3C . Theelectrolytic capacitor 322 is also disposed more closely to theelectronic component 312 than theelectronic component 311 as illustrated inFIG. 1 andFIGS. 3B and 3C . - In the printed
circuit board 100, the heat conduction of the electronic components are mainly through a conductor, particularly, theground conductor 220 because a conductor has a higher heat conductivity than that of an insulator. - According to the first exemplary embodiment, in the
ground conductor 220, the thermal resistance between theheat radiation pad 342 and theground terminal 351G is lower than the thermal resistance between theheat radiation pad 341 and theground terminal 351G. In other words, in theground conductor 220, the thermal resistance between theheat radiation pad 341 and theground terminal 351G is higher than the thermal resistance between theheat radiation pad 342 and theground terminal 351G. -
FIG. 4 is an electric circuit diagram illustrating a heat conduction path in the printed circuit board according to the first exemplary embodiment. A heat conduction path PA from theheat radiation pad 341 in theelectronic component 311 to theground terminal 351G of theelectrolytic capacitor 321 includes thejointing material 441, the heat radiation lands 241, the viaconductor 261, theconductor pattern 250, and thejointing material 451. - A heat conduction path PB from the
heat radiation pad 342 of theelectronic component 312 to theground terminal 352G of theelectrolytic capacitor 322 includes thejointing material 442, the heat radiation lands 242, the viaconductor 262, theconductor pattern 250, and thejointing material 452. - A heat conduction path PC from the
heat radiation pad 342 in theelectronic component 312 to theground terminal 351G of theelectrolytic capacitor 321 includes thejointing material 442, the heat radiation lands 242, the viaconductor 262, theconductor pattern 250, and thejointing material 451. - The heat conduction paths PA to PC have thermal resistances dependent on the dimensions and heat conductivities of the materials. In the heat conduction paths PA to PC, the
conductor pattern 250 is shared. It can be regarded that the thermal resistances of thejointing material 441 and thejointing material 442, the thermal resistances of thejointing material 451 and thejointing material 452, the thermal resistances of the heat radiation lands 241 and the heat radiation lands 242, and the thermal resistances of the viaconductor 261 and the viaconductor 262 are equal. Thus, the thermal resistances of the heat conduction paths PA to PC depend on the distances between the connection points of the viaconductors ground terminal 351G of theelectrolytic capacitor 321 in theconductor pattern 250 illustrated inFIG. 3C . - According to the first exemplary embodiment, the
electrolytic capacitor 321 is disposed more closely to theelectronic component 312 between theelectronic component 311 and theelectronic component 312. Therefore, in theconductor pattern 250, the distance between the connection point of the viaconductor 262 and the connection point of theground terminal 351G of theelectrolytic capacitor 321 is shorter than the distance between the connection point of the viaconductor 261 and the connection point of theground terminal 351G of theelectrolytic capacitor 321. As a result, in theground conductor 220, the thermal resistance between theheat radiation pad 342 and theground terminal 351G is lower than the thermal resistance between theheat radiation pad 341 and theground terminal 351G. - Thus, the
electrolytic capacitor 321 has an absorption of heat more in the heat conduction from the heat conduction path PC of theelectronic component 312 than the heat conduction from the heat conduction path PA in theelectronic component 311. Thus, heat generated from theelectronic component 312 is not only conducted to theelectrolytic capacitor 322 through the heat conduction path PB but also is conducted to theelectrolytic capacitor 321 through the heat conduction path PC so that the temperature of theelectronic component 312 can be reduced. - In other words, because the thermal resistance of the heat conduction path PA is higher than the thermal resistance of the heat conduction path PC, the amount of heat radiation to the
electrolytic capacitor 321 increases even when thermal interference from theelectronic component 311 occurs in theelectronic component 312. Therefore, the area of theconductor pattern 250 can be reduced, and the size of the printedcircuit board 100 having thecircuit modules - The thermal resistance of a conductor satisfies the following expression (1).
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θ=L/(K×W×t) (1) - where θ(° C./W) is the thermal resistance, L (mm) is a length, K (W/m*° C.) is a heat conductivity, W (mm) is a width, and a thickness is t (mm) of the conductor.
- The relationship between the thermal resistance of the heat conduction path PA and the thermal resistance of the heat conduction path PC satisfies the following expression (2).
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θ1(=L1/(K×t×W))>θ3(=L3/(K×t×W)) (2) - where L1 and θ1 are a length and a thermal resistance, respectively, of the heat conduction path PA, L3 and θe are a length and a thermal resistance, respectively, of the heat conduction path PC, K, W, and t are a heat conductivity, a width, and a thickness, respectively, of each of the conductors.
- According to Expression (2), the heat conductivities K, the thicknesses t, and the widths W of the heat conduction path PA and heat conduction path PC are equal. Therefore, from the magnitude relationship between the lengths L1 and L3 of the heat conduction paths, the values of the thermal resistances can be determined. The difference in value between the thermal resistance θ1 and the thermal resistance θ3 increases as the length of the heat conduction path PA increases and the length of the heat conduction path PC decreases. Thus, the temperature of the
electronic component 312 can be reduced, and the required area of theconductor pattern 250 can be reduced. The thermal resistance between two arbitrary points on theelectronic components wiring board 200 can be calculated by measuring the lengths, thicknesses, and widths of conductors on the printedwiring board 200 and using Expression (1). - Furthermore, assuming that the thermal resistance of a conductor is θ(° C./W), the heat value of an electronic component is Q (W), a junction temperature of the electronic component is T1 (° C.), and the temperature of an arbitrary point on the printed wiring board is T2 (° C.), the thermal resistance satisfies the following expression (3).
