Steel mesh hole opening method and system

Abstract

The present invention provides a method and system for opening holes in a steel mesh, the method comprising the following steps: obtaining structural data of a flip chip, the structural data including the number of metal layers of the chip and the size data of the solder metal layer on the side of the chip away from the epitaxial layer; determining the initial hole size of the steel mesh based on the size data; if the number of layers is greater than a preset number of layers, retracting the initial hole size to obtain a retracted hole size that satisfies a first retracting condition, the first retracting condition including: the difference between a boundary value of the size data and a boundary value of the retracted hole size being greater than a first preset value; and opening the steel mesh based on the retracted hole size. By setting the first retracting condition and retracting the hole size based on the retracted hole size, a certain distance is maintained between the hole size and the edge of the solder metal layer, thereby reducing the amount of solder paste flowing into the cutting path, ensuring that the solder paste can be pulled back to the pad of the solder metal layer during reflow soldering, preventing solder paste bridging in the middle of the cutting path, and ensuring product yield.

Description

Technical Field

[0001] The present invention relates to the technical field of semiconductor production, and in particular to a steel mesh hole opening method and system. Background Art

[0002] Flip-chip soldering technology was first developed by IBM in the 1960s. The original method involved prefabricating solder bumps on the flip-chip wafer pads, aligning the unit chip bumps with the PCB substrate, and then soldering them together, forming an intermetallic bond between the chip and the PCB substrate. This method met the miniaturization requirements of microelectronic devices while reducing costs, opening up greater potential for technological development.

[0003] With the continuous improvement and advancement of technology in the semiconductor industry, flip-chip structures are becoming increasingly complex, placing increasingly higher demands on the matching of chip pads with stencil printing. Usually, openings corresponding in size to the soldering metal layer on one side of the flip-chip need to be opened on the stencil. However, in the actual production process, solder paste is printed on the edge of the soldering metal layer. Due to the wettability of solder paste, the solder paste at the edge of the soldering metal layer will inevitably flow into the cutting path between the two chips. When a small amount of solder paste flows into the cutting path, this part of the solder paste can be pulled back to the pads of the soldering metal layer through reflow soldering. However, when too much solder paste flows into the cutting path, this pulling force cannot be achieved, and then bridging is likely to occur in the middle of the cutting path, causing the chip to short-circuit and become scrapped. Summary of the Invention

[0004] In view of the shortcomings of the prior art, the purpose of the present invention is to provide a steel mesh opening method, which aims to solve the technical problem in the prior art that solder paste bridging in the cutting path causes chip short circuit and scrapping.

[0005] In order to achieve the above object, the present invention is implemented through the following technical solution: a steel mesh hole opening method, applied to flip chip, comprising the following steps:

[0006] Acquiring structural data of the flip chip, wherein the structural data includes data on the number of metal layers of the flip chip and data on the size of a soldering metal layer on a side of the flip chip away from the epitaxial layer;

[0007] Determining the initial opening size of the steel mesh according to the size data;

[0008] If the number of layers is greater than the preset number of layers, the initial opening size is adjusted to obtain a shrinking opening size that satisfies a first shrinking condition;

[0009] The first shrinking condition includes: the difference between the boundary value of the size data and the boundary value of the shrinking hole size is greater than a first preset value;

[0010] The steel mesh is opened based on the inward opening size.

[0011] Compared with the prior art, the beneficial effects of the present invention are: by obtaining the structural data of the chip, the initial opening size is determined based on the size data of the welding metal layer, and according to the metal layer number data of the flip chip, it is decided whether to adjust the initial opening size inward; when the number of layers data is greater than the preset number of layers, the initial opening size is adjusted inward to obtain a shrinking opening size that meets the first shrinking condition, wherein the first shrinking condition includes that the difference between the boundary value of the size data and the boundary value of the shrinking opening size is greater than the first preset value; by setting the above-mentioned first shrinking condition and adjusting the opening size based on this It shrinks inward so that there is a certain distance between it and the edge of the welding metal layer, thereby reducing the amount of solder paste flowing into the cutting path, ensuring that the solder paste can be pulled back to the pad of the welding metal layer during reflow soldering, preventing solder paste bridging in the middle of the cutting path, and ensuring product yield. In addition, the above-mentioned preset number of layers is two layers. When the number of metal layers of the chip is on both sides or less, the chip height is relatively low, the steel mesh opening size and the pad size are basically the same, and the pulling force of the welding metal layer on the top layer of the chip is greater than the gravity of the solder paste. The solder paste can be effectively pulled back during reflow soldering, so there will be no bridging, and there is no need to shrink the initial opening size.

