Electronic packaging component reflow soldering thermal deformation testing method based on reliability analysis

Abstract

The invention discloses an electronic packaging component reflow soldering thermal deformation testing method based on reliability analysis, relates to the technical field of electronic packaging testing, and aims to solve the problems that a packaging body of an existing electronic packaging component is gradually thinned, and due to the difference of physical attributes of packaging body forming materials, the packaging body is not thinned. And the problem of packaging body warping caused by temperature change in the reflow soldering process of the electronic packaging component is solved. According to the electronic packaging component reflow soldering thermal deformation testing method based on reliability analysis, the thermal deformation condition of an electronic packaging component in a high-temperature state can be analyzed in a room-temperature state, reflow soldering thermal deformation testing of the electronic packaging component is achieved at low cost, the testing point coverage ranges from 11 DEG C to 313 DEG C, and the testing accuracy is high. The device can test component packaging including common BGA packaging, LGA packaging, QFN packaging and the like, can meet the assembly test requirements of electronic packaging components of most production lines, is high in applicability and low in cost, and can effectively evaluate the welding reliability of the components.

Description

Technical Field

[0001] The present invention relates to the technical field of electronic packaging testing, and more specifically to the technical field of a reflow soldering thermal deformation testing method for electronic packaging components based on reliability analysis. Background Art

[0002] As electronic products continue to develop towards miniaturization, the electronic packaging components are gradually becoming thinner. Due to the different elastic moduli and thermal expansion coefficients of the packaging materials, the packaging will warp due to temperature changes during the reflow soldering process of the electronic packaging components. Due to the difference in material stacking, the thermal deformation of electronic packaging components is generally divided into convex and concave shapes. Due to changes in the position and distance between the printed circuit board pads, assembly defects occur. Therefore, it is necessary to detect the warpage changes of electronic packaging components under different temperature conditions from the perspective of component reliability analysis to ensure the matching degree between the substrate and the components, and to ensure the welding quality and reliability of the product.

[0003] At present, the industry is paying more and more attention to the impact of thermal deformation of the package. Existing patents disclose the following technologies:

[0004] The patent with publication number CN107677697B discloses a chip thermal deformation test method based on scanning electron microscope. This patent takes advantage of the high depth of field and high resolution of the scanning electron microscope, integrates with the in-situ heating device, fully considers the measurement errors caused by thermal deformation and system distortion and corrects them; uses the distortion-corrected speckle image, and calculates the in-plane deformation field of the chip due to heat through the digital image correlation algorithm. Based on the above, the full-field thermal deformation measurement of the chip at the micro-nano scale is realized.

[0005] The patent with publication number US10018463B1 discloses a shadow moiré system for thermal deformation testing, the system comprising a glass grating disposed above a sample at the top of an oven and a glass cover assembly of the oven so that the glass grating can be adjusted vertically. In addition, the system comprises a shadow moiré optical device disposed above the glass grating. In addition, the system comprises a vertical motion assembly disposed in an oven bottom assembly of the oven together with a sample support to vertically move the sample support and the sample disposed thereon. In addition, the shadow moiré system comprises a top heater assembly and a bottom heater, the top heater being disposed in a glass cover assembly above the oven top and the glass grid, the bottom heater being individually controllable to generate heat and apply heat to the sample to observe any changes in deformation of the sample surface with temperature changes.

[0006] However, the testing equipment involved in the above patents is expensive and has the problem of high cost of use, which makes it difficult to promote and use the above patented technology on a large scale in general production occasions. Summary of the invention

[0007] The purpose of the present invention is to solve the technical problem of high cost of the prior art and provide a method for testing the thermal deformation of electronic packaging components during reflow soldering based on reliability analysis to meet the requirements of thermal deformation testing of electronic packaging components during assembly.

