Circuit board, and image forming apparatus

Abstract

To provide a circuit board that can prevent a reduction in yield due to leakage of solder from a through via.SOLUTION: A circuit board 601 includes a mounting area 10b for an IC 10 to be mounted, and a mounting area 20b for an IC 20 to be mounted. When seen in a direction perpendicular to a surface on which the mounting area 10b is provided, one portion of the mounting area 10b including its outer edge overlaps the mounting area 20b, and the other portion of the mounting area 10b is outside the mounting area 20b. When seen in the direction perpendicular to the surface on which the mounting area 10b is provided, one portion of the mounting area 20b including its outer edge overlaps the mounting area 10b, and the other portion of the mounting area 20b is outside the mounting area 10b. Through vias 502c penetrating the circuit board 601 are provided in an area where the mounting area 10b and the mounting area 20b overlap each other.SELECTED DRAWING: Figure 8

Description

[Technical field]

[0001] The present invention relates to a circuit board on which electronic components are mounted, and to an image forming apparatus, such as a printer, a copier, or a multifunction peripheral, that includes such a circuit board. [Background technology]

[0002] An image forming apparatus includes a plurality of circuit boards for operating a plurality of components for image formation. A typical circuit board has a plurality of electronic components mounted thereon, and the electronic components are connected by wiring such as printed wiring. The electronic components include, for example, electronic components for performing logical operations, electronic components for performing drive control, electronic components for generating power supply voltage, and the like. The electronic components realize a predetermined function by themselves or in cooperation with other electronic components arranged in the vicinity.

[0003] Patent Document 1 discloses a printed wiring board (circuit board) on which electronic components are mounted. This circuit board has through vias. When an electronic component with a heat sink is mounted, the through vias improve the matching between the heat transfer pattern on the circuit board and the heat sink of the electronic component, improving the heat dissipation of the electronic component. [Prior art documents] [Patent documents]

[0004] [Patent Document 1] Patent Publication No. 2022-6639 Summary of the Invention [Problem to be solved by the invention]

[0005] When through vias are provided for heat dissipation or other purposes, solder may leak from the through vias during soldering. Such solder leakage may cause, for example, a shortage of solder between the heat sink and the heat transfer pattern. The shortage of solder reduces the heat dissipation of electronic components. Alternatively, the leaked solder may cause unintended electrical connections, preventing the circuit board from performing its intended function. This reduces the yield of the circuit board.

[0006] In view of the above-mentioned problems, a main object of the present invention is to provide a circuit board capable of suppressing a decrease in yield due to solder leakage from through vias. [Means for solving the problem]

[0007] The circuit board of the present invention is a circuit board having a first mounting area for mounting a first electronic component and a second mounting area for mounting a second electronic component, and is characterized in that, when viewed in a direction perpendicular to a surface on which the first mounting area is provided, a portion of the first mounting area including its outer edge overlaps the second mounting area and another portion of the first mounting area is outside the second mounting area, when viewed in the same direction, a portion of the second mounting area including its outer edge overlaps the first mounting area and another portion of the second mounting area is outside the first mounting area, and a through via that penetrates the circuit board is provided in the overlapping area of ​​the first mounting area and the second mounting area. Effect of the Invention

[0008] According to the present invention, it is possible to suppress a decrease in yield due to solder leakage from through vias. [Brief description of the drawings]

[0009] [Figure 1] FIG. 1 is a system configuration diagram of an image forming apparatus. [Diagram 2] FIG. 1 is a diagram illustrating the configuration of an image forming apparatus. [Diagram 3] FIG. [Figure 4] FIG. 4 is a circuit diagram of a second voltage generating unit. [Diagram 5] An explanatory diagram of the IC mounting area on a circuit board. [Figure 6] (a) and (b) are diagrams illustrating the configuration of a circuit board when an IC is mounted. [Figure 7] (a) and (b) are diagrams illustrating the configuration of a circuit board when an IC is mounted. [Figure 8] 4(a) to 4(c) are diagrams illustrating the configuration of a circuit board when an IC is mounted. [Figure 9] 4(a) to 4(c) are diagrams illustrating the configuration of a circuit board when an IC is mounted. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0010] Hereinafter, preferred embodiments of the present invention will be described with reference to the accompanying drawings.

[0011] (Configuration of Image Forming Apparatus) 1 is a system configuration diagram of an image forming apparatus having a circuit board according to the present embodiment. Unless otherwise specified, it goes without saying that the image forming apparatus 100 may be a system made up of multiple devices connected via a network, as long as the functions of the image forming apparatus 100 are executed.

