Method for preparing bump array on packaging substrate

Abstract

The present invention provides a method for preparing a bump array on a packaging substrate. The bumps are formed by a 3D printing method, thereby realizing the preparation of a small-sized and fine-pitch bump array, and more types of special-shaped bumps can be prepared, thereby providing a structural basis for studying new bonding methods. The method is carried out on a single bump basis, thereby avoiding the processing process on the entire packaging substrate basis, making it easier to repair the bump array at any time, thereby significantly improving the production yield. The 3D printing method adopted by the present invention directly uses a laser to synchronously sinter and form the bumps, greatly simplifying the preparation process of the bump array, solving the problems of the traditional process being complex, requiring multiple equipment, and being expensive. For the production and research and development of small-batch packaging substrates, the method greatly reduces the cost investment in the early stage of production and manufacturing, greatly improves the processing efficiency, shortens the research and development time, and has a higher production yield.

Description

Technical Field

[0001] The present invention relates to the field of integrated circuits, and in particular to a method for preparing a bump array on a packaging substrate. Background Art

[0002] 3D printing, as a rapid prototyping technology, uses digital model files as a foundation and constructs objects through layer-by-layer printing using bondable materials such as powdered metal or plastic. Compared to traditional manufacturing technologies, 3D printing offers numerous advantages, including low cost, simple processing, suitability for a variety of materials, including rigid and flexible, as well as curved surfaces, high material utilization, a wide range of available materials, no need for masks or molds, and the ability to directly form. It possesses significant potential and unique advantages in the fabrication of complex three-dimensional structures, structures with large aspect ratios, multi-material composite structures, structures spanning macro, micro, and nanoscale scales, and embedded heterogeneous structures.

[0003] Flip Chip Ball Grid Array (FCBGA) is the mainstream packaging method for high-end chips in the integrated circuit field. To ensure reliable interconnection between the chip and the packaging substrate, FCBGA packaging requires the prefabrication of bump arrays on both the chip and the packaging substrate. Conventional processes for forming bump arrays include evaporation, stencil printing, ball planting, and electroplating. Evaporation is generally used to create the bump array on the chip, while stencil printing, ball planting, and electroplating are used on both the chip and the packaging substrate. However, with the increasing application of heterogeneous integration, in the manufacturing process of packaging substrates containing embedded silicon-based intermediate layers, the bump arrays are developing towards smaller pitches and smaller sizes. The traditional evaporation process and template printing process can no longer meet the requirements of the production of bump arrays with a size less than 70μm and a pitch less than 150μm on the embedded silicon-based intermediate layer. Although the ball planting process and electroplating process can meet the production of small-size and small-pitch bump arrays, in the production process of small batches of test boards, the screen needs to be remade each time, which incurs high costs. In addition, if one of the bumps is defective, the entire packaging substrate will be scrapped, making it difficult to control the production yield. Summary of the Invention

[0004] In view of the shortcomings of the prior art described above, the object of the present invention is to provide a method for preparing a bump array on a packaging substrate, which is used to solve the problems of high cost, long preparation cycle and low production yield caused by using existing conventional production processes to prepare small-size and small-pitch bump arrays in the process of small-batch production of packaging substrates in the prior art.

[0005] To achieve the above-mentioned and other related purposes, the present invention provides a method for preparing a bump array on a package substrate, the method comprising the following steps:

[0006] S1: providing a packaging substrate, wherein the packaging substrate comprises a front surface and a back surface that are opposite to each other, wherein the front surface of the packaging substrate is provided with a surface pad array, and the back surface of the packaging substrate is fixed on a carrier;

[0007] S2: using a first optical device to perform a first scan to identify and record second position information of the surface pad array;

[0008] S3: providing first position information of the surface pad array during initial design, and comparing the first position information with the second position information, thereby selecting the surface pad array on which bumps need to be formed;

[0009] S4: forming bumps for the first time on the surface pad array where a bump array needs to be formed using a 3D printing method;

[0010] S5: Scanning the surface pad array on which the bumps are formed for a second time using a second optical device to identify defect types and record locations of the defect types;

[0011] S6: forming a bump a second time at the location of the defect using the 3D printing method;

[0012] S7: Repeat steps S5 to S6 until all bumps on the surface pad array that need to be bumped are completed.

