A packaging method, a packaging structure and a superconducting quantum computer

Abstract

This application discloses a packaging method, packaging structure, and a superconducting quantum computer, belonging to the field of chip packaging. The packaging method includes providing a chip and a printed circuit board; positioning the chip and the printed circuit board such that a second post in the circuit board is inserted into a positioning hole while ensuring that the flux and solder balls do not contact; and performing thermocompression bonding while heating the chip but not the printed circuit board. The above packaging method enables more convenient packaging alignment and spacing control, and significantly reduces the probability of warping of the packaged printed circuit board.

Description

Technical Field

[0001] This application belongs to the field of quantum information, especially the field of chip packaging. In particular, this application relates to a packaging method, a packaging structure, and a superconducting quantum computer. Background Technology

[0002] Chip packaging can protect the chip, enable the chip to connect to external circuits, improve the chip's performance and reliability, and meet the size and shape requirements of the product in the application scenario.

[0003] Chip packaging refers to the process of encapsulating a chip (such as a bare wafer) with a substrate. Packaging methods include DIP (Dual In-line Package), BGA (Ball Grid Array Package), and surface mount technology (SMT).

[0004] BGA packaging offers high density, reliability, and heat dissipation. BGA packaging uses ball joints to connect the chip and the printed circuit board. Specifically, circuit connections are achieved by connecting the ball joints (metal pads arranged in a uniform grid pattern) on the back of the chip to the pads on the printed circuit board.

[0005] However, existing BGA packaging methods are prone to chip warping after packaging. Summary of the Invention

[0006] This application provides an example of a packaging method, a packaging structure, and a superconducting quantum computer. The packaging method enables higher quality and more convenient chip-to-printed circuit board packaging.

[0007] The solution presented in this application is implemented through the following steps.

[0008] In a first aspect, examples of this application disclose an encapsulation method, which includes:

[0009] A chip with positioning holes and solder balls at the pins is provided, and a printed circuit board with posts and flux formed at the pads is provided. The posts include a first post that is axially distributed and thicker and a second post that is thinner. The first post is connected to the printed circuit board and cannot pass through the positioning holes, while the second post can pass through the positioning holes.

[0010] Position the chip and printed circuit board so that the second post is inserted into the positioning hole and ensures that the flux and solder balls do not come into contact; and

[0011] Thermopressing is performed under conditions where the chip is heated but the printed circuit board is not.

[0012] According to some examples of this application, the packaging method includes one or more of the following limitations: First limitation: the positioning hole is made by deep silicon etching; Second limitation: the solder balls are manufactured by laser ball placement; Third limitation: the flux is formed by screen printing.

[0013] According to some examples of this application, methods for positioning chips and printed circuit boards such that the second post is inserted into the positioning hole and ensuring that flux and solder balls do not come into contact include:

[0014] Lay the printed circuit board flat;

[0015] The chip is moved to approach the printed circuit board, and the positioning hole is coaxially aligned with the post;

[0016] Additionally, the printed circuit board is lowered and held in a preset position so that the posts are inserted into or pass through the positioning holes, and the flux and solder balls are kept out of contact.

[0017] According to some examples of this application, during the thermocompression soldering process, an operational force is applied to the chip toward the printed circuit board to compress the chip so that the solder balls of the chip come into contact with the flux of the printed circuit board.

[0018] According to some examples in this application, the application of force continues until the thermocompression welding is completed.

[0019] According to some examples of this application, the column is a superconducting column integrally formed from a first column and a second column.

[0020] According to some examples of this application, the first post is welded to the front of the body and / or the first post is a cylinder, the second post is a prism, and the positioning hole is a prism hole that matches the second post.

[0021] According to some examples of this application, the printed circuit board defines an inner region and an outer region that extends outward from the inner region in a ring shape, and the number of posts is multiple and distributed in a rectangular manner in the outer region.

[0022] Secondly, examples of this application disclose an encapsulation structure obtained by implementing the above encapsulation method.

[0023] In a third aspect, examples of this application disclose a quantum computer that supersedes the aforementioned encapsulation structure. Attached Figure Description

[0024] To illustrate this more clearly, the accompanying drawings used in the description will be briefly introduced below.