[0012] The image forming apparatus 100 of this embodiment is communicatively connected to a host computer 101 via a network 105. The network 105 is configured with communication lines such as a local area network (LAN), a wide area network (WAN), and a public line. A plurality of image forming apparatuses 100 and a plurality of host computers 101 may be connected to the network 105. The host computer 101 generates a print job based on input information from a user acquired by an input device (not shown), and transmits the generated print job to the image forming apparatus 100 via the network 105.

[0013] The image forming apparatus 100 includes a controller board 110, a storage 115, a paper feed unit 140, a printer engine 150, and an operation panel 180. The controller board 110, the storage 115, the paper feed unit 140, the printer engine 150, and the operation panel 180 are connected to each other via a system bus 116 so as to be able to communicate with each other.

[0014] The controller board 110 includes an I / O control unit 111, a Read Only Memory (ROM) 112, a Random Access Memory (RAM) 113, and a Central Processing Unit (CPU) 114. The I / O control unit 111, the ROM 112, the RAM 113, and the CPU 114 are electronic components mounted on a circuit board. The controller board 110 functions as a main control unit of the image forming apparatus 100, performs various data processing, and controls the operation of the entire image forming apparatus 100. The circuit board is, for example, a printed wiring board on which printed wiring is formed.

[0015] The I / O control unit 111 controls communication with external devices such as the host computer 101 via the network 105. The CPU 114 controls operations such as image formation processing by the image forming apparatus 100 by executing computer programs stored in the ROM 112 and the storage 115. The RAM 113 provides a working area when the CPU 114 executes processing, and stores temporary data. The storage 115 stores large-capacity data such as image data and print data temporarily or for a long period of time. For example, the storage 115 stores image data for generating an adjustment image for adjusting image formation conditions (for example, an adjustment image for adjusting an image position). The storage 115 is a large-capacity storage device such as an HDD (Hard Disk Drive) or an SSD (Solid State Drive). Computer programs such as a boot program, a control program, and an operating system executed by the CPU 114 are stored in the ROM 112 and the storage 115.

[0016] Operation panel 180 is a user interface equipped with an input interface and an output interface. The input interface is, for example, a key button, a touch panel, etc. The output interface is a display, a speaker, etc. Operation panel 180 accepts instructions and the like by user operation and inputs them to CPU 114. CPU 114 controls the operation of image forming apparatus 100 in response to the instructions. Operation panel 180 also displays the status of image forming apparatus 100 and various setting screens in response to instructions from CPU 114.

[0017] The paper feed section 140 includes a paper feed device composed of one or more paper feed stages, and a conveying section that conveys paper from the paper feed stages to a paper discharge section. Each paper feed stage may store the same type of paper, or may store different types of paper. The paper feed section 140 feeds paper one sheet at a time from the paper feed stages in response to an instruction from the CPU 114.

[0018] Printer engine 150 includes image forming section 152, print position control section 153, image position detection section 154, fixing section 260, and image reading section 290. Image forming section 152 forms an image (toner image) on paper fed by paper feed section 140. Fixing section 260 fixes the image (toner image) on the paper. Image reading section 290 is provided downstream of fixing section 260 in the paper transport direction, and reads the adjustment image printed on the paper. Image position detection section 154 detects the image position on the paper based on the result of reading the adjustment image by image reading section 290. Print position control section 153 controls the position of the image printed on the paper based on the image position detected by image position detection section 154.

[0019] 2 is a configuration diagram of image forming apparatus 100. Image forming apparatus 100 has an operation panel 180 on the top of a housing 201. Inside housing 201, controller board 110, storage 115, paper feed unit 140, and printer engine 150 shown in FIG. 1 are provided. Printer engine 150 includes each mechanism constituting the engine unit and an engine control unit that controls the processing by each mechanism. Each mechanism constituting the engine unit includes an optical processing mechanism for forming an electrostatic latent image, visualizing the electrostatic latent image, and transferring the visual image to paper S, and a fixing processing mechanism for fixing the toner image transferred to paper S.

[0020] The image forming unit 152 of the printer engine 150 corresponds to an optical processing mechanism, and includes a Y station 220, an M station 221, a C station 222, a K station 223, an intermediate transfer belt 252, and a secondary transfer outer roller 251. The Y station 220, the M station 221, the C station 222, and the K station 223 have the same configuration, and only the colors of the images they form are different. The Y station 220 forms a yellow image. The M station 221 forms a magenta image. The C station 222 forms a cyan image. The K station 223 forms a black image. Here, the configuration of the Y station 220 will be described, and the configurations of the M station 221, the C station 222, and the K station 223 will not be described.

[0021] The Y station 220 includes a photosensitive drum 205, a charger 211, an exposure unit 207, and a developing unit 212. The photosensitive drum 205 is a drum-shaped photoconductor having a photosensitive layer on its surface. The charger 211 uniformly charges the surface of the photosensitive drum 205, which rotates around the drum axis. The exposure unit 207 scans the charged surface of the photosensitive drum 205 with a laser beam modulated according to image data.

