Bending fatigue testing method for interface failure of bonding layer

Abstract

The invention discloses a bending fatigue test method for interface failure of a bonding layer. The method comprises the following steps: preparing a sample; under the preset temperature condition, periodically changing external force is applied to the sample according to the preset external force condition, so that bending deformation testing is conducted on the sample; the final surface appearance of the sample at the bonding boundary is observed, and crack parameters of cracks on the bonding boundary are recorded; according to the crack parameters of the cracks on the bonding boundary line, the interface failure risk grade of the sample is judged. The thermal load and the force load are applied to the sample at the same time, so that the test environment is closer to the actual working environment of the chip, and the accuracy of failure risk judgment is improved. On the basis of thermal load, periodically changing external force is applied to the sample, so that the sample is deformed and bent, and through the double-field coupling rapid failure mechanism, the test period of the sample can be effectively shortened, and the test efficiency is improved.

Description

Technical Field

[0001] The present invention relates to the technical field of electronic packaging reliability testing, and in particular to a bending fatigue testing method for adhesive layer interface failure. Background Art

[0002] In microelectronic packaging, delamination at the interface between epoxy adhesive and the device is a core failure mode, directly impacting device lifespan. Traditional evaluation relies on thermal cycling testing (-55°C to 125°C) according to the JEDEC JESD22-A104 standard, which uses temperature fluctuations to induce thermal expansion mismatch stress and observe interface failure.

[0003] This method places the packaged sample in a temperature chamber and cycles it thousands of times, and observes macroscopic failure through metallographic sectioning or X-rays. This method only observes the impact of thermal load on the packaged sample and cannot reproduce the thermal-mechanical stress coupling effect of the chip in service. It also requires thousands of cycles (weeks to months), which cannot meet the needs of rapid material screening. At the same time, macroscopic observations make it difficult to capture the initiation behavior of interface microcracks, resulting in delayed risk assessment. Summary of the Invention

[0004] The present invention provides a bending fatigue testing method for adhesive layer interface failure, and simultaneously adopts a rapid failure mechanism of thermal-mechanical dual-field coupling, thereby shortening the sample testing cycle and improving the testing efficiency.

[0005] The present invention provides a bending fatigue testing method for adhesive layer interface failure, comprising:

[0006] Prepare a sample; the sample includes an upper substrate, a lower substrate and a glue layer; the glue layer is located between the upper substrate and the lower substrate, the glue layer adheres the upper substrate and the lower substrate and forms a bonding boundary on the side wall of the sample;

[0007] Under preset temperature conditions, applying a periodically changing external force to the sample according to preset external force conditions to perform a bending deformation test on the sample;

[0008] observing the final surface morphology of the sample at the bonding boundary, and recording crack parameters of the cracks at the bonding boundary;

[0009] The interface failure risk level of the sample is determined according to the crack parameters of the crack on the bonding boundary line.

[0010] Optionally, determining the interface failure risk level of the sample according to the crack parameters of the crack on the bonding boundary line includes:

[0011] When the crack parameter is within a first preset range, determining that the sample is at a first risk level;

[0012] When the crack parameter is within a second preset range, determining that the sample is at a second risk level;

[0013] The minimum value in the first preset range is greater than the maximum value in the second preset range, and the severity of the first risk level is greater than the severity of the second risk level.

[0014] Optionally, the crack parameters include at least one of crack length, crack width and crack morphology complexity.

[0015] Optionally, observing the final surface morphology of the sample at the bonding boundary and recording crack parameters of the cracks at the bonding boundary include:

[0016] Observing the final surface morphology of the sample at the bonding boundary, and selecting a crack on the bonding boundary whose size is larger than the resolution of the observation equipment as a target crack;

[0017] The crack parameters of the target crack are recorded.

[0018] Optionally, observing the final surface morphology of the sample at the bonding boundary includes:

[0019] The final surface morphology of the sample at the bonding boundary is observed using an electron scanning microscope or a laser confocal microscope.

