CN218336541U - Circuit board assembly and electronic equipment - Google Patents
Circuit board assembly and electronic equipment Download PDFInfo
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- CN218336541U CN218336541U CN202221589192.0U CN202221589192U CN218336541U CN 218336541 U CN218336541 U CN 218336541U CN 202221589192 U CN202221589192 U CN 202221589192U CN 218336541 U CN218336541 U CN 218336541U
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Abstract
The application provides a circuit board assembly and electronic equipment, circuit board assembly is through setting up the depressed part on printed circuit board, connects the connecting portion of flexible circuit board in the depressed part, can reduce circuit board assembly's whole thickness, reduces circuit board assembly's occupation space, can reserve more installation space for other functional unit in the electronic equipment, and is favorable to electronic equipment's frivolousization. And, preset the soldering paste through laying the steel mesh on the flexible circuit board, fill the soldering paste in each weld hole on the connecting portion of flexible circuit board, can guarantee the yield of soldering paste. Wherein, the solder hole includes first hole and second hole, and the internal face in first hole covers the conducting layer, realizes through first hole with the fixed connection and the electricity of corresponding pad and connect, and when the second hole can prevent to preset the soldering paste, the soldering paste flows to the opposite side of connecting portion, and the downthehole soldering paste of second can increase the joint strength of flexible circuit board and printed circuit board, reinforcing circuit board assembly's stability and reliability.
Description
Technical Field
The present application relates to the field of electronic devices, and in particular, to a circuit board assembly and an electronic device.
Background
With the explosive growth of electronic devices such as mobile phones, tablet computers and notebook computers, the electronic devices become necessities of modern life, and play an increasingly important role in the scenes of daily life, work contact and the like of people.
A Printed Circuit Board (PCB) is generally disposed in the electronic device, and other functional components in the electronic device may be electrically connected to the PCB to supply power to the functional components or control actions of the functional components through the PCB. Among them, these functional components may be connected to the PCB through a Flexible Printed Circuit (FPC), for example, the functional components are connected to one side surface of the FPC through a Board To Board (BTB) connector, and the other side surface of the FPC is connected to the PCB through a BTB connector.
However, the BTB connector has a large volume, so that the connection structure between the functional module and the PCB occupies a large installation space, which is not favorable for the light and thin electronic device.
SUMMERY OF THE UTILITY MODEL
The application provides a circuit board assembly and electronic equipment, circuit board assembly's thickness is little, and occupation space is little, and joint strength is high, is favorable to electronic equipment's frivolousization.
On one hand, the application provides a circuit board assembly, which comprises a printed circuit board and a flexible circuit board, wherein the printed circuit board is provided with a concave part, the concave part is concave from one side plate surface to the other side plate surface of the printed circuit board, the end part of the flexible circuit board is provided with a connecting part, and the connecting part is connected with the concave part;
a plurality of welding pads are arranged on the depressed part at intervals, a plurality of welding holes are arranged on the connecting part at intervals, welding paste is filled in the welding holes, and the welding holes correspond to the welding pads one by one and are connected through the welding paste; the plurality of soldering holes comprise a plurality of first holes and at least one second hole, and the inner wall surfaces of the first holes are covered with conductive layers.
The application provides a circuit board assembly, through set up the depressed part on printed circuit board, connect the connecting portion of flexible circuit board in the depressed part, can reduce circuit board assembly's whole thickness, reduce circuit board assembly's occupation space, can reserve more installation space for other functional unit in the electronic equipment, and be favorable to electronic equipment's frivolousization. And, preset the soldering paste through laying the steel mesh on the flexible circuit board, fill each weld hole on the connecting portion of flexible circuit board with the soldering paste, can guarantee the yield of soldering paste. Wherein, the solder hole includes first hole and second hole, and the internal face in first hole covers the conducting layer, through the first downthehole solder paste realize with the fixed connection of the corresponding pad in the depressed part, realize through the first downthehole conducting layer with the electricity of corresponding pad be connected, when the second hole can prevent to preset the solder paste, the solder paste flows to the opposite side of connecting portion, and the downthehole solder paste of second can increase the joint strength of flexible circuit board and printed circuit board, reinforcing circuit board assembly's stability and reliability.
In one possible embodiment, the cross-sectional area of the second aperture is greater than the cross-sectional area of the first aperture.
The cross-sectional area of the second hole is larger than that of the first hole, so that the solder paste filled in the second hole can be increased, the connection strength of the flexible circuit board and the printed circuit board can be increased, and the reliability and the stability of the circuit board assembly are ensured. The inner wall surface of the second hole is not covered with the conductive layer, the interface between the soldering paste and the inner wall surface of the second hole is a non-wetting interface, the inner wall surface of the second hole has larger obstruction to the flowing of the soldering paste, and the soldering paste can be prevented from flowing to the other side surface of the flexible circuit board.
In one possible embodiment, the number of second holes is one, and the second holes are located in a middle region of the connecting portion.
On the basis that the soldering paste in each first hole can satisfy the joint strength of flexible circuit board and printed circuit board, through add a second hole on the connecting portion of flexible circuit board, the downthehole soldering paste of second can promote the joint strength of flexible circuit board and printed circuit board, makes circuit board assembly's reliability and stability obtain the powerful guarantee. Wherein, through setting up the second hole in the middle zone of connecting portion, the downthehole soldering paste of second all has better effect to whole connecting portion, can prevent that circuit board components from appearing the phenomenon that local joint strength is not enough.
In one possible embodiment, the number of second holes is two or more.
On the basis that flexible circuit board realized through first hole and printed circuit board fixed connection and electricity is connected, a plurality of second holes provide a plurality of fixed connection point positions for flexible circuit board and printed circuit board, can improve flexible circuit board and printed circuit board's joint strength, promote circuit board subassembly's reliability and stability.
In a possible embodiment, the second holes are distributed in different areas of the connection.