[0008] In order to achieve the above-mentioned purpose, the present invention specifically adopts the following technical solutions:

[0009] The present invention provides a method for testing thermal deformation of electronic packaging components during reflow soldering based on reliability analysis, comprising the following steps:

[0010] S1. For electronic packaging components with built-in pads, use the pads of the components to carry out subsequent testing; for components without built-in pads, pre-set pads according to the polymer material electroplating method;

[0011] S2. Prepare a high-precision and high-thermal stability test reference board. Design it according to the maximum size of the package body of the electronic packaging components. The maximum size of the test reference board should be larger than the size of the electronic packaging components. Paste or apply a coating or film material that does not wet with solder on the reference board.

[0012] S3, pre-setting solder on the soldering end of the electronic packaging component in step S1, using a conventional method for planting balls of electronic packaging components, using a method of printing paste solder or pre-setting solid solder balls with a mesh tool to pre-set solder on the soldering end of the electronic packaging component, heating and melting the solder, forming a metallurgical bond between the soldering end of the electronic packaging component and the pre-set solder, and completing solder pre-setting;

[0013] S4, placing the electronic packaging components after the soldering in step S3 is pre-placed on the test reference board on which the coating layer is pasted or coated in step S2, so that the solder ball surface contacts the surface of the coating layer;

[0014] S5, putting the test reference board and the electronic packaging components of step S4 into the reflow soldering furnace for heating, requiring the peak temperature of heating to be greater than the solidus and liquidus temperatures of the preset solder in step S3. Since the film layer of step S2 does not react with the solder ball, after the solder ball melts, the side of the solder ball in contact with the film layer presents a shape consistent with the upper surface of the test substrate, i.e., a plane shape, under the action of the gravity of the package body itself. When the temperature is cooled to the eutectic point temperature, since the solidus temperature of the solder is the same as the liquidus temperature, there is no solid and liquid coexistence interval, and the solder ball changes from liquid to solid instantly. The deformation state of the electronic packaging components at the eutectic point temperature of the solder is mapped to the size of the plane of the end of the solder ball from the upper surface of the package body.

[0015] S6. After the substrate to be tested is cooled to room temperature and the deformation of the electronic packaging components is restored to a horizontal level, the electronic packaging components are turned over, the upper surface of the electronic packaging components contacts the film layer of the test substrate, and the height of the upper surface plane of each solder ball from the substrate is tested using an optical inspection device;

[0016] S7, performing fitting calculation on each test height value and solder ball position information to obtain deformation information of the package body when the solidus and liquidus temperatures of the solder are preset in step S3;

[0017] S8, repeating steps S3 to S7, changing the material type of the pre-solder for the soldering of the soldering end of the electronic packaging component in step S3, and obtaining the thermal deformation test results of the electronic packaging component at multiple temperature points.

[0018] In one embodiment, in step S2, the maximum outer dimension of the test reference board is 10 mm larger than the outer dimension of the electronic packaging component on one side.

[0019] Specifically, the maximum size of the test reference board should be larger than the size of the electronic packaging components, with a typical value of 10mm larger on one side;

[0020] In one embodiment, in step S2, the flatness of the test reference plate is no greater than 0.001 mm.

[0021] Specifically, in order to ensure the test accuracy, the test reference plate needs to have a high flatness accuracy, with a typical value of flatness not greater than 0.001 mm.

[0022] In one embodiment, in step S2, the material of the test reference plate is marble or mold steel.

[0023] Specifically, in order to ensure the stability of the dimensional accuracy of the reference plate during the heating process in the subsequent steps, the reference plate material is required to have greater rigidity and smaller thermal expansion coefficient, and typical materials are marble or mold steel.

[0024] In one embodiment, in step S2, the coating layer is treated with polyimide, polyester, polytetrafluoroethylene, polyvinyl alcohol, polyethylene naphthalate, anodizing or micro-arc oxidation process; the wetting angle between the coating layer and the paste solder above the liquidus line of the paste solder is greater than 135°; and it cannot chemically react with the paste solder to form intermetallic compounds.

[0025] In one embodiment, in step S3, the paste solder is characterized in that the solidus and liquidus temperatures of the material are the same, and the temperature test range can cover 11°C to 313°C, which is the temperature point corresponding to the deformation value tested in step S7.