[0013] Optionally, the first optical device is a CCD camera, and the second optical device is a laser camera.

[0014] Optionally, the pitch of the bumps on the surface pad array is 40 μm to 150 μm.

[0015] Optionally, the step of forming the bumps by the 3D printing method includes: spraying multiple layers of metal powder on the surface pad array where the bumps need to be formed according to a preset route using a 3D printing nozzle, and synchronously sintering the metal powder on the surface pad array layer by layer using a laser to obtain the bumps.

[0016] Optionally, the synchronous sintering method includes one or more of direct metal laser sintering, electron beam melting, selective laser melting, selective thermal sintering or selective laser sintering.

[0017] Optionally, the laser is a fiber laser or an ultraviolet laser.

[0018] Optionally, the metal powder includes at least one or more of copper, tin, gold, indium, nickel, and silver, and the particle size of the metal powder is 0.1 μm to 10 μm.

[0019] Optionally, the bumps on the surface pad array are in the shape of one or more of a sphere, a cylinder, a cone, a truncated cone, and a cuboid.

[0020] Optionally, a heating device for heating the packaging substrate is provided on the carrier, and the operating temperature range of the heating device is 30°C to 200°C.

[0021] Optionally, the defect types include missed pads and residual pads on the surface pad array.

[0022] Optionally, a method of fixing the back surface of the packaging substrate on the carrier includes fixing with pins, fixing with vacuum adsorption, or embedding the packaging substrate into a groove of the carrier.

[0023] As described above, the method for preparing a bump array on a packaging substrate of the present invention has the following beneficial effects: the present invention adopts a 3D printing method to replace the evaporation, template printing, ball planting and electroplating processes in the conventional process, thereby realizing the preparation of a small-size and small-pitch bump array, and using this preparation method can prepare more types of special-shaped bumps, thereby providing a certain structural basis for the research and development of new bonding methods between chips and packaging substrates. In addition, the preparation method is carried out on a single bump basis, thereby avoiding the processing process on the entire packaging substrate basis, making it more convenient to return the bump array at any time. The 3D printing method adopted by the present invention replaces the steps of flux coating, reflow soldering and flux cleaning in the conventional process, as well as the production cycle of auxiliary materials such as dry film, screen, fixture, and liquid medicine, which greatly simplifies the preparation process of the bump array and solves the problems of complex process flow, large number of equipment and high cost in the traditional process. In particular, for the production and research and development of small-batch packaging substrates with silicon-based intermediate layers, it greatly reduces the cost investment in the early stage of production and manufacturing, greatly improves processing efficiency, shortens the research and development time and has a higher production yield. BRIEF DESCRIPTION OF THE DRAWINGS

[0024] Figure 1 Shown is a schematic flow chart of a method for preparing a bump array on a packaging substrate according to the present invention.

[0025] Figure 2 Shown is a schematic structural diagram of bumps of different shapes formed in the method for preparing a bump array of the present invention.

[0026] Figure 3 Shown is a schematic structural diagram of a packaging substrate in the method for preparing a bump array of the present invention.

[0027] Figure 4 Shown is a structural schematic diagram of another packaging substrate in the method for preparing a bump array of the present invention.

[0028] Figure 5 It shows a schematic structural diagram of a packaging substrate being fixed on a carrier in the method for preparing a bump array of the present invention.

[0029] Figure 6 It is a schematic diagram showing the first scanning performed by the first optical device in the method for preparing the bump array of the present invention.

[0030] Figure 7 It is a schematic diagram showing the process of manufacturing a bump array according to the present invention after the bumps are formed for the first time.

[0031] Figure 8 It is a schematic structural diagram showing the defect types of the packaging substrate in the method for preparing the bump array of the present invention.

[0032] Figure 9 It is a schematic structural diagram showing that all bumps on the second pad array are completed in the method for preparing the bump array of the present invention.

[0033] Description of component numbers.