[0025] Figure 1 This is a schematic diagram of the structure of the printed circuit board in the example of this application;

[0026] Figure 2 for Figure 1 A schematic diagram of the printed circuit board from another perspective;

[0027] Figure 3 A schematic diagram of the structure of another type of printed circuit board pillar in this application is shown;

[0028] Figure 4 The example shown in this application is related to Figure 1 The printed circuit board and the chip shown are schematic diagrams of their structure from two different perspectives.

[0029] Figure 5 It was made public. Figure 1 The printed circuit board shown and Figure 4 The diagram shown illustrates the chip reflow soldering process.

[0030] Figure 6 This is a schematic diagram of a chip and printed circuit board packaging process in an example of this application;

[0031] Figure 7 This illustration shows a schematic diagram of the structural changes that occur during the packaging process of a chip and a printed circuit board by reflow soldering, as shown in an example of this application.

[0032] Figure 8 This is a schematic diagram of another chip and printed circuit board packaging process in the example of this application;

[0033] Figure 9 This is a schematic diagram of another chip and printed circuit board packaging process in this application example.

[0034] Explanation of reference numerals in the attached figures:

[0035] 100 - Printed circuit board; 101 - Body; 102 - Post; 1021 - First post; 1022 - Second post; 200 - Chip; 202 - Positioning hole; 300 - Solder ball. Detailed Implementation

[0036] The pursuit of universal superconducting quantum computers urgently requires the integration of more superconducting qubits into superconducting quantum chips. Due to the characteristics of superconducting qubits, numerous signal lines and various electronic components need to be configured near them for operation and readout. Therefore, when more superconducting qubits are integrated into a superconducting quantum chip, more lines and components are required, making the space within the superconducting quantum chip more crowded.

[0037] When space becomes too cramped in a superconducting quantum chip, it presents significant challenges to the spatial arrangement of various circuits and components. To overcome this problem, the industry typically chooses to adjust the planar distribution of superconducting quantum chips to a three-dimensional distribution. For example, distribution on a single surface of the chip substrate is changed to distribution on two surfaces of the substrate. Other attempts involve distributing various structures that were distributed on a single substrate across two or more substrates; for example, flip-chip bonding.

[0038] Flip-chip bonding holds immense potential. However, for superconducting quantum chips, the spatial distribution of some components can significantly impact their performance. For instance, intersections or proximity between circuits can generate non-negligible crosstalk. Furthermore, misalignment of components on different layers can lead to incorrect circuit connections or prevent the desired coupling from forming.

[0039] Therefore, the alignment of the upper and lower substrates is crucial for flip-chip applications. However, existing solutions mostly rely on positioning equipment for control or simply manual operation. These methods suffer from inconvenience and insufficient precision.

[0040] In view of this, the inventors propose a new solution in this application. This solution is easy to implement and does not require complex operations or expensive equipment. In the example of this application, the inventors choose to modify the structure of the chip. Specifically, in this example, the structure of the chip's substrate is adjusted.

[0041] In particular, this solution is also applicable to chip packaging, such as the BGA packaging mentioned above. Specifically, the inventors fit the chip substrate and the printed circuit board together in a nested manner.

[0042] Accordingly, the applicant discloses a printed circuit board structure based on the above concept in the example of this application.

[0043] As mentioned above, this printed circuit board can be used to connect to chip packages.

[0044] See Figure 1 , Figure 2 and Figure 3 The printed circuit board 100 includes a body 101 and a post 102.

[0045] The main body 101 is a component used to set up circuits and electronic components. These circuits and electronic components may transmit signals internally in the printed circuit board 100, or be connected to corresponding circuits and components in the chip 200, or both.

[0046] The pillar 102 is a structure used to mate with the chip 200. The pillar 102 mates with the chip 200 to ensure proper positioning and alignment between the printed circuit board 100 and the chip 200. This mate allows for rapid alignment of the chip 200 and the printed circuit board 100, significantly reducing operational complexity.

[0047] In the example, body 101 has a front and a back side that are opposite each other along the thickness direction, or it can be described as a top surface or a bottom surface, or it can be described as a first surface or a second surface.

[0048] In terms of shape, the main body 101 can be rectangular or square, etc. In terms of material, the printed circuit board 100 can be copper-clad laminate, fiberglass board, ceramic board, resin board, etc.