[0012] According to one aspect of the above technical solution, before the step of opening the steel mesh based on the shrinkage opening size, the method further includes:

[0013] The shrinking hole size that meets the first shrinking condition is adjusted for the second time to obtain the shrinking hole size that meets both the first shrinking condition and the second shrinking condition, wherein the second shrinking condition includes: the distance between the boundary values ​​of two adjacent shrinking hole sizes on the steel mesh is greater than a second preset value.

[0014] According to one aspect of the above technical solution, the steel mesh opening method further includes:

[0015] Acquire multiple sets of historical product data on completed aperture soldering, wherein the historical product data includes: the difference between the actual pad area and the area of ​​the stencil aperture, the stencil thickness, and the reflow solder ball height;

[0016] By means of three-variable linear regression fitting, a linear relationship between the difference between the actual pad area and the area of ​​the steel mesh opening, the steel mesh thickness and the height of the reflow solder ball is obtained;

[0017] Based on the linear relationship, the thickness of the steel mesh is linearly adjusted to meet the preset reflow solder ball height.

[0018] According to one aspect of the above technical solution, the linear relationship is:

[0019] Y=0.000392A+0.8238B-9.6659;

[0020] Wherein, Y is the height of the reflow solder ball, A is the difference between the actual pad area and the area of ​​the stencil opening, and B is the thickness of the stencil.

[0021] According to one aspect of the above technical solution, the method further includes:

[0022] The initial opening size, the shrinking opening size after the first shrinking adjustment, and the shrinking opening size after the second shrinking adjustment all satisfy the following formula:

[0023] W / T>1.5;

[0024] L*W / 2T(L+W)>0.7;

[0025] W>60um;

[0026] Where W is the opening width, L is the opening length, and T is the opening height.

[0027] According to one aspect of the above technical solution, before the initial opening size is adjusted inward, the method further includes:

[0028] An initial opening pattern is obtained according to the initial opening size, and rounded corners are performed on the initial opening pattern.

[0029] According to one aspect of the above technical solution, the first retraction condition is:

[0030] X2-X1>40um;

[0031] In the formula, X1 is the distance difference between the boundary value of the welding metal layer and the boundary value of the steel mesh, and X2 is the distance difference between the first boundary value of the inward-shrinking opening size and the boundary value of the steel mesh.

[0032] According to one aspect of the above technical solution, the second preset value is 100um.

[0033] On the other hand, the present invention also provides a steel mesh opening system, comprising:

[0034] An acquisition module, configured to acquire structural data of a flip chip, wherein the structural data includes data on the number of metal layers of the flip chip and data on the size of a soldering metal layer on a side of the flip chip away from the epitaxial layer;

[0035] An initial module, used to determine the initial opening size of the steel mesh according to the size data;

[0036] A first adjustment module is configured to adjust the initial opening size inwardly if the number of layers is greater than a preset number of layers, to obtain an inwardly shrunken opening size that satisfies a first inwardly shrunken condition;

[0037] The first shrinking condition includes: the difference between the boundary value of the size data and the boundary value of the shrinking hole size is greater than a first preset value;

[0038] A hole opening module is used to open holes in the steel mesh based on the inward-shrinking hole size.

[0039] According to one aspect of the above technical solution, the system further includes:

[0040] The second adjustment module is used to perform a secondary shrinkage adjustment on the shrinkage opening size that meets the first shrinkage condition to obtain the shrinkage opening size that meets both the first shrinkage condition and the second shrinkage condition, wherein the second shrinkage condition includes: the distance between the boundary values ​​of two adjacent shrinkage opening sizes located on the steel mesh is greater than a second preset value.