The second holes are distributed in different areas of the connecting portion of the flexible circuit board, so that the flexible circuit board and different portions of the printed circuit board are provided with fixed connecting point positions, the connecting strength of different portions between the flexible circuit board and the printed circuit board is enhanced, the overall connecting strength of the circuit board assembly is enhanced, and the situation that local connecting strength is insufficient in the circuit board assembly is prevented.
In a possible embodiment, the area between adjacent second holes is provided with first holes.
Through inserting the second hole between first hole, adjacent second hole is separated to first hole, and the soldering paste of filling in the second hole is high with the joint strength of printed circuit board's corresponding pad, can strengthen the joint strength of the soldering paste in the first hole around it and printed circuit board's corresponding pad to, reinforcing circuit board assembly's whole joint strength has also strengthened the reliability and the stability of the electric connection of conducting layer in the first hole and corresponding pad.
In a possible embodiment, the thickness of the connecting portion is smaller than the recess depth of the recess.
The thickness of the connecting part of the flexible circuit board is smaller than the sunken depth of the sunken part of the printed circuit board, so that the whole thickness of the connecting part and the printed circuit board after assembly is reduced, and the thickness space occupied by the circuit board assembly is reduced, so that more mounting spaces are reserved for other functional components in the electronic equipment, and the electronic equipment is light and thin.
In one possible embodiment, the connecting portion is accommodated in a thickness space of the printed circuit board.
The surface of the connecting part can be sunken in the board surface of the printed circuit board or flush with the board surface of the printed circuit board, so that the connecting part is completely accommodated in the thickness space of the printed circuit board, the flexible circuit board does not occupy extra thickness space, the thickness of the circuit board assembly only depends on the thickness of the printed circuit board, and the thickness space occupied by the circuit board assembly is small.
In one possible embodiment, the electrically conductive layer comprises a base section and an extension section connected to at least one end of the base section, the base section covering an inner wall surface of the first hole, the extension section extending along a surface of the connecting portion.
By making the conductive layer include the basic segment and the extension segment, the basic segment is located in the first hole, and the extension segment extends out of the first hole and along the surface of the connection portion of the flexible circuit board. The extension section is opposite to the bonding pad on the printed circuit board, so that the contact area of the conducting layer and the bonding pad is increased, and the reliability and the stability of the electric connection between the conducting layer and the bonding pad are ensured.
In one possible embodiment, an extension section is connected to one end of the base section, which extension section faces the recess.
The extending section is connected to one end of the basic section and is positioned on one side surface of the connecting part facing the concave part of the printed circuit board, so that the extending section is opposite to the pad in the concave part, and the contact area of the conducting layer and the pad is increased. At this time, when solder paste is preset on the connecting portion, the solder paste should be located on one side surface of the connecting portion on which the extension section is provided, and during soldering, the side surface of the connecting portion on which the solder paste is preset is directed toward the printed circuit board.
In one possible embodiment, the extension section is connected to both ends of the base section.
The extending sections are connected to the two ends of the basic section and are respectively located on the two side surfaces of the connecting portion, and during welding, the two side surfaces of the flexible circuit board can be arranged facing the printed circuit board. At this moment, when presetting the soldering paste on connecting portion, the soldering paste can be located any side surface of connecting portion, need not to adjust the position of flexible circuit board, can improve the efficiency of presetting the soldering paste. And during soldering, the surface of the connecting part, which is preset with the soldering paste, faces the printed circuit board.
In one possible embodiment, the conductive layer comprises a copper layer or a copper alloy layer.
Through the copper or copper alloy formation conducting layer of establishing of plating in the first hole of flexible circuit board, the electric conductive property of copper and copper alloy is good, can guarantee stability and the reliability of the electricity connection between flexible circuit board and the printed circuit board, and its cost is lower.
In another aspect, the present application provides an electronic device comprising a housing and a circuit board assembly as described above, the circuit board assembly being mounted within the housing.
The application provides an electronic equipment, including shell and the circuit board components of installation in the shell, circuit board components is through setting up the depressed part on printed circuit board, connects the connecting portion of flexible circuit board in the depressed part, can reduce circuit board components's whole thickness, reduces circuit board components's occupation space, can reserve more installation space for other functional unit in the electronic equipment, and is favorable to electronic equipment's frivolousization. And, preset the soldering paste through laying the steel mesh on the flexible circuit board, fill each weld hole on the connecting portion of flexible circuit board with the soldering paste, can guarantee the yield of soldering paste. Wherein, the solder hole includes first hole and second hole, the internal face in first hole covers the conducting layer, through the first downthehole solder paste realize with the corresponding pad's in the depressed part fixed connection, through the first downthehole conducting layer realize with the electric connection of corresponding pad, the second hole can prevent to preset when soldering paste, the solder paste flows to the opposite side of connecting portion, and the downthehole solder paste of second can increase the joint strength of flexible circuit board and printed circuit board, reinforcing circuit board assembly's stability and reliability.
Drawings
Fig. 1 is a schematic structural diagram of an electronic device according to an exemplary embodiment of the present disclosure;
FIG. 2 is an exploded view of FIG. 1;
FIG. 3 is a schematic diagram of a printed circuit board according to an exemplary embodiment of the present disclosure;
FIG. 4 is a partial block diagram of a flexible circuit board provided in an exemplary embodiment of the present application;
fig. 5 is a schematic structural diagram of a circuit board assembly provided in an exemplary embodiment of the present application;
FIG. 6 is a partial cross-sectional view of a flexible circuit board provided in an exemplary embodiment of the present application;
fig. 7 is a schematic diagram illustrating a state where a flexible circuit board is disposed on a printed circuit board according to an exemplary embodiment of the present application;
fig. 8 is a schematic diagram illustrating a state after a flexible circuit board and a printed circuit board are connected according to an exemplary embodiment of the present application.
Description of reference numerals:
1-an electronic device;
100-a display screen;
200-a housing;
210-middle frame; 220-rear cover;
211-a frame portion; 212-middle plate portion;
300-a circuit board assembly;
310-a printed circuit board; 320-a flexible circuit board;
311-a recess; 312-pad; 313-a component; 314-a metal wire; 321-a connecting part; 322-welding holes; 323-metal routing; 324-a conductive layer; 325-solder paste;
3221-a first hole; 3222-a second aperture; 3241-basic segment; 3242-epitaxial segment.
