WO2023174251A1

WO2023174251A1 - Circuit board assembly and processing method therefor, and electronic device

Info

Publication number: WO2023174251A1
Application number: PCT/CN2023/081293
Authority: WO
Inventors: 郭璇
Original assignee: 华为技术有限公司
Priority date: 2022-03-18
Filing date: 2023-03-14
Publication date: 2023-09-21
Also published as: CN116801482B; CN116801482A

Abstract

The present application provides a circuit board assembly and a processing method therefor, and an electronic device. The circuit board assembly comprises: a first circuit board and a second circuit board, wherein the first circuit board is electrically connected to the second circuit board by means of solder balls and a first solder pad. The first circuit board comprises a first circuit board substrate, the first solder pad, a first electrically conductive member and a plurality of solder resist layers, wherein the first solder pad and the first electrically conductive member are fixed on the same side of the circuit board substrate; the plurality of solder resist layers are stacked; the plurality of solder resist layers at least cover the first electrically conductive member on the side of the first electrically conductive member away from the circuit board substrate; and the sum of the heights of the plurality of solder resist layers and the first electrically conductive member is greater than the height of the first solder pad; and the plurality of solder resist layers are height limiting layers for a lamination process, and the height of the plurality of solder resist layers enables two adjacent solder balls to be spaced apart during the lamination of the first circuit board and the second circuit board. The present application can reduce the possibility of a lamination height being excessively small, and thus reduce the possibility of a tin connection between two adjacent solder pads, thereby improving the mechanical stability of the circuit board assembly.

Description

Circuit board components and processing methods thereof, electronic equipment

This application claims priority to the Chinese patent application filed with the China Patent Office on March 18, 2022, with application number 202210272332. incorporated in this application.

Technical field

This application relates to the field of electronic equipment, and more specifically, to circuit board components and processing methods thereof, and electronic equipment.

Background technique

Electronic devices have the characteristics and development trends of being light, thin, short, and small. Devices and components inside electronic equipment need to have characteristics such as high integration, thin stack thickness, and small unit size. In order to miniaturize electronic devices, the internal space of the electronic devices needs to be compressed without sacrificing functionality. If the spacing between two adjacent circuit boards is relatively small, it is beneficial to reduce the internal space occupied by the circuit board assembly in the electronic device. However, narrowing the spacing between two adjacent circuit boards makes it difficult to control the lamination height when laminating the two circuit boards, which may cause the solder balls to be over-compressed, increase process risks such as soldering, and reduce the risk of circuit board components. mechanical stability.

Contents of the invention

Embodiments of the present application provide a circuit board assembly, a processing method thereof, and electronic equipment. The purpose is to reduce the possibility that the lamination height is too small, thereby reducing the possibility of tin connection between two adjacent pads, and improving the circuit board Mechanical stability of components.

In a first aspect, a circuit board assembly is provided, which includes:

A first circuit board, the first circuit board includes a first circuit board base, a first soldering pad, a first conductive member and a plurality of solder resist layers, the first soldering pad and the first conductive member are fixed on the first circuit board On the same side of the base body, the plurality of solder resist layers are stacked and arranged. The plurality of solder resist layers at least cover the first conductive member on the side of the first conductive member away from the first circuit board base body. The plurality of solder resist layers The sum of the heights of the first conductive member and the first conductive member is greater than the height of the first pad;

The second circuit board is electrically connected to the first circuit board through solder balls and the first pad;

Among them, the plurality of solder resist layers are height limiting layers in the lamination process, and the heights of the plurality of solder resist layers satisfy that during the lamination process of the first circuit board and the second circuit board, two adjacent solder balls are Spaced out.

According to the circuit board assembly provided by the embodiment of the present application, by providing a plurality of solder resist layers on the first circuit board, when the second circuit board is electrically connected to the first circuit board through solder balls and the first pad, the first circuit The plurality of solder resist layers provided on the board can function as a height limiter, so that during the process of laminating the first circuit board and the second circuit board, two adjacent solder balls are spaced apart. Therefore, the circuit assembly provided by the embodiment of the present application plays a height limiting role by setting multiple solder resist layers, which is beneficial to controlling the distance between the first circuit board and the second circuit board and preventing the connection height from being too low. tin issues, which in turn can increase the mechanical stability of the circuit board assembly.

In conjunction with the first aspect, in some implementations of the first aspect, the plurality of solder resist layers include a first solder resist layer covering the first conductive member and in contact with the first circuit board base .

According to the circuit board assembly provided by the embodiment of the present application, the plurality of solder resist layers include a first solder resist layer, and the first solder resist layer covers the first conductive member and is in contact with the first circuit board substrate, thereby insulating the circuit board. electrical connection lines to avoid oxidation of the electrical connection lines when exposed to air as much as possible. In addition, the first solder resist layer covering the first conductive member can also increase the stability of the first conductive member and obtain a relatively stable circuit board assembly structure.

In connection with the first aspect, in some implementations of the first aspect, the plurality of solder resist layers further include a second solder resist layer, the second solder resist layer is in contact with the first conductive member and is located on the first solder resist layer. between the layer and the first conductive member.

According to the circuit board assembly provided by the embodiment of the present application, by adding a second solder resist layer, and the second solder resist layer is located between the first solder resist layer and the first conductive member, the second solder resist layer is first partially provided and then the whole Providing the first solder resist layer can further ensure the stability of the second solder resist layer and obtain a relatively stable padding structure, which can function as a height limiter and reduce the possibility of tin connection problems.

In conjunction with the first aspect, in some implementations of the first aspect, the plurality of solder resist layers further include a second solder resist layer, the first solder resist layer is in contact with the first conductive member and is located on the second solder resist layer. between the layer and the first conductive member.

According to the circuit board assembly provided by an embodiment of the present application, the plurality of solder resist layers include a first solder resist layer and a second solder resist layer, and the first solder resist layer is located between the second solder resist layer and the first conductive member. , by first arranging the first solder resist layer as a whole and then partially arranging the second solder resist layer, a relatively stable pad structure can also be obtained, which can play a height limiting role, thereby reducing the possibility of tin connection problems.

With reference to the first aspect, in some implementations of the first aspect, the first solder resist layer also covers a partial area of the first soldering pad, and the remaining area of the first soldering pad is connected to the solder ball.

According to the circuit board assembly provided by the embodiment of the present application, by arranging the first solder resist layer to cover part of the first pad, the possibility of the first pad falling off during the pad welding process can be further reduced, thereby improving the performance of the circuit board assembly. stability.

With reference to the first aspect, in some implementations of the first aspect, the first solder resist layer is disposed outside the spacing area between the first conductive member and the first pad.

According to the circuit board assembly provided by the embodiment of the present application, the first solder resist layer is disposed outside the spacing area between the first conductive member and the first pad, which can provide a larger surface area for pad welding and allow wider lines. wider and more through-hole flexibility.

With reference to the first aspect, in some implementations of the first aspect, the second solder resist layer is disposed opposite to the first conductive member.

According to the circuit board assembly provided by the embodiment of the present application, the second solder resist layer is arranged opposite to the first conductive member, and the second solder resist layer is in the projection area of the first circuit board base and the first conductive member is in the projection area of the first circuit board base. The projected areas intersect or overlap. That is to say, the size of the second solder resist layer should be smaller than or equal to the first conductive member, so as to prevent the left and right alignment tolerance from causing the second solder resist layer to fall into the unraised area or come into contact with other pads, affecting the quality of the circuit board. Processing and use.

With reference to the first aspect, in some implementations of the first aspect, the material of the second solder resist layer includes solder resist ink, photosensitive development cover film PIC, and ordinary cover film.

According to the circuit board assembly provided by the embodiment of the present application, the material of the second solder resist layer includes solder resist ink, photosensitive development cover film PIC, and ordinary cover film. When the circuit board is raised, more materials can be selected. Selecting appropriate materials for processing according to different needs can reduce circuit board processing costs, and on the basis of raising the circuit board, it can also ensure that the circuit board components are as light and thin as possible.

Combined with the first aspect, in some implementations of the first aspect, the second solder resist layer is cylindrical.

According to the circuit board assembly provided by the embodiment of the present application, the second solder resist layer is set in a cylindrical shape, so that the second solder resist layer can be adhered more reliably, and the cylindrical structure is relatively stable and difficult to fall off, thereby improving the stability of the circuit board assembly. sex.

With reference to the first aspect, in some implementations of the first aspect, the first conductive member is located at an edge of the first circuit board.

In a possible implementation, the edge position can be set in the corner areas on four sides of the circuit board.

According to the circuit board assembly provided by the embodiment of the present application, the first conductive member is located at the edge of the first circuit board, and multiple layers of solder resist are provided on the first conductive member, thereby providing a relatively uniform padding structure for the circuit board. , which can better play the role of height limit, thereby reducing the possibility of tin connection problems.

With reference to the first aspect, in some implementations of the first aspect, the length of the first circuit board is L, the circuit board assembly includes a plurality of first conductive members, and the number of the plurality of first conductive members is n, n ≥L/L', L' is 15mm, L>15mm, n is a positive integer.

In a possible implementation, the number of the first conductive members is set relative to the length of the first circuit board, and at least one first conductive member is disposed every 15 mm in the length direction of the first circuit board.

According to the circuit board assembly provided by the embodiment of the present application, when the length of the circuit board is greater than or equal to 15 mm, at least one first conductive member can be additionally added by providing a multi-layer solder resist layer on the at least one first conductive member (for example: The first solder resist layer and the second solder resist layer) can further ensure that the pad structure formed on the first circuit board is more stable, thereby better functioning as a height limiter and reducing the occurrence of tin connection problems.

In conjunction with the first aspect, in some implementations of the first aspect, the first conductive member includes one or more of the following: a conductive layer and a bonding pad.

According to the circuit board assembly provided by the embodiment of the present application, the first conductive component may include a conductive layer, a soldering pad, or a conductive layer and a soldering pad. By providing solder resist layers on different first conducting components, a stable padding structure can be provided , which can play the role of height limiter and avoid soldering problems to a certain extent.

With reference to the first aspect, in some implementations of the first aspect, the first circuit board further includes a second conductive member, and the second conductive member and the first conductive member are disposed on the same side of the first circuit board base, The distance between the first conductive member and the second conductive member is less than 2 mm.

According to the circuit board assembly provided by the embodiment of the present application, in addition to the first conductive member, a second conductive member can be additionally provided. By arranging solder resist layers on the multiple conductive members, a more stable padding structure can be provided. , which can play the role of height limiter and avoid soldering problems to a certain extent.

In conjunction with the first aspect, in some implementations of the first aspect, the first pad and the first conductive member are arranged adjacently.

According to the circuit board assembly provided by the embodiment of the present application, by arranging the first pad and the first conductive member adjacent to each other, the position of the pad can be set more accurately, and the height limiter can be better played, so that the height can be limited as much as possible. Avoid soldering problems.

In connection with the first aspect, in some implementations of the first aspect, the heights of the plurality of solder resist layers range from one-third to one-half the height of the solder ball.

According to the circuit board assembly provided by the embodiment of the present application, it is ensured that the height of the multiple solder resist layers is between one third of the height of the solder balls and one half of the height of the solder balls, which can further ensure that the multiple solder resist layers can It acts as a height limiter to prevent soldering problems caused by too low a height when the circuit board is pressed together, and the risk of false soldering caused by too high a height when the circuit board is pressed together.

In conjunction with the first aspect, in some implementations of the first aspect, the first circuit board is any one of the following: a mainboard, a frame board, a radio frequency board, an application processor or a module board.

According to the circuit board assembly provided by the embodiment of the present application, the first circuit board can be a main board, a frame board, a radio frequency board, an application processor or a module board. The circuit board assembly can be used in a sandwich structure board, and a more stable sandwich structure can be obtained. .

In conjunction with the first aspect, in some implementations of the first aspect, the total height of the plurality of solder resist layers is between 20 μm and 40 μm.

It should be understood that the height of the plurality of solder resist layers relative to the first pad or the first conductive member is between 20 μm and 40 μm.

The circuit board assembly provided according to the embodiment of the present application ensures that the total height of the multiple solder resist layers is between 20 μm and 40 μm, which can better serve as a height limiter and prevent the circuit board from being too low when laminating. This will cause soldering problems and the risk of virtual soldering caused by too high a height when laminating the circuit board.

In a possible implementation, the total height of the plurality of solder resist layers is 30 μm, that is, the plurality of solder resist layers are 30 μm higher than the height of the first pad or the first conductive member.

In conjunction with the first aspect, in some implementations of the first aspect, the second circuit board includes a second circuit board base, a second pad and a third solder resist layer, the second pad is fixed on the second circuit On the board base, the second solder pad is disposed opposite to the first conductive member, and the third solder resist layer is disposed in an area outside the second solder pad and is in contact with the second circuit board base.

In conjunction with the first aspect, in some implementations of the first aspect, the total height of the plurality of solder resist layers is between 25 μm and 45 μm.

It should be understood that the height of the plurality of solder resist layers relative to the first pad or the first conductive member is between 25 μm and 45 μm.

According to the circuit board assembly provided by the embodiment of the present application, the solder resist layer may not be provided on the second pad of the second circuit board corresponding to the first conductive member, thereby avoiding the problems caused by providing the solder resist layer on the second pad. The height tolerance can further improve the welding yield. At the same time, the total height of the multiple solder resist layers provided on the first circuit board can also be further increased, which can further prevent solder connection problems caused by too low a height when laminating the circuit boards, and the problem of solder joints caused by too high a height when laminating the circuit boards. The risk of welding can be eliminated, thereby improving the mechanical stability of the circuit board assembly.

A second aspect provides an electronic device, including the circuit board assembly according to any one of the above first aspects.

In a third aspect, a method for processing a circuit board assembly is provided, the method including:

Obtain a first circuit board. The first circuit board includes a first circuit board base, a first soldering pad, a first conductive member and a plurality of solder resist layers. The first soldering pad and the first conductive member are fixed on the first circuit board base. On the same side, a plurality of solder resist layers are stacked, and the plurality of solder resist layers at least cover the first conductive component on a side of the first conductive component away from the first circuit board base. The multiple solder resist layers are connected to the first conductive component. The sum of the heights of the components is greater than the height of the first pad;

The second circuit board and the first circuit board are pressed together, so that the second circuit board is electrically connected to the first circuit board through solder balls and first pads, wherein the plurality of solder resist layers are the height of the pressing process. The height of the limiting layer and the plurality of solder resist layers is such that during the lamination process of the first circuit board and the second circuit board, two adjacent solder balls are spaced apart.