[0034] 101. Package substrate; 102. Surface pad array; 103. Fixing hole; 104. Silicon-based intermediate layer; 105. First pad array; 106. Solder mask; 107. Carrier; 1071. Pin; 108. First optical device; 109. Laser; 110. 3D printing nozzle; 111. Powder feeder; 112. Bump; 1121. Square bump; 1122. Spherical bump; 1123. Cylindrical bump; 1124. Cone-shaped bump; 1125. Conical bump; 113. Missing dot; 114. Residual dot; 115. Second optical device; S1~S7, steps. DETAILED DESCRIPTION

[0035] The following describes the embodiments of the present invention through specific examples. Those skilled in the art will readily understand the other advantages and benefits of the present invention from the disclosure herein. The present invention may also be implemented or applied through various other specific embodiments, and the details in this specification may be modified or altered based on different viewpoints and applications without departing from the spirit of the present invention.

[0036] For example, when describing the embodiments of the present invention, schematic diagrams illustrating device structures may be partially enlarged for ease of explanation. These schematic diagrams are merely illustrative and should not limit the scope of the present invention. Furthermore, in actual production, three-dimensional dimensions, including length, width, and depth, should be included.

[0037] For convenience of description, spatially relative terms such as "under," "below," "below," "below," "above," and "upper" may be used herein to describe the relationship of one element or feature to other elements or features shown in the drawings. It will be understood that these spatially relative terms are intended to encompass other orientations of the device in use or operation in addition to the orientation depicted in the drawings.

[0038] In the context of the present application, a structure described as a first feature being "above" a second feature may include embodiments where the first and second features are in direct contact, and may also include embodiments where additional features are formed between the first and second features, such that the first and second features may not be in direct contact.

[0039] See also Figures 1 to 9 It should be noted that the diagrams provided in this embodiment are only used to schematically illustrate the basic concept of the present invention. Therefore, the diagrams only show components related to the present invention and are not drawn according to the number, shape and size of components in actual implementation. In actual implementation, the type, quantity and proportion of each component can be changed at will, and the component layout type may also be more complicated.

[0040] This embodiment provides a method for preparing an array of bumps 112 on a package substrate 101 having a silicon-based intermediate layer 104, such as Figure 1 As shown, it is shown as a process flow chart of the preparation method, comprising the following steps:

[0041] S1: providing a packaging substrate 101, wherein the packaging substrate 101 comprises a front surface and a back surface opposite to each other, and a surface pad array 102 is provided on the front surface of the packaging substrate 101;

[0042] S2: Fixing the back surface of the packaging substrate 101 on the stage 107 and using the first optical device 108 to perform a first scanning recognition and record the second position information of the surface pad array 102;

[0043] S3: providing first position information of the surface pad array 102 during initial design, and comparing the first position information with the second position information, thereby selecting the surface pad array 102 where the bumps 112 need to be formed;

[0044] S4: forming bumps 112 for the first time on the surface pad array 102 where the bump array 112 needs to be formed using a 3D printing method;

[0045] S5: Scanning the surface pad array 102 forming the bumps 112 for a second time using the second optical device 115 to identify defect types and record locations of the defect types.

[0046] S6: forming a bump 112 again at the location of the defect type using a 3D printing method;

[0047] S7: Repeat steps S5 to S6 until all bumps 112 on the surface pad array 102 where bumps 112 need to be formed are completed.

[0048] The following further describes the method for preparing the array of bumps 112 on the package substrate 101 with reference to the accompanying drawings, as follows:

[0049] In step S1, see Figure 1 、 Figure 3 and Figure 4 , providing a packaging substrate 101, the packaging substrate 101 includes a front side and a back side arranged opposite to each other, the front side of the packaging substrate 101 is provided with a surface pad array 102 and the back side of the packaging substrate 101 is fixed on a carrier 107.