Detailed Description
The terminology used in the description of the embodiments section of the present application is for the purpose of describing particular embodiments of the present application only and is not intended to be limiting of the present application.
An embodiment of the present application provides an electronic device, which may be referred to as User Equipment (UE), terminal Equipment (TE), and the like.
Exemplary electronic devices include, but are not limited to, mobile phones, PAD (portable android device), noteBook (NoteBook Computer, abbreviated as NoteBook), ultra-mobile personal Computer (UMPC), walkie-talkie, netbooks, POS (Point of sales) machines, personal Digital Assistants (PDA), wearable devices, virtual Reality (VR) devices, augmented Reality (AR) devices, wireless terminals in industrial control (industrial control), wireless terminals in unmanned driving (driving), wireless terminals in remote medical (remote medical), wireless terminals in smart grid (smart grid), wireless terminals in transportation security, wireless terminals in city (smart), wireless terminals in city (city) or home, and the like. The form of the terminal device is not particularly limited in the embodiment of the present application.
Fig. 1 is a schematic structural diagram of an electronic device according to an exemplary embodiment of the present disclosure. Referring to fig. 1, taking an electronic device 1 as a mobile phone as an example, the electronic device 1 may include a display screen 100 and a housing 200, a surface of one side of the display screen 100 has a display area (not shown in the figure) for displaying image information, the surface of the display screen 100 is generally defined as a front surface, and a surface of the other side opposite to the front surface is a back surface, and the housing 200 is disposed around the periphery and the back surface of the display screen 100 for supporting and fixing the display screen 100. The display screen 100 and the housing 200 together enclose an accommodation space, and some functional components of the electronic device 1 are disposed in the accommodation space, for example, components such as a main board, a camera module, a speaker, and a battery are disposed in the accommodation space.
The front surface of the display screen 100 is exposed outside the housing 200, so that a user can view the display content of the display screen 100 or perform input operations on the electronic device 1. In general, one side surface on which the display screen 100 is located is defined as a front surface of the electronic device 1, and the other side surface of the electronic device 1 opposite to the front surface thereof is defined as a back surface thereof.
Fig. 2 is an exploded view of fig. 1. Referring to fig. 2, the housing 200 of the electronic device 1 may include a middle frame 210 and a rear cover 220, the rear cover 220 being located at the rear of the electronic device 1, the middle frame 210 being connected between the display screen 100 and the rear cover 220. The middle frame 210 may include a frame portion 211 and a middle plate portion 212, the frame portion 211 is disposed around the electronic device 1, the middle plate portion 212 is located in an area surrounded by the frame portion 211, an edge of the middle plate portion 212 is connected to an inner side wall of the frame portion 211, and for example, the middle plate portion 212 and the frame portion 211 may be of an integrally molded structure.
The entire display screen 100 is generally supported on the middle plate portion 212 of the middle frame 210, and the edge of the display screen 100 is overlapped on the front end surface of the frame portion 211 of the middle frame 210 (the end surface of the side of the frame portion 211 facing the front surface of the electronic device 1), and the display screen 100 may be connected and fixed to the middle frame 210 by the frame adhesive. The edge of the rear cover 220 is overlapped on the rear end surface of the frame portion 211 of the middle frame 210 (the end surface of the side of the frame portion 211 facing the back of the electronic device 1), and may be connected to the frame portion 211 by frame glue. A gap is provided between the middle plate portion 212 of the middle frame 210 and the rear cover 220, and the gap forms an accommodation space in which a circuit board assembly 300 is disposed to dispose a functional component in the accommodation space between the middle plate portion 212 of the middle frame 210 and the rear cover 220, as shown in fig. 2, for example.
Referring to fig. 2, in practical applications, a Printed Circuit Board (PCB) 310 is generally disposed in the accommodating space of the electronic device 1, the PCB 310 can be used as a main Board of the electronic device 1, functional components of the electronic device 1 can be electrically connected to the PCB 310, the PCB 310 is used for supplying power to the functional components, and a component 313 disposed on the main Board can be used for connecting different functional components, controlling actions of the functional components and communication between different functional components. The functional components (not shown in the drawings) are typically connected to the Printed Circuit board 310 as a main board via a Flexible Printed Circuit (FPC) 320. In the present embodiment, the integral connection structure of the printed circuit board 310 and the flexible circuit board 320 is defined as a circuit board assembly 300.
The printed circuit board 310 may be a single-sided board or a double-sided board according to the number of the components 313 arranged on the printed circuit board 310, where the single-sided board refers to the printed circuit board 310 with the components 313 arranged on a single-sided board surface, and the double-sided board refers to the printed circuit board 310 with the components 313 arranged on both side board surfaces. Depending on the type of components 313 disposed on the printed circuit board 310, the printed circuit board 310 may be a Radio Frequency (RF) board or an Application Processor (AP) board. The rf board may be, but is not limited to, used for laying a radio frequency chip (RFIC), a Radio Frequency Power Amplifier (RFPA), a wireless fidelity (WIFI) chip, and the like. The application processor board may be, but is not limited to, for laying out System On Chip (SOC) elements, double Data Rate (DDR) memories, power Management Units (PMUs), secondary PMUs, and the like.
Referring to fig. 2, taking the printed circuit board 310 as an example of the main board of the electronic device 1, the components 313 disposed on the printed circuit board 310 may include, but are not limited to, a processor, an antenna module, a bluetooth module, a WiFi module, a Global Positioning System (GPS) module, a power supply and charging module, a graphics processing module, a screen display and operation module, and the like.
The flexible circuit board 320 is used to electrically connect some functional components of the electronic device 1 to corresponding components 313 on the printed circuit board 310. For example, the display screen 100 is electrically connected to a screen display and operation module disposed on the printed circuit board 310 through the flexible circuit board 320, and the camera module is electrically connected to a graphic processing module disposed on the printed circuit board 310 through the flexible circuit board 320.