According to the processing method of a circuit board assembly provided by an embodiment of the present application, the obtained first circuit board includes a plurality of solder resist layers. When the first circuit board and the second circuit board are pressed together, the first circuit board and the second circuit board are The second circuit board can be electrically connected to the first pad through solder balls. The multiple solder resist layers on the first circuit board can play a height limiting role, so that two adjacent solder balls are spaced apart, so that the Reduce the possibility of the lamination height being too small, thereby reducing the possibility of tin connection between two adjacent pads, and improving the mechanical stability of the circuit board assembly.

Combined with the third aspect, in some implementations of the third aspect, the plurality of solder resist layers include a first solder resist layer and a second solder resist layer, and obtaining the first circuit board includes:

A first solder resist layer is provided on one side of the first circuit board base and the first conductive member;

A second solder resist layer is disposed on a side of the first solder resist layer away from the first circuit board base.

According to the processing method of a circuit board assembly provided by an embodiment of the present application, by disposing a first solder resist layer on one side of the first circuit board base and the first conductive member, A second solder resist layer is provided on one side to obtain a relatively stable raising structure, which can act as a height limiter and prevent connection to a certain extent. Tin problem.

disposing a second solder resist layer on the first conductive member;

A first solder resist layer is disposed on the side of the first circuit board base body and the second solder resist layer away from the first circuit board base body.

According to the processing method of a circuit board assembly provided by an embodiment of the present application, by disposing a second solder resist layer on the first conductive member, the first circuit board base body and the second solder resist layer are disposed on the side away from the first circuit board base body. Setting up the first solder resist layer can further ensure the stability of the second solder resist layer and obtain a more stable padding structure, which can function as a height limiter and reduce the probability of tin connection problems to a certain extent.

Description of the drawings

Figure 1 is a schematic structural diagram of an electronic device.

Figure 2 is a schematic diagram of a conventional sandwich structural panel.

Figure 3 is a schematic flow chart of a processing method of a circuit board assembly.

Figure 4 is a schematic flow chart of another processing method of a circuit board assembly.

FIG. 5 is a schematic structural diagram of a circuit board assembly provided by an embodiment of the present application.

Figure 6 is a schematic side view of the structure when the solder ball is squeezed in the embodiment of the present application.

FIG. 7 is a schematic flow chart of a processing method of a circuit board assembly provided by an embodiment of the present application.

FIG. 8 is a schematic flow chart of another processing method of a circuit board assembly provided by an embodiment of the present application.

FIG. 9 is a schematic structural diagram of another circuit board assembly provided by an embodiment of the present application.

Figure 10 is a schematic structural diagram of another circuit board assembly provided by an embodiment of the present application.

Figure 11 is a schematic structural diagram of another circuit board assembly provided by an embodiment of the present application.

Figure 12 is a schematic structural diagram of another circuit board assembly provided by an embodiment of the present application.

Figure 13 is a schematic structural diagram of another circuit board assembly provided by an embodiment of the present application.

Figure 14 is a schematic flow chart of another processing method of a circuit board assembly provided by an embodiment of the present application.

Figure 15 is a schematic structural diagram of another circuit board assembly provided by an embodiment of the present application.

Figure 16 is a schematic structural diagram of another circuit board assembly provided by an embodiment of the present application.

Figure 17 is a schematic structural diagram of another circuit board assembly provided by an embodiment of the present application.

Figure 18 is a schematic structural diagram of another circuit board assembly provided by an embodiment of the present application.

Figure 19 is a schematic structural diagram of another circuit board assembly provided by an embodiment of the present application.

Figure 20 is a schematic structural diagram of another circuit board assembly provided by an embodiment of the present application.

Figure 21 is a schematic structural diagram of another circuit board assembly provided by an embodiment of the present application.

Figure 22 is a schematic structural diagram of another circuit board assembly provided by an embodiment of the present application.

Figure 23 is a schematic structural diagram of another circuit board assembly provided by an embodiment of the present application.

Figure 24 is a schematic structural diagram of another circuit board assembly provided by an embodiment of the present application.

Figure 25 is a schematic structural diagram of another circuit board assembly provided by an embodiment of the present application.

Figure 26 is a schematic structural diagram of another circuit board assembly provided by an embodiment of the present application.

Figure 27 is a schematic diagram of the elevated position provided by the embodiment of the present application.

Detailed ways

The technical solutions in the embodiments of the present application will be described below with reference to the accompanying drawings.

The terminology used in the following examples is for the purpose of describing specific embodiments only and is not intended to limit the application. As used in the specification and appended claims of this application, the singular expressions "a", "an", "said", "above", "the" and "the" are intended to also Expressions such as "one or more" are included unless the context clearly indicates otherwise. Reference in this specification to "one embodiment" or "some embodiments" or the like means that a particular feature, structure or characteristic described in connection with the embodiment is included in one or more embodiments of the application. Therefore, the phrases "in one embodiment", "in some embodiments", "in other embodiments", "in other embodiments", etc. appearing in different places in this specification are not necessarily References are made to the same embodiment, but rather to "one or more but not all embodiments" unless specifically stated otherwise. The terms “including,” “includes,” “having,” and variations thereof all mean “including but not limited to,” unless otherwise specifically emphasized.

It should be noted that "covering" in this manual means covering or concealing without direct contact with the object. For example: A covers B, which means that A is placed on top of B, but A is not in direct contact with the object. B has direct contact. "Contact" as used in this manual means direct contact between objects.

FIG. 1 is a schematic structural diagram of an electronic device 100 provided by an embodiment of the present application.

The electronic device 100 may be a mobile phone, a tablet computer, an e-reader, a notebook computer, a digital camera, a vehicle-mounted device, or a wearable device. The embodiment shown in FIG. 1 is explained by taking the electronic device 100 as a mobile phone as an example.

The electronic device 100 includes a housing 10 , a display screen 20 and a circuit assembly 30 . The display screen 20 and the circuit assembly 30 are installed on the housing 10 . Specifically, the housing 10 includes a frame and a back cover. The frame surrounds the outer periphery of the display screen 20 and the back cover, and the display screen 20 is spaced apart from the back cover. The cavity formed between the display screen 20 , the frame, and the back cover is used to place the circuit component 30 , and the housing 10 can be used to fix the circuit component 30 . Electronic device 100 also includes power supply 40 for powering circuit assembly 30 . The power source 40 may be, for example, a lithium electronic battery.

The circuit board can be a printed circuit board (PCB), a flexible circuit board, an integrated circuit (or chip), etc. Depending on the number of electronic components carried on the circuit board, the circuit board can be single-sided or double-sided. Single-sided boards can refer to circuit boards that carry electronic components on one side. Double-sided boards can refer to circuit boards that carry electronic components on both sides. Depending on the type of electronic components carried on the circuit board, the circuit board can be a motherboard, a module board, a frame board (FB), a radio frequency (RF) board, an application processor (application processor, AP) board, etc. A motherboard may be the main circuit board within an electronic device. RF boards can be used to carry radio frequency chips (radio frequency integrated circuit, RF IC), radio frequency power amplifier (radio frequency power amplifier, RF PA), wireless fidelity (wireless fidelity, WIFI) chips, etc. For example, the AP board can be used to carry system on chip (SOC) components, double data rate (DDR) memory, main power management unit (PMU), auxiliary PMU, etc.

The circuit board assembly 30 may include a sandwich structure board and a plurality of electronic components electrically connected to the circuit board in the sandwich structure board. A conventional sandwich structure usually consists of a radio frequency (RF) board, a frame board (FB), and an application processor (AP) board.

Figure 2 is a schematic diagram of a conventional sandwich structural panel. The sandwich structure board shown in Figure 2 is composed of an AP board 210, a FB board 220 and an RF board 230, and the AP board, FB board and RF board can carry different electronic components 240. The AP board and the FB board, the FB board and the RF board, and the AP board and the RF board can all be connected through the structure 250 . In order to further reduce the internal space of the electronic device, the structure 250 can be further compressed, so that more devices can be placed in the sandwich structure board and other space in the electronic device can be saved.

In the existing process, the processing of the structure 250 can be divided into two types. One is to use a solder mask limited pad design. (Solder-mask defined pad design, SMD), SMD uses green paint/green oil (solder-mask) to cover a larger area of copper foil, and then exposes it at the opening of the green paint (not covered by the green paint) Copper foil is used to form a soldering pad, and the size of the formed soldering pad depends on the size of the solder-mask opening. Using this process can reduce the possibility of welding plates falling off during welding or welding. The other is to use non-solder mask defined (NSMD), also known as copper foil independent pad design (CDPD). This process designs the copper foil to be greener than the solder mask. The openings are even smaller, providing more surface area for solder connections, and the larger gaps between pads allow for wider line widths and more via flexibility. Under normal circumstances, the SMD process is used to process small pads, and the SMD process or NSMD process can be used to process large pads.

The SMD process and the NSMD process will be described below in conjunction with Figures 2 and 3.

Figure 3 is a schematic flow chart of a processing method of a circuit board assembly. Figure 3 shows a schematic cross-sectional view of each step of the SMD process.

301. Obtain the circuit board base 311 and the pad 312 fixed on one side of the circuit board base 311.

The circuit board carrier base 311 can provide mechanical support for the raw material of the circuit board. Electroplating is completed on the outer layer of the circuit board base 311 and the useless copper is etched to expose the useful circuit structure (not shown in the figure) and the pad 312. The circuit structure can be, for example, metal connections, conductive plugs, conductive vias, etc. The pad material can be electronic grade copper foil with a purity of more than 99.7%.

The material of the circuit board base 311 includes prepreg (PP). The prepreg may include, for example, resin and reinforcing materials. The reinforcing materials may include at least one of the following: fiberglass cloth, paper base, composite materials, etc. The material of the circuit board base 311 may also be, for example, metal materials (such as copper, steel, iron, aluminum), glass, organic materials (such as resin), and the like.

302. Coat the solder resist layer 313 on the surface of the circuit board base 311.

A solder resist layer 313 is coated on the surface of the circuit board base 311 and the solder pad 312. The solder resist layer 313 completely covers the surfaces of the circuit board base 311 and the solder pad 312, and the solder resist layer 313 is higher than the solder pad 312 by a certain height. , the height is generally 15μm. The solder resist layer 313 can cover the electrical connection lines on the circuit board to prevent the electrical connection lines from being oxidized when exposed to the air as much as possible. In some examples, the solder resist layer 313 can be coated using general solder resist ink. The solder resist ink is essentially composed of resin, pigments and fillers. The solder resist ink can be, for example, green paint, green oil, or black paint. , black oil, etc. In other examples, the solder resist layer 313 can be made of other dielectric materials, such as epoxy resin (epoxy resin), polyimide (polyimide), polyphenylene oxide (PPE), polypropylene (PP) ), polytetrafluorethylene (PTFE) or polymethyl methacrylate (PMMA).

It should be noted that when the solder resist layer 313 is made of solder resist ink, one or more of the following processes can be used: screen printing and spraying, which is not limited in this application.

303. Expose and develop the solder resist layer 313 to expose the soldering pad 314 to be soldered, and the area of the soldering pad 314 is smaller than the area of the soldering pad 312.

After the solder resist layer 313 is coated on the circuit board base 311 and the solder pad 312, the soldered pads and holes are exposed through operations such as pre-baking, one-time exposure and development, and the solder pads 314 are formed. The other places are still covered with the solder resist layer. Prevent short circuits during welding. In the SMD process, the area of the exposed bonding pad 314 is smaller than the area of the bonding pad 312 .

Through the processing of steps 301 to 303, the first circuit board 310 and the second circuit board 330 can be obtained. The first circuit board 310 includes a circuit board base 311 , a soldering pad 312 fixed on one side of the circuit board base 311 , and a solder resist layer 313 covering the surfaces of the circuit board base 311 and the soldering pad 312 . The second circuit board 330 includes a circuit board base 331 fixed on The solder pad 332 on one side of the circuit board base 331 and the solder resist layer 333 covering the surfaces of the circuit board base 331 and the solder pad 332.

304. Electrically connect the first circuit board 310 and the second circuit board 330 through solder balls 320.

The first circuit board 310 and the second circuit board 330 are connected and fixed through solder balls 320 . One side of the solder ball 320 is in contact with the solder pad 312 on the first circuit board 310, and the other side is in contact with the solder pad 332 on the second circuit board 330. The first circuit board 310 and the second circuit board 330 are pressed by the solder ball 320. Together, the electrical connection between the pad 312 and the pad 332 is achieved. The bonding pad 312 and the bonding pad 332 are made of the same or similar material, and are essentially electronic grade copper foil. The black drum-shaped pattern in Figure 3 represents solder balls 320 for mechanical fixation and/or electrical connection. It should be noted that the solder balls described in this application actually refer to soldering materials that mechanically and/or electrically connect circuit boards to circuit boards, or refer to soldering materials that mechanically connect and/or electrically connect circuit boards and electronic components. The actual shape of the solder ball described in this application is not necessarily spherical, but may be polyhedron, sphere, ellipsoid, truncated cone, chamfer, etc. For the convenience of description, this application refers to various shapes of welding materials as solder balls. Unless otherwise specified, the connection function played by solder balls includes mechanical connection and/or electrical connection. That is, the solder ball connected between the circuit board and the electronic component can represent the mechanical connection and/or the solder ball electrically connected between the circuit board and the electronic component; that is, the solder ball connected between the two circuit boards can represent the solder ball connected between the circuit board and the electronic component. Solder balls that mechanically and/or electrically connect the two circuit boards.