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θ=(T1−T2)/Q (3) - The thermal resistance between two arbitrary points on the
electronic components wiring board 200 can be calculated by using Expression (3). The T1 (° C.) that is a junction temperature of an electronic component and the T2 (° C.) that is a temperature at an arbitrary point on a printed wiring board can be measured from a temperature distribution diagram of the printed circuit board by using an apparatus such as a thermograph. In this case, the thermal resistances of the heat conduction paths PA, PB, and PC do not impair the functionality of thecircuit modules conductors - Next, a printed circuit board according to a second exemplary embodiment will be described.
FIG. 5A is a plan view from a −Z direction of a first surface layer of a printed wiring board in the printed circuit board according to the second exemplary embodiment.FIG. 5B is a plan view from a −Z direction of a second surface layer of the printed wiring board in the printed circuit board according to the second exemplary embodiment. The second exemplary embodiment is different from the first exemplary embodiment in the configuration of a conductor pattern part in the printed wiring board and is the same as the first exemplary embodiment in the other configuration. Like numbers refer to like parts in descriptions and illustrations according to the first and second exemplary embodiments, and repetitive description will be omitted.FIG. 5B illustrateselectrolytic capacitors - A printed
wiring board 200A in the printed circuit board according to the second exemplary embodiment has a plurality of (two in the second exemplary embodiment) conductor layers including conductor layers 201 and 202A stacked through an insulator layer (dielectric layer). Referring toFIG. 5A , the wiring of a power supply line and so on, not illustrated, has the same configuration as that of theconductor layer 201 illustrated inFIG. 3B . According to the second exemplary embodiment, the printedwiring board 200A is a 2-layered printed wiring board. The number of layers in the printed wiring board is not limited to two but may be equal to or higher than three. - According to the second exemplary embodiment, the
electronic component 311 is mounted on thesurface layer 201 being a first conductor layer, and theelectrolytic capacitor 321 is mounted on asurface layer 202A being a second conductor layer. In other words, theelectronic component 311 and theelectrolytic capacitor 321 are mounted on mutually different surfaces of the printedwiring board 200A. Theelectronic component 312 is mounted on thesurface layer 201, and theelectrolytic capacitor 322 is mounted on thesurface layer 202A. In other words, theelectronic component 312 and theelectrolytic capacitor 322 are mounted on mutually different surfaces of the printedwiring board 200A. Theelectronic components wiring board 200A, and theelectrolytic capacitors wiring board 200A. - Like the first exemplary embodiment, the
electrolytic capacitor 321 is disposed more closely to theelectronic component 312 than theelectronic component 311. Theelectrolytic capacitor 322 is also disposed more closely to theelectronic component 312 than theelectronic component 311. - The printed
wiring board 200A has aconductor pattern part 250A. Theconductor pattern part 250A has plane-shapedconductor patterns conductor patterns identical surface layer 202A. - A projected region (first projected region) R1 is a region acquired by projecting the
heat radiation pad 341 in theelectronic component 311 to theconductor layer 202A in an arrow Z direction perpendicular to the surface of the printedwiring board 200A. A projected region (second projected region) R2 is a region acquired by projecting theheat radiation pad 342 in theelectronic component 312 to theconductor layer 202A in an arrow Z direction perpendicular to the surface of the printedwiring board 200A. A projected region (third projected region) R3 is a region acquired by projecting theground terminal 351G of theelectrolytic capacitor 321 to theconductor layer 202A in the arrow Z direction perpendicular to the surface of the printedwiring board 200A. A projected region (fourth projected region) R4 is a region acquired by projecting theground terminal 352G of theelectrolytic capacitor 322 to theconductor layer 202A in the arrow Z direction perpendicular to the surface of the printedwiring board 200A. - A
conductor pattern 251A being a first conductor pattern is provided so as to include the projected region R1. Aconductor pattern 252A being a second conductor pattern is provided so as to include the projected regions R2 and R3 (or projected regions R2, R3, and R4 more specifically). Theconductor pattern 251A and theconductor pattern 252A are spaced from each other. - A
conductor pattern 253A being a connection conductor is a third conductor pattern configured to connect theconductor pattern 251A and theconductor pattern 252A. Aconductor pattern 253A is provided such that the thermal resistance between theheat radiation pad 341 and theground terminal 351G can be higher than the thermal resistance between theheat radiation pad 342 and theground terminal 351G. More specifically, theconductor pattern 253A is narrower than theconductor patterns notch 260A is provided between theconductor pattern 251A and theconductor pattern 252A so that theconductor pattern 251A and theconductor pattern 252A can be connected through theconductor pattern 253A. In other words, thenotch 260A is provided between theconductor pattern 251A and theconductor pattern 252A such that theconductor pattern 251A and theconductor pattern 252A can be connected through thenarrow conductor pattern 253A. Theconductor pattern 253A formed with thenotch 260A can bring theconductor pattern 251A and theconductor pattern 252A into conduction and can increase the thermal resistance therein. Thenotch 260A is provided between theelectronic component 311 and theelectronic capacitor 321, viewed from the Z direction. - According to the second exemplary embodiment, the
conductor pattern 253A is not present on a straight line LA connecting the connection point between the viaconductor 261 and theconductor pattern 251A and the connection point between theground terminal 351G of theelectrolytic capacitor 321 and theconductor pattern 252A, viewed from the arrow Z direction. This means that theconductor pattern 253A is provided by avoiding the straight line LA. In other words, thenotch 260A is present on the straight line LA. - According to the second exemplary embodiment, as described above, the