[0050] It should be noted that the surface of the package substrate 101 having the surface pad array 102 is defined as the front side, and the other side opposite thereto is defined as the back side. Specifically, Figure 3 As shown, a schematic diagram of a cross-sectional structure of a packaging substrate 101 is provided. A silicon-based intermediate layer 104 and a wiring layer are respectively provided in the packaging substrate 101, wherein the silicon-based intermediate layer 104 is integrated with passive devices. In this embodiment, the passive devices include at least capacitors, resistors and inductors. A first pad array 105 is provided on the surface of the silicon-based intermediate layer 104. The first pad array 105 is arranged opposite to the surface pad array 102 as the pins of the passive devices and is electrically connected to the outside of the packaging substrate 101. The packaging substrate 101 includes a front side and a back side arranged opposite to each other. A surface pad array 102 is formed on the front side of the packaging substrate 101. This surface pad array 102 is a second pad array. One side of the second pad array is connected to the first pad array 105 of the silicon-based intermediate layer 104 in the packaging substrate 101, and the other side of the second pad array is bonded to the micro-bumps on the active surface of the chip (the side of the chip with micro-bumps is defined as the active surface), thereby realizing electrical connection between the chip and the packaging substrate 101.

[0051] like Figure 4 FIG. 1 shows another cross-sectional view of a package substrate 101. A solder resist layer 106 is provided on the front surface of the package substrate 101. The solder resist layer 106 has a plurality of through-holes formed therein to expose the second pad array to the outside. The subsequently formed bumps 112 are located precisely on the second pad array within the through-holes. The solder resist layer 106 prevents short circuits and effectively protects the circuit from moisture. For ease of description, the present invention will be described using an example in which the package substrate 101 has a silicon-based intermediate layer 104 and no solder resist layer 106.

[0052] In step S2, see Figure 1 、 Figure 5 and Figure 6 The back surface of the packaging substrate 101 is fixed on the carrier 107 and a first scan is performed using the first optical device 108 to identify and record the second position information of the surface pad array 102 .

[0053] In this embodiment, if Figure 5 As shown, in order to fix the packaging substrate 101, the back side of the packaging substrate 101 is fixed on the carrier 107. Optionally, the method of fixing the back side of the packaging substrate 101 on the carrier 107 includes fixing with a pin 1071, fixing by vacuum adsorption, or embedding the packaging substrate 101 into a groove on the carrier 107, that is, the back side of the packaging substrate 101 can be provided with a fixing hole 103, so that the packaging substrate 101 is fixed on the carrier 107 by the pin 1071. Alternatively, a vacuum adsorption device is further provided on the carrier 107. Preferably, the vacuum adsorption device is provided in the area where the packaging substrate 101 contacts the carrier 107, and an external vacuum source is connected to the outside of the vacuum adsorption device. The vacuum adsorption device includes multiple adsorption holes and the adsorption holes are evenly distributed. When the packaging substrate 101 is placed in the fixed area , the adsorption holes can be completely covered. At this time, turning on the external vacuum source can extract the air in the contact area between the packaging substrate 101 and the carrier 107 to make it a negative pressure state, so that the packaging substrate 101 can be vacuum-adsorbed by utilizing the air pressure difference, thereby achieving the effect of fixing the packaging substrate 101. After the bumps 112 are formed, turning off the vacuum source can break the vacuum adsorption device, so that the packaging substrate 101 can be removed, which is more conducive to actual use and will not cause damage to the packaging substrate 101 during use. In addition, the packaging substrate 101 can also be directly embedded in the groove of the carrier 107. At this time, the size of the packaging substrate 101 is consistent with the size of the groove of the carrier 107, so that the packaging substrate 101 will not be displaced during the process of printing to form the bump 112 array. Optionally, a heating device for heating the packaging substrate 101 is further provided on the carrier 107, and the operating temperature range of the heating device is 30°C~200°C. By heating the packaging substrate 101 by the heating device, the thermal stress generated on the packaging substrate 101 during the sintering process of metal powder using laser during 3D printing can be reduced, thereby preventing the side of the packaging substrate 101 where the bump 112 is formed from warping and deformation due to excessive temperature.

[0054] Specifically, such as Figure 6As shown, the packaging substrate 101 fixed on the carrier 107 is placed under the first optical device 108, and the first optical device 108 is communicated with the external computer unit. By starting the first optical device 108, the packaging substrate 101 is scanned for the first time to identify the second position information of the second pad array. Optionally, in this embodiment, the first optical device 108 is a CCD camera, which can scan the second pad array to form an image to facilitate identification of the second position information of the second pad array, and record the second position information in the computer unit.