[0041] According to one aspect of the above technical solution, the system further includes:

[0042] A data module is used to measure the product after soldering to obtain product data, wherein the product data includes: the difference between the actual pad area and the area of ​​the stencil opening, the stencil thickness, and the reflow solder ball height;

[0043] A fitting module, configured to obtain a linear relationship between the difference between the actual pad area and the area of ​​the stencil opening, the stencil thickness, and the reflow solder ball height through ternary linear regression fitting;

[0044] The third adjustment module is used to linearly adjust the thickness of the steel mesh based on the linear relationship to meet a preset reflow solder ball height.

[0045] According to one aspect of the above technical solution, the linear relationship is:

[0046] Y=0.000392A+0.8238B-9.6659;

[0047] Wherein, Y is the height of the reflow solder ball, A is the difference between the actual pad area and the area of ​​the stencil opening, and B is the thickness of the stencil.

[0048] According to one aspect of the above technical solution, the system further includes:

[0049] The limiting module is configured to ensure that the initial opening size, the shrinking opening size after the first shrinking adjustment, and the shrinking opening size after the second shrinking adjustment all satisfy the following formula:

[0050] W / T>1.5;

[0051] L*W / 2T(L+W)>0.7;

[0052] W>60um;

[0053] Where W is the opening width, L is the opening length, and T is the opening height.

[0054] According to one aspect of the above technical solution, the system further includes:

[0055] The rounding module is used to obtain an initial opening pattern according to the initial opening size and perform rounding processing on the initial opening pattern. BRIEF DESCRIPTION OF THE DRAWINGS

[0056] Figure 1 Flowchart of the steel mesh hole opening method in the first embodiment of the present invention;

[0057] Figure 2 Schematic diagram of the cross-sectional structure of the flip chip in the first embodiment of the present invention;

[0058] Figure 3 Schematic diagram of the top view of the flip chip structure in the first embodiment of the present invention;

[0059] Figure 4 Flowchart of the steel mesh opening method in the second embodiment of the present invention;

[0060] Figure 5 Flowchart of the steel mesh opening method in the third embodiment of the present invention;

[0061] Figure 6 Flowchart of the steel mesh opening method in the fourth embodiment of the present invention;

[0062] Figure 7 This is a summary table of actual product data of the shrinking steel mesh in the fourth embodiment of the present invention;

[0063] Figure 8 1 is a structural block diagram of a steel mesh opening system in a fifth embodiment of the present invention;

[0064] Description of main component symbols:

[0065]

[0066] The following specific embodiments will further illustrate the present invention in conjunction with the above-mentioned drawings. DETAILED DESCRIPTION

[0067] To facilitate understanding of the present invention, the present invention will be described more fully below with reference to the accompanying drawings. The drawings illustrate several embodiments of the present invention. However, the present invention may be implemented in many different forms and is not limited to the embodiments described herein. Rather, these embodiments are provided to provide a more thorough and comprehensive understanding of the present invention.

[0068] It should be noted that when an element is referred to as being "fixed to" another element, it may be directly on the other element or there may be an intermediate element. When an element is referred to as being "connected to" another element, it may be directly connected to the other element or there may be an intermediate element. The terms "vertical," "horizontal," "left," "right," and similar expressions used herein are for illustrative purposes only.

[0069] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by one skilled in the art to which this invention pertains. The terms used in this specification of the present invention are for the purpose of describing specific embodiments only and are not intended to limit the present invention. The term "and / or" as used herein includes any and all combinations of one or more of the associated listed items.