[0026] In one embodiment, in step S5, the heating method is to use gas phase heat exchange, hot air convection or infrared heat radiation heating equipment to heat the test reference board and the electronic packaging components.

[0027] In one embodiment, in step S5, the test reference board and the electronic packaging components of step S4 are placed together in a reflow soldering furnace for heating, and the peak temperature of the heating is required to be greater than the solidus and liquidus temperatures of the solder preset in step S3. The solidus temperature and liquidus temperature of the selected solder are the same, and the peak temperature is required to be greater than the preset solder temperature by 30°C.

[0028] In one embodiment, in step S6, the optical inspection equipment includes an AOI, SPI, ultra-depth-of-field microscope or a three-coordinate measuring machine commonly used in production lines.

[0029] In one embodiment, in step S7, the fitting method is as follows:

[0030] Set the height value of the upper surface of the solder ball after deformation to the substrate plane as Z k The position coordinates of each pad on the test substrate obtained by the test are (X k ,Y k ), where k = 1-n, n is the number of solder balls tested;

[0031] After hypothesis testing (X k ,Y k ,Z k )The general form of the surface is as follows:

[0032] Z=f(X,Y)=AX 2 +BXY+C,

[0033] The constructor H is as follows:

[0034]

[0035] By finding the extreme value of H, the values ​​of a, b, and c in the above formula can be obtained, and then the deformation information of the package body at the preset solder liquidus and solidus temperatures in step S3 can be obtained.

[0036] The beneficial effects of the present invention are as follows:

[0037] The present invention aims at the gradual thinning of the package of electronic packaging components. Due to the difference in thermal expansion coefficients of the materials constituting the package, the package will warp due to temperature changes during the reflow soldering process of the electronic packaging components. Due to the difference in material stacking, the thermal deformation of the electronic packaging components is generally divided into convex and concave shapes, which causes abnormal contact between the solder balls of the electronic packaging components and the solder on the printed circuit board, resulting in assembly reliability problems such as empty soldering and headrest effect. The present invention proposes a reflow soldering thermal deformation test method for electronic packaging components based on reliability analysis, which can analyze the thermal deformation of electronic packaging components at high temperature at room temperature, and realize the reflow soldering thermal deformation test of electronic packaging components at low cost. The test points cover 11°C to 313°C. The testable component packages include common BGA packages, LGA packages, QFN packages, etc., which can meet the assembly test requirements of most production lines for electronic packaging components. It has strong applicability and low cost, and can effectively evaluate the welding reliability of components. BRIEF DESCRIPTION OF THE DRAWINGS

[0038] In order to more clearly illustrate the technical solutions of the embodiments of the present invention, the following briefly introduces the drawings required for use in the embodiments. It should be understood that the following drawings only show certain embodiments of the present invention and therefore should not be regarded as limiting the scope. For ordinary technicians in this field, other related drawings can be obtained based on these drawings without creative work.

[0039] Figure 1 It is a flow chart of thermal deformation test of electronic packaging components of the present invention.

[0040] Figure 2 It is a structural diagram of electronic packaging components.

[0041] Figure 3 Schematic diagram of adding a coating layer to a test substrate.

[0042] Figure 4 It is a schematic diagram of planting balls on the surface of the electronic package components to be tested.

[0043] Figure 5 It is a schematic diagram of placing the electronic package components after ball implantation on the test substrate.

[0044] Figure 6 It is a schematic diagram of heating and deformation of electronic packaging components.

[0045] Figure 7 It is a schematic diagram of the deformation of electronic packaging components after cooling and returning to normal temperature.

[0046] Figure 8 The test component is turned over and placed on the test substrate with the solder balls facing upwards.

[0047] Fig. 9 The distance between the upper surface of the solder ball and the upper surface of the substrate is tested using optical equipment.

[0048] Fig.10 It is a schematic diagram of the coordinates of each test center point.

[0049] Fig.11 This is a schematic diagram of the LGA package structure.