ground terminal 351G of theelectrolytic capacitor 321 is disposed at a position facing theheat radiation pad 341 of theelectronic component 311 with thenotch 260A interposed therebetween and is provided closely to theelectronic component 312. - According to the second exemplary embodiment, as described above, because the
conductor pattern 253A is narrower than theconductor patterns heat radiation pad 341 and theheat radiation pad 342 can be higher than that in the first exemplary embodiment. This can reduce the influence of thermal interference from theelectronic component 311 to theelectronic component 312. Thus, the temperature of theelectronic component 312 can be reduced more than the first exemplary embodiment, and the size of the printed circuit board can further be reduced. - Because the thus further increased thermal resistance between the
ground terminal 351G of theelectrolytic capacitor 321 and the heat radiation pad 341 (via conductor 261) can reduce the heat of theelectronic component 311 conducted to theelectrolytic capacitor 321. Thus, the heat of theelectronic component 312 can be conducted effectively to theelectrolytic capacitor 321. Therefore, the temperature of theelectronic component 312 can effectively be reduced, and the size of the printed circuit board can further be reduced. - The heat conduction path between the
ground terminal 351G of theelectrolytic capacitor 321 and the viaconductor 261 can be redundant because of thenotch 260A, the length of the heat conduction path PA (FIG. 4 ) can be longer than that in the first exemplary embodiment, and the thermal resistance can further be increased than that of the heat conduction path PC. Therefore, the influence of thermal interference from theelectronic component 311 to theelectronic component 312 can further be reduced, and the temperature of theelectronic component 312 can be reduced more effectively. Then, the size of the printed circuit board can further be reduced. - Next, a printed circuit board according to a third exemplary embodiment will be described.
FIG. 6A is a plan view from a −Z direction of a first surface layer of a printed wiring board in the printed circuit board according to the third exemplary embodiment.FIG. 6B is a plan view from a −Z direction of a second surface layer of the printed wiring board in the printed circuit board according to the third exemplary embodiment. The third exemplary embodiment is different from the first and second exemplary embodiments in the configuration of a conductor pattern component and mounted states of electronic components in the printed wiring board and is the same as the first and second exemplary embodiments in the other configuration. Like numbers refer to like parts in descriptions and illustrations according to the first, second and third exemplary embodiments, and repetitive description will be omitted.FIG. 6B illustrateselectrolytic capacitors - A printed
wiring board 200B in the printed circuit board according to the third exemplary embodiment has a plurality of (two in the third exemplary embodiment) conductor layers including conductor layers 201B and 202B stacked through an insulator layer (dielectric layer). According to the third exemplary embodiment, the printedwiring board 200B is a 2-layered printed wiring board. The number of layers in the printed wiring board is not limited to two but may be equal to or higher than three. - According to the third exemplary embodiment, the
electronic component 311 and theelectrolytic capacitor 321 are mounted on asurface layer 202B being a second conductor layer. In other words, theelectronic component 311 and theelectrolytic capacitor 321 are mounted on a same surface of the printedwiring board 200B, unlike the first and second exemplary embodiments. Theelectronic component 312 is mounted on asurface layer 201B, and theelectrolytic capacitor 322 is mounted on asurface layer 202B. In other words, theelectronic component 312 and theelectrolytic capacitor 322 are mounted on mutually different surfaces of the printedwiring board 200B. Theelectronic component 311 and theelectronic component 312 is mounted on mutually different surfaces of the printedwiring board 200B, and theelectrolytic capacitors wiring board 200B, unlike the first and second exemplary embodiments. - Like the first and second exemplary embodiments, the
electrolytic capacitor 321 is disposed more closely to theelectronic component 312 than theelectronic component 311. Theelectrolytic capacitor 322 is also disposed more closely to theelectronic component 312 than theelectronic component 311. - The printed
wiring board 200B has aconductor pattern part 250B. Theconductor pattern part 250B has plane-shapedconductor patterns conductor pattern 251B is provided on a conductor layer (surface layer) 201B, and aconductor pattern 252B is provided on a conductor layer (surface layer) 202B different from thesurface layer 201B. In other words, theconductor pattern 251B is disposed on the opposite surface of the surface having theelectronic component 311, and theconductor pattern 252B is disposed on the opposite surface of the surface having theelectronic component 312. Theconductor pattern 251B and theconductor pattern 252B are connected through a viaconductor 253B. - A projected region (first projected region) R1 is a region acquired by projecting the
heat radiation pad 341 in theelectronic component 311 to theconductor layer 201B in an arrow Z direction perpendicular to the surface of the printedwiring board 200B. A projected region (second projected region) R2 is a region acquired by projecting theheat radiation pad 342 in theelectronic component 312 to theconductor layer 202B in an arrow Z direction perpendicular to the surface of the printedwiring board 200B. A projected region (third projected region) R3 is a region acquired by projecting theground terminal 351G of theelectrolytic capacitor 321 to theconductor layer 202B in the arrow Z direction perpendicular to the surface of the printedwiring board 200B. A projected region (fourth projected region) R4 is a region acquired by projecting theground terminal 352G of theelectrolytic capacitor 322 to theconductor layer 202B in the arrow Z direction perpendicular to the surface of the printedwiring board 200B. - A