[0020] Optionally, under a preset temperature condition, applying a periodically changing external force to the sample according to a preset external force condition to perform a bending deformation test on the sample includes:

[0021] At a fixed preset temperature or a periodically changing temperature, a periodically changing external force is applied to the sample according to a preset external force condition to perform a bending deformation test on the sample.

[0022] Optionally, under a preset temperature condition, applying a periodically changing external force to the sample according to a preset external force condition to perform a bending deformation test on the sample includes:

[0023] At a preset fixed temperature, a periodically changing external force is applied to the sample according to a preset force value change frequency, a preset force value change range, and a preset number of periodic force value changes to perform a bending deformation test on the sample; wherein the preset fixed temperature range is -55-125°C, the preset force value change frequency range is 1-100Hz, the preset force value change range is 0-500N, and the preset number of periodic force value changes range is 10-100 times.

[0024] Optionally, the preset temperature condition includes a preset temperature change rate, a preset temperature change range and a preset number of temperature periodic changes; the preset external force condition includes a preset force value change frequency, a preset force value change range and a preset number of force value periodic changes.

[0025] Optionally, prepare the sample, including:

[0026] providing the upper substrate and the lower substrate;

[0027] The sample is formed by filling the glue layer between the upper substrate and the lower substrate using a flow filling method.

[0028] Optionally, before applying a periodically changing external force to the sample according to a preset external force condition under a preset temperature condition to perform a bending deformation test on the sample, the method further includes:

[0029] The sidewall of the sample is subjected to mechanical polishing and nano-polishing in sequence until there is no crack on the sidewall of the sample.

[0030] The bending fatigue testing method for adhesive layer interface failure provided by this invention applies both thermal and mechanical loads to the sample, making the testing environment closer to the actual chip operating environment and improving the accuracy of failure risk assessment. In addition to the thermal load, a periodically varying external force is applied to the sample, causing it to deform and bend. This dual-field coupled rapid failure mechanism effectively shortens the sample testing cycle and improves testing efficiency. BRIEF DESCRIPTION OF THE DRAWINGS

[0031] Figure 1 A schematic flow chart of a bending fatigue testing method for adhesive layer interface failure provided by an embodiment of the present invention;

[0032] Figure 2 A schematic structural diagram of a sample provided in an embodiment of the present invention;

[0033] Figure 3 A structural diagram of a dynamic mechanical analyzer provided by an embodiment of the present invention;

[0034] Figure 4 A schematic flow chart of another bending fatigue testing method for adhesive layer interface failure provided by an embodiment of the present invention;

[0035] Figure 5 A schematic flow chart of another method for testing bending fatigue of adhesive layer interface failure provided by an embodiment of the present invention;

[0036] Figure 6 A schematic flow chart of another method for testing bending fatigue of adhesive layer interface failure provided by an embodiment of the present invention;

[0037] Figure 7 A schematic flow chart of another method for testing bending fatigue of adhesive layer interface failure provided by an embodiment of the present invention;

[0038] Figure 8 A schematic flow chart of another bending fatigue testing method for adhesive layer interface failure provided by an embodiment of the present invention. DETAILED DESCRIPTION

[0039] The present invention will be further described in detail below with reference to the accompanying drawings and examples. It will be understood that the specific embodiments described herein are intended only to illustrate the present invention and are not intended to limit the present invention. It should also be noted that, for ease of description, the accompanying drawings only illustrate portions relevant to the present invention, not all structures.