[0022] The exposure unit 207 includes a laser driver that controls the emission of a semiconductor laser (not shown) in accordance with image data obtained from the printer controller 203 (CPU 114), a rotating polygon mirror 208, and a reflecting mirror 209. The laser light emitted from the semiconductor laser moves in the main scanning direction in accordance with the rotation of the rotating polygon mirror 208, and is guided to the surface of the photosensitive drum 205 by the reflecting mirror 209. As a result, the laser light scans the surface of the photosensitive drum 205 in the drum axial direction. An electrostatic latent image is formed on the photosensitive drum 205 by exposing the surface to light.

[0023] The developing unit 212 visualizes the electrostatic latent image with toner of a corresponding color, forming a toner image on the surface of the photosensitive drum 205. A yellow toner image is formed on the photosensitive drum 205 of the Y station 220. A magenta toner image is formed on the photosensitive drum 205 of the M station 221. A cyan toner image is formed on the photosensitive drum 205 of the C station 222. A black toner image is formed on the photosensitive drum 205 of the K station 223.

[0024] The intermediate transfer belt 252 is wound around rollers such as the inner secondary transfer roller 240, and rotates in a clockwise direction in the figure. The toner images of each color formed on each photosensitive drum 205 are transferred to the rotating intermediate transfer belt 252 so as to be superimposed on each other. The toner images are transferred from the photosensitive drums 205 to the intermediate transfer belt 252 by applying a bias voltage having opposite characteristics to the toner images to the intermediate transfer belt 252. As a result, the intermediate transfer belt 252 carries a full-color toner image. The intermediate transfer belt 252 conveys the carried toner image to a secondary transfer section composed of the inner secondary transfer roller 240 and the outer secondary transfer roller 251 as it rotates.

[0025] The paper feed unit 140 corresponds to a feeding mechanism for the paper S, and includes a storage 210 which is a paper feed stage that stores the paper S, a transport path, transport rollers, etc. The paper feed unit 140 transports the paper S one by one from the storage 210 to the secondary transfer unit. The secondary transfer unit sandwiches and transports the intermediate transfer belt 252 and the paper S between the secondary transfer inner roller 240 and the secondary transfer outer roller 251. At this time, a bias voltage of the opposite polarity to the toner image is applied to the secondary transfer outer roller 251, so that the toner image is transferred from the intermediate transfer belt 252 to the paper S.

[0026] The paper S onto which the toner image has been transferred is transported to the fixing unit 260, which is a fixing processing mechanism. The fixing unit 260 includes a fixing roller 261 having an internal heat source, a pressure roller 262 that is biased toward the fixing roller 261, and a circuit board 300 that controls the fixing processing by the fixing unit 260. The fixing unit 260 fixes the toner image onto the paper S by sandwiching and transporting the paper S onto which the toner image has been transferred between the fixing roller 261 and the pressure roller 262. At that time, the fixing roller 261 heats and melts the toner image, and presses the paper S between the fixing roller 261 and the pressure roller 262.

[0027] In this manner, an image is printed on the paper S. In the case of double-sided printing, the paper S with an image printed on its first side (front side) is transported again to the secondary transfer unit via reversal path 270. By being transported to the secondary transfer unit via reversal path 270, the image-formed side of the paper S is reversed. After the image-formed side of the paper S has been reversed, an image is printed on its second side (back side), which is different from the first side, by the secondary transfer unit and fixing unit 260.

[0028] The paper S on which the image is printed passes through the image reading unit 290 and is discharged to the outside of the image forming apparatus 100. When the image formed on the paper S is an image for adjusting the image forming conditions, the image reading unit 290 is used to read the image for adjusting the image forming conditions.

[0029] (Circuit board) In order to perform the image formation process as described above, the image forming apparatus 100 is internally provided with various actuators such as motors and sensors. The actuators are connected to a circuit board on which electronic control components are mounted. The electronic components mounted on the circuit board are connected by wiring such as printed wiring. The actuators are controlled at optimal timing by electronic control components such as a CPU mounted on the circuit board. For this purpose, a large number of circuit boards are provided in the image forming apparatus 100 corresponding to the actuators. One or more actuators are controlled by one circuit board.

[0030] FIG. 3 is a functional block diagram of a circuit board 300 provided in the fixing unit 260. A plurality of motors 309-311 in the fixing unit 260 and a plurality of sensors 312-315 in the fixing unit 260 are electrically connected to the circuit board 300. The motor 309 is a drive source for driving the fixing roller 261, which is a rotating body. The motor 310 is a drive source for urging the pressure roller 262 toward the fixing roller 261. The motor 311 is a drive source for driving a roller, which is a rotating body, that transports the paper S after the fixing process to a subsequent stage. The sensor 312 is a detector for detecting the paper S transported to the fixing unit 260. The sensor 313 is a temperature detector for detecting the temperature of the fixing roller 261. The sensor 314 is a detector for detecting the paper S after the fixing process. The sensor 315 is a detector for detecting the rotation of the fixing roller 261.