conductor pattern 251B being a first conductor pattern is provided so as to include the projected region R1. Aconductor pattern 252B being a second conductor pattern is provided so as to include the projected regions R2 and R3 (or projected regions R2, R3, and R4 more specifically). - The via
conductor 253B is a connection conductor configured to connect theconductor pattern 251B and theconductor pattern 252B. The viaconductor 253B is provided such that the thermal resistance between theheat radiation pad 341 and theground terminal 351G can be higher than the thermal resistance between theheat radiation pad 342 and theground terminal 351G. - According to the third exemplary embodiment, as described above, because the
conductor pattern 251B and theconductor pattern 252B are connected through the viaconductor 253B, the thermal resistance between theheat radiation pad 341 and theheat radiation pad 342 can be higher than that in the first exemplary embodiment. This can reduce the influence of thermal interference from theelectronic component 311 to theelectronic component 312. Thus, the temperature of theelectronic component 312 can be reduced more than the first exemplary embodiment, and the size of the printed circuit board can further be reduced. - The
electronic component 311 and theelectronic component 312 are mounted on mutually different surfaces. The path from theground terminal 351G of theelectrolytic capacitor 321 to the viaconductor 261 through the viaconductor 253B is longer than that in first exemplary embodiment. The thermal resistance of the heat conduction path PA (FIG. 4 ) between theheat radiation pad 341 and theground terminal 351G is higher than the thermal resistance of the heat conduction path PC (FIG. 4 ) between theheat radiation pad 342 and theground terminal 351G. Furthermore, because the viaconductor 253B has a higher thermal resistance than those of theconductor patterns FIG. 4 ) can have a further higher thermal resistance. Thus, the temperature of theelectronic component 312 can effectively be reduced, and the size of the printed circuit board can further be reduced. - Next, a printed circuit board according to a fourth exemplary embodiment will be described.
FIG. 7 is a sectional view schematically illustrating a printed circuit board according to the fourth exemplary embodiment.FIG. 8A is a plan view illustrating a first surface layer viewed from a −Z direction of the printed wiring board in the printed circuit board according to the fourth exemplary embodiment.FIG. 8B is a plan view illustrating a second surface layer viewed from the −Z direction of the printed wiring board in the printed circuit board according to the fourth exemplary embodiment. The fourth exemplary embodiment is different from the first to third exemplary embodiments in the configuration of a conductor pattern part in the printed wiring board and the mounting of electrolytic capacitors and is the same as the first to third exemplary embodiments in the other configuration. Like numbers refer to like parts in descriptions and illustrations according to the first to fourth exemplary embodiments, and repetitive description will be omitted.FIG. 8B illustrates theelectrolytic capacitors - A printed wiring board 200C in a printed
circuit board 100C according to the fourth exemplary embodiment has a plurality of (two in the fourth exemplary embodiment) conductor layers including conductor layers 201C and 202C stacked through an insulator layer (dielectric layer). According to the fourth exemplary embodiment, the printed wiring board 200C is a 2-layered printed wiring board. The number of layers in the printed wiring board is not limited to two but may be equal to or higher than three. - According to the fourth exemplary embodiment, the
electronic components electrolytic capacitors surface layer 201C being a first conductor layer. In other words, theelectronic components electrolytic capacitors - Like the first to third exemplary embodiment, the
electrolytic capacitor 321 is disposed more closely to theelectronic component 312 than theelectronic component 311. Theelectrolytic capacitor 322 is also disposed more closely to theelectronic component 312 than theelectronic component 311. - The printed wiring board 200C has plane-shaped
conductor patterns 251C and 252C. Theseconductor patterns 251C and 252C are included in aconductor pattern part 250C. Aconductor pattern 251C is provided on asurface layer 202C, and a conductor pattern 252C is provided on asurface layer 201C. - The
conductor pattern 251C is provided in a region including theelectronic components electrolytic capacitor conductor pattern 251C is provided so as to include a projected region acquired by projecting theheat radiation pads electronic components ground terminals electrolytic capacitors conductor layer 202C in the arrow Z direction. - The
ground terminals electrolytic capacitors jointing materials - The
heat radiation land 241 and theconductor pattern 251C are connected by using a plurality of viaconductors 261, and theheat radiation land 242 and theconductor pattern 251C are connected by using a plurality of viaconductors 262. - In vicinity of the
ground terminal 351G of theelectrolytic capacitor 321, a plurality of (such as three) viaconductors 271 is disposed which connects theconductor pattern 251C and the conductor pattern 252C. In vicinity of theground terminal 352G of theelectrolytic capacitor 322, a plurality of (such as three) viaconductors 272 is disposed which connects theconductor pattern 251C and the conductor pattern 252C. - According to the fourth exemplary embodiment, by using the heat radiation lands 241 and 242, the
conductor patterns 251C and 252C and the viaconductors ground conductor 220C is provided across thesurface layer 201C and thesurface layer 202C. - According to the fourth exemplary embodiment, the temperature of the
electronic component 312 can be reduced, and the size of the printedcircuit board 100C can be reduced, like the first exemplary embodiment. Thecomponents - An electronic apparatus having the printed circuit board according to an embodiment of the present invention exhibited the excellent performance of heat radiation.