As for the connection structure between the functional component and the printed circuit board 310, in the related art, the functional component and the flexible circuit board 320 and the printed circuit board 310 may be connected by a Board To Board (BTB) connector. The board-to-board connector includes a male socket and a female socket, the male socket is connected to a structural member (e.g., the printed circuit board 310), the female socket is connected to another structural member (e.g., the flexible circuit board 320), and the male socket and the female socket are inserted into each other to connect the two structural members.
However, the connection structure of the functional component to the printed circuit board 310 occupies a large space due to the large volume of the board-to-board connector itself. Taking the height of the board-to-board connector as 0.6mm as an example, the total height of the two board-to-board connectors between the functional component and the flexible circuit board 320 and between the flexible circuit board 320 and the printed circuit board 310 is 1.2mm, and taking the thickness of the flexible circuit board 320 as an example, taking the thickness of the flexible circuit board 320 as 0.03mm, the total height of the connection structure of the functional component and the printed circuit board 310 reaches 1.23mm.
The connection structure between the functional components and the printed circuit board 310 occupies a large space, which is not favorable for the layout of the functional components in the electronic device 1, affects the overall thickness of the electronic device 1, and cannot meet the light and thin requirements of the electronic device 1. Also, for some functional components that are themselves bulky, the functional components themselves occupy a large space, resulting in insufficient accommodation space between the rear cover 220 and the middle frame 210 to provide a board-to-board connector for connecting the functional components with the printed circuit board 310.
In order to reduce the connecting height between the flexible circuit board 320 and the printed circuit board 310, a manner of locally reducing the thickness of the printed circuit board 310 has been developed, in which a recessed region is designed on the printed circuit board 310, and the flexible circuit board 320 is soldered in the recessed region, so as to reduce the total height of the flexible circuit board 320 after being connected with the printed circuit board 310.
Since solder paste is printed on the solder pads 312 in the recessed area of the flexible circuit board 320, a step steel mesh matching the recessed area is required, and solder paste is pre-placed in the recessed area of the printed circuit board 310 through the step steel mesh. However, the inevitable assembly gap between the stepped steel mesh and the recessed area due to the dimensional tolerance may result in poor solder paste printing, for example, some of the solder pads 312 may be stacked with too much solder, and some of the solder pads 312 may have too little solder, which may affect the reliability and stability of the connection between the flexible circuit board 320 and the printed circuit board 310, and in severe cases may even result in the failure of the electrical connection between the functional components and the printed circuit board 310.
In view of the above, the embodiment of the present application designs the connection structure of the circuit board assembly 300, and on the basis of locally reducing the thickness of the printed circuit board 310, by printing the solder paste on the flexible circuit board 320, the height of the connection structure of the circuit board assembly 300 can be reduced, the thickness of the circuit board assembly 300 can be reduced, the occupied space of the circuit board assembly 300 can be reduced, and the light and thin requirements of the electronic device 1 can be met. Moreover, the flexible circuit board 320 and the printed circuit board 310 can be firmly connected, bad welding spots do not exist, and the stability and reliability of the electrical connection between the functional components and the printed circuit board 310 are ensured.
The circuit board assembly 300 according to the embodiment of the present application will be described in detail below.
Fig. 3 is a schematic structural diagram of a printed circuit board according to an exemplary embodiment of the present application. Referring to fig. 3, the printed circuit board 310 has a recess 311, the recess 311 is recessed from one side of the printed circuit board 310 to the other side, the recess 311 forms a soldering area, and the flexible circuit board 320 is soldered in the recess 311. The plurality of pads 312 are disposed in the recess 311, and the pads 312 are disposed at intervals and distributed on the surface of the recess 311. The components 313 connected to the printed circuit board 310 are disposed on the printed circuit board 310 in a region outside the recess 311, and a plurality of metal wires 314 are disposed on the printed circuit board 310, wherein one ends of the metal wires 314 are connected to the components 313, and the other ends of the metal wires 314 are connected to the corresponding pads 312, so as to electrically connect the components 313 and the pads 312 through the metal wires 314.
Exemplary materials for forming the pads 312 and the metal traces 314 include, but are not limited to, copper or copper alloys, which have good electrical conductivity and low cost, and are easily processed to form the pads 312 and the metal traces 314 on the printed circuit board 310. In practical applications, a copper layer or a copper alloy layer may be plated on the substrate of the printed circuit board 310, and then the excess copper or copper alloy is removed by an etching process to form the metal wires 314 and the pads 312 on the substrate. It is also generally necessary to coat a solder resist layer on the metal wire 314, the solder resist layer covering the region other than the soldering region on the substrate, the protective layer for protecting the metal wire 314 formed on the substrate, and the material constituting the solder resist layer is, for example, a liquid photosolder resist.
In addition, the printed circuit board 310 may have one recess 311 or more than two recesses 311 depending on the number and portions of the flexible circuit boards 320 connected on the printed circuit board 310. When the printed circuit board 310 is provided with two or more recess portions 311, for a single panel, all the recess portions 311 may be located on one side of the printed circuit board 310 where the component 313 is disposed, and for a double-sided panel, all the recess portions 311 may be located on the same side of the printed circuit board 310, or both side of the printed circuit board 310 may have the recess portions 311.
Fig. 4 is a partial structural view of a flexible circuit board according to an exemplary embodiment of the present application. Referring to fig. 4, the end of the flexible circuit board 320 connected to the printed circuit board 310 is a connecting portion 321, a plurality of solder holes 322 are spaced on the connecting portion 321, and the solder holes 322 correspond to the pads 312 on the recess 311 of the printed circuit board 310 one by one.