The SMD processing process of the structure 250 in Figure 2 is explained through Figure 3. Combining Figures 2 and 3, it can be seen that the first circuit board 310 and the second circuit board 330 in the circuit board assembly shown in Figure 3 can be made of the same material. . In the sandwich structure board, the first circuit board 310 can be an AP board, and the second circuit board 330 can be an FB board, or the first circuit board 310 can be an FB board, and the second circuit board 330 can be an AP board. board, or the first circuit board 310 can be an FB board, and the second circuit board 330 can be an RF board, or the first circuit board 310 can be an RF board, and the second circuit board 330 can be an FB board, Alternatively, the first circuit board 310 may be an AP board, and the second circuit board 330 may be an RF board, or the first circuit board 310 may be an RF board, and the second circuit board 330 may be an AP board. In addition, the first circuit board The second circuit board may also be a module board, which is not limited in this application.

Figure 4 is a schematic flow chart of another processing method of a circuit board assembly. Figure 4 shows a cross-sectional schematic diagram of each step of the NSMD process.

401. Obtain the circuit board base 411 and the pad 412 fixed on one side of the circuit board base 411.

402. Coat the solder resist layer 413 on the surface of the circuit board base 411.

For the specific implementation of step 401 and step 402, reference can be made to step 301 and step 302 in the embodiment shown in FIG. 3, which will not be described again here.

403. Expose and develop the solder resist layer 413 to expose the soldering pad 414 to be soldered, and the area of the soldering pad 414 is larger than the area of the soldering pad 412.

After the solder resist layer 413 is coated on the circuit board base 411 and the solder pad 412, the soldered pads and holes are exposed through operations such as pre-baking, one-time exposure and development, and the solder pads 414 are formed. The other places are still covered with the solder resist layer. Prevent short circuits during welding. In the NSMD process, the area of the exposed bonding pad 414 is larger than the area of the bonding pad 412 .

Through the processing of steps 401 to 403, the first circuit board 410 and the second circuit board 430 can be obtained. The first circuit board 410 includes a circuit board base 411, a soldering pad 412 fixed on one side of the circuit board base 411, and a solder resist layer 413 covering the surfaces of the circuit board base 411 and the soldering pad 412. The second circuit board 430 includes a circuit board base 431, a soldering pad 432 fixed on one side of the circuit board base 431, and a solder resist layer 433 covering the surfaces of the circuit board base 431 and the soldering pad 432.

404. Electrically connect the first circuit board 410 and the second circuit board 430 through solder balls 420.

For the specific implementation of step 404, reference can be made to step 304 in the embodiment shown in FIG. 3, which will not be described again here.

The NSMD processing process of the structure 250 in Figure 2 is explained through Figure 4. Combining Figures 2 and 4, it can be seen that the first circuit board 410 and the second circuit board 430 in the circuit board assembly shown in Figure 4 can be made of the same material. . in sandwich In the structural board, the first circuit board 410 can be an AP board, and the second circuit board 430 can be a FB board, or the first circuit board 410 can be a FB board, and the second circuit board 430 can be an AP board, Alternatively, the first circuit board 410 may be an FB board, and the second circuit board 430 may be an RF board, or the first circuit board 410 may be an RF board, and the second circuit board 430 may be an FB board, or, The first circuit board 410 may be an AP board, and the second circuit board 430 may be an RF board, or the first circuit board 410 may be an RF board, and the second circuit board 430 may be an AP board. In addition, the first circuit board and the second circuit board 430 may be an AP board. The second circuit board can also be a module board, which is not limited in this application.

It can be seen from Figure 3 and Figure 4 that when the sandwich structure board is processed using the existing SMD process or NSMD process, when the two circuit boards are pressed together, the pressing height is difficult to control, and the pressing height is too small. The electrical connection between them may cause problems and may lead to the risk of virtual soldering, which may cause an unstable connection between the solder ball and the circuit board; the press-fit height is too large, which may cause the solder ball to be over-compressed, thus It may cause the solder ball to break, and two or more solder joints to be connected together by solder, resulting in poor product function and appearance, and tin connection problems. In addition, since the circuit board will expand and contract during processing, it may produce uneven and small warpage, and it is difficult to control the non-tin connection by controlling the force and spacing during lamination. Therefore, although the current industry's highest pad spacing accuracy can reach 0.35mm (drilling size 0.15mm, left and right tolerance 0.1mm), due to tin connection problems, the pad spacing in actual products can usually only reach 0.65mm.

This application provides a circuit board assembly, its processing method, and electronic equipment. The purpose is to reduce the possibility of the lamination height being too small, thereby reducing the possibility of tin connection between two adjacent pads, and improving the circuit board assembly. mechanical stability.

Figures 5 and 9 are schematic structural diagrams of a circuit board assembly provided by embodiments of the present application.

The circuit board assembly 500 includes a first circuit board 510 that includes a circuit board base 511, a pad 512, a conductive member 513, and a plurality of solder resist layers (eg, solder resist layer 514 and solder resist layer 515).

The circuit board base 511 can provide mechanical support for the original material of the circuit board. The material of the circuit board base 511 includes a prepreg. The prepreg can include, for example, resin and reinforcing materials. The reinforcing materials can include at least one of the following: fiberglass cloth, paper. base, composite materials, etc. The material of the circuit board base 511 may also be, for example, metal materials (such as copper, steel, iron, aluminum), glass, organic materials (such as resin), and the like.

The bonding pad 512 and the conductive member 513 are fixed on the same side of the circuit board base 511, and the conductive member 513 is located at the edge of the first circuit board 510 (see Figure 27 for details). The conductive member 513 can be a bonding pad or a conductive layer. The material of the bonding pad 512 and the conductive member 513 can be electronic grade copper foil with a purity of above 99.7%. In a possible implementation, the bonding pad 512 and the conductive member 513 are arranged adjacent to each other.

In one embodiment, the number of conductive members is set relative to the length of the first circuit board 510 , and at least one conductive member is disposed every 15 mm in the length direction of the first circuit board 510 . That is to say, the length of the first circuit board 510 is L, the circuit board assembly 500 may include multiple conductive members, and the number of the multiple conductive members is set to n, then n≥L/L', L' is 15mm, L> 15mm, n is a positive integer.

In one embodiment, the first circuit board 510 further includes a second conductive member. The second conductive member and the first conductive member are disposed on the same side of the circuit board base 511 , and the distance between the first conductive member and the second conductive member is less than 2 mm. For example, the first conductive member may be conductive member 513 .

The plurality of solder resist layers are arranged in a stack. The plurality of solder resist layers at least cover the conductive component 513 on the side of the conductive component 513 away from the circuit board base 511 . The sum of the heights of the plurality of solder resist layers and the conductive component 513 is greater than the height of the pad 512 . height, so that local padding can be performed.

In a possible implementation, the multiple solder resist layers include the solder resist layer 514 and the solder resist layer 515 in FIG. 5 or 9 , the solder resist layer 514 and the pad 512, the conductive member 513 and the circuit board base 511 contact, solder mask 515 covers the conductive 513 and in contact with the solder resist layer 514. In one embodiment, the solder resist 514 contacts the side of the conductive member 513 . In another embodiment, the solder resist layer 514 extends from the circuit board base 511 to a side of the conductive member 513 away from the circuit board base 511 . In addition, the solder resist layer 515 and the conductive member 513 are arranged oppositely, that is, the solder resist layer 515 intersects or overlaps the projected area of the circuit board base 511 and the conductive member 513 in the projected area of the circuit board base 511 .

It should be noted that the height of the solder resist layer 514 and the solder resist layer 515 is between one third of the solder ball height and one half of the solder ball height.

The solder resist layer 514 can be a general solder resist ink, which is essentially composed of resin, pigments and fillers. The solder resist ink can be, for example, green paint, green oil, black paint, black oil, etc. The materials of the solder resist layer 515 include solder resist ink, photoimageable coverlay (PIC) film, and ordinary cover film. By selecting the above materials to provide multiple layers of solder resist, the cost of circuit board processing can be reduced to a certain extent, and the resulting circuit board assembly is relatively thin and light.

It should be understood that when the solder resist layer 514 and the solder resist layer 515 are solder resist ink, one or more of the following processes may be used: screen printing and spraying.

In some embodiments, the material of the solder resist layer 515 can be solder resist ink, the solder resist layer 515 can be set in a cylindrical shape, the diameter of the ink column should be greater than or equal to 200 μm, and the size of the ink column should be smaller than the size of the conductive member 513 that needs to be raised. 50 μm is optimal to avoid alignment tolerances that may cause part of the solder resist layer 515 to not be on the pad, thereby affecting the processing of the circuit board.

In some embodiments, the solder resist layer 515 material can be an ordinary covering film. The ordinary covering film is composed of polyimide (PI) and glue, and can be matched with a thickness of 30 μm ± 3 μm or 35 μm ± 3 μm as required to meet the pad requirements. High demand. During processing, ordinary covering films can be applied using machines. The current extreme accuracy of the left and right tolerances of machine applied films can reach 50μm, which can meet the requirements of the padding process.

In some embodiments, the material of the solder resist layer 515 can be a photoimageable coverlay (PIC) film, which has the same function as the solder resist ink and can play a local padding role. When the solder resist layer 515 is a PIC film, the PIC film can be laid on the entire surface of the solder resist layer 514, and then retained through secondary exposure and development. The thickness of the PIC film can reach more than 20 μm, so that the solder resist layer 514 and the PIC film are The thickness and height are about 20 μm to 40 μm or 25 μm to 45 μm higher than the conductive member 513, thereby meeting the requirements for pad height.

It should be understood that the solder resist layer 515 can be provided in a cylindrical shape, and the adhesion between the cylindrical solder resist layer 515 and the solder resist layer 514 will be stronger, thereby improving the stability of the circuit board assembly.

In a possible implementation, the solder resist layer 514 also covers a partial area of the soldering pad 512 , and the remaining area of the soldering pad is connected to the solder ball 520 . The specific processing method can be referred to FIG. 7 and FIG. 8 and will not be described again here.

The circuit board assembly 500 includes a second circuit board 530 electrically connected to the first circuit board 510 through solder balls 520 and pads 512 . The second circuit board 530 includes a circuit board base 531, a welding pad 532, a welding pad 533 and a solder resist layer 534. The welding pad 533 and the conductive member 513 are relatively arranged. The relative arrangement here can be understood as that the welding pad 533 is on the circuit board base 511. The projected area of the soldering pad 533 on the circuit board base 531 completely overlaps with the projected area of the conductive member 513 on the circuit board base 531 , or the projected area of the soldering pad 533 on the circuit board base 531 completely overlaps with the projected area of the conductive member 513 on the circuit board base 531 . The specific processing method of the second circuit board 530 can be referred to FIG. 3 and will not be described again here. The first circuit board 510 and the second circuit board 530 may be a main board, an AP board, an FB board, an RF board, a module board, etc.

In some embodiments, the solder resist layer 534 on the second circuit board 530 is disposed on a side of the soldering pads 532 and 533 away from the circuit board base 531 and is in contact with the circuit board base 531 , the welding pads 532 and the welding pads 533 . touch. In this case, the total height of the solder resist layer 514 and the solder resist layer 515 on the first circuit board 510 relative to the conductive member 513 is between 20 μm and 40 μm (30 μm is optimal). For details, refer to FIG. 5 .

In some embodiments, the solder resist layer 534 on the second circuit board 530 is disposed in an area outside the pad 533 and is in contact with the solder resist layer 534 . The circuit board base 531 is in contact. In this case, the total height of the solder resist layer 514 and the solder resist layer 515 on the first circuit board 510 relative to the conductive member 513 is between 25 μm and 45 μm (35 μm is optimal). For details, refer to FIG. 9 . With the circuit board structure shown in Figure 9, there is no solder resist layer on the pads on the second circuit board that correspond to the pads that need to be padded on the first circuit board. This can avoid the need to install the solder resist layer. The high tolerance brought by the layer can also improve the welding yield.

It should be understood that the first circuit board base may be the circuit board base 511 , and the second circuit board base may be the circuit board base 531 . The first soldering pad is fixed on the first circuit board 510 and is connected to the soldering pad 532 on the second circuit board 530 through the soldering ball 520 , that is, the first soldering pad may be the soldering pad 512 . The first conductive member is a conductive layer or pad that needs to be partially elevated, that is, the first conductive member may be the conductive member 513 . The plurality of solder resist layers may include a solder resist layer 514 and a solder resist layer 515, where the solder resist layer 515 is a newly added solder resist layer. The second soldering pad is fixed on the second circuit board 530 and is arranged opposite to the first conductive member, that is, the second soldering pad may be the soldering pad 533 . The third solder resist layer is a solder resist layer covering the second circuit board, that is, the third solder resist layer may be the solder resist layer 534 .

It should be noted that multiple solder resist layers can provide a high degree of bottom line support for circuit board lamination. The solder resist layer 514 and the solder resist layer 515 are height limiting layers for the lamination process. The solder resist layer 514 and the solder resist layer 515 are height limiting layers for the lamination process. The height satisfies that during the lamination process of the first circuit board 510 and the second circuit board 530, two adjacent solder balls are spaced apart. It should be understood that a plurality of solder balls can be disposed between the first circuit board 510 and the second circuit board 530 , and the plurality of solder balls are separated by the conductive member 512 , the solder resist layer 514 and the solder resist layer 515 . In this way, by providing the newly added solder resist layer 515, tin connection between two adjacent solder balls can be avoided.

The circuit board assembly 500 is first entirely covered with a solder resist layer and processed using the SMD process, and then the conductive parts (for example, pads) in the circuit board are selected for local padding, which is beneficial to reducing the possibility of the pads falling off, and can be a sandwich The structural board provides strong bottom line support, thereby reducing the possibility of excessive compression of the solder balls and reducing soldering problems. At the same time, it can also reduce the pad spacing on the sandwich board motherboard from 0.65mm to 0.5mm or even 0.4mm, increasing the layout space inside the circuit board and helping to miniaturize electronic equipment.

It should be understood that there is a certain relationship between the pressing height of the solder ball and the left and right width values of the solder ball when it is squeezed, so that the problem of solder connection between the solder balls can be controlled based on the pressing height. When the solder ball between the circuit boards is squeezed, the solder ball is pressed from a spherical shape to a drum shape. The upper and lower height of the solder ball will decrease, while the left and right width will increase. The volume of the spherical cap formed by being squeezed up, down, and left is approximately equal. The total volume of the solder ball remains constant during the extrusion process. When the distance between solder balls is smaller than the lateral diameter of the solder balls, tin connection problems may occur.