[0070] See also Figure 1 , which is a flow chart of a steel mesh opening method according to a first embodiment of the present invention, comprises the following steps:

[0071] Step S100: Acquire structural data of the flip chip, where the structural data includes the number of metal layers of the flip chip and the dimensions of the solder metal layer on the side of the flip chip away from the epitaxial layer. Specifically, the stencil aperture method in this embodiment is applied to a flip chip, so it is necessary to obtain the dimensions of the solder metal layer on the side of the flip chip away from the epitaxial layer. In addition, since the solder paste is printed on the edge of the welding metal layer during the actual production process, due to the wettability of the solder paste, the solder paste at the edge of the welding metal layer will definitely flow into the cutting path between the two chips. When a small amount of solder paste flows into the cutting path, this part of the solder paste can be pulled back to the pad of the welding metal layer through reflow soldering. However, when too much solder paste flows into the cutting path, this part of the pulling force cannot be realized, and then bridging is likely to occur in the middle of the cutting path, causing the chip to short-circuit and be scrapped. The chip bridging caused by the "excessive amount of solder paste" is essentially because the gravity of the solder paste is greater than the pulling force of the reflow soldering. Based on this, in this embodiment, the purpose of obtaining the chip layer number data is that when the chip layer number is lower than the preset number of layers, the height of the chip is lower. At this time, the pulling force of the reflow soldering is greater than the gravity of the solder paste, which will not cause a large amount of solder paste to flow into the cutting path.

[0072] In this embodiment, the present invention takes the RB5628 chip as an example to facilitate the description and understanding of this solution. Figure 2 As shown, the chip structure includes, from bottom to top: epitaxial layer, CBL layer, MSA layer, PD1 layer, PV1 layer, PD3 layer, PD4 layer, PV2 layer and PD2 layer (welding metal layer).

[0073] Step S110, determining the initial opening size of the steel mesh according to the size data. Figure 3 The above-mentioned chip is shown as a top view of the structure. The above-mentioned size data is consistent with Figure 3 The shape of part A in corresponds to .

[0074] In step S120, if the number of layers is greater than a preset number of layers, the initial opening size is retracted to obtain a retracted opening size that satisfies a first retracting condition, wherein the first retracting condition includes: the difference between the boundary value of the size data and the boundary value of the retracted opening size is greater than a first preset value. Specifically, in this embodiment, the first retracting condition is:

[0075] X2-X1>40um;

[0076] In the formula, X1 is the distance difference between the boundary value of the welding metal layer and the boundary value of the steel mesh, and X2 is the distance difference between the first boundary value of the inward-shrinking opening size and the boundary value of the steel mesh.

[0077] In some application scenarios of this embodiment, when the number of metal layers is two or fewer, bridging will not occur. When the number of layers is less than three, that is, when X∈(-∞, 3) and X∈Z (an integer) in PDX, the stencil opening does not need to be retracted. In addition, the first preset value is 40, and the boundary value of the dimension data is the position of the left edge of the PD2 layer close to the chip boundary, that is, this side needs to be retracted more than 40μm toward the center of the chip.

[0078] Step S130: drilling holes in the steel mesh based on the shrinkage hole size.

[0079] In summary, the steel mesh opening method in the above embodiment of the present invention obtains the structural data of the chip, determines the initial opening size based on the size data of the welding metal layer, and decides whether to shrink the initial opening size according to the metal layer number data of the flip chip. When the number of layers is greater than the preset number of layers, the initial opening size is shrunk to obtain a shrinking opening size that meets the first shrinking condition, wherein the first shrinking condition includes that the difference between the boundary value of the size data and the boundary value of the shrinking opening size is greater than the first preset value. By setting the above-mentioned first shrinking condition and adjusting the opening size based on this, The rows are retracted so that there is a certain distance between them and the edge of the welding metal layer, thereby reducing the amount of solder paste flowing into the cutting path, ensuring that the solder paste can be pulled back to the pad of the welding metal layer during reflow soldering, preventing solder paste bridging in the middle of the cutting path, and ensuring product yield. In addition, the above-mentioned preset number of layers is two layers. When the number of metal layers of the chip is on both sides or less, the chip height is relatively low, the steel mesh opening size and the pad size are basically the same, and the pulling force of the welding metal layer on the top layer of the chip is greater than the gravity of the solder paste. The solder paste can be effectively pulled back during reflow soldering, so there will be no bridging, and there is no need to retract the initial opening size.