The solder holes 322 of the connecting portion 321 include a first hole 3221 and a second hole 3222, and the first hole 3221 and the second hole 3222 are both used for solder connection with the corresponding pad 312 of the printed circuit board 310. The inner wall surface of the first hole 3221 is covered with a conductive layer 324, the flexible circuit board 320 is provided with a plurality of metal traces 323, the conductive layers 324 in one end hole of the metal traces 323 are connected in a one-to-one correspondence, and the other end of the metal trace 323 is used for connecting with a functional component. The first holes 3221 are fixedly connected to the corresponding pads 312, and the conductive layer 324 can electrically connect to the corresponding pads 312, so that the functional components can be electrically connected to the related components 313 on the printed circuit board 310. The second holes 3222 are mainly used for fixedly connecting with the corresponding pads 312 of the printed circuit board 310, so as to improve the connection strength between the flexible circuit board 320 and the printed circuit board 310 and ensure that the flexible circuit board 320 and the printed circuit board 310 are firmly connected.
Similar to the pads 312 and metal traces 314 on the printed circuit board 310, the conductive layer 324 and metal traces 323 on the flexible circuit board 320 are made of a material including, but not limited to, copper or a copper alloy.
As for the arrangement design of the first holes 3221 and the second holes 3222 on the connecting portion 321 of the flexible circuit board 320, with continued reference to fig. 4, which shows a case that two or more second holes 3222 are disposed on the connecting portion 321 of the flexible circuit board 320, by disposing a plurality of second holes 3222 on the connecting portion 321, on the basis that the flexible circuit board 320 is fixedly connected and electrically connected with the printed circuit board 310 through the first holes 3221, the plurality of second holes 3222 provide a plurality of fixed connection points for the flexible circuit board 320 and the printed circuit board 310, so that the connection strength between the flexible circuit board 320 and the printed circuit board 310 can be improved, and the reliability and stability of the circuit board assembly 300 can be improved.
The second holes 3222 may be distributed at different positions of the connecting portion 321 of the flexible circuit board 320, so that the flexible circuit board 320 and the printed circuit board 310 have different fixing connection points, so that the connection strength between the flexible circuit board 320 and the printed circuit board 310 is enhanced, the overall connection strength of the circuit board assembly 300 is enhanced, and the phenomenon of insufficient local connection strength of the circuit board assembly 300 is prevented.
For example, taking the arrangement shown in fig. 4 as an example, the left side and the right side of the connection portion 321 of the flexible circuit board 320 are provided with the second holes 3222, so as to ensure that the left side and the right side of the flexible circuit board 320 have high connection strength with the printed circuit board 310, and the connection strength between each part of the flexible circuit board 320 and the printed circuit board 310 meets the requirement, so that the risk of connection failure of the circuit board assembly 300 is significantly reduced. When the connection portion 321 of the flexible circuit board 320 has a large span, the second hole 3222 may be provided on both the left and right sides of the connection portion 321, and the second hole 3222 may also be provided in the middle region of the connection portion 321, thereby sufficiently securing the connection strength of each portion of the flexible circuit board 320.
In practical applications, when the first holes 3221 and the second holes 3222 are designed and arranged on the connecting portion 321 of the flexible circuit board 320, the second holes 3222 may be arranged in a hollow manner between the first holes 3221, that is, the first holes 3221 are distributed around the second holes 3222, and the first holes 3221 separate adjacent second holes 3222. In this manner, the solder paste filled in the second hole 3222 has high connection strength with the corresponding pad 312 of the printed circuit board 310, and the connection strength between the solder paste filled in the first hole 3221 around the solder paste and the corresponding pad 312 of the printed circuit board 310 can be enhanced, so that the overall connection strength of the circuit board assembly 300 is enhanced, and the reliability and stability of the electrical connection between the conductive layer 324 in the first hole 3221 and the corresponding pad 312 are also enhanced.
Under the conditions that the area of the connection portion 321 of the flexible circuit board 320 is small, the number of the solder holes 322 is small, and the like, only one second hole 3222 may be disposed on the connection portion 321, and the solder paste in each first hole 3221 is fixedly connected with the corresponding pad 312 of the printed circuit board 310, so as to satisfy the connection strength between the flexible circuit board 320 and the printed circuit board 310, and on the basis that the fixed connection between the solder paste in the second hole 3222 and the corresponding pad 312 of the printed circuit board 310 is sufficient to ensure the connection strength between the flexible circuit board 320 and the printed circuit board 310, so that the reliability and the stability of the circuit board assembly 300 are strongly ensured. At this time, the second hole 3222 may be disposed in the middle area of the connecting portion 321, so that the solder paste in the second hole 3222 has a better effect on the whole connecting portion 321, the overall connection strength of the circuit board assembly 300 is enhanced, and the phenomenon of local insufficient connection strength of the circuit board assembly 300 is prevented.
For example, the cross-sectional shape of the welding hole 322 may be circular, oval, triangular, square, rectangular, rhombic, pentagonal, hexagonal, octagonal, and the like, and the shapes of the first hole 3221 and the second hole 3222 may be the same or different, and the shapes of the different first hole 3221 and the different second hole 3222 may also be the same or different, which is not limited in this embodiment. The following description will be given taking as an example the shape of the solder hole 322 as a circle.
In addition, the substrate of the flexible circuit board 320 is usually a flexible dielectric layer, and the flexible dielectric layer has good flexibility, so that the flexible circuit board 320 can be bent when being subjected to an external force. Thus, the functional components are connected to the printed circuit board 310 through the flexible circuit board 320, so that the flexibility of the circuit board assembly 300 is higher, and the layout arrangement of the functional components is facilitated. Exemplary materials of the flexible dielectric layer constituting the substrate of the flexible circuit board 320 include, but are not limited to, polyimide (PI), thermoplastic Polyimide (TPI), or Polyester (PET).
Fig. 5 is a schematic structural diagram of a circuit board assembly according to an exemplary embodiment of the present application. Referring to fig. 5, when the flexible circuit board 320 is connected to the printed circuit board 310, the connection portion 321 of the flexible circuit board 320 is embedded into the recess 311 of the printed circuit board 310, the solder holes 322 of the flexible circuit board 320 are aligned with the pads 312 of the recess 311 of the printed circuit board 310 one by one, and by disposing the solder paste 325 between the solder holes 322 and the pads 312, after the solder paste 325 is heated and melted, under pressure, the solder paste overflows from the solder holes 322 of the flexible circuit board 320 to the side of the flexible circuit board 320 away from the printed circuit board 310, and after the solder paste 325 is solidified, the flexible circuit board 320 is fixedly connected to the printed circuit board 310.