As shown in Figure 6, Figure 6 shows a schematic side view of the solder ball when it is squeezed. The shape of the solder ball shown in Figure 6 is spherical.

When the solder ball is not squeezed, the radius of the solder ball is R. When the solder ball is squeezed, the upper and lower distance d of the solder ball, the height EF of the spherical cap formed by extrusion is h, and the center radius of the spherical cap is r.

The calculation formula of the solder ball volume when not squeezed is:

The volume of the cylindrical part formed by the extrusion of the solder ball is:
V _column =π*BC ² *d (Formula 2)

The formula for calculating the volume of the spherical crown is:

According to the principle that the total volume of the solder ball remains unchanged, the following calculation formula can be obtained:
V _ball - V _column = 2V _crown (Formula 5)

In ΔAFG, according to the Pythagorean theorem we can get:

Combining Formula 5 and Formula 6, we can get:
4h ³ +3hd ² =16R ³ -12dR ² +3d ³ (Formula 7)

According to Formula 7, it can be seen that since the solder ball radius R is determined, there is a certain relationship between the ball crown height h and the solder ball pressing height d. Therefore, when pressing two circuit boards, the pressing height can be determined according to the Settings to control the problem of solder ball connection.

At present, in order to solve the soldering problem of small-pitch pads, a feasible idea is to add a layer of spacers with a height of 20 μm to 50 μm higher than the pad in the middle layer of the sandwich structure board, so as to avoid the soldering problem as much as possible. However, the addition of gaskets will increase the preparation process and the cost of PCB. Another feasible idea is to use the ink padding process and choose to make an ink padding ring directly on the local pad to avoid tin connection problems as much as possible. However, the padding ink ring has the risk of falling off easily and has low reliability. There is an alignment deviation when the ink ring is raised, which may result in insufficient soldering area of the pad, leading to the risk of virtual soldering. In addition, after the ink is raised, the warpage of the PCB board will become larger using the same stress relief method. Failure to use reasonable lamination and stress relief methods will lead to false soldering during welding.

In the embodiment of the present application, multiple layers of solder resist are selected at local points, and the solder resist can be set in a cylindrical shape. While functioning as a height limiter, it will also be more stable and less likely to fall off, so that the third layer can be controlled. The distance between the first circuit board and the second circuit board prevents tin connection problems caused by too low a lamination height, thereby increasing the mechanical stability of the circuit board assembly. In addition, in the embodiments of this application, the solder resist layer material can be any of the following: solder resist ink, photosensitive development cover film PIC, or ordinary cover film, which can reduce processing costs and the resulting circuit board assembly will be relatively thin and light.

Various possible processing methods of the circuit board assembly 500 shown in FIG. 5 are explained below through FIGS. 7 and 8 .

FIG. 7 is a processing method of the circuit board assembly 500 shown in FIG. 5 .

701. Obtain the circuit board base 511 and the soldering pad 512 and conductive member 513 fixed on one side of the circuit board base 511.

702. Coat the solder resist layer 514 on the surface of the circuit board base 511.

703. Expose and develop the solder resist layer 514 to expose the soldering pad 710 to be soldered, and the area of the soldering pad 710 is smaller than the area of the soldering pad 512.

For specific implementation methods of steps 701 to 703, reference can be made to steps 301 to 303 in the embodiment shown in FIG. 3, and there is no need to repeat them here.

704. Set the solder resist layer 515 on the side of the solder resist layer 514 away from the circuit board base 511.

The material of the solder resist layer 515 may be a PIC film or solder resist ink coated on the entire board. The PIC film or the whole-board solder resist ink is entirely covered on the side of the solder resist layer 514 away from the circuit board base 511 , that is, the PIC film or the whole-board solder resist ink is combined with the solder resist layer 514 and the circuit board base 511 direct contact.

705 , the solder resist layer 515 is exposed and developed, and the solder resist layer 515 located directly above the conductive member 513 is retained.

It should be noted that the solder resist layer 515 and the conductive member 513 are arranged oppositely, that is, the solder resist layer 515 intersects or overlaps the projected area of the circuit board base 511 and the conductive member 513 in the projected area of the circuit board base 511 . Set like this It can be ensured that the solder resist layer 515 can completely cover the conductive component 513 and the solder resist ink 514, and be in complete contact with the solder resist layer 514, thereby avoiding the left and right alignment tolerances causing the solder resist layer 515 to fall into the unpadded area and affect the circuit. Processing and use of boards.

706. Electrically connect the first circuit board 510 and the second circuit board 530 through the solder balls 520.

The second circuit board 530 and the first circuit board 510 are pressed together, so that the second circuit board 530 is electrically connected to the first circuit board 510 through the solder balls 520 and the pads 512 . Among them, the multiple solder resist layers are height limiting layers for the lamination process, and the heights of the multiple solder resist layers meet the requirements. During the lamination process of the first circuit board 510 and the second circuit board 530, two adjacent solder balls are Spaced out. It should be understood that a plurality of solder balls can be disposed between the first circuit board 510 and the second circuit board 530 , and the plurality of solder balls are separated by the conductive member 512 , the solder resist layer 514 and the solder resist layer 515 . In this way, by providing the newly added solder resist layer 515, tin connection between two adjacent solder balls can be avoided.

The specific implementation of step 706 may refer to step 304 in the embodiment shown in FIG. 3 , and there is no need to repeat it here.

FIG. 8 is another processing method of the circuit board assembly 500 shown in FIG. 5 .

801. Obtain the circuit board base 511 and the soldering pad 512 and conductive member 513 fixed on one side of the circuit board base 511.

802. Coat the solder resist layer 514 on the surface of the circuit board base 511.

803. Expose and develop the solder resist layer 514 to expose the soldering pad 810 to be soldered, and the area of the soldering pad 810 is smaller than the area of the soldering pad 512.

For specific implementation methods of steps 801 to 803, reference can be made to steps 301 to 303 in the embodiment shown in FIG. 3, and there is no need to repeat them here.

804. Set the solder resist layer 515 on the side of the solder resist layer 514 away from the circuit board base 511.

The material of the solder resist layer 515 may be partially applied solder resist ink or a common cover film. If the solder resist layer 515 is partially coated solder resist ink, the solder resist layer 515 can be fixed on the side of the solder resist layer 514 away from the circuit board base 511 by using double exposure and development. If the solder resist layer 515 is a common covering film, a machine can be used to apply the film, so that the solder resist layer 515 is fixed on the side of the solder resist layer 514 away from the circuit board base 511 .

It should be noted that the solder resist layer 515 and the conductive member 513 are arranged oppositely, that is, the solder resist layer 515 intersects or overlaps the projected area of the circuit board base 511 and the conductive member 513 in the projected area of the circuit board base 511 . This arrangement can ensure that the solder resist layer 515 can completely cover the conductive member 513 and the solder resist ink 514, and fully contact the solder resist layer 514, thereby avoiding the left and right alignment tolerances causing the solder resist layer 515 to fall into the unraised area. This affects the use and processing of circuit boards.

805. Electrically connect the first circuit board 510 and the second circuit board 530 through the solder balls 520.

The second circuit board 530 and the first circuit board 510 are pressed together, so that the second circuit board 530 is fixedly connected to the first circuit board 510 through the solder balls 520 and the pads 512, wherein the plurality of solder resist layers are formed by a lamination process. The height limiting layer meets the height of the multiple solder resist layers. During the lamination process of the first circuit board 510 and the second circuit board 530, two adjacent solder balls are spaced apart. It should be understood that a plurality of solder balls can be disposed between the first circuit board 510 and the second circuit board 530 , and the plurality of solder balls are separated by the conductive member 512 , the solder resist layer 514 and the solder resist layer 515 . In this way, by providing the newly added solder resist layer 515, tin connection between two adjacent solder balls can be avoided.

The specific implementation of step 805 may refer to step 304 in the embodiment shown in FIG. 3 , and there is no need to repeat it here.

Through the processing method shown in Figure 7 or Figure 8, first apply a solder resist layer on the entire circuit board to isolate the electrical connection lines on the circuit board, so as to avoid oxidation of the electrical connection lines when exposed to the air as much as possible, and at the same time It can also reduce the possibility of the welding board falling off during welding or welding; then, by selecting conductive parts at appropriate locations for local padding, the height tolerance of the circuit board when padding is within a certain error range, which is more conducive to the circuit board. processing.

Figures 10 and 11 are schematic structural diagrams of another circuit board assembly provided by an embodiment of the present application.

The circuit board assembly 900 includes a first circuit board 910 that includes a circuit board base 911, a pad 912, a conductive member 913, and a plurality of solder resist layers (eg, solder resist layer 914 and solder resist layer 915).

The bonding pad 912 and the conductive member 913 are fixed on the same side of the circuit board base 911, and the conductive member 913 is located at the edge of the first circuit board 910 (see Figure 27 for details). The conductive component 913 can be a soldering pad or a conductive layer. The material of the soldering pad 912 and the conducting component 913 can be electronic grade copper foil with a purity of above 99.7%. In a possible implementation, the bonding pad 912 and the conductive member 913 are arranged adjacent to each other.

In one embodiment, the number of conductive members is set relative to the length of the first circuit board 910 , and at least one conductive member is disposed every 15 mm in the length direction of the first circuit board 910 . That is to say, the length of the first circuit board 910 is L, the circuit board assembly 900 may include multiple conductive members, and the number of the multiple conductive members is set to n, then n≥L/L', L' is 15mm, L> 15mm, n is a positive integer.

In one embodiment, the first circuit board 910 further includes a second conductive member. The second conductive member and the first conductive member are disposed on the same side of the circuit board base 911. The distance between the first conductive member and the second conductive member is less than 2 mm. For example, the first conductive member may be conductive member 913 .

Multiple solder resist layers are arranged in a stack. The multiple solder resist layers at least cover the conductive component 913 on the side of the conductive component 913 away from the circuit board base 911. The sum of the heights of the solder resist layer 914, the solder resist layer 915 and the conductive component 913 is greater than the height of the solder resist layer 914, the solder resist layer 915, and the conductive component 913. The height of the disk 912 can be partially raised.

In a possible implementation, the multiple solder resist layers include the solder resist layer 914 and the solder resist layer 915 in FIG. 10 or 11 . The solder resist layer 914 covers the conductive component 913 and is connected with the conductive component 913 and the circuit board substrate. 911 is in contact with each other, and the solder resist layer 914 is located between the solder resist layer 915 and the conductive component 913 , that is, the solder resist layer 915 is in contact with the solder resist layer 914 and covers the conductive component 913 .

In one embodiment, the solder mask 914 contacts the side of the conductive member 913 .

In another embodiment, the solder resist layer 914 extends from the circuit board base 911 to a side of the conductive member 913 away from the circuit board base 911 .

In addition, the solder resist layer 915 and the conductive member 913 are arranged oppositely, that is, the solder resist layer 915 intersects or overlaps the projected area of the circuit board base 911 and the conductive member 913 in the projected area of the circuit board base 911 . This arrangement can prevent the solder resist layer 915 from falling into the gap or covering other pads, which may affect the processing of the circuit board and the performance of the circuit board.

It should be understood that the solder resist layer 915 can be provided in a cylindrical shape, and the adhesion between the cylindrical solder resist layer 915 and the solder resist layer 914 will be stronger, thereby improving the stability of the circuit board assembly.

Optionally, the height of the solder resist layer 914 and the solder resist layer 915 is between one third of the solder ball height and one half of the solder ball height.

Among them, the solder resist layer 914 can be a general solder resist ink, and the material of the solder resist layer 915 includes solder resist ink, PIC film, and ordinary cover film. By selecting the above materials to provide multiple layers of solder resist, the cost of circuit board processing can be reduced to a certain extent, and the resulting circuit board assembly is relatively thin and light.

It should be understood that when the solder resist layer 914 and the solder resist layer 915 are solder resist ink, one or more of the following processes may be used: screen printing and spraying.

In a possible implementation, the solder resist layer 914 is disposed outside the spacing area between the conductive member 913 and the bonding pad 912 .

The circuit board assembly 900 further includes a second circuit board 930 , and the second circuit board 930 is electrically connected to the first circuit board 910 through solder balls 920 and pads 912 . The second circuit board 930 includes a circuit board base 931, a soldering pad 932, and a soldering pad 933. The solder resist layer 934, the pad 933 and the conductive member 913 are arranged relative to each other. The relative arrangement here can be understood as the projection area of the soldering pad 933 on the circuit board base 911 completely overlaps with the projection area of the conductive member 913 on the circuit board base 911. Alternatively, the projected area of the soldering pad 933 on the circuit board base 931 and the projected area of the conductive member 913 on the circuit board base 931 completely overlap. The specific processing method of the second circuit board 930 can be referred to FIG. 4 and will not be described again here. The first circuit board 910 and the second circuit board 930 may be a main board, an AP board, an FB board, an RF board, a module board, etc.

In some embodiments, the solder resist layer 934 on the second circuit board 930 is disposed on a side of the soldering pads 932 and 933 away from the circuit board base 931 and in contact with the circuit board base 931 and the soldering pads 933 . In this case, the total height of the solder resist layer 914 and the solder resist layer 915 on the first circuit board 910 relative to the conductive member 913 is between 20 μm and 40 μm (30 μm is optimal). For details, refer to FIG. 10 .

In some embodiments, the solder resist layer 934 on the second circuit board 930 is disposed in an area other than the solder pads 932 and 933 and is in contact with the circuit board base 931 . In this case, the total height of the solder resist layer 914 and the solder resist layer 915 on the first circuit board 910 relative to the conductive member 913 is between 25 μm and 45 μm (35 μm is optimal). When the second circuit board 930 is processed using the NSMD process, the local padding position may refer to Figure 11 (the solder resist layer 934 is not shown). With the circuit board structure shown in Figure 11, no solder resist layer is provided on the pads on the second circuit board that correspond to the pads that need to be padded on the first circuit board. This can avoid the need to install the solder resist layer. The high tolerance brought by the layer can also improve the welding yield.