[0040] The terms used in the embodiments of the present invention are only for the purpose of describing specific embodiments and are not intended to limit the present invention. It should be noted that the directional words such as "upper", "lower", "left", and "right" described in the embodiments of the present invention are described based on the angles shown in the accompanying drawings and should not be understood as limiting the embodiments of the present invention. In addition, in the context, it is also necessary to understand that when it is mentioned that an element is formed "on" or "under" another element, it can not only be formed directly "on" or "under" another element, but can also be formed indirectly "on" or "under" another element through an intermediate element. The terms "first", "second", etc. are only used for descriptive purposes and do not indicate any order, quantity or importance, but are only used to distinguish different components. For those of ordinary skill in the art, the specific meanings of the above terms in the present invention can be understood according to specific circumstances.

[0041] The term "including" and its variations used in the present invention are open inclusions, that is, "including but not limited to." The term "based on" means "based at least in part on." The term "one embodiment" means "at least one embodiment."

[0042] It should be noted that the concepts such as "first" and "second" mentioned in the present invention are only used to distinguish the corresponding contents, and are not used to limit the order or mutual dependence.

[0043] It should be noted that the modifications of "one" and "multiple" mentioned in the present invention are illustrative rather than restrictive. Those skilled in the art should understand that unless otherwise clearly indicated in the context, it should be understood as "one or more".

[0044] Figure 1 A schematic flow chart of a bending fatigue testing method for adhesive layer interface failure provided by an embodiment of the present invention is shown as follows: Figure 1 As shown, the test method includes:

[0045] S101. Prepare samples.

[0046] in, Figure 2 A schematic diagram of the structure of a sample provided by an embodiment of the present invention, such as Figure 2 As shown, the sample includes an upper substrate 10, a lower substrate 11 and a glue layer 12; the glue layer 12 is located between the upper substrate 10 and the lower substrate 11, and the glue layer 12 bonds the upper substrate 10 and the lower substrate 11 and forms a bonding boundary 20 on the side wall of the sample.

[0047] Specifically, due to the different thermal expansion coefficients of different materials, internal stress is generated at the interface between the two materials when the ambient temperature changes, causing delamination at the interface and affecting the reliability of the device. In addition, the device will be subjected to mechanical stress during actual use, which may also lead to device failure. Therefore, an adhesive layer 12 is used to bond the upper substrate 10 and the lower substrate 11 to form a test sample. After the test, the changes in the bonding boundary 20 formed on the sidewall of the sample are observed. For example, the upper substrate 10 and the lower substrate 11 can be silicon, silicon nitride, silicon oxide, or copper, and the adhesive layer 12 can be an epoxy resin adhesive.

[0048] S102. Under preset temperature conditions, apply a periodically changing external force to the sample according to preset external force conditions to perform a bending deformation test on the sample.

[0049] Specifically, the prepared sample is placed in a testing device that can simultaneously adjust the test temperature conditions and periodically change the external force applied to the sample surface, so that the sample undergoes a bending deformation test while undergoing a temperature fatigue test, making the test conditions of the sample more stringent, which is conducive to shortening the time of the sample fatigue test. Furthermore, according to the temperature changes and possible mechanical stresses to which the sample is subjected during actual use, the sample is subjected to a corresponding preset temperature and preset external force, and then a fatigue failure test is performed on the sample. Exemplarily, the testing device can be a dynamic mechanical analyzer (DMA), which performs a cyclic test through DMA and collects DMA data after the cycle is completed.

[0050] Figure 3 A structural diagram of a dynamic mechanical analyzer provided by an embodiment of the present invention is shown in FIG. Figure 3 As shown, the device includes a DMA host 31, a high rigidity frame 32, a DMA base 33, an upper fixture 34, a lower fixture 35, a rigidity force sensor 36 and a temperature control box 37. The prepared sample is placed between the upper fixture 34 and the lower fixture 35, with reference to Figure 3The sample is fixed by three-point support between the upper clamp 34 and the lower clamp 35. Therefore, when the rigid force sensor 36 applies different force values ​​between the upper clamp 34 and the lower clamp 35, the surface of the sample can bend and deform due to uneven force. At the same time, the temperature conditions during the test are adjusted in conjunction with the temperature control box 37 to realize the accelerated failure mechanism of thermal-mechanical dual-field coupling, which can effectively shorten the test time and improve the test efficiency. In another optional embodiment, when the test sample is an ultra-thin sample, the upper clamp 34 and the lower clamp 35 that fix the sample at three points can be replaced with four-point support to fix the sample, thereby improving the reliability of sample fixation.