Since the printed circuit board 310 has a large thickness and high hardness, it is convenient to perform an operation of printing the solder paste 325, and the solder paste 325 is generally printed on the pads 312 of the printed circuit board 310. However, in the present embodiment, since the connection portion 321 of the flexible circuit board 320 is soldered in the recess 311 of the printed circuit board 310, in order to avoid poor printing of the solder paste 325 due to the step steel mesh arranged on the printed circuit board 310, the solder paste 325 may be printed on the flexible circuit board 320 in advance, the surface of the flexible circuit board 320 is flat, and the steel mesh is conveniently arranged, so that the solder paste 325 is printed on each solder hole 322 of the flexible circuit board 320 through the steel mesh.
Fig. 6 is a partial cross-sectional view of a flexible circuit board provided in an exemplary embodiment of the present application. Referring to fig. 6, in the present embodiment, the solder paste 325 is printed on each solder hole 322 of the flexible circuit board 320 in advance, so that a steel mesh can be laid on the surface of the side of the flexible circuit board 320 to be soldered to the printed circuit board 310, the steel mesh can be designed as a planar steel mesh which is well attached to the connection portion 321 of the flexible circuit board 320, each mesh on the steel mesh corresponds to each solder hole 322 on the connection portion 321 one by one, the fluid solder paste 325 is laid on the steel mesh, and the solder paste 325 is printed on each solder hole 322 of the connection portion 321 by means of the fluidity of the solder paste 325 and a tool (e.g., a doctor blade).
Through presetting soldering paste 325 on connecting portion 321 of flexible circuit board 320, the steel mesh is laminated with connecting portion 321 and is leveled, can improve the homogeneity of solder paste printing, each soldering hole 322 is gone up the homoenergetic and is covered sufficient soldering paste 325, in order to guarantee that soldering hole 322 of flexible circuit board 320 and printed circuit board 310's pad 312 are firm in connection, and, can avoid the condition that accumulational soldering paste 325 is too thick on soldering hole 322, in order to avoid the flowing and interconnect of soldering paste 325, it prints well to ensure that soldering paste 325, guarantee the reliability and the stability that flexible circuit board 320 and printed circuit board 310 are connected.
In the process of printing the solder paste 325 on the flexible circuit board 320, the size of each solder hole 322 on the connecting portion 321 may be limited to prevent the solder paste 325 from flowing to the other side surface of the flexible circuit board 320, and for example, when the cross-sectional shape of the solder hole 322 is circular, the aperture of the solder hole 322 may be appropriately reduced by controlling the aperture of the solder hole 322, so as to increase the resistance to the flow of the solder paste 325 in the solder hole 322, and prevent the solder paste 325 from flowing to the other side surface of the flexible circuit board 320 through the solder hole 322.
As shown in fig. 6, for the first hole 3221 used for electrically connecting the flexible circuit board 320 and the printed circuit board 310, since the inner wall surface of the first hole 3221 is covered with the conductive layer 324, the interface between the solder paste 325 and the conductive layer 324 is a wetting interface, and the fluidity of the solder paste 325 in the first hole 3221 is high, the cross-sectional area (aperture) of the first hole 3221 can be designed to be small, so that the resistance of the first hole 3221 to the solder paste 325 is increased, and the solder paste 325 is prevented from flowing to the other side of the flexible circuit board 320.
For the second hole 3222 only used for realizing the fixed connection between the flexible circuit board 320 and the printed circuit board 310, the cross-sectional area (aperture) of the second hole 3222 may be designed to be larger, for example, the cross-sectional area of the second hole 3222 may be larger than the cross-sectional area of the first hole 3221, so that more solder paste 325 is filled in the second hole 3222, which may increase the connection strength between the flexible circuit board 320 and the printed circuit board 310, improve the connection strength of the circuit board assembly 300, and ensure the reliability and stability of the circuit board assembly 300. Moreover, the inner wall surface of the second hole 3222 is not covered by the conductive layer 324, that is, the inner wall surface of the second hole 3222 is a base material of the flexible circuit board 320, and an interface between the base material and the solder paste 325 is a non-wetting interface, so that the solder paste 325 is greatly hindered from flowing, and the solder paste 325 can be prevented from flowing to the other side surface of the flexible circuit board 320.
In order to facilitate electrical connection between the conductive layer 324 and the pad 312 on the printed circuit board 310 in the first hole 3221, the conductive layer 324 may protrude out of the first hole 3221, the conductive layer 324 includes a basic segment 3241 and an extension segment 3242, the basic segment 3241 is located in the first hole 3221 and covers an inner wall surface of the first hole 3221, the extension segment 3242 is connected to an end portion of the basic segment 3241, and the extension segment 3242 is located outside the first hole 3221 and extends along a surface of the connecting portion 321. The contact area of the conductive layer 324 and the pad 312 is increased by the extension section 3242, so that the reliability and stability of the electrical connection between the conductive layer 324 and the pad 312 are ensured. Illustratively, the extension section 3242 and the base section 3241 are of unitary construction.
In some embodiments, only one end of the basic segment 3241 is connected with an extension segment 3242, and the extension segment 3242 is located on one side surface of the connection portion 321 of the flexible circuit board 320 facing the recess 311 of the printed circuit board 310, so that the extension segment 3242 is opposite to the pad 312 in the recess 311, the contact area between the conductive layer 324 and the pad 312 is increased, and the conductive layer 324 and the pad 312 are ensured to be well electrically connected. At this time, when the solder paste 325 is preset on the connection portion 321 of the flexible circuit board 320, the solder paste 325 should be positioned on the surface of the connection portion 321 on which the extension section 3242 is provided, and when soldering, the surface of the connection portion 321 on which the solder paste 325 is preset is directed toward the printed circuit board 310.