[0050] Fig.12 is a schematic diagram of test substrate selection.

[0051] Fig.13 It is a schematic diagram of the LGA package 183 degrees Celsius thermal deformation test results.

[0052] Fig.14 It is a schematic diagram of the BGA package structure.

[0053] Fig.15 is a schematic diagram of test substrate selection.

[0054] Fig.16 It is a schematic diagram of the BGA package 183℃ thermal deformation test results. DETAILED DESCRIPTION

[0055] In order to make the technical problems, technical solutions and technical effects of the present invention clearer, the technical solutions 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. Generally, the components of the embodiments of the present invention described and shown in the drawings here can be arranged and designed in various different configurations.

[0056] Therefore, the following detailed description of the embodiments of the present invention provided in the accompanying drawings is not intended to limit the scope of the invention claimed for protection, but merely represents selected embodiments of the present invention. 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.

[0057] The present invention provides a method for testing thermal deformation of electronic packaging components during reflow soldering based on reliability analysis, comprising the following steps:

[0058] Step S1, such as Figure 1As shown, for electronic packaging components that already have their own pads, the pads provided by the components can be used to carry out subsequent testing work; for components such as QFP that do not have their own array pads, the pads are pre-set according to the method of polymer material electroplating; the basic process of pad pre-setting is to first use the magnetron sputtering method, the principle of which is to bombard the target material with high-energy ions so that the target material obtains enough energy to separate from the parent material, and leaps out in the corresponding sputtering direction and is deposited on the surface of the component body; after completing the magnetron sputtering, the metal material for welding is deposited on the magnetron sputtering seed layer by chemical plating or electroplating; in some possible implementations, the relationship between the plating and thickness of the preset pad material is 20-25um for the copper layer, 3-5um for the nickel layer, and 0.05-0.1um for the gold layer; the relationship between the spacing of the preset pads and the pad size is shown in Table 1.

[0059] Table 1 Spacing and pad size matching relationship

[0060]

[0061]

[0062] Step S2: Figure 2 As shown, prepare a high-precision and high thermal stability test reference plate. It is designed according to the maximum size of the electronic packaging component package body. The maximum size of the reference plate should be larger than the size of the electronic packaging component, and the typical value is 10mm larger on one side. At the same time, in order to ensure the test accuracy, the test reference plate needs to have a higher flatness accuracy, and the typical value is that the flatness is not greater than 0.001mm. In order to ensure the stability of the dimensional accuracy of the reference plate during the heating process in the subsequent steps, the reference plate material is required to have a larger rigidity and a smaller thermal expansion coefficient. Typical materials are marble or mold steel.

[0063] like Figure 3 As shown, a coating or film material that does not wet with solder is pasted or coated on the reference plate of part 2; in some possible implementations, the coating layer is made of materials or processes such as polyimide, polyester, polytetrafluoroethylene, polyvinyl alcohol, polyethylene naphthalate, anodizing, micro-arc oxidation, etc. Among them, the wetting angle between the coating layer and the paste solder above the liquidus line of the paste solder is greater than 135°; and it cannot react chemically with the paste solder to form intermetallic compounds.

[0064] Step S3: Figure 4As shown, the solder is pre-set on the solder end of the grid package component, and the conventional electronic package component ball planting method is adopted. The solder is pre-set on the solder end of the electronic package component by printing paste solder or pre-setting solid solder balls with a mesh tool. The solder is melted by heating, and a metallurgical bond is formed between the solder end of the electronic package component and the pre-set solder to complete the solder pre-setting; the paste solder is any alloy solder in the table, and its characteristic is that the solidus and liquidus temperatures of the material are the same, and the temperature test range can cover 11°C to 313°C, and the temperature is the temperature point corresponding to the deformation value tested in step 7. The solder composition and temperature correspond to Table 2.

[0065] Table 2 Solder material selection

[0066]

[0067]

[0068] The volume or diameter of the paste solder or solid solder ball matches the packaging pitch of the grid package component. In some possible implementations, possible matching relationships are shown in Table 3.