[0080] Please refer to Figure 4 , which is a flow chart of a steel mesh opening method according to a second embodiment of the present invention, the method comprises the following steps:

[0081] Step S200 , obtaining structural data of the flip chip, wherein the structural data includes data on the number of metal layers of the flip chip and size data of a soldering metal layer on a side of the flip chip away from the epitaxial layer.

[0082] Step S210: determining the initial opening size of the steel mesh according to the size data.

[0083] Step S220: If the number of layers is greater than the preset number of layers, the initial opening size is adjusted inward to obtain a shrinking opening size that meets the first shrinking condition, wherein the first shrinking condition includes: the difference between the boundary value of the size data and the boundary value of the shrinking opening size is greater than a first preset value.

[0084] In step S230, a secondary shrinkage adjustment is performed on the shrinkage opening size that meets the first shrinkage condition to obtain a shrinkage opening size that meets both the first shrinkage condition and the second shrinkage condition, wherein the second shrinkage condition includes: the distance between the boundary values ​​of the two adjacent shrinkage opening sizes on the steel mesh is greater than a second preset value. Specifically, in this step, the above-mentioned one shrinkage adjustment is equivalent to moving the opening position of the steel mesh toward the middle of the chip. On this basis, the boundary value of the two adjacent shrinkage opening sizes on the same steel mesh, that is, the position of one side of the PD2 layer close to the middle of the chip, that is, the distance between the two openings on the same steel mesh, whose side edges are close to each other, needs to be greater than the second preset value, and the above-mentioned second preset value is 100um.

[0085] Step S240: Perforate the steel mesh based on the shrinkage opening size. Specifically, the shrinkage opening size in this step satisfies both the first shrinkage condition and the second shrinkage condition.

[0086] Please refer to Figure 5 , which is a flow chart of a steel mesh opening method according to a third embodiment of the present invention, the method comprises the following steps:

[0087] Step S300 : Acquire structural data of the flip chip, wherein the structural data includes data on the number of metal layers of the flip chip and size data of a soldering metal layer on a side of the flip chip away from the epitaxial layer.

[0088] Step S310: determining the initial opening size of the steel mesh according to the size data.

[0089] In step S320, an initial aperture pattern is obtained based on the initial aperture size, and the initial aperture pattern is rounded. Specifically, in this step, all four corners of the stencil aperture pattern are rounded to provide better solder paste release fluidity and plump solder paste bumps on the wafer after demolding.

[0090] Step S330: If the number of layers is greater than the preset number of layers, the initial opening size is adjusted inward to obtain a shrinking opening size that meets the first shrinking condition, wherein the first shrinking condition includes: the difference between the boundary value of the size data and the boundary value of the shrinking opening size is greater than a first preset value.

[0091] In step S340, a secondary retraction adjustment is performed on the retracted hole size that satisfies the first retraction condition, resulting in a retracted hole size that satisfies both the first and second retraction conditions. The second retraction condition includes the distance between the boundary values ​​of two adjacent retracted hole sizes on the steel mesh being greater than a second preset value. It should be noted that the retraction adjustments in steps S220 and S230 are performed based on the initial hole size after rounding.

[0092] Step S350: The initial opening size, the shrinking opening size after the first shrinking adjustment, and the shrinking opening size after the second shrinking adjustment all satisfy the following formula:

[0093] W / T>1.5;

[0094] L*W / 2T(L+W)>0.7;

[0095] W>60um;

[0096] Where W is the aperture width, L is the aperture length, and T is the aperture height. Specifically, the above three conditions are effective solder paste release conditions, and when met, the solder paste transfer rate can be greater than 70%.

[0097] Step S360: drilling holes in the steel mesh based on the shrinkage hole size.

[0098] Please refer to Figure 6 , which is a flow chart of a steel mesh opening method according to a fourth embodiment of the present invention, the method comprises the following steps:

[0099] Step S400 : Acquire structural data of the flip chip, wherein the structural data includes data on the number of metal layers of the flip chip and size data of a soldering metal layer on a side of the flip chip away from the epitaxial layer.

[0100] Step S410: determining the initial opening size of the steel mesh according to the size data.