It should be understood that the first circuit board base may be the circuit board base 911 , and the second circuit board base may be the circuit board base 931 . The first soldering pad is fixed on the first circuit board 910 and is connected to the soldering pad 932 on the second circuit board 930 through the soldering ball 920 , that is, the first soldering pad may be the soldering pad 912 . The first conductive member is a conductive layer or pad that needs to be partially elevated, that is, the first conductive member may be the conductive member 913 . The multiple solder resist layers may include a solder resist layer 914 and a solder resist layer 915, where the solder resist layer 915 is a newly added solder resist layer. The second soldering pad is fixed on the second circuit board 930 and is arranged opposite to the first conductive member, that is, the second soldering pad may be the soldering pad 933 . The third solder resist layer is a solder resist layer covering the second circuit board, that is, the third solder resist layer may be the solder resist layer 934 .

It should be noted that the solder resist layer 914 and the solder resist layer 915 can provide a high bottom line support for the circuit board lamination. The solder resist layer 914 and the solder resist layer 915 are height limiting layers for the lamination process. The solder resist layer 914 and The height of the solder resist layer 915 is such that during the lamination process of the first circuit board 910 and the second circuit board 930, two adjacent solder balls are spaced apart. It should be understood that a plurality of solder balls may be disposed between the first circuit board 910 and the second circuit board 930 , and the plurality of solder balls are separated by the conductive member 912 , the solder resist layer 914 and the solder resist layer 915 . In this way, by providing the newly added solder resist layer 915, tin connection between two adjacent solder balls can be avoided.

The processing method of the circuit board assembly 900 can refer to FIG. 7 and FIG. 8 . The difference from FIG. 7 or FIG. 8 lies in step 703 and step 803 . Specifically, the circuit board assembly 500 is processed by SMD, and the circuit board assembly 900 is processed by NSMD.

The difference between the circuit board assembly 900 shown in FIG. 10 and the circuit board assembly 500 shown in FIG. 5 or the circuit board assembly 900 shown in FIG. 11 and the circuit board assembly 500 shown in FIG. 9 is that in the circuit board assembly 900 , the solder resist layer 914 is disposed outside the spacing area between the conductive member 913 and the pad 912 (processed using the NSMD process). In the circuit board assembly 500, the solder resist layer 514 covers part of the pad 512, and the remaining area of the pad 512 is connected to the solder ball 520 (processed using the SMD process).

The circuit board assembly 900 first sets the solder resist layer as a whole and processes it using the NSMD process, and then selects conductive parts (for example, solder pads) in the circuit board for local padding, which can provide a larger surface area for solder joint connections, and the solder pads A larger gap between allows for wider line widths and more via flexibility. In addition, the circuit board assembly 900 can also be used for three Meiji structural boards provide strong bottom line support, thereby reducing the possibility of excessive compression of solder balls and reducing soldering problems. At the same time, it can also reduce the pad spacing on the sandwich board motherboard from 0.65mm to 0.5mm or even 0.4mm, increasing the layout space inside the circuit board and helping to miniaturize electronic equipment.

Figures 12 and 13 are schematic structural diagrams of another circuit board assembly provided by embodiments of the present application.

The circuit board assembly 1000 includes a first circuit board 1010. The first circuit board 1010 includes a circuit board base 1011, a pad 1012, a conductive member 1013, and a plurality of solder resist layers (eg, solder resist layer 1014 and solder resist layer 1015).

The pad 1012 and the conductive member 1013 are fixed on the same side of the circuit board base 1011, and the conductive member 1013 is located at the edge of the first circuit board 1010 (see Figure 27 for details). Alternatively, the conductive member 1013 may be a bonding pad or a conductive layer, and the bonding pad 1012 and the conductive member 1013 are arranged adjacently.

The solder resist layer 1014 and the solder resist layer 1015 are stacked. The solder resist layer 1014 is in contact with the conductive component 1013 and is located between the solder resist layer 1015 and the conductive component 1013 . The solder resist layer 1015 covers the conductive component 1012 and is in contact with the circuit board base 1011 and the solder resist layer 1014 . The sum of the heights of the solder resist layer 1014, the solder resist layer 1015 and the conductive member 1013 is greater than the height of the pad 1012, so that local padding processing can be performed.

In one embodiment, the solder mask 1015 is in contact with the side of the conductive member 1013 .

In another embodiment, the solder resist layer 1015 extends from the circuit board base 1011 to a side of the conductive member 1013 away from the circuit board base 1011 .

It should be understood that the solder resist layer 1014 can be arranged in a cylindrical shape, and the adhesion between the cylindrical solder resist layer 1014 and the solder resist layer 1015 will be stronger, thereby improving the stability of the circuit board assembly.

In one embodiment, the number of conductive members 1013 is set relative to the length of the first circuit board 1010, and at least one conductive member is disposed every 15 mm in the length direction of the first circuit board 1010. That is to say, the length of the first circuit board 1010 is L, the circuit board assembly 1000 may include multiple conductive parts, and the number of the multiple conductive parts is set to n, then n≥L/L', L' is 15mm, L> 15mm, n is a positive integer.

In one embodiment, the first circuit board 1010 further includes a second conductive member, the second conductive member and the first conductive member are disposed on the same side of the circuit board base 1011, and the distance between the first conductive member and the second conductive member is less than 2 mm. For example, the first conductive member may be conductive member 1013.

It should be noted that the solder resist layer 1014 and the conductive component 1013 are arranged oppositely, that is, the solder resist layer 1014 intersects or overlaps the projected area of the circuit board base 1011 and the conductive component 1013 in the projected area of the circuit board base 1011 . This arrangement can prevent the solder resist layer 1014 from falling into the gap or covering other pads, which may affect the processing of the circuit board and the performance of the circuit board.

Optionally, the height of the solder resist layer 1014 and the solder resist layer 1015 is between one third of the solder ball height and one half of the solder ball height.

Among them, the solder resist layer 1015 can be a general solder resist ink; the material of the solder resist layer 1014 includes solder resist ink, PIC film, and ordinary cover film. By selecting the above materials to provide multiple layers of solder resist, the cost of circuit board processing can be reduced to a certain extent, and the resulting circuit board assembly is relatively thin and light.

It should be understood that when the solder resist layer 1014 and the solder resist layer 1015 are solder resist ink, one or more of the following processes may be used: screen printing and spraying.

In a possible implementation, the solder resist layer 1015 also covers a partial area of the soldering pad 1012 , and the remaining area of the soldering pad 1012 is connected to the solder ball 1020 .

The circuit board assembly 1000 also includes a second circuit board 1030, and the second circuit board 1030 is electrically connected to the first circuit board 1010 through solder balls 1020 and pads 1012. The second circuit board 1030 includes a circuit board base 1031, a soldering pad 1032, and a soldering pad 1032. The pad 1033 and the solder resist layer 1034, and the pad 1033 and the conductive member 1013 are relatively arranged. The relative arrangement here can be understood that the projection area of the soldering pad 1033 on the circuit board base 1011 is completely consistent with the projection area of the conductive member 1013 on the circuit board base 1011. Overlap, or the projected area of the soldering pad 1033 on the circuit board base 1031 completely overlaps the projected area of the conductive member 1013 on the circuit board base 1031 . The specific processing method of the second circuit board 1030 can be referred to FIG. 3 and will not be described again here. The first circuit board 1010 and the second circuit board 1030 may be a main board, an AP board, a FB board, an RF board, a module board, etc.

In some embodiments, the solder resist layer 1034 on the second circuit board 1030 is disposed on a side of the soldering pads 1032 and 1033 of the second circuit board 1030 away from the circuit board base 1031 and is soldered to the circuit board base 1031 and 1033 . Pad 1032 and pad 1033 are in contact. In this case, the total height of the solder resist layer 1014 and the solder resist layer 1015 on the first circuit board 1010 relative to the conductive member 1013 is between 20 μm and 40 μm (30 μm is optimal). For details, refer to FIG. 12 .

In some embodiments, the solder resist layer 1034 on the second circuit board 1030 is disposed in an area outside the soldering pad 1033 and is in contact with the circuit board base 1031 and the soldering pad 1032 . In this case, the total height of the solder resist layer 1014 and the solder resist layer 1015 on the first circuit board 1010 relative to the conductive member 1013 is between 25 μm and 45 μm (35 μm is optimal). For details, refer to FIG. 13 . With the circuit board structure shown in Figure 13, no solder resist layer is provided on the pads on the second circuit board that correspond to the pads on the first circuit board that need to be padded. This can avoid the need to install the solder resist layer. The high tolerance brought by the layer can also improve the welding yield.

It should be understood that the first circuit board base may be the circuit board base 1011 , and the second circuit board base may be the circuit board base 1031 . The first soldering pad is fixed on the first circuit board 1010 and is connected to the soldering pad 1032 on the second circuit board 1030 through solder balls 1020, that is, the first soldering pad may be the soldering pad 1012. The first conductive member is a conductive layer or pad that needs to be partially elevated, that is, the first conductive member may be the conductive member 1013 . The multiple solder resist layers may include a solder resist layer 1014 and a solder resist layer 1015, where the solder resist layer 1014 is a newly added solder resist layer. The second soldering pad is fixed on the second circuit board 1030, and is arranged opposite to the first conductive member, that is, the second soldering pad may be the soldering pad 1033. The third solder resist layer is a solder resist layer covering the second circuit board, that is, the third solder resist layer may be the solder resist layer 1034 .

It should be noted that the multiple solder resist layers (solder resist layer 1014 and solder resist layer 1015) are height limiting layers for the lamination process, and the heights of the multiple solder resist layers satisfy that the first circuit board 1010 and the second circuit board During the 1030 lamination process, two adjacent solder balls are spaced apart. It should be understood that multiple solder balls may be disposed between the first circuit board 1010 and the second circuit board 1030, and the multiple solder balls are separated by the conductive member 1013, the solder resist layer 1014 and the solder resist layer 1015. In this way, by providing the new solder resist layer 1014, tin connection between two adjacent solder balls can be avoided.

The difference between the circuit board assembly 1000 shown in FIG. 12 and the circuit board assembly 500 shown in FIG. 5 or the circuit board assembly 1000 shown in FIG. 13 and the circuit board assembly 500 shown in FIG. 9 lies in the processing of the circuit board assembly 1000. The method is to first set the solder resist layer 1014 on one side of the circuit board base 1011 and the conductive member 1012, and then set the solder resist layer 1015 on the side of the solder resist layer 1014 away from the circuit board base 1011, and the solder resist layer 1014 is a partial pad. High solder mask. In other words, the circuit board assembly 1000 first partially sets the solder resist layer 1014, which is in direct contact with the conductive member 1013, and then sets the solder resist layer 1015 as a whole, and the solder resist layer 1015 is connected with the solder resist layer 1014, the pad 1012 and the circuit board. The surface of the substrate 1011 is in direct contact. The circuit board assembly 500 is first provided with a solder resist layer 514 as a whole. The solder resist layer 514 is in direct contact with the conductive member 513 and the circuit board base 511. Then, a high resistance layer is selectively placed on the side of the solder resist layer 514 away from the circuit board base 511. Solder layer 515.

The circuit board assembly 1000 first selects the conductive parts (for example, solder pads) in the circuit board for local padding, and then completely covers the solder resist layer and processes it using the SMD process, thereby ensuring that the solder resist layer in the padded area is not easy to fall off. Have better stability. In addition, the circuit board assembly 1000 can also provide strong bottom line height support for the sandwich structure board, thereby reducing the possibility of excessive compression of the solder balls and reducing the probability of soldering problems. Also possible The pad spacing on the sandwich board motherboard is reduced from 0.65mm to 0.5mm or even 0.4mm, which increases the layout space inside the circuit board and helps the miniaturization of electronic equipment.

FIG. 14 is a method of processing the circuit board assembly 1000 shown in FIG. 12 .

1401. Obtain the circuit board base 1011 and the soldering pad 1012 and conductive member 1013 fixed on one side of the circuit board base 1011.

The specific implementation of step 1401 may refer to step 301 in the embodiment shown in FIG. 3 , and there is no need to repeat it here.

1402. Set the solder resist layer 1014 on the surface of the circuit board base 1011.

The material of the solder resist layer 1014 can be solder resist ink or a common cover film. If the solder resist layer 1014 is solder resist ink, exposure and development can be used to fix the solder resist layer 1014 on the side of the conductive component 1013 away from the circuit board base 1011 . If the solder resist layer 1014 is a common covering film, a machine can be used to apply the film, so that the solder resist layer 1014 is fixed on the side of the conductive member 1013 away from the circuit board base 1011 .

The material of the solder resist layer 1014 can also be a PIC film. If the solder resist layer 1014 is a PIC film, the solder resist layer 1014 can be integrally disposed on the circuit board base 1011 and in contact with the conductive component 1013 and the circuit board base 1011 . The solder resist layer 1014 (made of PIC film) is fixed on the side of the conductive member 1013 away from the circuit board base 1011 by exposure and development.

It should be noted that the solder resist layer 1014 and the conductive component 1013 are arranged oppositely, that is, the solder resist layer 1014 intersects or overlaps the projected area of the circuit board base 1011 and the conductive component 1013 in the projected area of the circuit board base 1011 . Such an arrangement can ensure that the solder resist layer 1014 can completely cover the conductive member 1013 and the solder resist ink 1014, and be in complete contact with the solder resist layer 1014, thereby avoiding the left and right alignment tolerance causing the solder resist layer 1014 to fall into the unraised area. This affects the processing and use of circuit boards.

1403. Coat the solder resist layer 1015 on the surface of the solder resist layer 1014 and the circuit board base 1011.

1404. Expose and develop the solder resist layer 1015 to expose the soldering pad 1410 to be soldered, and the area of the soldering pad 1110 is smaller than the area of the soldering pad 1012.

For specific implementation methods of step 1403 and step 1404, reference can be made to step 302 and step 303 in the embodiment shown in FIG. 3, and there is no need to repeat them here.