[0049] The pillar 102 stands upright from the front of the body 101 and has a segmented structure—for example, described as a first pillar 1021 and a second pillar 1022 respectively. The first pillar 1021 is connected to the front, while the second pillar 1022 extends coaxially from the end of the first pillar 1021. Therefore, it is known that the second pillar 1022 has a free end. When using the printed circuit board 100, the aforementioned free end of the second pillar 1022 can pass through a hole corresponding to the chip 200, thereby engaging with it; this will be described in detail later in the use of the printed circuit board 100.

[0050] Specifically, the first pillar 1021 and the second pillar 1022 are also relatively large in size. Specifically, along the thickness direction, the projected outline of the second pillar 1022 lies within the projected outline of the first pillar 1021; that is, the second pillar 1022 is thinner than the first pillar 1021; or in other words, the first pillar 1021 is thicker than the second pillar 1022. Therefore, as mentioned above, the second pillar 1022 can pass through the corresponding hole in the chip 200, while the first pillar 1021 cannot pass through the corresponding hole in the chip 200. Thus, the chip 200 can be supported by the first pillar 1021 in the pillars 102 and limited by the second pillar 1022.

[0051] Accordingly, the distance between the chip 200 and the substrate is also defined by the first pillar 1021 in the pillar 102. For example, the first pillar 1021 has a preset height measured from the front side of the substrate, and this preset height is related to the package spacing between the printed circuit board 100 and the chip 200. In different specific examples, the preset height of the first pillar 1021 can be set as needed, without particular limitation.

[0052] For example, the preset height can be selected as the distance between the chip 200 and the substrate after the chip 200 and the substrate are packaged, which is the package spacing described above. When the substrate and the chip 200 are soldered using solder balls in a BGA-like scheme, the package spacing can be the diameter or radius of the solder balls; correspondingly, the preset spacing can be equal to the package spacing, or the preset spacing can be smaller than the diameter of the solder balls (i.e., the preset height of the first pillar 1021 is smaller than the distance between the chip 200 and the printed circuit board 100), or the radius.

[0053] During the soldering process, the solder balls melt due to heat and deform under pressure. Therefore, the height of the solder balls will be smaller than the final package spacing. Consequently, when the height of the solder balls is greater than the height of the first post 1021, the surface of the chip 200 is pressed against the solder balls when the hole of the chip 200 mates with the post 102 of the printed circuit board 100. Then, during soldering, the chip 200 can be pressed down (the solder balls melt), causing it to contact the surface of the first post 1021, thus limiting its position.

[0054] The above discussion primarily focused on the heights of the first column 1021 and the second column 1022. Furthermore, the way they connect can also be designed. For example, the first column 1021 and the second column 1022 can be designed as a single piece. That is, the first column 1021 and the second column 1022 exist as a single unit and are not designed to be detachable. In other examples, for greater flexibility, the first column 1021 and the second column 1022 can also be designed as separate structures, thus allowing for detachable connection.

[0055] For example, to achieve a detachable connection, the two (first post 1021 and second post 1022) can be connected by threads; one has a threaded hole, and the other has a threaded post. The reverse is also true. Alternatively, they can be designed as a plug-in connection; one has a smooth hole, and the other has a post that mates with that hole, and the reverse is also true.

[0056] Similarly, the connection method between the post 102 and the body 101 in the printed circuit board 100 can also be selected. For example, the first post 1021 can be fixedly connected to the body 101, for example, by soldering. In other examples, the first post 1021 can also be detachably connected to the front of the body 101—such as by a threaded connection.

[0057] In terms of quantity, the number of posts 102 can be one or more (two or more). When there are multiple posts 102, the height of the first post 1021 of each post 102 relative to the front of the body 101 is the same. The number of posts 102 can be determined according to the area of ​​the printed circuit board 100. For example, the larger the size of the printed circuit board 100, the more posts 102 are provided therein. Conversely, the larger the size of the printed circuit board 100, the fewer posts 102 are provided therein, but it is advisable to have an appropriate number (for example, at least three in some examples).

[0058] When there are multiple pillars 102, the pillars 102 can form more contact positions with the chip 200, which makes the chip 200 more stable and less prone to tilting or unevenness.