[0101] Step S420 , obtaining an initial opening pattern according to the initial opening size, and performing rounding processing on the initial opening pattern.

[0102] Step S430: If the number of layers is greater than the preset number of layers, the initial opening size is adjusted inward to obtain a shrinking opening size that meets the first shrinking condition, wherein the first shrinking condition includes: the difference between the boundary value of the size data and the boundary value of the shrinking opening size is greater than a first preset value.

[0103] In step S440, a secondary retraction adjustment is performed on the retracted hole size that satisfies the first retraction condition, resulting in a retracted hole size that satisfies both the first and second retraction conditions. The second retraction condition includes the distance between the boundary values ​​of two adjacent retracted hole sizes on the steel mesh being greater than a second preset value. It should be noted that the retraction adjustments in steps S220 and S230 are performed based on the initial hole size after rounding.

[0104] Step S450: The initial opening size, the shrinking opening size after the first shrinking adjustment, and the shrinking opening size after the second shrinking adjustment all satisfy the following formula:

[0105] W / T>1.5;

[0106] L*W / 2T(L+W)>0.7;

[0107] W>60um;

[0108] Where W is the aperture width, L is the aperture length, and T is the aperture height. Specifically, the above three conditions are effective solder paste release conditions, and when met, the solder paste transfer rate can be greater than 70%.

[0109] Step S460, obtaining multiple sets of historical product data of completed hole welding, wherein the historical product data includes: the difference between the actual pad area and the area of ​​the steel mesh hole, the steel mesh thickness and the reflow solder ball height.

[0110] Step S470, through ternary linear regression fitting, a linear relationship between the difference between the actual pad area and the area of ​​the steel mesh opening, the steel mesh thickness and the reflow solder ball height is obtained. Specifically, Figure 7 As shown in the figure, it is a summary table of the actual product data of the shrinking steel mesh in this embodiment. Based on the above table, the linear relationship obtained by Excel three-variable linear regression fitting is:

[0111] Y=0.000392A+0.8238B-9.6659;

[0112] Wherein, Y is the height of the reflow solder ball, A is the difference between the actual pad area and the area of ​​the stencil opening, and B is the thickness of the stencil.

[0113] In step S480, based on the linear relationship, the thickness of the steel mesh is linearly adjusted to meet the preset reflow solder ball height. It can be understood that in this step, by summarizing the above-mentioned groups of data, a linear relationship is obtained between the reflow solder ball height, the difference between the actual pad area and the area of ​​the steel mesh opening, and the reflow solder ball height. In some application scenarios of this embodiment, the optimal steel mesh thickness can be obtained based on the customer's expected solder joint height and the actual pad area and the preset steel mesh opening area (i.e., the optimal indented opening size after step S450). Furthermore, the purpose of the above-mentioned steps S460 and S470 is to obtain the above-mentioned linear relationship. In other embodiments of the present invention, the above-mentioned steps S460 and S470 can be skipped after step S450, and the steel mesh thickness can be directly adjusted based on the linear relationship already obtained to improve the opening efficiency.

[0114] Step S490: Perforate the stencil based on the inward-shrinking hole size. Based on the processing from steps S400 to S480, data with both the optimal stencil thickness and the optimal stencil hole size can be obtained. In this step, by perforating the stencil after thickness adjustment based on the optimal stencil hole size, chip bridging can be avoided while ensuring that the stencil inward-shrinking size and the pad size are as close to the solder paste wetting range as possible, while also taking into account the customer's desired bump height, thereby ensuring soldering reliability.

[0115] Please refer to Figure 8 , which is a structural block diagram of the steel mesh opening system in the fifth embodiment of the present invention, Figure 8 It can be seen that the above steel mesh opening system includes:

[0116] An acquisition module 100 is configured to acquire structural data of a flip chip, wherein the structural data includes data on the number of metal layers of the flip chip and data on the size of a soldering metal layer on a side of the flip chip away from the epitaxial layer;

[0117] An initial module 200 is used to determine the initial opening size of the steel mesh according to the size data;

[0118] The first adjustment module 300 is configured to adjust the initial opening size inward if the number of layers is greater than a preset number of layers, to obtain an inward-shrinking opening size that satisfies a first inward-shrinking condition;

[0119] The first shrinking condition includes: the difference between the boundary value of the size data and the boundary value of the shrinking hole size is greater than a first preset value;

[0120] The hole opening module 910 is used to open holes in the steel mesh based on the inward-shrinking hole size.