1405. Electrically connect the first circuit board 1010 and the second circuit board 1030 through the solder balls 1020.

The second circuit board 1020 and the first circuit board 1010 are pressed together, so that the second circuit board 1030 is electrically connected to the first circuit board 1010 through the solder balls 1020 and the pads 1012, wherein the plurality of solder resist layers are pressed together The height limiting layer of the process is satisfied by multiple solder resist layers. During the lamination process of the first circuit board 1010 and the second circuit board 1030, two adjacent solder balls are spaced apart. It should be understood that multiple solder balls may be disposed between the first circuit board 1010 and the second circuit board 1030, and the multiple solder balls are separated by the conductive member 1013, the solder resist layer 1014 and the solder resist layer 1015. In this way, by providing the new solder resist layer 1014, tin connection between two adjacent solder balls can be avoided.

The specific implementation of step 1405 may refer to step 304 in the embodiment shown in FIG. 3, and there is no need to repeat it here.

Through the processing method shown in Figure 14, first select conductive parts to partially raise the solder mask layer, and then apply the solder mask layer on the entire circuit board, which can further ensure that the solder mask layer at the local raised position is not easy to fall off, thereby making the circuit The board assembly has better stability. In addition, the processing method shown in Figure 14 can also make the height tolerance of the circuit board when it is raised within a certain error range, which is more conducive to the processing of the circuit board.

Figures 15 and 16 are schematic structural diagrams of another circuit board assembly provided by embodiments of the present application.

The circuit board assembly 1200 includes a first circuit board 1212 that includes a circuit board base 1211, a pad 1212, a conductive member 1213, and a plurality of solder resist layers (eg, solder resist layer 1214 and solder resist layer 1215).

The pad 1212 and the conductive member 1213 are fixed on the same side of the circuit board base 1211, and the conductive member 1213 is located on the first circuit The edge position of the plate 1210 (see Figure 27 for details). The conductive member 1213 may be a bonding pad or a conductive layer. In a possible implementation, the bonding pad 1212 and the conductive member 1213 are arranged adjacent to each other.

The solder resist layer 1214 and the solder resist layer 1215 are stacked and arranged in a stacked manner. The solder resist layer 1214 is in contact with the conductive component 1213 and is located between the solder resist layer 1215 and the conductive component 1213 . The solder resist layer 1215 covers the conductive member 1213 and is in contact with the circuit board base 1211 and the solder resist layer 1214. The sum of the heights of the solder resist layer 1214, the solder resist layer 1215 and the conductive member 1213 is greater than the height of the pad 1212, so that local padding processing can be performed.

In one embodiment, the solder resist 1215 contacts the side of the conductive member 1213 .

In another embodiment, the solder resist layer 1215 extends from the circuit board base 1211 to a side of the conductive member 1213 away from the circuit board base 1211 .

It should be understood that the solder resist layer 1214 can be arranged in a cylindrical shape, and the adhesion between the cylindrical solder resist layer 1214 and the solder resist layer 1215 will be stronger, thereby improving the stability of the circuit board assembly.

In one embodiment, the number of conductive members is set relative to the length of the first circuit board 1210, and at least one conductive member is provided every 15 mm in the length direction of the first circuit board 1210. That is to say, the length of the first circuit board 1210 is L, the circuit board assembly 1200 may include multiple conductive members, and the number of the multiple conductive members is set to n, then n≥L/L', L' is 15mm, L> 15mm, n is a positive integer.

In one embodiment, the first circuit board 1210 further includes a second conductive member. The second conductive member and the first conductive member are disposed on the same side of the circuit board base 1211. The distance between the first conductive member and the second conductive member is less than 2 mm. For example, the first conductive member may be conductive member 1213.

It should be noted that the solder resist layer 1214 and the conductive member 1213 are arranged oppositely, that is, the solder resist layer 1214 intersects or overlaps the projected area of the circuit board base 1211 and the conductive member 1213 in the projected area of the circuit board base 1211 . This arrangement can prevent the solder resist layer 1214 from falling into the gap or covering other pads, which may affect the processing of the circuit board and the performance of the circuit board.

Optionally, the height of the solder resist layer 1214 and the solder resist layer 1215 is between one third of the solder ball height and one half of the solder ball height.

Among them, the solder resist layer 1215 can be a general solder resist ink; the material of the solder resist layer 1214 includes solder resist ink, PIC film, and ordinary cover film. By selecting the above materials to provide multiple layers of solder resist, the cost of circuit board processing can be reduced to a certain extent, and the resulting circuit board assembly is relatively thin and light.

It should be understood that when the solder resist layer 1214 and the solder resist layer 1215 are solder resist ink, one or more of the following processes may be used: screen printing and spraying.

In a possible implementation, the solder resist layer 1215 is disposed outside the spacing area between the conductive member 1213 and the pad 1212 .

The circuit board assembly 1200 also includes a second circuit board 1230 , and the second circuit board 1230 is electrically connected to the first circuit board 1212 through solder balls 1220 and pads 1212 . The second circuit board 1230 includes a circuit board base 1231, a welding pad 1232, a welding pad 1233 and a solder resist layer 1234. The welding pad 1233 and the conductive member 1213 are relatively arranged. The relative arrangement here can be understood as the welding pad 1233 is on the circuit board base. The projected area of 1211 completely overlaps with the projected area of conductive component 1213 on circuit board base 1211, or the projected area of pad 1233 on circuit board base 1231 completely overlaps the projected area of conductive component 1213 on circuit board base 1231. The specific processing method of the second circuit board 1230 can be referred to FIG. 4 and will not be described again here. The first circuit board 1210 and the second circuit board 1230 may be a main board, an AP board, an FB board, an RF board, a module board, etc.

In some embodiments, the solder mask layer 1234 on the second circuit board 1230 contacts the circuit board base 1231 and the pad 1233 . In this case, the solder resist layer 1214 and the solder resist layer 1215 on the first circuit board 1210 are relative to the conductive member 1213 The total height is between 20μm and 40μm (30μm is optimal), please refer to Figure 15 for details.

In some embodiments, the solder resist layer 1234 on the second circuit board 1230 is disposed in an area other than the pad 1233 and is in contact with the circuit board base 1231 . In this case, the total height of the solder resist layer 1214 and the solder resist layer 1215 on the first circuit board 1210 relative to the conductive member 1213 is between 25 μm and 45 μm (35 μm is optimal). When the second circuit board 1230 is processed using the NSMD process, the local padding position may refer to Figure 16 (the solder resist layer 1234 is not shown). With the circuit board structure shown in Figure 16, no solder resist layer is provided on the pads on the second circuit board that correspond to the pads that need to be raised on the first circuit board. This can avoid the need to install the solder resist layer. The high tolerance brought by the layer can also improve the welding yield.

It should be understood that the first circuit board base may be the circuit board base 1211 and the second circuit board base may be the circuit board base 1231. The first soldering pad is fixed on the first circuit board 1210 and is connected to the soldering pad 1232 on the second circuit board 1230 through the soldering ball 1220 , that is, the first soldering pad may be the soldering pad 1212 . The first conductive member is a conductive layer or pad that needs to be partially elevated, that is, the first conductive member may be the conductive member 1213 . The plurality of solder resist layers may include a solder resist layer 1214 and a solder resist layer 1215, where the solder resist layer 1214 is a newly added solder resist layer. The second soldering pad is fixed on the second circuit board 1230, and is arranged opposite to the first conductive member, that is, the second soldering pad may be the soldering pad 1233. The third solder resist layer is a solder resist layer covering the second circuit board, that is, the third solder resist layer may be the solder resist layer 1234 .

It should be noted that the solder resist layer 1214 and the solder resist layer 1215 are the height limiting layers of the lamination process. The heights of the solder resist layer 1214 and the solder resist layer 1215 meet the requirements that the first circuit board 1210 and the second circuit board 1230 are laminating. During the process, two adjacent solder balls are spaced apart. It should be understood that a plurality of solder balls can be disposed between the first circuit board 1210 and the second circuit board 1230, and the plurality of solder balls are separated by the conductive member 1213, the solder resist layer 1214 and the solder resist layer 1215. In this way, by providing the new solder resist layer 1214, tin connection between two adjacent solder balls can be avoided.

The difference between the circuit board assembly 1200 shown in FIG. 15 and the circuit board assembly 1000 shown in FIG. 12 or the circuit board assembly 900 shown in FIG. 16 and the circuit board assembly 500 shown in FIG. 13 is that: in the circuit board assembly 1200 , the solder resist layer 1214 is disposed outside the spacing area between the conductive member 1213 and the pad 1212 (processed using the NSMD process). In the circuit board assembly 1000, the solder resist layer 1014 covers part of the pad 1012, and the remaining area of the pad 1012 is connected to the solder ball 1020 (processed using an SMD process).

The circuit board assembly 1200 first selects the conductive parts (for example, pads) in the circuit board for local padding, and then sets the solder resist layer as a whole and processes it using the NSMD process, thereby providing a larger surface area for solder joint connection, and Wider gaps between pads allow for wider line widths and more via flexibility. In addition, the circuit board assembly 1200 can also provide strong bottom line height support for the sandwich structure board, thereby reducing the possibility of excessive compression of the solder balls and reducing soldering problems. At the same time, it can also reduce the pad spacing on the sandwich board motherboard from 0.65mm to 0.5mm or even 0.4mm, increasing the layout space inside the circuit board and helping to miniaturize electronic equipment.

It can be seen from the structure of the above circuit board assembly that the partially raised solder resist layer of the circuit board assembly 1000 and the circuit board assembly 1200 is less likely to fall off compared to the circuit board assembly 500 and the circuit board assembly 900 , thus providing higher stability. The circuit board assembly 1000 and the circuit board assembly 500 are processed by the SMD process, and the circuit board assembly 1200 and the circuit board assembly 900 are processed by the NSMD process. The use of the SMD process can reduce the possibility of the welding board falling off during welding or welding, and the structure is more stable. stable. The use of the NSMD process can provide a larger surface area for solder joint connections, and the larger gaps between pads allow wider line widths and more through-hole flexibility, but relatively speaking, the NSMD process is less stable. Compared with SMD process, it is inferior. The specific choice of circuit board components can be selected based on actual needs.

The above-mentioned embodiment mainly performs the raising process from the perspective that the conductive member is a pad or the conductive member is a conductive layer (for example, copper foil), thereby providing bottom line height support for the circuit board. While selecting local pads for padding, also You can choose a conductive layer (such as copper foil) for additional padding treatment, which can provide more powerful bottom line height support and ensure the circuit board padding effect.

The following is a schematic structural diagram of performing local padding processing on both the pad and the conductive layer with reference to FIGS. 17 to 26 . Among them, Figures 17 to 21 show that local padding is performed on both the pad and the conductive layer under the SMD process. Figures 22 to 26 show that the pad and conductive layer are processed under the NSMD process. All above are partially raised. A detailed explanation will be given below with reference to the accompanying drawings.

17 to 21 are schematic structural diagrams of various circuit board assemblies provided by embodiments of the present application.

The circuit board assembly 1300 includes a first circuit board, which includes a circuit board base 1311, a soldering pad 1312, a soldering pad 1313, a conductive layer 1314 (the conductive component in the above embodiment includes a soldering pad 1313 and a conductive layer 1314) and multiple solder resist layers (such as solder resist layer 1315, solder resist layer 1316 and solder resist layer 1317).

The welding pads 1312, 1313 and the conductive layer 1314 are fixed on the same side of the circuit board base 1311, and the welding pad 1313 is located at the edge of the first circuit board 1310 (see Figure 27 for details). Optionally, the bonding pad 1312 and the bonding pad 1313, the bonding pad 1313 and the conductive layer 1314, and the bonding pad 1312 and the conductive layer 1314 can be arranged adjacently.

It should be understood that both the solder resist layer 1316 and the solder resist layer 1317 can be arranged in a cylindrical shape. The adhesion between the cylindrical solder resist layer 1316 and the solder resist layer 1317 and the solder resist layer 1315 will be stronger, thereby improving the performance of the circuit board assembly. stability.

In one embodiment, the number of pads 1313 is set relative to the length of the first circuit board 1310, and at least one pad is provided every 15 mm in the length direction of the first circuit board 1310. That is to say, the length of the first circuit board 1310 is L, the circuit board assembly 1300 may include multiple pads or multiple conductive layers, and the number of multiple pads or multiple conductive layers is set to n, then n≥L/ L', L' is 15mm, L>15mm, n is a positive integer.

In one embodiment, the conductive layer 1314 and the bonding pad 1313 are disposed on the same side of the circuit board base 1311, and the distance between the conductive layer 1314 and at least one bonding pad 1313 is less than 2 mm.

In a possible implementation, for example, in the structure shown in FIG. 13 , the solder resist layer 1315 is in contact with the pads 1312 , 1313 , the conductive layer 1314 and the circuit board base 1311 . The solder resist layer 1316 covers the pad 1313, and the solder resist layer 1317 covers the conductive layer 1314. The solder resist layer 1315 is located between the solder resist layer 1316 and the pad 1313, and the solder resist layer 1315 is also located between the solder resist layer 1317 and the conductive layer 1314. In this implementation, by setting multiple padding positions, local points can be selected for padding on both the pad and the conductive layer. Compared with padding only on the pad or on the conductive layer, Can have better stability.

In one possible implementation, for example, in the structure shown in FIG. 14 , the solder resist layer 1315 is in contact with the pad 1312 , the solder resist layer 1316 , the conductive layer 1314 and the circuit board base 1311 . The solder resist layer 1316 is in contact with the pad 1313, and the solder resist layer 1317 covers the conductive layer 1314. The solder resist layer 1315 is located between the solder resist layer 1317 and the conductive layer 1314, and the solder resist layer 1316 is located between the solder resist layer 1315 and the pad 1313. In this implementation, by setting multiple padding positions, local points can be selected for padding on both the pad and the conductive layer. Compared with padding only on the pad or on the conductive layer, Can have better stability. In addition, the solder resist layer 1316 is disposed between the solder resist layer 1315 and the pad 1313, which can avoid the problem of the solder resist layer 1316 falling off, so that a more stable circuit board assembly can be obtained.