[0059] Furthermore, in addition to considering the number of posts 102, the shape of the posts 102 can also be selected. The shape can be designed for the second post 1022, or for the first post 1021 and the second post 1022. For example, designing the shape of the second post 1022 can make it easier, or more precise, to align the chip 200 with the printed circuit board 100.

[0060] In some examples, the second pillar 1022 is designed as a cylindrical structure, and correspondingly, the holes on the chip 200 are also designed as cylindrical holes. A better approach is to design the second pillar 1022 as a prism, and correspondingly, the holes on the chip 200 are designed as prism holes. That is, the first pillar 1021 can be either a cylinder or a prism. For the prism structure, since it has different positioning orientations in various directions, a better alignment effect can be achieved, especially when the number of pillars 102 is small, such as one, the prism-shaped pillar 102 performs better.

[0061] Specifically, the hole can be slightly larger than the second post 1022, allowing the chip 200 to undergo the required displacement during reflow soldering. In other words, the fit between the second post 1022 and the positioning hole 202 of the chip 200 (which can be manufactured by deep silicon etching) can be a clearance fit. By constructing a clearance fit, positioning can be facilitated, and it also facilitates the vertical displacement of the chip 200 (the direction in which the chip 200 and the PCB are opposite) during reflow, ensuring alignment.

[0062] Furthermore, the diameter of the first pillar 1021 can be much larger than the diameter of the positioning hole 202 of the chip 200, thereby preventing the chip 200 from continuing to move downward in the vertical direction, and ensuring sufficient reflow while actively controlling the spacing between the chip 200 and the PCB to achieve the purpose of spacing control.

[0063] Otherwise, if the spacing between chip 200 and the PCB is too small, chip 200 will be too close to the PCB. The solution in this application controls the spacing between chip 200 and the PCB within the designed range, thus preventing the PCB solder ball flux (which can be formed by screen printing) from evaporating due to excessive spacing (not conforming to the designed spacing) and remaining on the surface of chip 200. Simultaneously, the solution in this application also prevents chip 200 from being too heavy, causing the reflow solder balls to become too flat during reflow, thereby controlling the reflow solder ball structure and ensuring a strong solder joint.

[0064] Furthermore, the first column 1021 can have the same shape as the second column 1022, or they can be constructed with different shapes. In the case of multiple columns 102, the shapes of each column 102 can be of the same design, or some columns 102 can be the same while the remaining columns 102 have different shapes—the first column 1021 can have the same shape while the second column 1022 has a different shape, or both can be different. In the example, the second column 1022 of some columns 102 has a circular cross-section, while the second column 1022 of the remaining columns 102 has a polygonal cross-section.

[0065] Since the area of ​​chip 200 may be relatively large, the size of printed circuit board 100 may also need to be large when packaging it. Therefore, the number of posts 102 in printed circuit board 100 can be increased. However, since chip 200 contains numerous lines and components, the distribution of posts 102 can be adjusted to accommodate the configuration of these lines and components. To achieve this adjustment, an inner region and an outer region extending outward in a ring shape can be defined on the front side of the body 101 of printed circuit board 100. Based on this, the posts 102 in printed circuit board 100 are constructed in the aforementioned outer region, while the inner region can be used to configure various components and lines in chip 200.

[0066] In general, in the example of this application, the printed circuit board is provided with pillars. These pillars are also segmented (i.e., a first pillar and a second pillar), and the outline of the second pillar projected along the thickness direction lies within the outline of the first pillar projected. Therefore, the first pillar is thicker, while the second pillar is relatively thinner.

[0067] Based on this structure, the chip can be correspondingly equipped with positioning holes that mate with the column, such as... Figure 4 As shown. When the chip is connected to the printed circuit board package, the second post of the printed circuit board can pass through the positioning hole of the chip and contact the end of the first post through the chip, so that the distance between the chip and the printed circuit board is limited by the height of the first post.

[0068] In this way, the positioning holes of the chip and the posts of the printed circuit board (PCB) mate to position the chip and the PCB relative to each other. The first post has a preset height measured from the front, which is related to the package spacing between the PCB and the chip. Therefore, the distance between the chip and the PCB is limited, thus preventing damage or breakage of components on the chip surface due to compression. Furthermore, the selection of the post's position on the PCB surface can control the lateral positioning of the chip and the PCB, accurately associating corresponding components or circuits, such as establishing signal connections or physical connections.