[0055] In step S3, see Figure 1 , providing the first position information of the surface pad array 102 during the initial design, and comparing the first position information with the second position information, so as to select the surface pad array 102 where the bump 112 array needs to be formed.

[0056] Specifically, the computer unit stores the first position information of the surface pad array 102 during the initial design. The first position information represents the surface pad location where the bump array 112 needs to be formed. The first position information is compared and analyzed with the second position information to determine the surface pad location where the bump array 112 needs to be formed, and this information is transmitted to the 3D printing control unit.

[0057] In step S4, see Figure 1 and Figure 7 , the bumps 112 are formed for the first time on the surface pad array 102 where the bump array 112 needs to be formed using a 3D printing method.

[0058] Specifically, such as Figure 7 As shown, according to the surface pad locations on the package substrate 101 where bumps 112 need to be formed determined in step S3, the control unit is used to start the 3D printing device to form bumps 112 on the surface pad array 102 for the first time.

[0059] As an example, the steps of forming the bump 112 using a 3D printing method include: using a 3D printing nozzle 110 to spray multiple layers of metal powder on the surface pad array 102 where the bump 112 needs to be formed according to a preset route, and using a laser 109 to synchronously sinter the metal powder on the surface pad array 102 layer by layer to obtain the bump 112. Specifically, the metal powder is first loaded into the consumable box, the 3D printing nozzle 110 is connected to the consumable box, and the metal powder is sprayed onto the surface pad array 102 through the 3D printing nozzle 110 through the powder feeder 111. In this embodiment, the 3D printing nozzle 110 first sprays a first layer of metal powder on the surface pad array 102 where the bumps 112 need to be formed according to a preset route. At the same time, the laser 109 is used to sinter the first layer of metal powder on the surface pad array 102. After sintering is completed, the above steps are repeated to feed powder through the powder feeder 111 to spray multiple layers of metal powder on the surface pad array 102 and synchronously sinter each layer of metal powder until the bumps 112 are formed on the surface pad array 102.

[0060] As an example, the simultaneous sintering method includes one or more of direct metal laser sintering, electron beam melting, selective laser melting, selective thermal sintering or selective laser sintering.

[0061] Specifically, direct metal laser sintering, electron beam melting, selective laser melting, selective thermal sintering, or selective laser sintering, as powder-based additive manufacturing technologies, are often used in layer-by-layer additive manufacturing. In this embodiment, direct metal laser sintering is selected as the method for simultaneously sintering each layer of metal powder. Of course, in other embodiments, other processes may be selected for the simultaneous sintering method, which is not limited herein. Optionally, the type of laser 109 is either a fiber laser 109 or a UV laser 109. Specifically, optical fiber, as a cylindrical waveguide medium, has a small core diameter, which easily forms a high power density within the fiber, thereby causing a population inversion of the laser working material energy level. The resulting laser 109 has advantages such as a low laser threshold, high conversion efficiency, and good beam quality. The optical fiber output can be well matched with existing communication optical fibers, making coupling easier. The ultraviolet laser generated by the UV laser 109 not only has high beam quality and a smaller focused spot, but also can achieve ultrafine marking, with a wider range of applications. By using the laser light generated by the fiber laser 109 or the ultraviolet laser 109 to synchronously sinter each layer of metal powder, the bumps 112 can be better formed.

[0062] As an example, the types of the metal powder include at least one or more of copper, tin, gold, indium, nickel, and silver, and the particle size of the metal powder is 0.1 μm to 10 μm.

[0063] Specifically, the types of metal powder include at least one or more of copper, tin, gold, indium, nickel, and silver. Since different 3D printing equipment and forming processes have different requirements for the particle size distribution of metal powder, the selection of metal powder particle size used in 3D printing is mainly based on the division of printers with different energy sources. In this embodiment, the printer using laser 109 as the energy source has a fine focused spot of the laser, which makes it easier to melt fine powder. In this embodiment, the particle size of the metal powder is set to 0.1μm~10μm, and the metal powder is supplied in a layer-by-layer manner through the powder feeder 111.