In other embodiments, the extension sections 3242 are connected to both ends of the base section 3241, and the extension sections 3242 of both ends are respectively located on both side surfaces of the connection section 321 of the flexible circuit board 320, so that both side surfaces of the flexible circuit board 320 can be disposed facing the printed circuit board 310 when the flexible circuit board 320 and the printed circuit board 310 are soldered. At this time, when the solder paste 325 is preset on the connection part 321 of the flexible circuit board 320, the solder paste 325 may be located on any side surface of the connection part 321, and the orientation of the flexible circuit board 320 does not need to be adjusted, so that the efficiency of presetting the solder paste 325 may be improved. In soldering, the surface of the connecting portion 321 on which the solder paste 325 is placed is directed toward the printed circuit board 310.
Fig. 7 is a schematic view illustrating a state where a flexible circuit board according to an exemplary embodiment of the present application is mounted on a printed circuit board; fig. 8 is a schematic diagram illustrating a state after a flexible circuit board and a printed circuit board are connected according to an exemplary embodiment of the present application. Referring to fig. 7, after the solder paste 325 printed on the flexible circuit board 320 is cured, the flexible circuit board 320 is placed on the printed circuit board 310, the connection portion 321 of the flexible circuit board 320 is embedded in the recess 311 of the printed circuit board 310, and the pads 312 of the connection portion 321 are aligned with the pads 312 of the recess 311 one by one. Referring to fig. 8, after the flexible circuit board 320 is placed and fixed, a pressure F is applied to the flexible circuit board 320 and the printed circuit board 310, and the solder paste 325 filled in the solder hole 322 of the flexible circuit board 320 is heated, the solder paste 325 absorbs heat to melt, and the melted solder paste 325 flows in the thickness direction of the flexible circuit board 320 in the solder hole 322 under the pressure F and overflows from the other side of the flexible circuit board 320. After the solder paste 325 overflows and solidifies, the flexible circuit board 320 and the printed circuit board 310 are fixedly coupled together.
For example, when the flexible circuit board 320 and the printed circuit board 310 are pressed together, the flexible circuit board 320 may be placed above the printed circuit board 310, and the melted solder paste 325 may flow upward in the solder holes 322 along the thickness direction of the flexible circuit board 320 and overflow from the side of the flexible circuit board 320 facing away from the printed circuit board 310 by the pressure F. Alternatively, the flexible circuit board 320 may be placed under the printed circuit board 310, and the melted solder paste 325 flows downward in the solder hole 322 along the thickness direction of the flexible circuit board 320 by the pressure F, and overflows from the side of the flexible circuit board 320 facing away from the printed circuit board 310.
The first hole 3221 of the flexible circuit board 320 and the corresponding pad 312 of the printed circuit board 310 are fixedly connected to the pad 312 through the solder paste 325, and the conductive layer 324 on the inner wall surface of the first hole 3221 is electrically connected to the pad 312, so that the conductive layer 324 is electrically connected to the pad 312. Between the second hole 3222 of the flexible circuit board 320 and the corresponding pad 312 of the printed circuit board 310, the pad 312 of the printed circuit board 310 at the position of the second hole 3222 is fixedly connected mainly through the solder paste 325, so as to increase the connection strength between the flexible circuit board 320 and the printed circuit board 310.
In addition, since the flux contained in the solder paste 325 is volatile, before the flexible circuit board 320 and the printed circuit board 310 are soldered, a layer of flux can be further sprayed on the to-be-soldered portion of the flexible circuit board 320 or the printed circuit board 310 to improve the soldering performance of the flexible circuit board 320 and the printed circuit board 310. For example, after the solder paste 325 is printed on the flexible circuit board 320, a layer of flux is sprayed on the solder paste 325 to remove oxides on the surface of the solder paste 325, and then the flexible circuit board 320 is placed on the printed circuit board 310.
As for the manner of soldering the flexible circuit board 320 and the printed circuit board 310, as an embodiment, a laser soldering process may be used, the flexible circuit board 320 and the printed circuit board 310 are placed on a worktable, a pressing plate is pressed on the flexible circuit board 320 and the printed circuit board 310, at least one of the pressing plate and the worktable is glass, a laser beam passes through the glass and is converged on the soldering paste 325, and the soldering paste 325 is heated and melted to achieve the purpose of soldering the flexible circuit board 320 and the printed circuit board 310. As another embodiment, a hot-pressing molten-tin soldering (HotBar) process may be used, in which the flexible circuit board 320 and the printed circuit board 310 are placed on a worktable, the hot-pressing head presses the flexible circuit board 320 and the printed circuit board 310 downward, and the hot-pressing head heats and melts a tin paste by using electric heat generated when a pulse current flows through a material having a high resistance characteristic, such as molybdenum, titanium, and the like, so as to achieve the purpose of soldering the flexible circuit board 320 and the printed circuit board 310.
In practice, the flexible circuit board 320 and the printed circuit board 310 may be fabricated first, and then they are joined together and soldered. For the flexible circuit board 320, for example, first, solder Paste 325 is preset on each Solder hole 322 of the flexible circuit board 320 by SMT (Surface Mount Technology) printing process, and then, the printing quality (Solder Paste printing amount, printing height, printing area/volume, printing flatness, etc.) of the Solder Paste 325 is detected by SPI (Solder Paste Inspection), and after the detection is passed, the flexible circuit board is put into a standby state. For the printed circuit board 310, a large board including a plurality of printed circuit boards 310 arranged in an array is usually designed initially, quality Inspection, such as Automatic Optical Inspection (AOI), is performed on the large board, and after the Inspection is qualified, board separation is performed to divide the large board into the required printed circuit boards 310, and the printed circuit boards 310 are put into use. Then, the soldering flux is sprayed on the soldering paste 325 of the flexible circuit board 320, the flexible circuit board 320 and the printed circuit board 310 are placed on a workbench in a matching manner, the flexible circuit board 320 and the printed circuit board 310 are soldered and assembled into the circuit board assembly 300, and the CCD (Charge Coupled Device) detection is performed on the circuit board assembly 300.