[0069] Accordingly, based on the use of the printed circuit board 100 described above, a packaging structure is also disclosed in this application. This packaging structure includes a chip 200 and the preceding printed circuit board 100, wherein the chip 200 has positioning holes 202.

[0070] In the packaged structure, chip 200 and printed circuit board 100 are arranged face-to-face. Further, a second post 1022 of the post 102 passes through the positioning hole 202 of chip 200, and the surface of chip 200 contacts and is supported by the end face of the first post 1021. Chip 200 is soldered to the ball grid array of printed circuit board 100.

[0071] Furthermore, the example also discloses a superconducting quantum computer including the aforementioned encapsulation structure.

[0072] Overall, the solution in this application example is adapted to the BGA packaging process of the quantum chip 200 compared to the traditional BGA packaging process, so that when the quantum chip 200 is packaged with the printed circuit board 100, the accuracy and spacing control of the chip meet the product requirements.

[0073] Specifically, holes can be drilled on chip 200 (which can be described as positioning holes 202), and positioning posts can be manufactured on the PCB (which can be manufactured through subsequent soldering). In particular, the positioning posts are not straight posts, but rather have a stepped structure (different segments have stepped changes in diameter). Alignment accuracy and solder pad spacing are controlled by alignment holes and double-layer alignment posts.

[0074] See Figure 5 , Figure 6 The specific encapsulation methods are as follows.

[0075] S101, Ball placement on PCB and chip 200; ball placement can be done on one or both; ball placement methods can be, for example, screen printing or laser ball placement. Figure 6 In the example, both the printed circuit board 100 and the chip 200 are ball-mounted.

[0076] S102. Chip 200 and PCB Alignment: After ball placement, invert chip 200 (with the solder ball 300 side facing down) and align the alignment holes of chip 200 with the alignment posts on the PCB. At this time, the solder balls 300 on chip 200 and the solder balls 300 on the PCB are in contact and support each other, and the chip spacing is greater than the height of the lower half post.

[0077] S103, Reflow Soldering: The temperature is increased, and as the circuit reflows, the upper and lower solder balls 300 begin to melt and fuse together. The chip 200 moves downwards as a whole, reducing the inter-die pitch. When the chip 200 contacts the lower half-pillar, the diameter of the positioning hole 202 is smaller than the diameter of the lower half-pillar, and the chip 200 stops moving downwards. At this point, the inter-die pitch remains constant. The upper and lower solder balls 300 remain fused together until the reflow is complete. During this process, the chip 200 and the printed circuit board 100 can be heated separately.

[0078] The above welding process can be carried out using BGA welding methods known to the applicant, and can be briefly described as follows.

[0079] 1. Preparation of Printed Circuit Board 100:

[0080] (1) Pre-treat the printed circuit board 100 to ensure that its surface is clean and free of contamination.

[0081] (2) Design and lay out pads on the printed circuit board 100 to ensure that they correspond to the pin positions and numbers of the chip to be packaged 200.

[0082] (3) Using a printing method (such as screen printing), solder balls are placed on the pads of the printed circuit board 100 (i.e., solder balls 300 are manufactured).

[0083] 2. Chip 200 installation:

[0084] (1) The packaged chip 200 is accurately placed on the printed circuit board 100 using automated equipment or manual operation, so that the solder balls 300 of the chip 200 correspond to the pads. During this process, positioning tools or vision-assisted equipment can be used to ensure correct alignment to avoid offset or misalignment.

[0085] In this step, accurately controlling the distance between chip 200 and printed circuit board 100 will help improve packaging quality and yield. Existing solutions often rely on vision devices for auxiliary control, which is difficult to implement and inconvenient to operate. Furthermore, poor spacing control can easily lead to problems such as cold solder joints on some pads.

[0086] In this example, because the chip 200 is provided with positioning holes 202 and the printed circuit board 100 is provided with posts 102, the difficulty of alignment is alleviated. More importantly, through the stepped structure design of the posts 102, the difficulty of spacing control is significantly reduced (the problem of cold solder joints will be significantly reduced), and the consistency between different batches is higher.

[0087] 3. Welding:

[0088] Hot air reflow soldering or hot plate heating soldering is performed. The aforementioned method involves heating the entire chip 200 and printed circuit board 100, and controlling the heating temperature and time to melt the solder paste and reach the appropriate soldering temperature for soldering connection.