[0064] In step S5, see Figure 1 and Figure 8 , a second optical device 115 is used to scan the surface pad array 102 forming the bump 112 for a second time, identify the defect type and record the location of the defect type.

[0065] Specifically, such as Figure 8 As shown, the package substrate 101 after the first formation of the bumps 112 is re-placed under the second optical device 115. The second optical device 115 is in communication with the external computer unit. By starting the second optical device 115, the package substrate 101 is scanned a second time to identify the defect type on the surface pad array 102, and the location information of the defect type is recorded in the computer unit. Optionally, in this embodiment, the second optical device 115 is a laser camera, which can emit a laser beam to the surface pad array 102 and receive the beam reflected back from the surface pad array 102, thereby forming three-dimensional image information to facilitate identification of the defect type of the surface pad array 102 after the first formation of the bumps 112.

[0066] As an example, the defect types include missed pads 113 and residual pads 114 on the surface pad array 102 .

[0067] Specifically, such as Figure 8 As shown, it is a schematic diagram of the cross-sectional structure of the missed points 113 and the residual points 114 on the surface pad array 102, wherein the missed points 113 are defined as no bumps 112 are formed at the pad sites of the surface pad array 102, and the residual points 114 are defined as only some of the bumps 112 are printed on the pad sites of the surface pad array 102. The missed points 113 and the residual points 114 on the surface pad array 102 will affect the interconnection performance between the packaging substrate 101 and the chip. Therefore, the missed points 113 and the residual points 114 on the surface pad array 102 need to be reconstructed. The missed points 113 and the residual points 114 can be identified by using a laser camera, and the spatial positions of the missed points 113 and the residual points 114 and the heights of the residual points 114 can be recorded.

[0068] In step S6, refer to Figure 1 and Figure 9 , a 3D printing method is used to form a bump 112 for the second time at the location of the defect type.

[0069] Specifically, such as Figure 9 As shown, according to the spatial positions of the missed points 113 and the residual points 114 in the surface pad array 102 determined in step S5, the control unit is used to start the 3D printing device again to form bumps 112 again at the positions of the missed points 113 and the residual points 114 in the surface pad array 102. In this process, by controlling the amount of metal powder entering the 3D printing nozzle 110 through the powder feeder 111, it is ensured that the height of the finally completed bumps 112 has good uniformity.

[0070] Since in actual operation, the number of missed dots 113 and residual dots 114 may be large, making it impossible to identify them all at once, therefore, step S7 is executed, i.e., steps S5 to S6 are repeated, i.e., the missed dots 113 and residual dots 114 are identified and recorded multiple times until the array of bumps 112 on the surface pad array 102 is completely formed.

[0071] Specifically, in this embodiment, after all the bumps 112 are formed, the bumps 112 formed on the surface pad array 102 are electrically connected to the pads in the first pad array 105 provided on the surface of the silicon-based intermediate layer 104. The distance between two adjacent pads in the first pad array 105 is the pitch of the formed bumps 112. The pitch of the bumps 112 on the surface pad array 102 is 40 μm to 150 μm, for example, 40 μm, 80 μm, 120 μm, or 150 μm, which is not limited here. Since the pitch of the bumps 112 formed on the surface pad array 102 is smaller, it can meet its application in advanced packaging and heterogeneous integration.

[0072] As an example, the bumps 112 on the surface pad array 102 are shaped in one or more of a sphere, a cylinder, a cone, a truncated cone, and a cuboid.

[0073] Specifically, such as Figure 2 As shown, one or more of square bumps 112, spherical bumps 112, cylindrical bumps 112, truncated cone bumps 112, and conical bumps 112 are formed on the surface pad array 102 by 3D printing. By manufacturing various special-shaped bumps 112, a structural basis is provided for the research and development of new bonding methods between the packaging substrate 101 and the chip.