[0031] The circuit board 300 is mounted with a plurality of electronic components to realize various functions. In the example of FIG. 3, the circuit board 300 includes a first voltage generating unit 302 used to generate a predetermined DC voltage from an AC voltage, and a second voltage generating unit 303 that converts the voltage value of the DC voltage. The circuit board 300 further includes a CPU 304 used to control the actuator, an ASIC (Application Specific Integrated Circuit) 305, and motor driver ICs 306 to 308. The circuit board 300 is mounted with a plurality of semiconductor devices (hereinafter referred to as "ICs") as described above as electronic components, and peripheral electronic components corresponding to each IC. The electronic components are electrically connected by wiring such as a wiring pattern.

[0032] The first voltage generating unit 302 is an AC / DC converter that generates a DC power supply voltage having a predetermined voltage value from AC power supplied from the power supply unit 301. The first voltage generating unit 302 of this embodiment generates a DC voltage of 12 [V] from an AC voltage of 24 [V]. The first voltage generating unit 302 supplies the generated DC power supply voltage to the second voltage generating unit 303. The second voltage generating unit 303 is a DCDC converter that generates a DC power supply voltage of a voltage value different from the power supply voltage supplied from the first voltage generating unit 302. The second voltage generating unit 303 of this embodiment generates a DC voltage of 5 [V] from the DC voltage of 12 [V]. The power supply voltage generated by the second voltage generating unit 303 is supplied to the CPU 304, the ASIC 305, etc. The CPU 304 and the ASIC 305 operate by the power supply voltage supplied from the second voltage generating unit 303. The power supply voltage output from the first voltage generating unit 302 is also supplied to electronic components and motors 309 to 311 that operate at a voltage value different from that of the CPU 304 and the ASIC 305.

[0033] The CPU 304 is connected to the motor driver ICs 306-308 and the sensors 312-315 via the ASIC 305. The motor driver IC 306 is connected to the motor 309. The motor driver IC 307 is connected to the motor 310. The motor driver IC 308 is connected to the motor 311. The CPU 304 acquires the detection results of the sensors 312-315 and detects the state of the fixing unit 260 based on these detection results. The CPU 304 controls the motor driver ICs 306-308 via the ASIC 305 according to the detected state of the fixing unit 260, thereby controlling the drive of the motors 309-311. In this manner, the CPU 304 and the ASIC 305 control the operation of the fixing unit 260.

[0034] Since circuit board 300 is provided in fixing unit 260, it controls the operation of fixing unit 260, but other circuit boards provided in image forming apparatus 100 also control the operation of corresponding components. Each circuit board (including circuit board 300 and other circuit boards) in image forming apparatus 100 is communicatively connected to controller board 110. Each circuit board can communicate with each other via controller board 110. Each circuit board appropriately controls the components in image forming apparatus 100 while sharing information related to the detection results of each sensor and the control state of the motors with each other.

[0035] In this way, many electronic components are mounted on the circuit board. However, due to reasons such as distribution, the environment, and accidents, it may become difficult to procure at least some of the many electronic components. For example, ICs have become difficult to obtain recently due to supply shortages. In order to deal with situations where electronic components are difficult to procure, there is a method of researching in advance substitute electronic components that have the same or similar shapes and specifications as genuine electronic components. In the event that a problem occurs in procuring genuine parts, the production of circuit boards can be continued by procuring substitute parts and mounting them on the circuit boards.

[0036] However, when selecting a replacement for an electronic component such as a DC-DC converter, the genuine product and the replacement product differ in size and terminal arrangement depending on the manufacturer and specifications. This makes it difficult to use the same wiring pattern on the circuit board for the genuine product and the replacement product. It is possible to prepare separate circuit boards with different wiring patterns and use different circuit boards for the genuine product and the replacement product, but this can increase the costs of manufacturing, managing, and inspecting the circuit boards, and can cause confusion in the manufacturing process.

[0037] For this reason, it is preferable to provide wiring patterns corresponding to both the genuine product and the replacement product on one circuit board, and when one electronic component is mounted, the other electronic component is left unmounted. In other words, the genuine product and the replacement product are mounted exclusively.