[0089] The heating equipment used in this process can heat air or nitrogen to a sufficiently high temperature. The hot air is then blown onto the back of the chip 200, to which components have already been attached, and simultaneously heated from the back of the printed circuit board 100, melting the solder on both sides of the components and bonding them to the motherboard. The heating temperature can be controlled using a reflow temperature profile. For example, a non-linear RSS (Ramp-Soak-Spike) temperature profile can be used. This is the heating-holding-reflow temperature profile. The entire reflow process is typically strictly divided into four temperature zones: preheating, isothermal, reflow, and cooling. The reflow temperature zone has the highest temperature and is determined based on the solder ball material (generally, the reflow temperature zone should be 40-50 degrees Celsius higher than the melting point of the solder ball 300).

[0090] 4. Cooling and curing:

[0091] After soldering, allow the chip 200 and the printed circuit board 100 to cool naturally, or use cooling equipment or a cooling environment in combination or independently to accelerate cooling so that the solder paste solidifies and hardens.

[0092] In practice, due to issues such as materials, the applicant discovered that the printed circuit board 100 might warp after soldering. Warping of the printed circuit board 100 could further degrade the performance of the packaged structure; for example, the chip 200 and the printed circuit board 100 might separate in localized areas (the solder pads would not make contact).

[0093] Through analysis, the applicant is convinced that the cause of the above problems is that the printed circuit board 100 is also heated during the reflow soldering process. Because the PCB material is highly susceptible to temperature changes, conventional PCB warpage varies with temperature cycles and can be... Figure 7 As shown.

[0094] The problem mentioned above is that the printed circuit board 100 also has solder balls 300, and therefore is heated in practice. However, this causes the printed circuit board 100 to warp in the later stages of reflow soldering.

[0095] Therefore, as an improvement to the above solution, ball bearings can be placed at the pins on the surface of chip 200, while flux is formed at the pads of printed circuit board 100 instead of ball bearings. Furthermore, during the reflow soldering process, chip 200 is heated, but printed circuit board 100 is not heated. The improved soldering process is as follows: Figure 8 As shown.

[0096] Step S201: Apply flux to the pads of the PCB and place solder balls on the pins of the chip 200 (forming solder balls 300).

[0097] Step S202: Position the PCB and chip 200 face to face, and insert the second post 1022 of the post 102 into the positioning hole 202 of the chip 200, so that there is a preset distance between the PCB and the chip 200, and the ball of the chip 200 does not contact the flux of the PCB.

[0098] Step S203: While heating the chip 200 until the solder balls 300 melt, and without heating the printed circuit board 100, bring the chip 200 and the printed circuit board 100 face to face so that the solder balls 300 contact the printed circuit board 100 for thermo-press welding, and cool to weld the chip 200 and the printed circuit board 100 together.

[0099] In specific implementation, in step S201, the amount of flux can be appropriately reduced, and flux can be applied only to the pad area. This can be achieved by using a screen corresponding to the pads of the printed circuit board 100 for coating. This method also allows control over the uniformity of flux distribution and the consistency of flux height.

[0100] Similarly, ball placement can also be achieved by covering the surface of chip 200 with a screen, leaving the mesh openings exposed to the pins of chip 200. Then, the ball placement material (such as solder paste) is applied to the screen, and excess material is removed. Subsequently, heat is used to form solder balls 300 with rounded and bright surfaces.

[0101] In step S202, the printed circuit board 100, which is placed flat, can be supported by a machine or support mechanism table. The printed circuit board 100 is then fixed by means of suction cups on the machine or table, or by clamping with a fixture. After the printed circuit board 100 is fixed, the chip 200 is moved by the operation of a robotic arm, for example, by adsorbing and fixing the back of the chip 200, and then moving it toward the printed circuit board 100. That is, the chip 200 moves in a manner that approaches the printed circuit board 100, or described as a downward pressing movement of the chip 200 to approach the printed circuit board 100.

[0102] For example, a robotic arm (ARM) can pick up a chip 200 that is placed upside down and has undergone laser balling; a suction cup (CHUCK) can pick up a PCB that has been coated with flux.