[0069] Table 3 Pitch and solder ball size matching relationship

[0070] Spacing(mm) Ball diameter(mm) 1.27 0.75 1.0 0.6 0.8 0.5 0.75 0.45 0.5 0.3 0.4 0.25 0.3 0.2 0.25 0.15

[0071] Step S4: Figure 5 As shown, the electronic packaging component after the ball planting and pre-soldering in step S3 is placed on the substrate pasted or coated with the coating layer in step S2, and the solder ball surface contacts the surface of the film layer.

[0072] Step S5: Figure 6 As shown, the substrate and components of step S4 are placed together in a reflow soldering furnace for heating. Some possible heating methods are to use gas phase heat exchange, hot air convection or infrared heat radiation heating equipment for heating. The peak temperature of heating is required to be greater than the solidus and liquidus temperatures of the preset solder in step S3 (the selected solidus temperature of the solder is the same as the liquidus temperature). In some possible implementations, the peak temperature is required to be greater than the preset solder temperature by 30°C. Since the film layer of step S2 does not react with the solder ball, after the solder ball melts, the side of the solder ball in contact with the film layer is in a shape consistent with the upper surface of the substrate, i.e., a plane shape, under the action of the gravity of the package body itself. When the temperature is cooled to the eutectic point temperature, since the solidus temperature of the material solder is the same as the liquidus temperature, there is no solid and liquid coexistence interval, and the solder ball changes from liquid to solid instantly. The deformation state of the electronic packaging component at the eutectic point temperature of the solder is mapped to the size of the solder ball end plane from the upper surface of the package body.

[0073] Step S6: Figure 7As shown, after the substrate cools down to room temperature and the deformation of the component body is restored to normal, the electronic packaging components are pressed Figure 8 As shown in the figure, the upper surface of the package body contacts the substrate film layer, and an optical inspection device is used to test the height of the upper surface plane of each solder ball from the substrate. In some possible implementations, the optical inspection equipment includes AOI, SPI, ultra-depth of field microscope, three-coordinate tester, etc. commonly used in production lines.

[0074] Step S7, perform fitting calculation on each test height value and solder ball position information to obtain the deformation information of the package body at the preset solder solidus and liquidus temperatures in step S3. The fitting method in some possible implementations is as follows:

[0075] like Fig. 9 As shown in the figure, the height value information of the upper surface of the solder ball after deformation from the substrate plane is set as Z k The test results are as follows Fig.10 The position coordinates of each pad on the substrate are shown as (X k ,Y k ), where k = 1-n, and n is the number of solder balls tested.

[0076] After hypothesis testing (X k ,Y k ,Z k )The general form of the surface is as follows:

[0077] Z=f(X,,Y)=AX 2 +BXY+C,

[0078] The constructor H is as follows:

[0079]

[0080] By finding the extreme value of H, the values ​​of a, b, and c in the above formula can be obtained, and then the deformation information of the package body at the preset solder liquidus and solidus temperatures in step 3 can be obtained.

[0081] Repeating steps S3 to S7, the material type of the pre-set solder for the grid package component soldering end implant in step S3 can obtain the thermal deformation test results of the grid package component at multiple temperature points.

[0082] Example 1

[0083] This embodiment is specifically aimed at the test of thermal deformation of LGA package, and the specific steps are as follows:

[0084] Step 1: Prepare the high-precision and high thermal stability test reference plate. Select CrWMn abrasive steel with a thickness of 5mm. Design it according to the maximum size of the electronic packaging component package. The maximum size of the reference plate is 50mmX50mm. The flatness of the substrate is required to be less than 0.001mm. The substrate size is shown in Fig.12 .

