Preparation method of substrate bump structure

Abstract

The embodiment of the invention provides a preparation method of a substrate bump structure, and relates to the technical field of electronic manufacturing, and the preparation method comprises the steps: S10, employing a printing technology to deposit solder paste and solder on a substrate; s20, the deposited solder paste solder is leveled, and the size parameters of the leveled solder paste solder are obtained; and step S30, according to the size parameters of the solder paste solder, controlling the laser processing platform to cut the leveled solder paste solder to form a substrate bump structure. According to the method, the solder paste solder is deposited by adopting a printing process, and the deposited solder paste solder is leveled and then cut by adopting a laser processing mode, so that on the premise of ensuring high cutting precision and small line spacing, the preparation process is simplified, and the efficiency of preparing the bump structure of the substrate is improved.

Description

Technical Field

[0001] The invention relates to the technical field of electronic manufacturing, and in particular to a method for preparing a substrate convex point structure. Background Art

[0002] In order to meet the requirements of high performance, multi-function, high reliability, thinness, lightness and portability of packaged parts, advanced packaging technologies such as flip chip are usually used to replace traditional packaging technologies. Flip chip bonding refers to picking up the chip with bumps from the blue film and flipping it so that its solder joint pattern faces down and is placed on the substrate. Among them, bump preparation is one of the core technologies to achieve chip flip bonding.

[0003] The existing bump preparation methods mainly include vapor deposition and electroplating. Vapor deposition and electroplating have the advantages of good consistency, small line width and line spacing, but the disadvantages are that the process is relatively complicated, the cycle is long, and the preparation efficiency is low. Summary of the invention

[0004] The embodiment of the present invention provides a method for preparing a substrate bump structure, so as to solve the technical problem of low efficiency in preparing a substrate bump structure in the prior art in the related art.

[0005] An embodiment of the present invention provides a method for preparing a substrate bump structure, comprising the following steps:

[0006] A printing process is used to deposit solder paste on the substrate;

[0007] Leveling the deposited solder paste and obtaining the size parameters of the leveled solder paste;

[0008] According to the size parameters of the solder paste, the laser processing platform is controlled to cut and level the solder paste to form a substrate bump structure.

[0009] In some embodiments, the step of depositing solder paste on the substrate using a printing process includes:

[0010] Depending on the size of the chip to be bonded and the distribution of the pads, solder paste is deposited on the substrate using single-point printing or planar printing technology.

[0011] In some embodiments, the step of leveling the deposited solder paste and obtaining the size parameters of the leveled solder paste includes the following steps:

[0012] Heating the deposited solder paste;

[0013] Use a flat ceramic block to squeeze and level the heated solder paste;

[0014] Measure the solder paste height after leveling.

[0015] In some embodiments, the step of heating the deposited solder paste comprises:

[0016] When the solder paste is heated, the heating temperature is lower than the melting point of the solder paste.

[0017] In some embodiments, the step of using a flat ceramic block to extrude and flatten the heated solder paste comprises:

[0018] When the heated solder paste is squeezed, the maximum pressure is greater than the product of the compressive strength of the solder paste and the sum of the bottom area.

[0019] In some embodiments, the step of controlling the laser processing platform to cut the leveled solder paste according to the size parameters of the solder paste to form the substrate bump structure includes the following steps:

[0020] Calculate the laser output power and processing time according to the height of the solder paste after leveling;

[0021] According to the calculated laser output power and processing time, the laser processing platform is controlled to cut the leveled solder paste to form a substrate bump structure.

[0022] In some embodiments, the substrate is a gold-plated ceramic substrate.

[0023] In some embodiments, the solder paste is lead-free solder.

[0024] In some embodiments, the lead-free solder is gold-tin solder.

[0025] In some embodiments, the laser processing platform is a picosecond laser processing platform.

[0026] The beneficial effects brought about by the technical solution provided by the present invention include:

[0027] The embodiment of the present invention provides a method for preparing a substrate bump structure, the preparation method comprising depositing solder paste on a substrate by a printing process, leveling the deposited solder paste, obtaining the size parameters of the leveled solder paste, and controlling a laser processing platform to cut the leveled solder paste according to the size parameters of the solder paste to form a substrate bump structure. The present invention deposits solder paste by a printing process, and cuts the deposited solder paste by laser processing after leveling. Under the premise of ensuring high cutting accuracy and small line spacing, the preparation process is simplified and the efficiency of preparing the substrate bump structure is improved. BRIEF DESCRIPTION OF THE DRAWINGS

[0028] In order to more clearly illustrate the technical solutions in the embodiments of the present invention, the following briefly introduces the drawings required for use in the description of the embodiments. Obviously, the drawings described below are only some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without creative work.