- A printed circuit board according to a first example will be described. In the configuration of the printed
circuit board 100 according to the first exemplary embodiment illustrated inFIG. 1 , conditions were defined for the printedwiring board 200,electronic component 311,electronic component 312,electrolytic capacitor 321,electrolytic capacitor 322 andjointing materials - The printed
wiring board 200 was a 1.6 [mm]-thick two-layered substrate having a size of 60×60 [mm]. The heat radiation lands 241 and 242 facing theheat radiation pads electronic components electronic components - The plurality of via conductors 261 (262) were formed by forming a total of nine φ0.3 [mm] vias in a 3×3 matrix on the heat radiation lands 241 (242) and were plated within corresponding via holes. The plating was 20 [μm] thick and was made of Cu. The vias were disposed at pitches of 0.7 [mm]. The
conductor pattern 250 was disposed on the opposite surface of the surface having theelectronic components - The
electronic components heat radiation pads electronic components electronic components - The
electrolytic capacitors ground terminals electrolytic capacitors electrolytic capacitors ground terminals electrolytic capacitors - The
jointing materials jointing materials - The positional conditions for the
electronic components electrolytic capacitors wiring board 200 as a point of origin, the central position of theelectronic component 311 was disposed at a position at −10.5 [mm] in the X direction from the point of origin, and theelectronic component 312 was disposed at a position at 10.5 [mm] in the X direction from the point of origin. The center distance between theelectronic component 311 and theelectronic component 312 was equal to 21 [mm]. - The
electrolytic capacitors electronic components electrolytic capacitor 321 is disposed at a position at −4 [mm] in the Y direction from the central position of theelectronic component 312, and theelectrolytic capacitor 322 is disposed at a position at 4 [mm] in the Y direction from the central position of theelectronic component 312. - The central position of the
conductor pattern 250 was equal to the central position of the printedwiring board 200. - Thermal analysis conditions in the configuration of the first example as described above will be described. The power consumption in the
electronic component 311 was assumed as 0.3 [W], and the power consumption in theelectronic component 312 was assumed as 0.6 [W]. The center of the upper surface of a silicon chip within theelectronic component 312 is analyzed with respect to the junction temperature of theelectronic component 312. The same was also applied to theelectronic component 311. The ambient temperature of the printedcircuit board 100 was defined as 25[° C.], and the ambient environment was defined as natural convection. - A thermal analysis was performed to evaluate the area (14 [mm]×41 [mm]) of the
conductor pattern 250 necessary for the junction temperature of theelectronic component 312 to be equal to or lower than 80[° C.], for example. - As a result of calculation of the thermal resistances of the heat conduction paths PA and PC in the first example, the thermal resistance of the heat conduction path PA was 59[° C./W], and the thermal resistance of the heat conduction path PC was 15[° C./W]. The area of the
conductor pattern 250 necessary for the junction temperature of theelectronic component 312 to be equal to or lower than 80[° C.] was also acquired. -
FIG. 9 is a graph illustrating an area of a conductor pattern in printed circuit boards according to the first to third examples and a first comparison example. As illustrated inFIG. 9 , the area of theconductor pattern 250 was 570 [mm2] (14 [mm]×41 [mm]). - A printed circuit board according to a first comparison example will be described. The first comparison example is different from the first example in positions of the
electrolytic capacitors FIG. 11A is a sectional view schematically illustrating a printed circuit board according to the first comparison example.FIG. 11B is a plan view illustrating a first surface layer (surface layer 201X) viewed from the −Z direction of the printed wiring board in the printed circuit board according to the first comparison example.FIG. 11C is a plan view illustrating a first surface layer (surface layer 202X) viewed from the −Z direction of the printed wiring board in the printed circuit board according to the second comparison example. - In the configuration of a printed
circuit board 100X illustrated inFIG. 11A , the central position of theelectrolytic capacitor 321 is the same as the central position of theelectronic component 311, and the central position of theelectrolytic capacitor 322 is the same as the central position of theelectronic component 312, unlike the first example. The first comparison example is also different from the first example in that theconductor pattern 250X of the first comparison example has a size of 44 [mm]×14 [mm] (X [mm]×Y [mm]). For comparison in reduced amount of the area of the conductor pattern, the other configuration of the first comparison example is the same as that of the first example. - The thermal resistance of the heat conduction path PA between the
heat radiation pad 341 and theground terminal 351G of theelectrolytic capacitor 321 in the first comparison example was 10.8[° C./W]. The thermal resistance of the heat conduction path PC between theheat radiation pad 342 and theground terminal 351G of theelectrolytic capacitor 321 in the first comparison example was 50.2[° C./W]. The area of theconductor pattern 250X necessary for the junction temperature of theelectronic component 312 of the printedcircuit board 100X to be equal to or lower than 80[° C.] was acquired. The area of theconductor pattern 250X was 620 [mm2] (44 [mm]×14 [mm]) as illustrated inFIG. 9 . -