[0038] A through via is provided on the circuit board to mount electronic components and improve heat dissipation. When the mounting area of ​​the genuine product and the mounting area of ​​the replacement product overlap in the same area, a through via used when mounting the other electronic component may be provided in the center of the mounting area of ​​the heat sink of one electronic component. In this case, there is a possibility that the solder paste melted when mounting one electronic component may flow to the opposite side of the mounting surface through the through via used when mounting the other electronic component. This causes an insufficient amount of solder between the heat sink and the mounting surface of the circuit board, reducing the heat dissipation of the electronic components and reducing the yield of the circuit board.

[0039] By separating the mounting areas of the genuine product and the replacement product by a certain distance or more, such a decrease in heat dissipation can be suppressed, but simply isolating them will result in an increase in the size of the circuit board. In this embodiment, the increase in size and the decrease in the heat dissipation of the electronic components are suppressed, and the decrease in the yield of the circuit board is suppressed. The specific configuration of the circuit board is described below.

[0040] (Second voltage generating unit) 4 is a circuit diagram of the second voltage generating unit 303. As described above, the second voltage generating unit 303 is a DCDC converter. The second voltage generating unit 303 is supplied with a DC voltage of 12 [V] as an input voltage from a VDD_IN terminal (input terminal), and outputs a DC voltage of 5 [V] as an output voltage from a VDD_OUT terminal (output terminal). The second voltage generating unit 303 includes an electronic component component for implementing a predetermined function (here, a DCDC conversion function) by combining a plurality of electronic components. In this embodiment, the second voltage generating unit 303 exclusively includes a first electronic component component 3031 and a second electronic component component 3032.

[0041] The first electronic component component 3031 and the second electronic component component 3032 are mounted exclusively on the circuit board of the second voltage generating unit 303 according to available electronic components. The first electronic component component 3031 and the second electronic component component 3032 both convert a DC input voltage of 12 [V] to a DC output voltage of 5 [V]. For example, the first electronic component component 3031 is a genuine product, and the second electronic component component 3032 is a substitute product.

[0042] The first electronic component 3031 includes IC10, which is a DC-DC converter, and resistor R10 and capacitors C11-C16, which are specific electronic components required for the operation of IC10. The second electronic component 3032 includes IC20, which is a DC-DC converter, and capacitors C21-C26, which are specific electronic components required for the operation of IC20. The second voltage generating unit 303 includes resistors R1-R3, capacitors C1-C5, and inductor L1, which are common electronic components required when either the first electronic component 3031 or the second electronic component 3032 is implemented.

[0043] An input voltage inputted from the VDD_IN terminal is supplied to a VIN terminal of IC10 of the first electronic component component 3031 or a VIN terminal of IC20 of the second electronic component component 3032. An output voltage outputted from the VDD_OUT terminal is generated in the first electronic component component 3031 or the second electronic component component 3032. The output voltage is outputted from a SW terminal of IC10 of the first electronic component component 3031 or a SW terminal of IC20 of the second electronic component component 3032.

[0044] The output enable signal input from the IN terminal is input to the CE terminal of IC10 of the first electronic component component 3031 or the EN terminal of IC20 of the second electronic component component 3032. The output enable signal can be input to both IC10 of the first electronic component component 3031 and IC20 of the second electronic component component 3032, and is connected to a connection point between a resistor R1 and a capacitor C1, which are common electronic components. The output enable signal is a signal that permits IC10 and IC20 to output an output voltage. The output status signal output from the OUT terminal is an output signal specific to IC20 of the second electronic component component 3032, and is output from the PG terminal of IC20. The output status signal is a signal indicating that IC20 is normally outputting an output voltage.

[0045] When the second electronic component 3032 is mounted, the output voltage output from the SW terminal of IC20 is divided by resistors R2 and R3 via an inductor L1. This divided voltage is input to the VFB terminal of IC20. IC20 can determine whether the output voltage is a normal voltage value depending on whether the divided voltage is within a target voltage range. If the divided voltage is within the target voltage range, IC20 determines that the output voltage is normal and outputs an output status signal (e.g., high voltage) indicating that the output voltage is normal. If the divided voltage is not within the target voltage range, IC20 determines that the output voltage is abnormal and outputs an output status signal (e.g., low voltage) indicating that the output voltage is abnormal.

[0046] Note that IC10 of the first electronic component 3031 does not have a function to output an output status signal. When the first electronic component 3031 is mounted, the output voltage output from the SW terminal of IC10 is divided by resistors R2 and R3, and the divided voltage is input to the FB terminal of IC10. However, IC10 does not have a function to determine whether the output voltage is being output normally. Therefore, when the first electronic component 3031 is mounted, an output status signal is not output from the OUT terminal.