[0085] Step 2, performing hard anodizing treatment on the reference plate in step 1;

[0086] Step 3: Pre-set solder on the solder end of the grid packaged component. Pre-set solid balls on the solder end of the LGA packaged component by using the method of pre-setting solid balls with the mesh tooling. Select a solder ball diameter of 0.75mm. Heat and melt the solder to form a metallurgical bond between the solder end of the electronic packaged component and the pre-set solder to complete the solder ball pre-setting. The solder ball composition is Sn63Pb37 solder, and the test temperature point is the liquidus point of Sn63Pb37 solder, 183 (℃). The corresponding solder composition and temperature are shown in Table 4:

[0087] Table 4 Solder material selection

[0088] Solder Paste Ingredients Liquidus(℃) Solidus(℃) Test temperature (℃) Sn63Pb37 183 183 183

[0089] The volume or diameter of the paste solder or solid solder ball matches the packaging pitch of the grid package component. In some possible implementations, possible matching relationships are shown in Table 5.

[0090] Table 5 Pitch and solder ball size matching relationship

[0091] Spacing(mm) Ball diameter(mm) 1.27 0.75

[0092] Step 4: Figure 5 As shown, the electronic packaging components after the pre-soldering of the balls in step 3 are placed on the substrate pasted or coated with the coating layer in step 2, and the solder ball surface contacts the surface of the coating layer;

[0093] Step 5: Place the substrate and components from step 4 into a reflow soldering furnace for heating. Some possible heating methods include using hot air convection for heating, and the peak temperature of the heating is required to be greater than the solidus and liquidus temperatures of the preset solder in step 3. The selected temperature curve settings are shown in Table 6.

[0094] Table 6 Heating parameters

[0095]

[0096]

[0097] Step 6: Figure 7As shown, after the substrate cools down to room temperature and the deformation of the component body is restored to horizontal, the LGA packaged component is turned over so that the upper surface of the package body contacts the substrate film layer, and the height of the upper surface plane of each solder ball from the substrate is tested using an ultra-depth of field microscope. Test height and coordinate correspondence information table 7.

[0098] Table 7 Solder ball height tested at room temperature after reflow soldering

[0099]

[0100]

[0101]

[0102] Step 7: Fitting and calculating each test height value and the solder ball position information to obtain the deformation information of the package body when the solidus and liquidus temperatures of the solder are preset in step 3. The fitted deformation surface information is as follows: Fig.13 shown.

[0103] Through the above example, the thermal deformation information of LGA 144 at 183°C was obtained.

[0104] Repeat steps 3 to 7, and use the following components to select 145℃ and 221℃ liquidus bumping in step 3 to obtain the thermal deformation information of the components at the key temperature nodes of preheating temperature 145℃ and soldering peak temperature 235℃.

[0105] Table 8 Solder ball material selection

[0106] Solder Paste Ingredients Liquidus Solidus Test temperature Sn51.2Pb30.6Cd18.2 145 145 145 Sn99Sb1.0 235 235 235

[0107] Embodiment 2:

[0108] This embodiment is specifically for the test of thermal deformation of BGA 256 package, with a pitch of 1.0 and an outer size of 17mmX17mm. The specific steps are as follows:

[0109] Step 1: Prepare a high-precision and high thermal stability test reference plate. Select a marble reference plate with a thickness of 3mm. Design it according to the maximum size of the electronic packaging component package. The maximum size of the reference plate is 50mmX50mm. The flatness of the substrate is required to be less than 0.001mm. The substrate size is shown in Figure 1 .

[0110] Step 2, coating the reference plate in step 1 with a polyimide film;

[0111] Step 3: Pre-set solder on the solder end of the grid packaged component, and pre-set solid spheres on the solder end of the PCBA packaged component. The solder ball diameter is selected to be 0.6mm. The solder is melted by heating to form a metallurgical bond between the solder end of the electronic packaged component and the pre-set solder to complete the solder ball pre-setting. The solder ball composition is Sn63Pb37 solder, and the test temperature point is 183 degrees Celsius, the liquidus point of Sn63Pb37 solder. The solder composition and temperature correspond to Table 9.

[0112] Table 9 Solder ball material selection

[0113] Solder Paste Ingredients Liquidus Solidus Test temperature Sn63Pb37 183 183 183

[0114] The volume or diameter of the paste solder or solid solder ball matches the package spacing of the grid package component. In some possible implementations, possible matching relationships are shown in Table 10.