[0103] Then, the ARM processor is subjected to a temperature profile for solder ball reflow, with the CHUCK not heated throughout the process. Upon reaching the reflow temperature range (the temperature profile can include four zones: preheating, isothermal, reflow, and cooling; or a preheating, isothermal, and reflow temperature regime can be set), the ARM processor increases pressure or lowers displacement (window parameters can be pre-set) to bring the molten solder balls into contact with the pads on the soldering substrate. Because the solder balls on the surface of chip 200 are heated, when they contact the flux on the substrate surface, the flux is heated and acts to assist the reflow of the solder balls from chip 200 to the pads on the PCB. Since the CHUCK is not heated throughout this process, soldering yield issues caused by PCB warping are avoided.

[0104] The temperature curve can be determined based on the specific composition of the balls implanted on the surface of chip 200.

[0105] After completing the heating and contact steps described above, the area can be cooled to achieve welding.

[0106] By using the above methods, since the printed circuit board 100 is not heated, there is no deformation due to different temperatures, thereby reducing the problem of warping of the chip 200 and the printed circuit board 100 caused by deformation.

[0107] In summary, by selecting a welding method (changing from reflow soldering to thermoforming; not heating the printed circuit board 100), and by setting positioning holes 202 on the chip 200 and setting pillars 102 on the printed circuit board 100 mainly for limiting spacing, the packaging process of the chip 200 and the printed circuit board 100 becomes easier and simpler, and the yield of packaged products is higher, and the consistency between batches of products is higher.

[0108] In this application, the applicant proposes an alternative packaging method that achieves better packaging results by positioning the chip and printed circuit board and adjusting the heating method.

[0109] See Figure 9 The encapsulation method includes:

[0110] Step S301: Provide a chip with positioning holes and solder balls at the pins, and a printed circuit board with posts and flux formed at the pads. The posts include a first post that is axially distributed and thicker and a second post that is thinner. The first post is connected to the printed circuit board and cannot pass through the positioning holes, while the second post can pass through the positioning holes.

[0111] Step S302: Position the chip and printed circuit board so that the second post is inserted into the positioning hole and ensures that the flux and solder balls do not contact; and

[0112] Step S302: Perform thermoforming while heating the chip but not the printed circuit board.

[0113] The chip and printed circuit board can be prefabricated or manufactured on-site during the implementation of this method. The manufacturing process can be found in semiconductor processes, which will not be elaborated upon here—briefly, it may include operations such as photolithography, etching, and coating.

[0114] Specifically, based on the need for convenient positioning and assembly, as well as operational precision, this application provides positioning holes in the chip, and correspondingly, the printed circuit board provides posts that mate with the positioning holes. The posts include a second post (thinner) inserted into the positioning holes to constrain the lateral relative position of the chip and the printed circuit board, and a first post (thicker) that positions the chip and the printed circuit board relative to each other longitudinally to constrain their spacing.

[0115] Furthermore, solder balls are placed at the chip's pins, while flux is applied to the pads on the printed circuit board. The solder balls connect the chip and the printed circuit board, while the flux helps the solder balls wet both the chip and the printed circuit board, ensuring thorough contact and melting. Additionally, the flux promotes the soldering process and protects against unwanted oxidation reactions.

[0116] Based on general operating methods and convenience, step S302, positioning the chip and printed circuit board, thereby inserting the second post into the positioning hole and ensuring that the flux and solder balls do not contact, may include:

[0117] Lay the printed circuit board flat;

[0118] The chip is moved to approach the printed circuit board, and the positioning hole is coaxially aligned with the post;

[0119] Additionally, the printed circuit board is lowered and held in a preset position so that the posts are inserted into or pass through the positioning holes, and the flux and solder balls are kept out of contact.

[0120] In some examples, the positioning of the chip and the printed circuit board can be such that the printed circuit board is fixed or not moved, but the chip is moved to a preset position. In other examples, the printed circuit board may be moved to a preset position, but the chip is not moved. Alternatively, the chip and the printed circuit board may move towards each other to a preset position.

[0121] Because the printed circuit board has a relatively large area, it is possible to prioritize moving the chip and bring it close to the printed circuit board along a specified path until the two maintain a specified distance.