[0047] The resistor R10 and the capacitor C16 of the first electronic component 3031 are dedicated electronic components required for IC10, and therefore are inherent components of the first electronic component 3031. The capacitors C11-C15 of the first electronic component 3031 and the capacitors C21-C26 of the second electronic component 3032 have similar connection configurations with respect to IC10 and IC20, respectively. However, the capacitors C11-C15 have characteristics for maintaining optimal operating performance of IC10, and the capacitors C21-C26 have characteristics for maintaining optimal operating performance of IC20. For this reason, the capacitors C11-C15 are inherent electronic components of the first electronic component 3031, and the capacitors C21-C26 are inherent electronic components of the second electronic component 3032.

[0048] The inductor L1 and capacitors C2 to C5, which are common electronic components, are electronic components provided in the wiring path from IC10 and IC20 to the VDD_OUT terminal, which is the output terminal of the circuit board. The capacitors C2 to C5 are capacitors for smoothing the output voltage, and together with the inductor L1, they suppress the AC component of the output voltage. The inductor L1 and the capacitors C2 to C5 are large in size among the common electronic components. In a circuit board on which the first electronic component component 3031 and the second electronic component component 3032 are exclusively mounted, treating large electronic components as common electronic components as much as possible is advantageous for miniaturizing the circuit board.

[0049] The resistors R2 and R3, which are common electronic components, are voltage dividing resistors that divide the output voltage as described above. The divided voltage is input to the FB terminal, which is the feedback terminal of IC10, or the VFB terminal, which is the feedback terminal of IC20. If the divided voltage is lower than the target voltage, both IC10 and IC20 short the SW terminal and the VIN terminal internally. If the divided voltage is higher than the target voltage, both IC10 and IC20 short the SW terminal and the GND terminal internally. Therefore, the divided voltage becomes a control signal that controls the output voltage. In this way, the resistors R2 and R3 are common electronic components required by the first electronic component 3031 and the second electronic component 3032.

[0050] (Connection Land Configuration) 5 is an explanatory diagram of an IC mounting area on a circuit board. The IC mounting area is provided with a plurality of connection lands 501 to which the IC is connected, and lead lands 503 to which the IC leads are connected. Through vias 502 are provided in the connection lands 501. When mounting the IC, the IC is soldered to the connection lands 501 and the lead lands 503.

[0051] The central portions of the connection lands 501 are formed to have the same area and shape (circular in this example) to prevent solder from leaking from the connection lands 501 when the IC is mounted. The through vias 502 are provided at the four corners of the outer edge of the connection lands 501 to prevent the generation of solder balls when the IC is mounted. The through vias 502 may be provided at places other than the four corners. When the IC is mounted, a heat sink for the IC is attached to the connection lands 501 with solder.

[0052] Fig. 6 is a diagram showing an example of the configuration of a circuit board when ICs are mounted in a conventional manner when the package sizes of IC10 and IC20 are the same. Fig. 6 is a diagram showing a circuit board 601 of the second voltage generating unit 303 as viewed from the side. Fig. 6(a) shows the case where IC10 is mounted. Fig. 6(b) shows the case where IC20 is mounted.

[0053] The mounting areas of IC10 and IC20 are provided facing each other with a circuit board 601 in between. A connection land 501a to which the heat dissipation surface 10a of IC10 is soldered is provided in the mounting area of ​​IC10. A connection land 501b to which the heat dissipation surface 20a of IC20 is soldered is provided in the mounting area of ​​IC20. A through via 502 is provided penetrating from the first surface on which IC10 is mounted to the second surface on which IC20 is mounted.

[0054] Depending on the procurement situation of electronic components, a first mounting pattern (FIG. 6(a)) in which IC10 is mounted on the first surface and a second mounting pattern (FIG. 6(b)) in which IC20 is mounted on the second surface are used. Since the package sizes of IC10 and IC20 are the same, the arrangement of the through vias 502 can be made common. Furthermore, the mounting areas of IC10 and IC20 are provided so as to be in the same position when viewed from above (the first surface side) of the circuit board.

[0055] However, the package sizes of IC10 and IC20 are often different, and it is necessary to provide through vias for each IC. Fig. 7 is a diagram illustrating the configuration of a circuit board when IC10 and IC20 are mounted in a conventional manner when the package sizes of IC10 and IC20 are different. Fig. 7 is a diagram of a circuit board 601 of the second voltage generating unit 303 viewed from the side. Fig. 7(a) shows the case where IC10 is mounted. Fig. 7(b) shows the case where IC20 is mounted. Here, a case where the package size of IC10 is larger than the package size of IC20 will be described.

[0056] The mounting areas of IC10 and IC20 are provided facing each other with the circuit board 601 in between. Since the package sizes of IC10 and IC20 are different, the areas (areas) of the mounting areas are also different. In this embodiment, the mounting area of ​​IC10 is provided wider than the mounting area of ​​IC20. In the mounting area of ​​IC10, a connection land 501a to which the heat dissipation surface 10a of IC10 is soldered is provided. In the mounting area of ​​IC20, a connection land 501b to which the heat dissipation surface 20a of IC20 is soldered is provided. The through via 502a is for IC10 and is provided so as to penetrate from the first surface on which IC10 is mounted to the second surface on which IC20 is mounted. The through via 502b is for IC20 and is provided so as to penetrate from the second surface on which IC20 is mounted to the first surface on which IC10 is mounted. The through via 502b is provided within the area of ​​the connection land 501a.