[0121] Preferably, in this embodiment, the steel mesh opening system further includes:

[0122] The second adjustment module 400 is configured to perform a secondary shrinkage adjustment on the shrinkage opening size that satisfies the first shrinkage condition, thereby obtaining a shrinkage opening size that satisfies both the first shrinkage condition and the second shrinkage condition;

[0123] The second shrinking condition includes: the distance between the boundary values ​​of the sizes of two adjacent shrinking openings on the steel mesh is greater than a second preset value. Specifically, in this embodiment, the first shrinking condition is:

[0124] X2-X1>40um;

[0125] Wherein, X1 is the distance difference between the boundary value of the welding metal layer and the boundary value of the steel mesh, and X2 is the distance difference between the first boundary value of the shrinkage hole size and the boundary value of the steel mesh;

[0126] The second preset value is 100um.

[0127] Preferably, in this embodiment, the steel mesh opening system further includes:

[0128] The data module 500 is used to measure the product after soldering to obtain product data, wherein the product data includes: the difference between the actual pad area and the area of ​​the stencil opening, the stencil thickness, and the reflow solder ball height;

[0129] A fitting module 600 is configured to obtain a linear relationship between the difference between the actual pad area and the area of ​​the stencil opening, the stencil thickness, and the reflow solder ball height through a three-variable linear regression fit;

[0130] The third adjustment module 700 is configured to linearly adjust the thickness of the steel mesh based on the linear relationship to meet a preset reflow solder ball height.

[0131] Furthermore, in this embodiment, the above linear relationship is:

[0132] Y=0.000392A+0.8238B-9.6659;

[0133] Wherein, Y is the height of the reflow solder ball, A is the difference between the actual pad area and the area of ​​the stencil opening, and B is the thickness of the stencil.

[0134] Preferably, in this embodiment, the steel mesh opening system further includes:

[0135] The limiting module 800 is configured to ensure that the initial opening size, the shrinking opening size after the first shrinking adjustment, and the shrinking opening size after the second shrinking adjustment all satisfy the following formula:

[0136] W / T>1.5;

[0137] L*W / 2T(L+W)>0.7;

[0138] W>60um;

[0139] Where W is the opening width, L is the opening length, and T is the opening height.

[0140] Preferably, in this embodiment, the steel mesh opening system further includes:

[0141] The rounding module 900 is used to obtain an initial opening pattern according to the initial opening size and perform rounding processing on the initial opening pattern.

[0142] Throughout this specification, reference to terms such as "one embodiment," "some embodiments," "examples," "specific examples," or "some examples" means that the specific features, structures, materials, or characteristics described in conjunction with that embodiment or example are included in at least one embodiment or example of the present invention. In this specification, schematic representations of the above terms do not necessarily refer to the same embodiment or example. Furthermore, the specific features, structures, materials, or characteristics described may be combined in any suitable manner in any one or more embodiments or examples.

[0143] The above-described embodiments merely illustrate several implementations of the present invention, and while their descriptions are relatively specific and detailed, they should not be construed as limiting the scope of the present invention. It should be noted that a person skilled in the art would be able to make numerous variations and improvements without departing from the spirit of the present invention, all of which fall within the scope of protection of the present invention. Therefore, the scope of protection of the present invention shall be determined by the appended claims.