[0051] S103. Observe the final surface morphology of the sample at the bonding boundary and record the crack parameters of the crack on the bonding boundary.

[0052] Specifically, after testing a sample under preset temperature and external force conditions, cracks may appear at the bonding line 20 between the upper substrate 10 and the adhesive layer 12, or at the bonding line 20 between the lower substrate 11 and the adhesive layer 12. This can lead to delamination between the upper substrate 10 and the adhesive layer 12, or between the lower substrate 11 and the adhesive layer 12, and ultimately to sample failure. Therefore, after testing, the final surface morphology of the sample at the bonding line 20 is observed to check for cracks, and the crack parameters of the cracks at the bonding line 20 are recorded.

[0053] S104. Determine the interface failure risk level of the sample based on crack parameters of the crack on the bonding boundary line.

[0054] Specifically, using different materials for the upper substrate 10, lower substrate 11, and adhesive layer 12, or changing the test conditions, can lead to inconsistent cracks at the bonding boundary 20 after testing. If there are few or no cracks, the sample can be considered healthy. If there are many cracks or obvious delamination at the bonding boundary 20, the sample interface can be considered to have failed. Furthermore, the failure risk of the sample can be categorized into multiple levels based on different crack parameters, allowing for a delamination risk assessment and report output.

[0055] By simultaneously applying thermal and mechanical loads to the sample, the present invention brings the test environment closer to the chip's actual operating environment, improving the accuracy of failure risk assessment. In addition to the thermal load, a periodically varying external force is applied to the sample, causing it to deform and bend. This dual-field coupled rapid failure mechanism effectively shortens the sample's test cycle and improves test efficiency.

[0056] Figure 4A flow chart of another bending fatigue testing method for adhesive layer interface failure provided by an embodiment of the present invention is provided. This embodiment is a refinement of the above embodiment. Specifically, the step of determining the interface failure risk level of the sample based on the crack parameters of the crack on the bonding boundary line can be specifically refined as follows:

[0057] When the crack parameter is within a first preset range, determining that the sample is at a first risk level;

[0058] When the crack parameter is within a second preset range, determining that the sample is at a second risk level;

[0059] The minimum value in the first preset range is greater than the maximum value in the second preset range, and the severity of the first risk level is greater than the severity of the second risk level.

[0060] For details not yet provided in this embodiment, please refer to the previous embodiment. Figure 4 As shown, the testing method provided in this embodiment includes:

[0061] S201. Prepare samples.

[0062] S202. Under preset temperature conditions, apply a periodically changing external force to the sample according to preset external force conditions to perform a bending deformation test on the sample.

[0063] S203. Observe the final surface morphology of the sample at the bonding boundary, and record the crack parameters of the cracks on the bonding boundary.

[0064] S204: When the crack parameter is within a first preset range, determine that the sample is at a first risk level.

[0065] S205: When the crack parameter is within a second preset range, determine that the sample is at a second risk level.

[0066] The minimum value in the first preset range is greater than the maximum value in the second preset range, and the severity of the first risk level is greater than the severity of the second risk level.