[0115] Table 10 Pitch and solder ball size matching relationship

[0116] Spacing(mm) Ball diameter(mm) 1.0 0.6

[0117] Step 4: Figure 5 As shown, the electronic packaging components after the pre-soldering of the balls in step 3 are placed on the substrate pasted or coated with the coating layer in step 2, and the solder ball surface contacts the surface of the coating layer;

[0118] Step 5: Place the substrate and components from step 4 into a reflow soldering furnace for heating. Some possible heating methods include using hot air convection for heating, and the peak temperature of the heating is required to be greater than the solidus limit and liquidus temperature of the preset solder in step 3. The selected temperature curve settings are shown in Table 11.

[0119] Table 11 Heating parameters

[0120] upper temperature zone 120 150 160 165 170 175 200 230 230 230 Lower temperature zone 120 150 160 165 170 175 200 230 230 230

[0121] Step 6: Figure 7 As shown, after the substrate cools down to room temperature and the deformation of the component body is restored to horizontal, the BGA packaged component is turned over so that the upper surface of the package body contacts the substrate film layer, and the height of the upper surface plane of each solder ball from the substrate is tested using an optical three-coordinate tester. The corresponding information of the test height and coordinates is shown in Table 12.

[0122] Table 12 Solder ball height tested at room temperature after reflow soldering

[0123]

[0124]

[0125] Step 7: Fitting and calculating each test height value and the solder ball position information to obtain the deformation information of the package body when the solidus and liquidus temperatures of the solder are preset in step 3. The fitted deformation surface information is as follows: Fig.16 .

[0126] Through the above examples, the thermal deformation information of PBGA256 at 183°C was obtained.

[0127] Repeat steps 3 to 7, and use the following components to select solder balls with liquidus temperatures of 145°C and 221°C in step 3 to obtain the thermal deformation information of components at the key temperature nodes of preheating temperature 145°C and soldering peak temperature 221°C.

[0128] Table 13 Solder material selection

[0129] Solder Paste Ingredients Liquidus Solidus Test temperature Sn51.2Pb30.6Cd18.2 145 145 145 Sn96.5Ag3.5 221 221 221

Claims

1. A method for testing thermal deformation of electronic packaging components during reflow soldering based on reliability analysis, characterized in that: The steps include: S1. For electronic packaging components with built-in pads, use the pads of the components to carry out subsequent testing; for components without built-in pads, pre-set pads according to the polymer material electroplating method; S2. Prepare a high-precision and high-thermal stability test reference board. Design it according to the maximum size of the package body of the electronic packaging components. The maximum size of the test reference board should be larger than the size of the electronic packaging components. Paste or apply a coating or film material that does not wet with solder on the reference board. S3, pre-setting solder on the soldering end of the electronic packaging component in step S1, using a conventional method for planting balls of electronic packaging components, using a method of printing paste solder or pre-setting solid solder balls with a mesh tool to pre-set solder on the soldering end of the electronic packaging component, heating and melting the solder, forming a metallurgical bond between the soldering end of the electronic packaging component and the pre-set solder, and completing solder pre-setting; S4, placing the electronic packaging components after the soldering in step S3 is pre-placed on the test reference board on which the coating layer is pasted or coated in step S2, so that the solder ball surface contacts the surface of the coating layer; S5, putting the test reference board and the electronic packaging components of step S4 into the reflow soldering furnace for heating, requiring the peak temperature of heating to be greater than the solidus and liquidus temperatures of the preset solder in step S3. Since the film layer of step S2 does not react with the solder ball, after the solder ball melts, the side of the solder ball in contact with the film layer presents a shape consistent with the upper surface of the test substrate, i.e., a plane shape, under the action of the gravity of the package body itself. When the temperature is cooled to the eutectic point temperature, since the solidus temperature of the solder is the same as the liquidus temperature, there is no solid and liquid coexistence interval, and the solder ball changes from liquid to solid instantly. The deformation state of the electronic packaging components at the eutectic point temperature of the solder is mapped to the size of the plane of the end of the solder ball from the upper surface of the package body. S6. After the substrate to be tested is cooled to room temperature and the deformation of the electronic packaging components is restored to a horizontal level, the electronic packaging components are turned over, the upper surface of the electronic packaging components contacts the film layer of the test substrate, and the height of the upper surface plane of each solder ball from the substrate is tested using an optical inspection device; S7, performing fitting calculation on each test height value and solder ball position information to obtain deformation information of the package body when the solidus and liquidus temperatures of the solder are preset in step S3; S8, repeating steps S3 to S7, changing the material type of the pre-solder for the soldering of the soldering end of the electronic packaging component in step S3, and obtaining the thermal deformation test results of the electronic packaging component at multiple temperature points.