In a possible implementation, for example, in the structure shown in FIG. 15 , the solder resist layer 1315 is in contact with the pads 1312 , 1313 , the solder resist layer 1317 and the circuit board base 1311 . The solder resist layer 1316 covers the pad 1313, and the solder resist layer 1317 is in contact with the conductive layer 1314. The solder resist layer 1315 is located between the solder resist layer 1316 and the pad 1313, and the solder resist layer 1317 is located between the solder resist layer 1315 and the conductive layer 1314. In this implementation, by setting multiple padding positions, local points can be selected for padding on both the pad and the conductive layer. Compared with padding only on the pad or on the conductive layer, Can have better stability. In addition, the solder resist layer 1317 is disposed between the solder resist layer 1315 and the conductive layer 1314 In this way, the problem of peeling off of the solder resist layer 1317 can be avoided as much as possible, so that a relatively stable circuit board assembly can be obtained.

In a possible implementation, for example, in the structure shown in FIG. 16 , the solder resist layer 1315 is in contact with the pad 1312 , the solder resist layer 1316 , the solder resist layer 1317 and the circuit board base 1311 . The solder resist layer 1316 is in contact with the pad 1313, and the solder resist layer 1317 is in contact with the conductive layer 1314. The solder resist layer 1316 is located between the solder resist layer 1315 and the pad 1313, and the solder resist layer 1317 is located between the solder resist layer 1315 and the conductive layer 1314. In this implementation, by setting multiple padding positions, local points can be selected for padding on both the pad and the conductive layer. Compared with padding only on the pad or on the conductive layer, Can have better stability. In addition, disposing the solder resist layer 1316 and the solder resist layer 1317 between the solder resist layer 1315 and the conductive member can avoid the problem of the solder resist layer 1316 and the solder resist layer 1317 falling off, thereby further obtaining a more stable circuit. board components.

It should be noted that the solder resist layer 1316 is arranged opposite to the pad 1313, and the solder resist layer 1317 is arranged opposite to the conductive layer 1314. That is to say, the solder resist layer 1316 intersects or overlaps with the solder pad 1313 in the projected area of the circuit board base 1311, and the solder resist layer 1317 intersects or overlaps with the conductive layer 1314 in the projected area of the circuit board base 1311. The projected areas of the plate base 1311 intersect or overlap. This arrangement can prevent the solder resist layer 1316 and the solder resist layer 1317 from falling into the gap or covering other pads, which may affect the processing of the circuit board and the performance of the circuit board.

Optionally, the height of the solder resist layer 1315 and the solder resist layer 1316 or the solder resist layer 1315 and the solder resist layer 1317 is between one third of the solder ball height and one half of the solder ball height.

Among them, the solder resist layer 1315 can be a general solder resist ink; the materials of the solder resist layer 1316 and the solder resist layer 1317 include solder resist ink, PIC film, and ordinary cover film. By selecting the above materials to provide multiple layers of solder resist, the cost of circuit board processing can be reduced to a certain extent, and the resulting circuit board assembly is relatively thin and light.

It should be understood that when the solder resist layer 1315, the solder resist layer 1316 and the solder resist layer 1317 are solder resist ink, one or more of the following processes can be used: screen printing and spraying.

In a possible implementation, the solder resist layer 1315 also covers a partial area of the soldering pad 1312 , and the remaining area of the soldering pad 1312 is connected to the solder ball 1320 .

The circuit board assembly 1300 also includes a second circuit board. The second circuit board 1330 is electrically connected to the first circuit board 1310 through solder balls 1320 and pads 1312 . The second circuit board 1330 includes a circuit board base 1331, a welding pad 1332, a welding pad 1333, a conductive layer 1334 and a solder resist layer 1335. The welding pad 1333 and the welding pad 1313 are relatively arranged. The relative arrangement here can be understood as the welding pad 1333 is in The projected area of the circuit board base 1311 completely overlaps with the projected area of the soldering pad 1313 on the circuit board base 1311 , or the projected area of the soldering pad 1333 on the circuit board base 1331 completely overlaps with the projected area of the soldering pad 1313 on the circuit board base 1331 . The specific processing method of the second circuit board 1330 can be referred to FIG. 3 and will not be described again here. The first circuit board 1310 and the second circuit board 1330 may be a main board, an AP board, an FB board, an RF board, a module board, etc.

In some embodiments, the solder mask layer 1335 on the second circuit board 1330 contacts the circuit board base 1331, the solder pads 1332, the solder pads 1333, and the conductive layer 1334. In this case, the total height of the solder resist layer 1315 and the solder resist layer 1316 relative to the pad 1313 is between 20 μm and 40 μm (30 μm is optimal), and the solder resist layer 1315 and the solder resist layer 1317 are relative to the conductive layer. The total height of 1314 is between 20 μm and 40 μm (30 μm is optimal). For details, please refer to Figures 17 to 20.

In some embodiments, the solder resist layer 1335 on the second circuit board 1330 is disposed outside the solder pad 1333 and in the conductive layer 1334 except for the projection area of the solder resist layer 1317, and is connected to the circuit board base 1331, the solder pad 1332 and the conductive layer 1335. Layer 1334 contacts. In this case, the total height of the solder resist layer 1315 and the solder resist layer 1316 relative to the pad 1313 is between 25 μm and 45 μm (35 μm is optimal), and the solder resist layer 1315 and the solder resist layer 1317 are relative to the conductive layer. Total height of 1314 Between 25μm and 45μm (35μm is optimal), please refer to Figure 21 for details. Through the circuit board structure shown in Figure 21, there is no solder resist layer on the pads on the second circuit board that correspond to the pads that need to be padded on the first circuit board. This can avoid the problem of setting the solder resist. The high tolerance brought by the layer can also improve the welding yield.

It should be understood that the first circuit board base may be the circuit board base 1311 and the second circuit board base may be the circuit board base 1331. The first soldering pad is fixed on the first circuit board 1310 and is connected to the soldering pad 1332 on the second circuit board 1330 through the soldering ball 1320 , that is, the first soldering pad may be the soldering pad 1312 . The first conductive member is a conductive layer or pad that needs to be partially elevated, that is, the first conductive member may be the conductive member 1313 or the conductive layer 1314. The multiple solder resist layers may include a solder resist layer 1315, a solder resist layer 1316, and a solder resist layer 1317, where the solder resist layer 1316 and the solder resist layer 1317 are newly added solder resist layers. The second soldering pad is fixed on the second circuit board 1330, and is arranged opposite to the first conductive member, that is, the second soldering pad may be the soldering pad 1333. The third solder resist layer is a solder resist layer covering the second circuit board, that is, the third solder resist layer may be the solder resist layer 1335 .

It should be noted that the plurality of solder resist layers (solder resist layer 1315, solder resist layer 1316, and solder resist layer 1317) are height limiting layers for the lamination process, and the heights of the multiple solder resist layers satisfy that the first circuit board 1310 During the lamination process with the second circuit board 1330, two adjacent solder balls are spaced apart. It should be understood that a plurality of solder balls can be disposed between the first circuit board 1310 and the second circuit board 1330, and the plurality of solder balls are separated by the second solder pad 1313, the solder resist layer 1315 and the solder resist layer 1316. In this way, by providing the new solder resist layer 1316, tin connection between two adjacent solder balls can be avoided. At the same time, it can also reduce the pad spacing on the sandwich board motherboard from 0.65mm to 0.5mm or even 0.4mm, increasing the layout space inside the circuit board and helping to miniaturize electronic equipment.

In the circuit board assembly 1300 shown in Figures 17 to 21, the solder resist layer 1315 also covers part of the pad 1312, and the remaining area of the pad 1312 is connected to the solder ball 1320. That is, the SMD process is used to process the circuit board. The risk of the pads falling off during soldering is reduced, and the resulting circuit board assembly 1300 has better stability.

22 to 26 are schematic structural diagrams of various circuit board assemblies provided by embodiments of the present application.

The circuit board assembly 1400 includes a first circuit board. The first circuit board includes a circuit board base 1411, a soldering pad 1412, a soldering pad 1413, a conductive layer 1414 (the above-mentioned conductive component includes a soldering pad 1413 and a conductive layer 1414) and a plurality of solder resist layers. (Solder mask 1415, solder mask 1416 and solder mask 1417).

The welding pads 1412, 1413 and the conductive layer 1414 are fixed on the same side of the circuit board base 1411, and the welding pad 1413 is located at the edge of the first circuit board 1410 (see Figure 27 for details). Optionally, the bonding pad 1412 and the bonding pad 1413, the bonding pad 1413 and the conductive layer 1414, and the bonding pad 1412 and the conductive layer 1414 can be arranged adjacently.

It should be understood that the solder resist layer 1416 and the solder resist layer 1417 can be arranged in a cylindrical shape. The adhesion between the cylindrical solder resist layer 1416 and the solder resist layer 1417 and the solder resist layer 1415 will be stronger, thereby improving the stability of the circuit board assembly. sex.

In one embodiment, the number of pads 1413 is set relative to the length of the first circuit board 1410, and at least one pad is provided every 15 mm in the length direction of the first circuit board 1410. That is to say, the length of the first circuit board 1410 is L, the circuit board assembly 1400 may include multiple pads or multiple conductive layers, and the number of multiple pads or multiple conductive layers is set to n, then n≥L/ L', L' is 15mm, L>15mm, n is a positive integer.

In one embodiment, the conductive layer 1414 and the bonding pad 1413 are disposed on the same side of the circuit board base 1411, and the distance between the conductive layer 1414 and at least one bonding pad 1413 is less than 2 mm.

In one possible implementation, for example, in the structure shown in FIG. 17 , the solder resist layer 1415 is in contact with the pad 1413 , the conductive layer 1414 and the circuit board base 1411 . The solder resist layer 1416 covers the pad 1413, and the solder resist layer 1417 covers the conductive layer 1414. The solder resist layer 1415 is located between the solder resist layer 1416 and the pad 1413, and the solder resist layer 1415 is also located between the solder resist layer 1417 and the conductive layer 1414. In this implementation, by setting multiple padding position points, the pads and leads are The electrical layer can select local points for padding treatment, which can provide better stability than padding only on the pads or only on the conductive layer.

In one possible implementation, for example, in the structure shown in FIG. 18 , the solder resist layer 1415 is in contact with the solder resist layer 1416 , the conductive layer 1414 and the circuit board base 1411 . The solder resist layer 1416 is in contact with the pad 1413, and the solder resist layer 1417 covers the conductive layer 1414. The solder resist layer 1415 is located between the solder resist layer 1417 and the conductive layer 1414, and the solder resist layer 1416 is located between the solder resist layer 1415 and the pad 1413. In this implementation, by setting multiple padding position points, local points can be selected for padding on both the pad and the conductive layer. Compared with padding only on the pad or on the conductive layer, it is possible to Have better stability. In addition, the solder resist layer 1416 is disposed between the solder resist layer 1415 and the pad 1413, which can avoid the problem of the solder resist layer 1416 falling off as much as possible, so that a more stable circuit board assembly can be obtained.

In one possible implementation, for example, in the structure shown in FIG. 19 , the solder resist 1415 is in contact with the pad 1413 , the solder resist 1417 and the circuit board base 1411 . The solder resist layer 1416 covers the pad 1413, and the solder resist layer 1417 is in contact with the conductive layer 1414. The solder resist layer 1415 is located between the solder resist layer 1416 and the pad 1413, and the solder resist layer 1417 is located between the solder resist layer 1415 and the conductive layer 1414. In this implementation, by setting multiple padding position points, local points can be selected for padding on both the pad and the conductive layer. Compared with padding only on the pad or on the conductive layer, it is possible to Have better stability. In addition, the solder resist layer 1417 is disposed between the solder resist layer 1415 and the conductive layer 1414, which can avoid the problem of the solder resist layer 1417 falling off, so that a relatively stable circuit board assembly can be obtained.

In a possible implementation, for example, in the structure shown in FIG. 20 , the solder resist layer 1415 is in contact with the solder resist layer 1416 , the solder resist layer 1417 and the circuit board base 1411 . The solder resist layer 1416 is in contact with the pad 1413, and the solder resist layer 1417 is in contact with the conductive layer 1414. The solder resist layer 1416 is located between the solder resist layer 1415 and the pad 1413, and the solder resist layer 1417 is located between the solder resist layer 1415 and the conductive layer 1414. In this implementation, by setting multiple padding position points, local points can be selected for padding on both the pad and the conductive layer. Compared with padding only on the pad or on the conductive layer, it is possible to Have better stability. In addition, disposing the solder resist layer 1416 and the solder resist layer 1417 between the solder resist layer 1415 and the conductive member can avoid the problem of the solder resist layer 1416 and the solder resist layer 1417 falling off, thereby further obtaining a more stable circuit. board components.

It should be noted that the solder resist layer 1416 is arranged opposite to the pad 1413, and the solder resist layer 1417 is arranged opposite to the conductive layer 1414. That is to say, the solder resist layer 1416 intersects or overlaps with the solder pad 1413 in the projected area of the circuit board base 1411, and the solder resist layer 1417 intersects or overlaps with the conductive layer 1414 in the projected area of the circuit board base 1411. The projected areas of the board base 1411 intersect or overlap. This arrangement can reduce the possibility that the solder resist layer 1416 and the solder resist layer 1417 fall into the gap or cover other pads, thereby affecting the processing of the circuit board and the performance of the circuit board.

Optionally, the height of the solder resist layer 1415 and the solder resist layer 1416 or the solder resist layer 1415 and the solder resist layer 1417 is between one third of the solder ball height and one half of the solder ball height.

Among them, the solder resist layer 1415 can be a general solder resist ink; the materials of the solder resist layer 1416 and the solder resist layer 1417 include solder resist ink, PIC film, and ordinary cover film. By selecting the above materials to provide multiple layers of solder resist, the cost of circuit board processing can be reduced to a certain extent, and the resulting circuit board assembly is relatively thin and light.

It should be understood that when the solder resist layer 1415, the solder resist layer 1416 and the solder resist layer 1417 are solder resist ink, one or more of the following processes can be used: screen printing and spraying.

In a possible implementation, the solder resist layer 1415 is disposed outside the spacing area between the soldering pad 1413 and the soldering pad 1412 .