[0067] Specifically, the minimum value in the first preset range can be determined by a first determination threshold, and the maximum value in the second preset range can be determined by a second determination threshold. In an optional embodiment, the crack parameter includes at least one of crack length, crack width, and crack morphology complexity. When the crack parameter is crack length or crack width, the first determination threshold can be expressed as the product of the sample size and a first percentage, that is, the first determination threshold corresponding to the crack length can be expressed as the product of the sample length and the first percentage, the first determination threshold corresponding to the crack width can be expressed as the product of the sample width and the first percentage, and the second determination threshold can be expressed as the product of the sample size and the second percentage, that is, the second determination threshold corresponding to the crack length can be expressed as the product of the sample length and the second percentage, and the second determination threshold corresponding to the crack width can be expressed as the product of the sample width and the second percentage, wherein the first percentage is greater than the second percentage. Under the condition of the same sample size, the first determination threshold is greater than the second determination threshold, that is, the minimum value in the first preset range is greater than the maximum value in the second preset range. Therefore, when the crack parameter is in the first preset range, the length or width of the crack is greater than when the crack parameter is in the second preset range. Since after the test, the longer the crack length or width indicates a higher possibility of failure of the sample, the risk level of the sample is correspondingly determined as the first risk level and the second risk level, and the severity of the first risk level is greater than the severity of the second risk level.

[0068] For example, when the crack parameter is crack length or crack width, if the crack length of a sample on the bonding boundary 20 is greater than a first judgment threshold, or if the crack width is greater than the first judgment threshold, the crack parameter is within a first preset range. In this case, the crack length or crack width is large, and the sample can be assigned to a first risk level (i.e., a high risk level). It is worth noting that the first percentages corresponding to the crack length and crack width can be the same or different. For example, the first percentage corresponding to the crack length can be 20%, and the first percentage corresponding to the crack width can be 10%. If the crack length of a sample on the bonding boundary 20 is less than a second judgment threshold, or if the crack width is less than the second judgment threshold, the crack parameter is within a second preset range, and the crack length or crack width is small. The sample can be assigned to a second risk level (i.e., a low risk level). Similarly, the second percentages corresponding to the crack length and crack width can be the same or different. For example, the second percentage corresponding to the crack length can be 5%, and the second percentage corresponding to the crack width can be 3%.

[0069] Furthermore, when the crack parameter is the complexity of the crack morphology, the crack morphology value can be used to characterize the complexity of the crack morphology. The more complex the crack morphology, the larger the corresponding crack morphology value. When the crack morphology value is greater than the first judgment threshold, the crack parameter is within the first preset range, indicating that the sample has many cracks on the bonding boundary 20 and is in the stage of network expansion or delamination. The sample is determined to be at the first risk level, i.e., a high risk level. When the crack morphology value is less than the second judgment threshold, the crack parameter is within the second preset range, indicating that the sample has few or no cracks on the bonding boundary 20. The sample is determined to be at the second risk level, i.e., a low risk level.

[0070] In another optional embodiment, the crack parameter may be within a third preset range. When the crack parameter is within the third preset range, the sample is determined to be at a third risk level. The minimum value in the third preset range is greater than the maximum value in the second preset range and less than the minimum value in the first preset range. The severity of the third risk level is greater than the severity of the second risk level and less than the severity of the first risk level.

[0071] Exemplarily, when the crack parameter is crack length or crack width, the crack length of the crack of the sample on the bonding boundary 20 is less than or equal to the first judgment threshold and greater than or equal to the second judgment threshold, or the crack width of the crack of the sample on the bonding boundary 20 is less than or equal to the first judgment threshold and greater than or equal to the second judgment threshold, then it is determined that the crack parameter of the sample is in the third preset range, and the risk level of the sample is determined to be the third risk level, which is a medium risk level.

[0072] Furthermore, when the crack parameter is the complexity of the crack morphology, the crack morphology value is less than or equal to the first judgment threshold and greater than or equal to the second judgment threshold, it is determined that the crack parameter of the sample is in the third preset range, indicating that local micro-branching may appear in the crack morphology at this time, and therefore the sample is determined to be the third risk level, that is, the medium risk level.

[0073] The embodiment of the present invention limits different preset ranges of crack parameters and divides samples into multiple risk levels according to the preset ranges, thereby avoiding the waste of samples due to unclear risk level division, facilitating the subsequent more targeted proposals to solve the sample failure risk, and improving the efficiency of sample failure risk analysis.