2. A method for testing thermal deformation of electronic packaging components during reflow soldering based on reliability analysis according to claim 1, characterized in that: In step S2, the maximum outer dimension of the test reference board is 10 mm larger than the outer dimension of the electronic packaging component on one side.

3. A method for testing thermal deformation of electronic packaging components during reflow soldering based on reliability analysis according to claim 1, characterized in that: In step S2, the flatness of the test reference plate is not greater than 0.001 mm.

4. A method for testing thermal deformation of electronic packaging components during reflow soldering based on reliability analysis according to claim 1, characterized in that: In step S2, the material of the test reference plate is marble or mold steel.

5. A method for testing thermal deformation of electronic packaging components during reflow soldering based on reliability analysis according to claim 1, characterized in that: In step S2, the coating layer is treated by polyimide, polyester, polytetrafluoroethylene, polyvinyl alcohol, polyethylene naphthalate, anodizing or micro-arc oxidation process; the wetting angle between the coating layer and the paste solder above the liquidus line of the paste solder is greater than 135°; and it cannot chemically react with the paste solder to form intermetallic compounds.

6. A method for testing thermal deformation of electronic packaging components during reflow soldering based on reliability analysis according to claim 1, characterized in that: In step S3, the paste solder is characterized in that the solidus and liquidus temperatures of the material are the same, and the temperature test range can cover 11°C to 313°C, which is the temperature point corresponding to the deformation value tested in step S7.

7. A method for testing thermal deformation of electronic packaging components during reflow soldering based on reliability analysis according to claim 1, characterized in that: In step S5, the heating method is to use gas phase heat exchange, hot air convection or infrared heat radiation heating equipment to heat the test reference board and the electronic packaging components.

8. A method for testing thermal deformation of electronic packaging components during reflow soldering based on reliability analysis according to claim 1, characterized in that: In step S5, the test reference board and the electronic packaging components of step S4 are placed in a reflow soldering furnace for heating. The peak temperature of the heating is required to be greater than the solidus and liquidus temperatures of the solder preset in step S3. The solidus temperature and liquidus temperature of the selected solder are the same, and the peak temperature is required to be 30°C greater than the preset solder temperature.

9. A method for testing thermal deformation of electronic packaging components during reflow soldering based on reliability analysis according to claim 1, characterized in that: In step S6, the optical inspection equipment includes AOI, SPI, ultra-depth of field microscope or three-coordinate measuring machine commonly used in production lines.

10. A method for testing thermal deformation of electronic packaging components during reflow soldering based on reliability analysis according to claim 1, characterized in that: In step S7, the fitting method is as follows: Set the height value of the upper surface of the solder ball after deformation to the substrate plane as Z k The position coordinates of each pad on the test substrate obtained by the test are (X k ,Y k ), where k = 1-n, n is the number of solder balls tested; After hypothesis testing (X k ,Y k ,Z k )The general form of the surface is as follows: Z=f(X,Y)=AX 2 +BXY+C, The constructor H is as follows: By finding the extreme value of H, the values ​​of a, b, and c in the above formula can be obtained, and further the deformation information of the package body when the liquidus and solidus temperatures of the solder are preset in step S3 can be obtained.

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