[0122] After positioning the chip and the printed circuit board (PCB), during thermocompression bonding, the compression effect can be achieved by applying a force to the chip towards the PCB, compressing the chip so that the solder balls on the chip come into contact with the flux on the PCB. Therefore, it can be understood that in this packaging method, the chip is heated, moved, and subjected to compression force. Furthermore, to achieve good bonding results, the applied force continues until the thermocompression bonding is complete. A certain amount of compression force can also be maintained during the cooling phase after completion until it cools to room temperature.

[0123] The embodiments described above with reference to the accompanying drawings are exemplary and are only used to explain this application, and should not be construed as limiting this application.

[0124] To make the objectives, technical solutions, and advantages of the embodiments of this application clearer, one or more embodiments have been described above with reference to the accompanying drawings. Throughout the description, similar reference numerals are used to denote similar components. In the foregoing description, numerous specific details have been set forth for illustrative purposes in order to provide a more thorough understanding of one or more embodiments. However, it will be apparent that one or more embodiments may be practiced in various circumstances without these specific details, and the embodiments may be combined with and referenced to each other without contradiction.

[0125] It should be noted that the terms "first," "second," etc., in the specification, claims, and accompanying drawings of this application are used to distinguish similar objects and are not necessarily used to describe a specific order or sequence. It should be understood that such data can be interchanged where appropriate so that the embodiments of this application described herein can be implemented in sequences other than those illustrated or described herein.

[0126] Furthermore, the terms “comprising” and “having”, and any variations thereof, are intended to cover non-exclusive inclusion, such that a process, method, system, product, or apparatus that includes a series of steps or units is not necessarily limited to those steps or units that are explicitly listed, but may include other steps or units that are not explicitly listed or that are inherent to such process, method, product, or apparatus.

[0127] The above description of the structure, features and effects of this application is based on the embodiments shown in the drawings. The above are only preferred embodiments of this application. However, this application does not limit the scope of implementation to what is shown in the drawings. Any changes made in accordance with the concept of this application, or modifications to equivalent embodiments, that do not exceed the spirit covered by the specification and drawings, should be within the protection scope of this application.

Claims

1. A packaging method, characterized in that... include: A chip with positioning holes and solder balls at the pins is provided, and a printed circuit board with posts and flux formed at the pads is provided. The posts include a first post that is axially distributed and thicker and a second post that is thinner. The first post is connected to the printed circuit board and cannot pass through the positioning holes, while the second post can pass through the positioning holes. Position the chip and printed circuit board so that the second post is inserted into the positioning hole and ensures that the flux and solder balls do not come into contact. as well as Thermopressing is performed under conditions where the chip is heated but the printed circuit board is not.

2. The packaging method according to claim 1, characterized in that, The packaging method includes one or more of the following limitations: First limitation: The positioning hole is fabricated using deep silicon etching; Second limitation: The method of manufacturing solder balls is laser ball implantation; Third limitation: The flux is formed by screen printing.

3. The packaging method according to claim 1, characterized in that, Methods for positioning the chip and printed circuit board so that the second post is inserted into the positioning hole and ensuring that the flux and solder balls do not come into contact include: Lay the printed circuit board flat; The chip is moved to approach the printed circuit board, and the positioning hole is coaxially aligned with the post; Additionally, the printed circuit board is lowered and held in a preset position so that the posts are inserted into or pass through the positioning holes, and the flux and solder balls are kept out of contact.

4. The packaging method according to claim 1, 2, or 3, characterized in that, During the hot-press soldering process, an operational force is applied to the chip toward the printed circuit board to compress the chip, causing the chip's solder balls to come into contact with the flux on the printed circuit board.

5. The packaging method according to claim 4, characterized in that, The application of force continues until the thermo-pressure welding is completed.

6. The packaging method according to claim 1, characterized in that, The column is a superconducting column formed by integrally molding the first column and the second column.

7. The packaging method according to claim 1, characterized in that, The first column is welded to the front of the main body; And / or, the first post is a cylinder, the second post is a prism, and the positioning hole is a prism hole that matches the second post.

8. The packaging method according to claim 1, characterized in that, The printed circuit board defines an inner region and an outer region that extends outward from the inner region in a ring shape, and the number of pillars is multiple and distributed in a rectangular pattern in the outer region.

9. A packaging structure obtained by implementing the packaging method according to any one of claims 1 to 8.

10. A superconducting quantum computer, characterized in that, Includes the packaging structure described in claim 9.

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