Claims

1. A steel mesh hole opening method, applied to flip chip, characterized in that: The following steps are involved: Acquiring structural data of the flip chip, wherein the structural data includes data on the number of metal layers of the flip chip and data on the size of a soldering metal layer on a side of the flip chip away from the epitaxial layer; Determining the initial opening size of the steel mesh according to the size data; If the number of layers is greater than a preset number of layers, the initial opening size is adjusted to obtain a shrinking opening size that satisfies a first shrinking condition, wherein the first shrinking condition includes: a difference between a boundary value of the size data and a boundary value of the shrinking opening size is greater than a first preset value; Performing hole opening on the steel mesh based on the shrinkage hole size; The preset number of layers is three, the first preset value is 40 μm, the boundary value of the dimension data is the distance difference between the boundary value of the welding metal layer and the boundary value of the steel mesh, and the boundary value of the shrinkage hole size is the distance difference between the first boundary value of the shrinkage hole size and the boundary value of the steel mesh; The first shrinking condition is: X2-X1>40um; In the formula, X1 is the distance difference between the boundary value of the welding metal layer and the boundary value of the steel mesh, and X2 is the distance difference between the first boundary value of the inward-shrinking opening size and the boundary value of the steel mesh.

2. The steel mesh opening method according to claim 1, characterized in that: Before the step of opening the steel mesh based on the inwardly shrunk opening size, the method further includes: The shrinking hole size that meets the first shrinking condition is adjusted for the second time to obtain the shrinking hole size that meets both the first shrinking condition and the second shrinking condition, wherein the second shrinking condition includes: the distance between the boundary values ​​of two adjacent shrinking hole sizes on the steel mesh is greater than a second preset value.

3. The steel mesh opening method according to claim 1, characterized in that: Before the step of opening the steel mesh based on the inwardly shrunk opening size, the method further includes: Acquire multiple sets of historical product data on completed aperture soldering, wherein the historical product data includes: the difference between the actual pad area and the area of ​​the stencil aperture, the stencil thickness, and the reflow solder ball height; By means of three-variable linear regression fitting, a linear relationship between the difference between the actual pad area and the area of ​​the steel mesh opening, the steel mesh thickness and the height of the reflow solder ball is obtained; Based on the linear relationship, the thickness of the steel mesh is linearly adjusted to meet the preset reflow solder ball height.

4. The steel mesh opening method according to claim 3, characterized in that: The linear relationship is: Y=0.000392A+0.8238B-9.6659; Wherein, Y is the height of the reflow solder ball, A is the difference between the actual pad area and the area of ​​the stencil opening, and B is the thickness of the stencil.

5. The steel mesh opening method according to claim 2, characterized in that: The method further comprises: The initial opening size, the shrinking opening size after the first shrinking adjustment, and the shrinking opening size after the second shrinking adjustment all satisfy the following formula: W / T>1.5; L*W / 2T(L+W)>0.7; W>60um; Where W is the opening width, L is the opening length, and T is the opening height.

6. The steel mesh opening method according to claim 1, characterized in that: Before adjusting the initial opening size inward, the method further includes: An initial opening pattern is obtained according to the initial opening size, and rounded corners are performed on the initial opening pattern.

7. The steel mesh opening method according to claim 2, characterized in that: The second preset value is 100um.

8. A steel mesh hole opening system based on the steel mesh hole opening method according to any one of claims 1 to 7, characterized in that: include: An acquisition module, configured to acquire structural data of a flip chip, wherein the structural data includes data on the number of metal layers of the flip chip and data on the size of a soldering metal layer on a side of the flip chip away from the epitaxial layer; An initial module, used to determine the initial opening size of the steel mesh according to the size data; A first adjustment module is configured to adjust the initial opening size inwardly if the number of layers is greater than a preset number of layers, to obtain an inwardly shrunken opening size that satisfies a first inwardly shrunken condition; The first shrinking condition includes: the difference between the boundary value of the size data and the boundary value of the shrinking hole size is greater than a first preset value; A hole opening module is used to open holes in the steel mesh based on the inward-shrinking hole size.

9. The steel mesh opening system according to claim 8, characterized in that: The system further comprises: A second adjustment module is used to perform a secondary shrinkage adjustment on the shrinkage opening size that meets the first shrinkage condition, so as to obtain the shrinkage opening size that meets both the first shrinkage condition and the second shrinkage condition; Wherein, the second shrinking condition includes: the distance between the boundary values ​​of the sizes of two adjacent shrinking openings on the steel mesh is greater than a second preset value.

Images