[0074] In summary, the method for preparing a bump array on a packaging substrate of the present invention adopts a 3D printing method to replace the evaporation, template printing, ball planting and electroplating processes in conventional processes, thereby realizing the preparation of a small-size and small-pitch bump array, and using this preparation method, more types of special-shaped bumps can be prepared, thereby providing a certain structural basis for the research and development of new bonding methods between chips and packaging substrates. In addition, the preparation method is carried out on a single bump basis, thereby avoiding the processing process on the entire packaging substrate basis, making it easier to repair the bump array at any time, thereby significantly improving the production efficiency of the packaging substrate. Yield rate; The 3D printing method adopted by the present invention replaces the steps of flux coating, reflow soldering and flux cleaning in the conventional process, as well as the production cycle of auxiliary materials such as dry film, screen, fixture, and liquid medicine. It directly uses a laser to synchronously sinter the bumps, greatly simplifying the preparation process of the bump array and solving the problems of complex traditional process flow, multiple equipment and high cost. Especially for the production and research and development of small batches of packaging substrates with silicon-based intermediate layers, it greatly reduces the cost investment in the early stage of production and manufacturing, greatly improves processing efficiency, shortens the research and development time and has a high production yield. Therefore, the present invention effectively overcomes the various shortcomings of the existing technology and has high industrial utilization value.

[0075] The above embodiments are merely illustrative of the principles and effects of the present invention and are not intended to limit the present invention. Anyone skilled in the art may modify or alter the above embodiments without departing from the spirit and scope of the present invention. Therefore, all equivalent modifications or alterations made by one of ordinary skill in the art without departing from the spirit and technical principles disclosed herein are intended to be covered by the claims of the present invention.

Claims

1. A method for preparing a bump array on a packaging substrate, characterized in that: The preparation method comprises the following steps: S1: providing a packaging substrate, wherein the packaging substrate comprises a front surface and a back surface disposed opposite to each other, and a surface pad array is provided on the front surface of the packaging substrate; S2: Fixing the back surface of the packaging substrate on a carrier and performing a first scan using a first optical device to identify and record second position information of the surface pad array, wherein a heating device for heating the packaging substrate is provided on the carrier, and the operating temperature range of the heating device is 30° C. to 200° C.; S3: providing first position information of the surface pad array during initial design, and comparing the first position information with the second position information, thereby selecting the surface pad array on which bumps need to be formed; S4: forming bumps for the first time on the surface pad array where a bump array needs to be formed using a 3D printing method; S5: Scanning the surface pad array on which the bumps are formed for a second time using a second optical device to identify defect types and record locations of the defect types; S6: forming a bump a second time at the location of the defect using the 3D printing method; S7: Repeat steps S5 to S6 until all bumps on the surface pad array that need to be bumped are completed.

2. The method for preparing a bump array on a package substrate according to claim 1, wherein: The first optical device is a CCD camera, and the second optical device is a laser camera.

3. The method for preparing a bump array on a package substrate according to claim 2, wherein: The pitch size of the bumps on the surface pad array is 40 μm to 150 μm.

4. The method for preparing a bump array on a package substrate according to claim 1, wherein: The steps of forming bumps in the 3D printing method include: spraying multiple layers of metal powder on the surface pad array where bumps are to be formed according to a preset route using a 3D printing nozzle, and synchronously sintering the metal powder on the surface pad array layer by layer using a laser to obtain the bumps.

5. The method for preparing a bump array on a package substrate according to claim 4, wherein: The synchronous sintering method includes one or more of direct metal laser sintering, electron beam melting, selective laser melting, selective thermal sintering or selective laser sintering.

6. The method for preparing a bump array on a package substrate according to claim 4, wherein: The laser is a fiber laser or an ultraviolet laser.

7. The method for preparing a bump array on a package substrate according to claim 4, wherein: The metal powder includes at least one or more of copper, tin, gold, indium, nickel, and silver, and the particle size of the metal powder is 0.1 μm to 10 μm.

8. The method for preparing a bump array on a package substrate according to claim 1, wherein: The bumps on the surface pad array are in one or more shapes of sphere, cylinder, cone, truncated cone, and cuboid.

9. The method for preparing a bump array on a package substrate according to any one of claims 1 to 8, wherein: The defect types include missed pads and residual pads on the surface pad array.

10. The method for preparing a bump array on a package substrate according to claim 9, wherein: Methods for fixing the back surface of the packaging substrate on the carrier include fixing with pins, fixing with vacuum adsorption, or embedding the packaging substrate into a groove of the carrier.

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