FIG. 12 is a schematic diagram illustrating a heat distribution of a surface opposite against a surface having an electronic component thereon of a printed wiring board in the printed circuit board according to the first comparison example.FIG. 12 illustrates regions A, B, and C of a heat distribution representing isotherms of the heat distribution and that the temperatures decrease in order of the regions A, B, and C. In the region B, the heats generated from theelectronic component 311 and theelectronic component 312 are conducted to the printedwiring board 200X and interfere with each other. In the area C, the heats generated from theelectronic component 311 and theelectronic component 312 interfere with each other. The heat radiation from theelectronic component 312 to theconductor pattern 250X is prevented by the thermal interference from theelectronic component 311. As a result, theelectronic component 312 has a higher temperature than that of theelectronic component 311. - A printed circuit board according to a second example will be described. The printed circuit board according to the second example corresponds to the printed circuit board of the second exemplary embodiment illustrated in
FIGS. 5A and 5B . In the second example, aconductor pattern part 250A is provided which has anotch 260A on a 37 [mm]×14 [mm] (X [mm]×Y [mm]) conductor pattern. Theelectrolytic capacitor 321 faces theelectronic component 311 with thenotch 260A interposed therebetween. The configuration other than theconductor pattern part 250A in the second example is the same as that of the first example. - The
notch 260A had a size of 1 [mm]×13.5 [mm] (X [mm]×Y [mm]). Thenotch 260A was provided at a position at 2 [mm] in the X direction from the central position of theelectronic component 311. - The thermal resistance of the heat conduction path PA between the
heat radiation pad 341 and theground terminal 351G in the printed circuit board of the second example was 187[° C./W], and the thermal resistance of the heat conduction path PC between theheat radiation pad 342 and theground terminal 351G was 15[° C./W]. As a result of calculation of an area of theconductor pattern part 250A necessary for the junction temperature of theelectronic component 312 to be equal to or lower than 80[° C.], the area of theconductor pattern part 250A was 515 [mm2] (14 [mm]×37 [mm]) as illustrated inFIG. 9 . -
FIG. 10 is a schematic diagram illustrating a heat distribution of the opposite surface of a surface having an electronic component thereon of a printed wiring board in the printed circuit board according to the second example.FIG. 10 illustrates regions A, B, and C of a heat distribution representing isotherms of the heat distribution and that the temperatures decrease in order of the regions A, B, and C. FromFIG. 12 , it may be understood that thenotch 260A provided between theelectronic component 311 and theelectronic component 312 can prevent mutual interferences between heat distributions of theelectronic component 311 and theelectronic component 312. In other words, because the heats generated from theelectronic component 311 and theelectronic component 312 do not interfere with each other, the heat radiation from theelectronic component 312 can efficiently be performed. - A printed circuit board according to a third example will be described. The printed circuit board according to the third example corresponds to the printed circuit board of the third exemplary embodiment illustrated in
FIGS. 6A and 6B . The printed circuit board of the third example is different from the printed circuit board of the first example in position of theelectronic component 311 and configuration of a conductor pattern part. - A
conductor pattern 251B is disposed on the opposite surface of a surface having theelectronic component 311. Theconductor pattern 251B had a size of 12.5 [mm]×14 [mm] (X [mm]×Y [mm]) and was made of Cu. The central position of theconductor pattern 251B was equal to the central position of theelectronic component 311. - A
conductor pattern 252B is disposed on the opposite surface of the surface having theelectronic component 312. Theconductor pattern 252B had a size of 27 [mm]×14 [mm] (X [mm]×Y [mm]) and was made of Cu. The central position of theconductor pattern 252B was equal to the central position of theelectronic component 312. - The via
conductor 253B was provided at a position at −6.5 [mm] in the X direction and −6 [mm] in the Y direction from the central position of the printed wiring board as the point of origin. The hole diameter of the via having the viaconductor 253B was 0.3 [mm]. The thickness of plating provided within the via hole was 20 [μm], and the plating was made of Cu. The viaconductor 253B electrically connects theconductor pattern 251B and theconductor pattern 252B. The other configuration of the third example illustrated inFIGS. 6A and 6B is the same as that of the first example. - A thermal analysis was performed to evaluate the area of the
conductor pattern part 250B necessary for the junction temperature of theelectronic component 312 to be equal to or lower than 80[° C.], for example, in the printed circuit board of the third example. According to the third example, the area of theconductor pattern part 250B was equal to a sum total of theconductor pattern 251B (12.5 [mm]×14 [mm]) and theconductor pattern 252B (27 [mm]×14 [mm]). - The thermal resistance of the heat conduction path PA between the
heat radiation pad 341 and theground terminal 351G was 77[° C./W], and the thermal resistance of the heat conduction path PC between theheat radiation pad 342 and theground terminal 351G was 15[° C./W]. - The area of the