[0074] Figure 5 A flow chart of another method for testing bending fatigue of adhesive layer interface failure provided by an embodiment of the present invention is provided. This embodiment is a refinement of the above embodiment. Specifically, the step of observing the final surface morphology of the sample at the bonding boundary and recording the crack parameters of the crack at the bonding boundary can be specifically refined as follows:

[0075] Observe the final surface morphology of the sample at the bonding boundary, and select the cracks on the bonding boundary that are larger than the resolution of the observation equipment as the target cracks;

[0076] Record the crack parameters of the target crack.

[0077] For details not yet provided in this embodiment, please refer to the previous embodiment. Figure 5 As shown, the testing method provided in this embodiment includes:

[0078] S301. Prepare samples.

[0079] S302 . Under preset temperature conditions, apply a periodically changing external force to the sample according to preset external force conditions to perform a bending deformation test on the sample.

[0080] S303. Observe the final surface morphology of the sample at the bonding boundary, and select a crack on the bonding boundary whose size is larger than the resolution of the observation equipment as a target crack.

[0081] S304: Record crack parameters of the target crack.

[0082] Specifically, after the sample is subjected to a bending deformation test, cracks may appear at the bonding boundary 20 of the sample due to the effects of thermal loads and force loads, resulting in delamination between the substrate and the adhesive layer, affecting the reliability of the device. The size of the cracks may be submicron, so when observing the final surface morphology at the bonding boundary 20 of the sample, an observation device with a higher resolution should be used as much as possible. In an optional embodiment, an electron scanning microscope or a laser confocal microscope is used to observe the final surface morphology of the sample at the bonding boundary 20, and the crack parameters are quantitatively measured and annotated. Furthermore, when using an observation device to observe the final surface morphology at the bonding boundary 20 of the sample, it is necessary to select a crack on the bonding boundary 20 whose size is larger than the resolution of the observation device as the target crack, so that the observation device can more clearly observe the crack parameters of the target crack, thereby more accurately determining the interface failure risk level of the sample.

[0083] S305. Determine the interface failure risk level of the sample based on crack parameters of the crack on the bonding boundary line.

[0084] The embodiment of the present invention more accurately selects the target crack at the bonding boundary of the sample after the failure test, so that the size of the target crack is larger than the resolution of the observation equipment, thereby improving the accuracy of the crack parameters of the target crack recorded by the observation equipment, thereby further improving the accuracy of determining the interface failure risk level of the sample.

[0085] Figure 6A flow chart of another bending fatigue testing method for adhesive layer interface failure provided in an embodiment of the present invention is provided. This embodiment is a refinement of the above embodiment. Specifically, the step of applying a periodically changing external force to a sample under preset temperature conditions according to preset external force conditions to perform a bending deformation test on the sample can be specifically refined as follows:

[0086] At a fixed preset temperature or a periodically changing temperature, a periodically changing external force is applied to the sample according to the preset external force conditions to perform a bending deformation test on the sample.

[0087] For details not yet provided in this embodiment, please refer to the previous embodiment. Figure 6 As shown, the testing method provided in this embodiment includes:

[0088] S401. Prepare samples.

[0089] S402 . Apply a periodically changing external force to the sample at a fixed preset temperature or a periodically changing temperature according to a preset external force condition to perform a bending deformation test on the sample.