The circuit board assembly 1400 also includes a second circuit board. The second circuit board 1430 is electrically connected to the first circuit board 1410 through solder balls 1420 and pads 1412 . The second circuit board 1430 includes a circuit board base 1431, a soldering pad 1432, and a soldering pad 1432. 1433. The conductive layer 1434 and the solder resist layer 1435, the soldering pad 1433 and the soldering pad 1413 are arranged relatively. The relative arrangement here can be understood as the projection area of the soldering pad 1433 on the circuit board base 1411 and the projection area of the soldering pad 1413 on the circuit board base 1411. The projected areas completely overlap, or the projected area of the soldering pad 1433 on the circuit board base 1431 completely overlaps with the projected area of the soldering pad 1413 on the circuit board base 1431 . The specific processing method of the second circuit board 1430 can be referred to FIG. 4 and will not be described again here. The first circuit board 1410 and the second circuit board 1430 may be a main board, an AP board, an FB board, an RF board, a module board, etc.

In some embodiments, the solder mask layer 1435 on the second circuit board 1430 contacts the circuit board base 1431, the pads 1433, and the conductive layer 1434. In this case, the total height of the solder resist layer 1415 and the solder resist layer 1416 relative to the pad 1413 is between 20 μm and 40 μm (30 μm is optimal), and the solder resist layer 1415 and the solder resist layer 1417 are relative to the conductive layer. The total height of 1414 is between 20 μm and 40 μm (30 μm is optimal). For details, please refer to Figures 22 to 25.

In some embodiments, the solder resist layer 1435 on the second circuit board 1430 is disposed outside the solder pad 1433 and in the area of the conductive layer 1434 except the projection area of the solder resist layer 1417, and is in contact with the circuit board base 1431 and the conductive layer 1434. In this case, the total height of the solder resist layer 1415 and the solder resist layer 1416 relative to the pad 1413 is between 25 μm and 45 μm (35 μm is optimal), and the solder resist layer 1415 and the solder resist layer 1417 are relative to the conductive layer. The total height of 1414 is between 25 μm and 45 μm (35 μm is optimal). Please refer to Figure 26 for details. With the circuit board structure shown in Figure 26, no solder resist layer is provided on the pads on the second circuit board that correspond to the pads that need to be padded on the first circuit board. This can avoid the need to install the solder resist layer. The high tolerance brought by the layer can also improve the welding yield.

It should be understood that the first circuit board base may be the circuit board base 1411 and the second circuit board base may be the circuit board base 1431. The first soldering pad is fixed on the first circuit board 1410 and is connected to the soldering pad 1432 on the second circuit board 1430 through solder balls 1420, that is, the first soldering pad may be the soldering pad 1412. The first conductive member is a conductive layer or pad that needs to be partially raised, that is, the first conductive member can be the pad 1413 or the conductive layer 1414. The multiple solder resist layers may include a solder resist layer 1415, a solder resist layer 1416, and a solder resist layer 1417, where the solder resist layer 1416 and the solder resist layer 1417 are newly added solder resist layers. The second soldering pad is fixed on the second circuit board 1430, and the second soldering pad is arranged opposite to the first conductive member, that is, the second soldering pad may be the soldering pad 1433. The third solder resist layer is a solder resist layer covering the second circuit board, that is, the third solder resist layer may be the solder resist layer 1435 .

It should be noted that the multiple solder resist layers (solder resist layer 1415, solder resist layer 1416, and solder resist layer 1417) are height limiting layers for the lamination process, and the heights of the multiple solder resist layers meet the requirements of the first circuit board 1410 During the lamination process with the second circuit board 1430, two adjacent solder balls are spaced apart. It should be understood that a plurality of solder balls may be disposed between the first circuit board 1410 and the second circuit board 1430, and the plurality of solder balls are separated by the second solder pad 1413, the solder resist layer 1416 and the solder resist layer 1415. In this way, by providing the new solder resist layer 1416, tin connection between two adjacent solder balls can be avoided. At the same time, it can also reduce the pad spacing on the sandwich board motherboard from 0.65mm to 0.5mm or even 0.4mm, increasing the layout space inside the circuit board and helping to miniaturize electronic equipment.

In the circuit board assembly 1400 shown in Figures 22 to 26, the solder resist layer 1415 is disposed outside the spacing area between the second pad 1413 and the pad 1412, that is, the NSMD process is used to process the circuit board, and it can be a solder joint. The connections provide greater surface area, and the larger gaps between pads allow for wider linewidths and more via flexibility.

Figure 27 is a schematic diagram of a raising position provided by an embodiment of the present application.

As shown in Figure 27, Figure 27 shows a top view of a square circuit board. Taking the square circuit board as an example, the selection of local padding points in this application is explained.

The point 2710 circled by the black circle in Figure 27 is the position of the pad that needs to be partially raised. The pad is located at the edge of the circuit board. Point 2710 is generally located in the ground hole area on the four sides of the circuit board, usually in the ground hole area of the circuit board. Select 4 to 30 pads each for local padding. In addition, when the length of the long side of the circuit board exceeds 15mm, an additional pad will be selected for padding at about half of the total length.

Specifically, the selection principle of the local padding position is generally the "corner" position of the circuit board. This "corner" position corresponds to the contact position of the mold that presses the first circuit board and the second circuit board. The contacts usually consist of four Composed of a sphere with a diameter of 2mm. Depending on the size of the circuit board, the position and size of the contacts will be slightly adjusted, so the local padding position is specifically determined based on the position of the mold contacts. Point 2710 is generally located directly below the contact. Select 4 to 30 pads for local padding, at least 4, that is, select one pad on each of the four sides of the circuit board for padding to prevent unevenness on the four sides of the circuit board and warping. By selecting appropriate points for padding, a "limiting pad" can be obtained that ensures that the minimum height does not cause the risk of soldering when laminating sandwich structural panels.

The point 2720 circled by the hollow circle in Figure 27 is the location of the conductive layer that needs to be partially elevated. It can be seen from Figure 27 that point 2720 is located near point 2710. In one possible implementation, the partially elevated conductive layer is located near the partially elevated pad, that is, the distance between the conductive layer and the pad closest to the conductive layer is less than 2 mm. By selecting points where additional padding of the conductive layer (e.g. copper foil) is required, a high level of support for the sandwich panel can be further ensured.

An embodiment of the present application also provides an electronic device. The electronic device may include a circuit board assembly as shown in any one of FIG. 5, FIG. 9 to FIG. 13, and FIG. 15 to FIG. 26.

Embodiments of the present application also provide a processing method of a circuit board assembly. The method includes: obtaining a first circuit board, which includes a first circuit board base, a first pad, a first conductive member and a plurality of resistors. The solder layer, the first pad and the first conductive member are fixed on the same side of the first circuit board base, and multiple solder resist layers are stacked on a side of the first conductive member away from the first circuit board base. The side at least covers the first conductive member, and the sum of the heights of the plurality of solder resist layers and the first conductive member is greater than the height of the first pad; press the second circuit board to the first circuit board so that the second circuit board passes through the solder ball and the first pad is electrically connected to the first circuit board, wherein the plurality of solder resist layers are height limiting layers for the lamination process, and the heights of the plurality of solder resist layers meet the requirements that the first circuit board and the second circuit board are laminate. During the process, two adjacent solder balls are spaced apart.

Optionally, the plurality of solder resist layers include a first solder resist layer and a second solder resist layer. The method of obtaining the first circuit board may include: setting a first resistor on one side of the first circuit board base and the first conductive member. Solder layer; a second solder resist layer is provided on the side of the first solder resist layer away from the first circuit board base body.

Optionally, the plurality of solder resist layers include a first solder resist layer and a second solder resist layer. The method of obtaining the first circuit board may include: disposing a second solder resist layer on the first conductive member; The first solder resist layer is disposed on the side of the base body and the second solder resist layer away from the first circuit board base body.

The specific processing method can be referred to Figure 7, Figure 8 and Figure 13. It should be understood that the methods shown in Figure 7, Figure 8 and Figure 13 are only illustrative, and those skilled in the art can easily think of changes or replacements. are covered by the protection scope of this application.

When actually assembling circuit components or electronic equipment, factors such as the difficulty of wiring, the space occupied by the circuit components, and the key protection scope of the circuit components will be considered. Therefore, the heightening process in the circuit board assembly can be flexibly carried out according to the actual situation and with reference to the examples shown in Figures 5 to 26. Many modifications and other embodiments of the present application will occur to those skilled in the art, having the benefit of the guidance presented in the foregoing description and associated drawings. Therefore, it is to be understood that the application is not limited to the specific embodiments disclosed.

The above are only specific embodiments of the present application, but the protection scope of the present application is not limited thereto. Any person familiar with the technical field can easily think of changes or substitutions within the technical scope disclosed in the present application. should be covered by the protection scope of this application. Therefore, the protection scope of this application should be subject to the protection scope of the claims.

Claims

A circuit board assembly, characterized by including:

A first circuit board, the first circuit board includes a first circuit board base, a first soldering pad, a first conductive member and a plurality of solder resist layers, the first soldering pad and the first conductive member are fixed on On the same side of the first circuit board base, the plurality of solder resist layers are stacked, and the plurality of solder resist layers at least cover the first conductive member on the side away from the first circuit board base. A first conductive member, the sum of the heights of the plurality of solder resist layers and the first conductive member is greater than the height of the first pad;

The second circuit board is electrically connected to the first circuit board through solder balls and the first pad;

Wherein, the plurality of solder resist layers are height limiting layers in the lamination process, and the heights of the plurality of solder resist layers satisfy that during the lamination process of the first circuit board and the second circuit board, adjacent The two solder balls are spaced apart.
The circuit board assembly according to claim 1, wherein the plurality of solder resist layers include a first solder resist layer covering the first conductive member and connected with the first solder resist layer. Circuit board substrate contact.
The circuit board assembly according to claim 2, wherein the plurality of solder resist layers further comprise a second solder resist layer, the second solder resist layer is in contact with the first conductive member and is located on the between the first solder resist layer and the first conductive member.
The circuit board assembly according to claim 2, wherein the plurality of solder resist layers further comprise a second solder resist layer, the first solder resist layer is in contact with the first conductive member and is located on the between the second solder resist layer and the first conductive member.
The circuit board assembly according to any one of claims 2 to 4, wherein the first solder resist layer also covers a partial area of the first soldering pad, and the remaining area of the first soldering pad is The solder ball connection.
The circuit board assembly according to any one of claims 2 to 4, wherein the first solder resist layer is disposed outside the spacing area between the first conductive member and the first pad.
The circuit board assembly according to any one of claims 3 to 6, wherein the second solder resist layer is arranged opposite to the first conductive member.
The circuit board assembly according to any one of claims 3 to 7, characterized in that the material of the second solder resist layer includes solder resist ink, photosensitive development cover film, and ordinary cover film.
The circuit board assembly according to any one of claims 3 to 8, wherein the second solder resist layer is cylindrical.
The circuit board assembly according to any one of claims 1 to 9, wherein the first conductive member is located at an edge of the first circuit board.
The circuit board assembly according to any one of claims 1 to 10, wherein the length of the first circuit board is L, the circuit board assembly includes a plurality of the first conductive members, and the plurality of first conductive members are The number of first conductive members is n, n≥L/L', L' is 15mm, L>15mm, and n is a positive integer.
The circuit board assembly according to any one of claims 1 to 11, wherein the first conductive member includes one or more of the following: a conductive layer and a pad.
The circuit board assembly according to any one of claims 1 to 12, wherein the first circuit board further includes a second conductive member, and the second conductive member and the first conductive member are disposed on the On the same side of the first circuit board base, the distance between the first conductive member and the second conductive member is less than 2 mm.
The circuit board assembly according to any one of claims 1 to 13, wherein the first pad disposed adjacent to the first conductive member.
The circuit board assembly according to any one of claims 1 to 14, wherein the height of the plurality of solder resist layers ranges from one third of the height of the solder ball to one half of the height of the solder ball. between.
The circuit board assembly according to any one of claims 1 to 15, characterized in that the first circuit board is any one of the following: a main board, a frame board, a radio frequency board, an application processing board or a module board.
The circuit board assembly according to any one of claims 1 to 16, wherein the total height of the plurality of solder resist layers is between 20 μm and 40 μm.
The circuit board assembly according to any one of claims 1 to 16, wherein the second circuit board includes a second circuit board base, a second solder pad and a third solder resist layer, and the second solder resist layer The pad is fixed on the second circuit board base, the second soldering pad is arranged opposite to the first conductive member, and the third solder resist layer is arranged in an area outside the second soldering pad and is connected with the first conductive member. The second circuit board substrate is in contact.
The circuit board assembly according to claim 18, wherein the total height of the plurality of solder resist layers is between 25 μm and 45 μm.
An electronic device, characterized by comprising the circuit board assembly according to any one of claims 1 to 19.
A processing method for circuit board components, characterized by including:

Obtain a first circuit board, the first circuit board includes a first circuit board base, a first soldering pad, a first conductive member and a plurality of solder resist layers, the first soldering pad and the first conductive member are fixed on On the same side of the first circuit board base, the plurality of solder resist layers are stacked and cover at least all the solder resist layers on the side of the first conductive member away from the first circuit board base. As for the first conductive member, the sum of the heights of the plurality of solder resist layers and the first conductive member is greater than the height of the first pad;

The second circuit board is pressed against the first circuit board, so that the second circuit board is electrically connected to the first circuit board through solder balls and the first pad, wherein the plurality of solder resists The layer is a height limiting layer in the lamination process. The height of the plurality of solder resist layers meets the requirements. During the lamination process of the first circuit board and the second circuit board, two adjacent solder balls are spaced apart. .
The processing method according to claim 21, wherein the plurality of solder resist layers include a first solder resist layer and a second solder resist layer, and obtaining the first circuit board includes:

The first solder resist layer is provided on one side of the first circuit board base and the first conductive member;

The second solder resist layer is disposed on a side of the first solder resist layer away from the first circuit board base.
The processing method according to claim 21, wherein the plurality of solder resist layers include a first solder resist layer and a second solder resist layer, and obtaining the first circuit board includes:

disposing the second solder resist layer on the first conductive member;

The first solder resist layer is disposed on the first circuit board base and the side of the second solder resist layer away from the first circuit board base.