conductor pattern part 250B necessary for the junction temperature of theelectronic component 312 to be equal to or lower than 80[° C.] was also acquired. As illustrated inFIG. 9 , the area of theconductor pattern part 250B was equal to 553 [mm2] ((12.51 [mm]×14 [mm])+(27 [mm]×14 [mm])). - A printed circuit board according to a fourth example will be described. The printed circuit board according to the fourth example corresponds to the printed circuit board illustrated in
FIG. 7 . The printed circuit board of the fourth example is different from the printed circuit board of the first example in positions of theelectrolytic capacitors - The
electrolytic capacitors electronic components electrolytic capacitor 321 was mounted at a position at 4 [mm] in the Y direction from the central position of theelectronic component 312, and theelectrolytic capacitor 322 was mounted at a position at −4 [mm] in the Y direction from the central position of theelectronic component 312. - Three via
conductors 271 were disposed in vicinity of theground terminal 351G of theelectrolytic capacitor 321. The three viaconductors 271 electrically connect theground terminal 351G of theelectrolytic capacitor 321 and aconductor pattern part 250C. The hole diameters of vias having the viaconductors 271 are all equal to 0.3 [mm], and the vias are arranged at pitches of 0.8 [mm]. - Three via
conductors 272 are disposed in vicinity of theground terminal 352G of theelectrolytic capacitor 322. The three viaconductors 272 electrically connect theground terminal 352G of theelectrolytic capacitor 322 and theconductor pattern part 250C. The hole diameters of vias having the viaconductors 272 are all equal to 0.3 [mm], and the vias are arranged at pitches of 0.8 [mm]. - The other configuration of the fourth example illustrated in
FIG. 7 is the same as that of the first example. - Performing a thermal analysis on the printed circuit board of the fourth example, the thermal resistance of the heat conduction path PA between the
heat radiation pad 341 and theground terminal 351G was 73[° C./W], and the thermal resistance of the heat conduction path PC between theheat radiation pad 342 and theground terminal 351G was 30[° C./W]. - The area of the
conductor pattern part 250C necessary for the junction temperature of theelectronic component 312 to be equal to or lower than 80[° C.], for example, was acquired as 580 [mm2] (42 [mm]×14 [mm]). - Because of the difference in thermal resistance between the heat conduction path PA and the heat conduction path PC, how the area of the conductor pattern part necessary for the junction temperature of the
electronic component 312 to be equal to or lower than 80[° C.] changes can be grasped. - The area of a conductor pattern of copper foil necessary for the junction temperature of the
electronic component 312 of the first example to be equal to or lower than 80[° C.] was 570 [mm2] (41 [mm]×14 [mm]). The area in the second example was 515 [mm2] (37 [mm]×14 [mm]). The area in the third example was 553 [mm2] (12.5 [mm]×14 [mm]+27 [mm]×14 [mm]). The area in the fourth example was 559 [mm2] (40 [mm]×14 [mm]). The area in the first comparison example was 620 [mm2] (44 [mm]×14 [mm]). - When the thermal resistance of the heat conduction path PA is increased to be higher than the thermal resistance of the heat conduction path PC based on the configuration of the first example, the necessary area of the
conductor pattern 250 is reduced by about 9.0% of that of the first comparison example. - In the first example, because the thermal resistance of the heat conduction path PA higher than the thermal resistance of the heat conduction path PC allow efficient heat radiation of heat generated from the
electronic component 312, the area of theconductor pattern 250 necessary for the heat radiation decreases. In other words, it can reduce the size of the printed circuit board having a plurality of circuit modules having electronic components. - In the second example, the
notch 260A provided in theconductor pattern part 250A can further increase the thermal resistance of the heat conduction path PA so that the necessary area of theconductor pattern part 250A decreases. In the second example, compared with the first comparison example, the heat distributions of theelectronic component 311 and theelectronic component 312 do not interfere with each other because of thenotch 260A. Thus, heat generated from theelectronic component 312 can efficiently be dissipated more, and the necessary area of theconductor pattern part 250A can be reduced, which thus can reduce the size of the printed circuit board. - Also in the third example, the necessary area of the
conductor pattern part 250B decreases more than that in the first comparison example, and the size of the printed circuit board can further be reduced. - Also in the fourth example, the necessary area of the
conductor pattern part 250C decreases more than that of the first comparison example, and the size of the printed circuit board can further be reduced. - It should be understood that the present invention is not limited to the aforementioned exemplary embodiments, and many changes, modifications and/or alterations may be made within the technical concept of the invention. The effects of the exemplary embodiments of the present invention were given for illustration only, and effects of the invention are not limited to those of the exemplary embodiments of the present invention.
- Having described that the
electrolytic capacitors - Having described that, according to the aforementioned exemplary embodiments and examples, ground conductors are used to form the heat conduction paths PA to PC, the invention is not limited thereto. Power supply conductors may be used to form the heat conduction paths PA to PC, for example. Because a ground conductor has a wider area than those of other conductors (such as a power supply conductor), ground conductors may be used to form the heat conduction paths PA to PC.