[0029] Figure 1 A first flow chart of a method for preparing a substrate bump structure provided by an embodiment of the present invention;

[0030] Figure 2 A second flow chart of a method for preparing a substrate bump structure provided by an embodiment of the present invention;

[0031] Figure 3 A first preparation state diagram of a substrate bump structure provided by an embodiment of the present invention;

[0032] Figure 4 A second preparation state diagram of a substrate bump structure provided by an embodiment of the present invention;

[0033] Reference numerals:

[0034] 1. Substrate;

[0035] 2. convex point; 21. convex point;

[0036] 3. Solder surface coating area. DETAILED DESCRIPTION

[0037] In order to make the purpose, technical solution and advantages of the embodiments of the present invention clearer, the technical solution in the embodiments of the present invention will be clearly and completely described below in conjunction with the drawings in the embodiments of the present invention. Obviously, the described embodiments are part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0038] The embodiment of the present invention provides a method for preparing a substrate bump structure, which can solve the technical problem of low efficiency in preparing a substrate bump structure in the prior art in the related art.

[0039] See also Figure 1 As shown, a method for preparing a substrate bump structure provided by an embodiment of the present invention comprises the following steps:

[0040] Step S10, depositing solder paste on the substrate using a printing process;

[0041] Specifically, the solder paste is deposited on the surface of the substrate 1 by a printing process, and the shape, spacing and number of bumps of the deposited solder paste are determined according to specific requirements. The method of depositing solder paste by a printing process is simple and easy to operate.

[0042] Step S20, leveling the deposited solder paste and obtaining the size parameters of the leveled solder paste, that is, leveling the solder paste deposited in step S10 to ensure the uniformity of the solder paste and improve the quality of the substrate bump structure preparation.

[0043] Step S30, according to the size parameters of the solder paste, control the laser processing platform to cut the solder paste after leveling to form the substrate bump structure. The solder paste leveled in step S20 is cut by laser processing to ensure high cutting accuracy and realize the preparation of small line pitch bumps. The present invention simplifies the preparation process and improves the efficiency of preparing the substrate bump structure while ensuring high cutting accuracy and small line pitch.

[0044] The embodiment of the present invention provides a method for preparing a substrate bump structure, which simplifies the preparation process and improves the efficiency of preparing the substrate bump structure while ensuring high cutting accuracy and small line pitch.

[0045] As an optional implementation, in one embodiment of the invention, the step S10 uses a printing process to deposit solder paste on the substrate, including depositing solder paste on the substrate using single-point printing or planar printing technology according to the size of the chip to be bonded and the distribution of the pads. Single-point printing can be used when the chip to be bonded is small or the pad spacing is large. When the chip to be bonded is large or the pad distribution is dense, planar printing is used to reduce the workload. Single-point printing can be achieved by manual or mechanical dispensing. When the number of pads is small and the distribution is sparse, single-point printing can meet the needs. When the number of pads increases and the distribution is dense, auxiliary tools such as steel mesh can be used for planar printing.

[0046] See also Figure 3 and Figure 4 As shown, the deposited solder paste includes a solder surface coating area 3 and a plurality of spherical structures. The solder surface coating area 3 is arranged on the upper surface of the substrate 1. When the required spacing between the bumps 21 is small, the solder surface coating area 3 can be deposited for processing.

[0047] As an optional implementation, in an embodiment of the invention, see Figure 2 As shown, the step S20, leveling the deposited solder paste and obtaining the size parameters of the leveled solder paste, includes the following steps:

[0048] Step S201, heating the deposited solder paste;

[0049] Specifically, before leveling, the solder paste is heated, and the heating temperature and heating time are determined according to the properties and requirements of the solder paste. By adjusting the heating temperature and time, the solder paste reaches the required temperature, which facilitates leveling.

[0050] Step S202, using a flat ceramic block to extrude and flatten the heated solder paste; that is, the flat ceramic block is attached to the solder paste, and pressure is applied to the heated solder paste through the ceramic block.

[0051] Step S203, measuring the height of the solder paste after leveling. The present invention includes step S20 of leveling the deposited solder paste and obtaining the size parameters of the solder paste after leveling, so as to improve the preparation quality.