As shown in fig. 8, in order to reduce the overall thickness of the circuit board assembly 300, the thickness of the connecting portion 321 of the flexible circuit board 320 may be smaller than the recess depth of the recess 311 of the printed circuit board 310, the connecting portion 321 is connected in the recess 311, the thickness of the connecting portion 321 and the recess depth of the recess 311 are controlled to reduce the overall thickness of the connecting portion 321 and the printed circuit board 310 after assembly, and the thickness space occupied by the circuit board assembly 300 is reduced to reserve more installation space for other functional components in the electronic device 1, and to facilitate the light and thin of the electronic device 1.
In practical applications, the thickness of the flexible circuit board 320 is usually between 0.1mm and 0.2mm according to the number of layers of the flexible dielectric layer in the substrate of the flexible circuit board 320, and the recess depth of the recess 311 of the printed circuit board 310 may be designed according to the thickness of the flexible circuit board 320, so that the recess depth of the recess 311 is greater than the thickness of the connection portion 321 of the flexible circuit board 320.
By making the thickness of the connecting portion 321 of the flexible circuit board 320 smaller than the depth of the recess 311 of the printed circuit board 310, after the connecting portion 321 of the flexible circuit board 320 and the printed circuit board 310 are assembled, the surface of the connecting portion 321 may be recessed in the surface of the printed circuit board 310 or flush with the surface of the printed circuit board 310, so that the connecting portion 321 may be completely accommodated in the thickness space of the printed circuit board 310, the flexible circuit board 320 does not occupy additional thickness space, the thickness of the circuit board assembly 300 depends only on the thickness of the printed circuit board 310, and the thickness space occupied by the circuit board assembly 300 is small.
In some cases, the surface of the connection portion 321 of the flexible circuit board 320 may slightly protrude from the surface of the printed circuit board 310, and the thickness of the connection portion (where the connection portion 321 is located) of the circuit board assembly 300 is slightly larger than the thickness of the printed circuit board 310. However, compared to the flexible circuit board 320 connected to the printed circuit board 310 through a board-to-board connector, or the flexible circuit board 320 directly attached to the surface of the printed circuit board 310, the thickness of the connection portion of the circuit board assembly 300 is significantly reduced by embedding the connection portion 321 of the flexible circuit board 320 into the recess 311 formed on the printed circuit board 310, and the occupied space of the circuit board assembly 300 is saved.
In the description of the embodiments of the present application, it should be noted that unless otherwise explicitly stated or limited, the terms "mounted," "connected," and "connected" are to be construed broadly, and may be, for example, a fixed connection, an indirect connection via an intermediary, a connection between two elements, or an interaction between two elements. Specific meanings of the above terms in the embodiments of the present application can be understood by those of ordinary skill in the art according to specific situations.
The terms "first," "second," "third," "fourth," and the like in the description and in the claims of the embodiments of the application and in the drawings described above, if any, are used for distinguishing between similar elements and not necessarily for describing a particular sequential or chronological order.
Claims (13)
1. A circuit board assembly is characterized by comprising a printed circuit board and a flexible circuit board, wherein the printed circuit board is provided with a concave part, the concave part is concave from one side plate surface to the other side plate surface of the printed circuit board, and the end part of the flexible circuit board is provided with a connecting part which is connected with the concave part;
a plurality of welding pads are arranged on the concave part at intervals, a plurality of welding holes are arranged on the connecting part at intervals, welding paste is filled in the welding holes, and the welding holes correspond to the welding pads one by one and are connected through the welding paste; the plurality of welding holes comprise a plurality of first holes and at least one second hole, and the inner wall surfaces of the first holes are covered with conductive layers.
2. The circuit board assembly of claim 1, wherein the cross-sectional area of the second aperture is greater than the cross-sectional area of the first aperture.
3. The circuit board assembly according to claim 1, wherein the second hole is one in number and is located at a middle region of the connection portion.
4. The circuit board assembly of claim 1, wherein the number of the second holes is two or more.
5. A circuit board assembly according to claim 4, wherein the second holes are distributed in different areas of the connection portion.
6. A circuit board assembly according to claim 4, wherein the first holes are provided in the areas between adjacent second holes.
7. A circuit board assembly according to any of claims 1-6, wherein the thickness of the connecting portion is smaller than the recess depth of the recess.
8. The circuit board assembly of claim 7, wherein the connecting portion is received in a thickness space of the printed circuit board.
9. A circuit board assembly according to any one of claims 1-6, characterised in that the electrically conductive layer comprises a basic section and an extension section to which at least one end of the basic section is connected, the basic section covering an inner wall surface of the first hole, the extension section extending along a surface of the connection portion.
10. The circuit board assembly of claim 9, wherein the extension segment is connected to one end of the base segment, the extension segment facing the recess.
11. The circuit board assembly of claim 9, wherein the extension segment is connected to both ends of the base segment.
12. A circuit board assembly according to any of claims 1-6, wherein the electrically conductive layer comprises a copper layer or a copper alloy layer.
13. An electronic device comprising a housing and the circuit board assembly of any one of claims 1-12, the circuit board assembly mounted within the housing.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN202221589192.0U CN218336541U (en) | 2022-06-17 | 2022-06-17 | Circuit board assembly and electronic equipment |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN202221589192.0U CN218336541U (en) | 2022-06-17 | 2022-06-17 | Circuit board assembly and electronic equipment |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| CN218336541U true CN218336541U (en) | 2023-01-17 |
Family
ID=84869539
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CN202221589192.0U Active CN218336541U (en) | 2022-06-17 | 2022-06-17 | Circuit board assembly and electronic equipment |
Country Status (1)
| Country | Link |
|---|---|
| CN (1) | CN218336541U (en) |
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2022
- 2022-06-17 CN CN202221589192.0U patent/CN218336541U/en active Active
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