- According to the aforementioned exemplary embodiments and examples, each pair of the heat radiation lands 241 and the second heat radiation lands 242, the via
conductor 261 and the viaconductor 262, thejointing material 441 and thejointing material 442, and thejointing material 451 and thejointing material 452 has an identical configuration. However, they may have different configurations. - While the present invention has been described with reference to exemplary embodiments, it is to be understood that the invention is not limited to the disclosed exemplary embodiments. The scope of the following claims is to be accorded the broadest interpretation so as to encompass all such modifications and equivalent structures and functions.
- This application claims the benefit of Japanese Patent Application No. 2015-186700, filed Sep. 24, 2015, which is hereby incorporated by reference herein in its entirety.
Claims (13)
1. A printed circuit board comprising:
a printed wiring board;
a first electronic component having a first heat radiation pad;
a first circuit component provided for the first electronic component and having a first terminal;
a second electronic component having a second heat radiation pad and generating heat exhibiting a higher heat value than that of the first electronic component;
a second circuit component provided for the second electronic component and having a second terminal; and
a conductor provided on the printed wiring board and having a conductor pattern part,
wherein the first electronic component, the first circuit component, the second electronic component, and the second circuit component are mounted on the printed wiring board, the first heat radiation pad of the first electronic component, the first terminal of the first circuit component, the second heat radiation pad of the second electronic component, and the second terminal of the second circuit component are connected through the conductor; and
a thermal resistance between the second heat radiation pad and the first terminal is lower than a thermal resistance between the first heat radiation pad and the first terminal.
2. The printed circuit board according to claim 1 , wherein the conductor pattern part has a first conductor pattern including a first projected region acquired by projecting the first heat radiation pad in a direction perpendicular to a surface of the printed wiring board, and a second conductor pattern including a second projected region acquired by projecting the second heat radiation pad and a third projected region acquired by projecting the first terminal in the direction perpendicular to the surface of the printed wiring board; and
the first conductor pattern and the second conductor pattern are connected by using a connection conductor provided such that the thermal resistance between the first heat radiation pad and the first terminal can be higher than the thermal resistance between the second heat radiation pad and the first terminal.
3. The printed circuit board according to claim 2 , wherein
the first conductor pattern and the second conductor pattern are provided on a same layer in the printed wiring board; and
the connection conductor is a third conductor pattern narrower than the first conductor pattern and the second conductor pattern provided on the same layer.
4. The printed circuit board according to claim 3 , wherein a notch is provided between the first conductor pattern and the second conductor pattern such that the first conductor pattern and the second conductor pattern can be connected through the third conductor pattern.
5. The printed circuit board according to claim 4 , wherein the notch is provided between the first electronic component and the first circuit component, viewed from the direction perpendicular to the surface of the printed wiring board.
6. The printed circuit board according to claim 2 , wherein
the first conductor pattern and the second conductor pattern are provided on different layers in the printed wiring board; and
the connection conductor is a via conductor provided in the printed wiring board.
7. The printed circuit board according to claim 1 , wherein the first and second circuit components are passive elements.
8. The printed circuit board according to claim 7 , wherein the passive elements are aluminum electrolytic capacitors.
9. The printed circuit board according to claim 1 , wherein the conductor is a ground conductor, and the first terminal and the second terminal are ground terminals connected to the ground conductor.
10. The printed circuit board according to claim 9 , wherein the first electronic component has a power supply terminal connected to a power supply terminal of the first circuit component by using a first power supply conductor provided on the printed wiring board, and the second electronic component has a power supply terminal connected to a power supply terminal of the second circuit component by using a second power supply conductor provided on the printed wiring board.
11. The printed circuit board according to claim 1 , wherein the first electronic component and the first circuit component are mounted on mutually different surfaces or a same surface of the printed wiring board.
12. The printed circuit board according to claim 1 , wherein the second electronic component and the second circuit component are mounted on mutually different surfaces or a same surface of the printed wiring board.
13. An electronic apparatus comprising the printed circuit board according to claim 1 .
Applications Claiming Priority (2)
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JP2015186700A JP6602132B2 (en) | 2015-09-24 | 2015-09-24 | Printed circuit board |
JP2015-186700 | 2015-09-24 |
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US20170094771A1 true US20170094771A1 (en) | 2017-03-30 |
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KR102561987B1 (en) * | 2017-01-11 | 2023-07-31 | 삼성전기주식회사 | Semiconductor package and manufacturing method for the same |
CN113395826B (en) * | 2021-08-17 | 2022-01-21 | 中国电子科技集团公司第九研究所 | High-thermal-conductivity circuit substrate structure for lumped parameter nonreciprocal magnetic device of PCB (printed circuit board) |
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JP4396005B2 (en) | 2000-07-11 | 2010-01-13 | 株式会社村田製作所 | Circuit module and component placement method |
CN101960591A (en) * | 2008-03-28 | 2011-01-26 | 日本电气株式会社 | Semiconductor device, semiconductor device manufacturing method, printed circuit board and electronic device |
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US9609741B1 (en) | 2017-03-28 |
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