[0052] As an optional implementation, in an embodiment of the invention, in the step S20 of heating the deposited solder paste, when heating the solder paste, the heating temperature is lower than the melting point of the solder paste, so as to ensure the plasticity of the solder paste and facilitate leveling.

[0053] As an optional implementation, in an embodiment of the invention, in the step S202 of using a flat ceramic block to extrude and level the heated solder paste, when the heated solder paste is extruded, the maximum pressure is greater than the product of the compressive strength of the solder paste and the sum of the bottom area, wherein the compressive strength refers to the maximum stress value that the solder paste can withstand when it is compressed or extruded per unit area. When the maximum value of the extrusion pressure is greater than the product of the compressive strength of the solder paste and the sum of the bottom area, effective leveling of the solder paste is achieved.

[0054] As an optional implementation, in an embodiment of the invention, the step S30 of controlling the laser processing platform to cut the leveled solder paste according to the size parameters of the solder paste to form the substrate bump structure comprises the following steps:

[0055] Step S301, calculating the laser output power and processing time according to the height of the solder paste after leveling.

[0056] Step S302, according to the calculated laser output power and processing time, control the laser processing platform to cut the leveled solder paste to form the substrate bump structure. According to the obtained solder paste height, combined with the size requirements of the substrate bump structure, the laser output power and processing time are calculated and the laser processing platform is controlled to cut, thereby improving the preparation accuracy.

[0057] As an optional implementation, in an inventive embodiment, the substrate 1 is a gold-plated ceramic substrate. The ceramic substrate used in the embodiment of the present invention has excellent insulation, heat resistance and mechanical strength, and the gold-plated ceramic substrate combines the excellent performance of the ceramic substrate with the high electrical conductivity and high thermal conductivity of gold metal, has strong mechanical stress, stable shape and is easy to process, providing a more reliable and efficient support platform.

[0058] As an optional implementation, in an embodiment of the invention, the solder paste is lead-free solder. The present invention uses lead-free solder to cover the substrate 1. Specifically, according to the size of the chip to be bonded and the distribution of pads, the solder paste is deposited on the substrate 1, i.e., the gold-plated ceramic substrate, and the lead-free solder is used to form bumps, which is environmentally friendly while optimizing electrical performance and meeting environmental protection requirements.

[0059] As an optional implementation, in one embodiment of the invention, the lead-free solder is gold-tin solder. The lead-free gold-tin solder is used to prepare the substrate bump structure. On the one hand, the lead-free material is environmentally friendly while optimizing the electrical performance, meeting the requirements of environmental protection and improving production safety. On the other hand, the gold-tin solder has good electrical conductivity and thermal conductivity, effectively improving the heat dissipation performance and electrical performance of the substrate bump structure, and at the same time has high corrosion resistance and oxidation resistance.

[0060] As an optional implementation, in an embodiment of the invention, the laser processing platform is a picosecond laser processing platform, and cutting is performed using the picosecond laser processing platform, which improves cutting efficiency while ensuring high precision and material integrity.

[0061] Specifically, the preparation method is as follows: First, according to the size of the chip to be bonded and the distribution of the pads, a single-point printing or planar printing technology is used to deposit solder paste on the substrate. The substrate is a ceramic substrate, which has excellent insulation, heat resistance and mechanical strength. The gold-plated ceramic substrate combines the excellent performance of the ceramic substrate with the high electrical conductivity and high thermal conductivity of gold metal, has strong mechanical stress, stable shape and is easy to process, providing a more reliable and efficient support platform. The solder used includes but is not limited to gold-tin solder. After the solder is coated, it is reflowed and heated to solidify the solder. In order to ensure the consistency and coplanarity of the finished bump 21, the solder after reflow needs to be leveled, that is, a flat ceramic block is used to level the solder surface coating area 3 and the spherical structure after reflow. The pressure value during leveling should not be less than the product of the solder compressive strength and the solder area. In order to improve the leveling efficiency and reduce stress accumulation, the leveling can be heated to below 30°C of the solder melting point. After leveling, the height of the solder paste after leveling is measured, and the laser output power and processing time are calculated according to the height of the solder paste after leveling. According to the calculated laser output power and processing time, the laser processing platform is controlled to cut the solder paste after leveling to obtain the bumps 21 and leads of suitable sizes to complete the preparation. The bumps 21 have a minimum diameter of about 40 μm, with high preparation accuracy and fine spacing, which meets the flip-chip requirements of high-performance chips, and the preparation process is simple, thereby improving the preparation efficiency.