[0057] Depending on the procurement status of electronic components, a first mounting pattern (FIG. 7(a)) in which an IC10 is mounted on a first surface and a second mounting pattern (FIG. 7(b)) in which an IC20 is mounted on a second surface are used. When mounting an IC10 as shown in FIG. 7(a), a heat sink 10a of the IC10 is soldered to a connection land 501a. At that time, the solder of the connection land 501a may leak to the second surface through a through via 502b. This causes an insufficient amount of solder between the IC10 and the connection land 501a. Due to the insufficient amount of solder, the IC10 and the connection land 501a may become open.

[0058] By ensuring a sufficient distance between the mounting area of ​​IC10 and the mounting area of ​​IC20 when viewed from above (the first surface side) of the circuit board, it is possible to prevent the solder from leaking out of the through via 502b. However, this increases the area of ​​the circuit board 601. To reduce the size of the circuit board 601, it is preferable that the distance between the mounting area of ​​IC10 and the mounting area of ​​IC20 is short.

[0059] FIG. 8 is a diagram showing an example of the configuration of the circuit board when IC is mounted in this embodiment. The package sizes of IC10 and IC20 are different. FIG. 8(a) shows the case where IC10 is mounted. FIG. 8(b) shows the case where IC20 is mounted. FIG. 8(a) and FIG. 8(b) are diagrams showing the circuit board 601 of the second voltage generating unit 303 as viewed from the side. FIG. 8(c) is a diagram showing the circuit board 601 as viewed from above (the first surface side). The mounting area 10b of IC10 and the mounting area 20b of IC20 are provided so as to overlap in part when viewed from above (the direction perpendicular to the surface on which the mounting areas are provided) the mounting surface (the first surface side). That is, a part including the outer edge of the mounting area 10b of IC10 overlaps with the mounting area 20b of IC20, and another part of the mounting area 10b of IC10 is outside the mounting area 20b of IC20. Also, a part of the mounting area 20b of the IC20, including the outer edge, overlaps with the mounting area 10b of the IC10, and another part of the mounting area 20b of the IC20 is outside the mounting area 10b of the IC10.

[0060] The mounting areas 10b and 20b of the IC10 and IC20 are provided facing each other with the circuit board 601 in between. Since the package sizes of the IC10 and IC20 are different, the areas (areas) of the mounting areas 10b and 20b are also different. In this embodiment, the mounting area 10b of the IC10 is provided larger than the mounting area 20b of the IC20. The mounting area 10b of the IC10 is provided with a connection land 501a to which the heat dissipation surface 10a of the IC10 is soldered. The mounting area 20b of the IC20 is provided with a connection land 501b to which the heat dissipation surface 20a of the IC20 is soldered. The through via 502a is for the IC10 and is provided so as to penetrate from the first surface on which the IC10 is mounted to the second surface on which the IC20 is mounted. The through via 502b is for the IC20 and is provided so as to penetrate from the second surface on which the IC20 is mounted to the first surface on which the IC10 is mounted. The through via 502c is provided in an overlapping region between the mounting region 10b of the IC 10 and the mounting region 20b of the IC 20, and penetrates from the first surface to the second surface. The through via 502c is used in common for the heat dissipation of both the IC 10 and the IC 20.

[0061] The through vias 502a and 502c are provided for heat dissipation of the IC 10. The through vias 502b and 502c are provided for heat dissipation of the IC 20. In this configuration, when the IC 10 is mounted, the solder of the connection land 501a is prevented from leaking to the second surface through the through vias 502a, 502b, and 502c. Also, when the IC 20 is mounted, the solder of the connection land 501b is prevented from leaking to the first surface through the through vias 502a, 502b, and 502c.

[0062] FIG. 9 is another exemplary diagram of the circuit board when IC is mounted in this embodiment. The package sizes of IC10 and IC20 are different. FIG. 9(a) shows the case where IC10 is mounted. FIG. 9(b) shows the case where IC20 is mounted. FIG. 9(a) and FIG. 9(b) are diagrams of the circuit board 601 of the second voltage generating unit 303 as viewed from the side. FIG. 9(c) is a diagram of the circuit board 601 as viewed from above (the first surface side). The mounting area 10b of IC10 and the mounting area 20b of IC20 are provided so as to overlap in part when viewed from above the mounting surface (in a direction perpendicular to the surface on which the mounting areas are provided). That is, a part of the mounting area 10b of IC10 including the outer edge overlaps with the mounting area 20b of IC20, and another part of the mounting area 10b of IC10 is outside the mounting area 20b of IC20. Also, a part of the mounting area 20b of the IC20, including the outer edge, overlaps with the mounting area 10b of the IC10, and another part of the mounting area 20b of the IC20 is outside the mounting area 10b of the IC10.