[0062] like Figure 4 As shown, a prepared substrate bump structure includes a substrate 1 and a plurality of bump portions 2, wherein the plurality of bump portions 2 are arranged on the surface of the substrate 1 in a rectangular array, each of the bump portions 2 includes a plurality of bumps 21 arranged at intervals, and each of the bumps 21 is a cylindrical structure, and the bumps 21 of the cylindrical structure are easy to process and have a stable connection.

[0063] In the description of the present invention, it should be noted that the terms "upper", "lower", etc. indicate positions or positional relationships based on the positions or positional relationships shown in the accompanying drawings, and are only for the convenience of describing the present invention and simplifying the description, rather than indicating or implying that the device or element referred to must have a specific position, be constructed and operated in a specific position, and therefore cannot be understood as a limitation on the present invention. Unless otherwise clearly specified and limited, the terms "installed", "connected", and "connected" should be understood in a broad sense, for example, it can be a fixed connection, a detachable connection, or an integral connection; it can be a mechanical connection or an electrical connection; it can be a direct connection, or it can be an indirect connection through an intermediate medium, or it can be a connection between the two elements. For those of ordinary skill in the art, the specific meanings of the above terms in the present invention can be understood according to the specific circumstances.

[0064] It should be noted that, in the present invention, relational terms such as "first" and "second" are only used to distinguish one entity or operation from another entity or operation, and do not necessarily require or imply any such actual relationship or order between these entities or operations. Moreover, the terms "include", "comprise" or any other variants thereof are intended to cover non-exclusive inclusion, so that a process, method, article or device including a series of elements includes not only those elements, but also other elements not explicitly listed, or also includes elements inherent to such process, method, article or device. In the absence of further restrictions, the elements defined by the sentence "comprise a ..." do not exclude the existence of other identical elements in the process, method, article or device including the elements.

[0065] The above description is only a specific embodiment of the present invention, so that those skilled in the art can understand or implement the present invention. Various modifications to these embodiments will be apparent to those skilled in the art, and the general principles defined herein may be implemented in other embodiments without departing from the spirit or scope of the present invention. Therefore, the present invention will not be limited to the embodiments shown herein, but should conform to the widest scope consistent with the principles and novel features of the present invention.

Claims

1. A method for preparing a substrate bump structure, characterized in that: The following steps are involved: A printing process is used to deposit solder paste on the substrate; Leveling the deposited solder paste and obtaining the size parameters of the leveled solder paste; According to the size parameters of the solder paste, the laser processing platform is controlled to cut and level the solder paste to form a substrate bump structure.

2. The method for preparing a substrate bump structure according to claim 1, characterized in that: The step of depositing solder paste on the substrate by printing process comprises: Depending on the size of the chip to be bonded and the distribution of the pads, solder paste is deposited on the substrate using single-point printing or planar printing technology.

3. The method for preparing a substrate bump structure according to claim 1, characterized in that: The step of leveling the deposited solder paste and obtaining the size parameters of the leveled solder paste includes the following steps: Heating the deposited solder paste; Use a flat ceramic block to squeeze and level the heated solder paste; Measure the solder paste height after leveling.

4. The method for preparing a substrate bump structure according to claim 3, characterized in that: The step of heating the deposited solder paste comprises: When the solder paste is heated, the heating temperature is lower than the melting point of the solder paste.

5. The method for preparing a substrate bump structure according to claim 3, characterized in that: The steps of using a flat ceramic block to extrude and flatten the heated solder paste include: When the heated solder paste is squeezed, the maximum pressure is greater than the product of the compressive strength of the solder paste and the sum of the bottom area.

6. The method for preparing a substrate bump structure according to claim 1, characterized in that: The step of controlling the laser processing platform to cut and level the solder paste solder according to the size parameters of the solder paste solder to form the substrate bump structure includes the following steps: Calculate the laser output power and processing time according to the height of the solder paste after leveling; According to the calculated laser output power and processing time, the laser processing platform is controlled to cut the leveled solder paste to form a substrate bump structure.

7. The method for preparing a substrate bump structure according to claim 1, characterized in that: The substrate is a gold-plated ceramic substrate.

8. The method for preparing a substrate bump structure according to claim 1, characterized in that: The solder paste is lead-free solder.

9. The method for preparing a substrate bump structure according to claim 8, characterized in that: The lead-free solder is gold-tin solder.

10. The method for preparing a substrate bump structure according to claim 1, characterized in that: The laser processing platform is a picosecond laser processing platform.

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