[0063] The mounting areas 10b and 20b of the IC10 and IC20 are provided on the same surface of the circuit board 601. Since the package sizes of the IC10 and IC20 are different, the areas (areas) of the mounting areas 10b and 20b are also different. In this embodiment, the mounting area 10b of the IC10 is provided larger than the mounting area 20b of the IC20. The mounting area 10b of the IC10 is provided with a connection land 501a to which the heat dissipation surface 10a of the IC10 is soldered. The mounting area of ​​the IC20 is provided with a connection land 501b to which the heat dissipation surface 20a of the IC20 is soldered. The configuration of the through vias 502a, 502b, and 502c is the same as that of FIG. 8. In this configuration, as in the case of FIG. 8, when mounting the IC10 and 1C20, the solder is prevented from leaking through the through vias 502a, 502b, and 502c.

[0064] As described above, since the electronic components are exclusively mounted on the circuit board 601, the circuit board 300 can suppress the risk of obtaining the electronic components to be mounted, and can continue manufacturing the circuit board even when the electronic components are in short supply. In addition, the mounting area of ​​each electronic component is shifted when viewed from above the circuit board, and some of the through vias for preventing the occurrence of solder balls are shared. Therefore, the heat dissipation performance of the electronic components is not impaired, and the solder is prevented from leaking through the through vias when the electronic components are mounted, and a decrease in yield is suppressed. Furthermore, the distance between the electronic components can be set to the minimum distance that allows the solder to be prevented from leaking, and therefore the area of ​​the circuit board 601 can be suppressed from increasing.

[0065] In the present embodiment, the semiconductor devices IC10 and IC20 are described as examples of electronic components, but the electronic components are not limited to these. The functions of the electronic components are not limited as long as they are configured to be mounted by soldering on lands on the circuit board 601. For example, the electronic components may be switching ICs, FETs (Field effect transistors), etc.

[0066] Also, an example has been described in which the semiconductor devices IC10 and IC20 are substitute components. However, the effects obtained by this embodiment are not limited to such an example. For example, the circuit board 601 may be designed as a common platform for a plurality of devices. In this case, in one model, a first electronic component having a first function is mounted in the mounting area 10a, while in another model, a second electronic component different from the first electronic component is mounted in the mounting area 10b. Even in such a case, the effects described in this embodiment can be obtained.

Claims

1. A circuit board including a first mounting area for mounting a first electronic component and a second mounting area for mounting a second electronic component, When viewed in a direction perpendicular to a surface on which the first mounting area is provided, a portion of the first mounting area including an outer edge of the first mounting area overlaps with the second mounting area, and another portion of the first mounting area is outside the second mounting area, When viewed in the direction, a portion including an outer edge of the second mounting area overlaps with the first mounting area, and another portion of the second mounting area is outside the first mounting area, a through via penetrating the circuit board is provided in an area where the first mounting area and the second mounting area overlap, Circuit board.

2. a first connection land for bonding the first electronic component is provided in the first mounting region; The second mounting area is provided with a second connection land for bonding the second electronic component. The circuit board according to claim 1.

3. a first through via that penetrates the circuit board is provided in a portion of the first mounting area outside the second mounting area; a second through via penetrating the circuit board is provided in a portion of the second mounting area outside the first mounting area, The circuit board according to claim 1.

4. a first heat dissipation surface of the first electronic component is bonded to the first connection land, The circuit board according to claim 2.

5. The first connection land and the first heat dissipation surface are bonded to each other by soldering. The circuit board according to claim 4.

6. the first mounting area is provided on a first surface of the circuit board, The second mounting area is provided on a second surface of the circuit board that is different from the first surface. The circuit board according to claim 1.

7. The first mounting area and the second mounting area are provided on the same surface of the circuit board. The circuit board according to claim 1.

8. The through via is used for heat dissipation of the first electronic component or the second electronic component. The circuit board according to claim 1.

9. the first electronic component and the second electronic component are both semiconductor devices, a first lead land for connecting a lead of the first electronic component is provided in the first mounting area; a second lead land for connecting a lead of the second electronic component is provided in the second mounting area, The circuit board according to claim 1.

10. The area of ​​the first mounting area is different from the area of ​​the second mounting area. The circuit board according to claim 1.

11. A circuit board according to claim 1; a component that forms an image under the control of either the first electronic component or the second electronic component mounted on the circuit board, Image forming device.

Images