[0090] Specifically, when a sample is subjected to a thermal load failure test at a fixed preset temperature or a cyclically varying temperature, delamination may occur at the sample's bonding boundary 20 due to a mismatch in the thermal expansion coefficients between the sample substrate and the adhesive layer. When the sample is subjected to a failure test under cyclically varying temperature conditions, in an alternative embodiment, the speed of the sample fatigue failure test can be adjusted by varying the preset temperature change rate, the preset temperature change range, and the number of cyclic temperature changes. A greater preset temperature change rate and temperature change range increase the rate at which cracks appear at the sample's bonding boundary 20. To further improve the efficiency of the sample fatigue failure test, a cyclically varying external force is applied to the sample according to preset external force conditions to perform a bending deformation test, which better matches the sample's actual usage conditions. In an alternative embodiment, the preset external force conditions include a preset force value change frequency, a preset force value change range, and a preset number of force value cyclic changes. A faster preset force value change frequency or a larger preset force value change range indicates a faster cracking rate at the sample's bonding boundary 20. When a periodically changing external force is applied to the surface of the sample, the external force is usually lower than the maximum stress that the sample can withstand. By cyclically changing the external force, a crack can be induced at the bonding boundary 20 of the sample, and the crack will gradually grow as the number of cycles increases. In this way, the failure risk level or fatigue limit of the sample can be determined.

[0091] S403. Observe the final surface morphology of the sample at the bonding boundary and record the crack parameters of the crack on the bonding boundary.

[0092] S404. Determine the interface failure risk level of the sample based on crack parameters of the crack on the bonding boundary line.

[0093] The embodiment of the present invention forms a multi-physical field coupling testing method by applying a periodically changing external force to the sample at a fixed preset temperature or a periodically changing temperature to perform a bending deformation test. This method can synchronously reproduce the coupling effect of temperature fluctuations and mechanical load cycles in actual applications, simulating real working conditions.

[0094] Figure 7 A flow chart of another bending fatigue testing method for adhesive layer interface failure provided by an embodiment of the present invention is provided. This embodiment is a refinement of the above embodiment. Specifically, the steps include: applying a periodically changing external force to a sample according to a preset external force condition under a preset temperature condition to perform a bending deformation test on the sample;

[0095] At a preset fixed temperature, a periodically changing external force is applied to the sample according to a preset force value change frequency, a preset force value change range, and a preset number of periodic force value changes to perform a bending deformation test on the sample;

[0096] The preset fixed temperature range is -55-125° C., the preset force value change frequency range is 1-100 Hz, the preset force value change range is 0-500 N, and the preset force value periodic change times range is 10-100 times.

[0097] For details not yet provided in this embodiment, please refer to the previous embodiment. Figure 7 As shown, the testing method provided in this embodiment includes:

[0098] S501. Prepare samples.

[0099] S502 , at a preset fixed temperature, applying a periodically changing external force to the sample according to a preset force value change frequency, a preset force value change range, and a preset number of periodic force value changes, so as to perform a bending deformation test on the sample.

[0100] Among them, the preset fixed temperature range is -55-125°C, the preset force value change frequency range is 1-100Hz, the preset force value change range is 0-500N, and the preset force value periodic change times range is 10-100 times.

[0101] Specifically, a preset fixed temperature can be set according to the temperature resistance of the sample so that the sample slowly deforms at this temperature. For example, the temperature can be set to 85°C. At the same time, according to the maximum stress value that the sample can withstand, the force value variation range applied to the sample is set. The larger the force value variation range, the greater the degree of bending deformation of the sample and the faster the failure rate. For example, the force value variation range can be set to 0-500N. At the same time, a preset force value variation frequency can be set. When the force value variation frequency is smaller, it indicates that the preset force value changes faster within the preset force value variation range, which can also make the failure rate of the sample faster. For example, the preset force value variation frequency can be 50Hz. By superimposing a periodically changing external force under fixed temperature conditions, the test time for causing cracks in the sample can be effectively shortened. The range of the number of periodic changes of the preset force value for the cyclic test of the sample in the embodiment of the present invention is 10-100 times. Compared with thousands of cycles in the prior art, the test efficiency has been significantly improved.

[0102] For example, in a validation test, two different underfill materials were used for the adhesive layer, and silicon was used for both the upper and lower substrates. The test conditions were: a fixed temperature of 85°C, a force range of 0-500N, a force frequency of 85Hz, and 30 cycles. This test took only a few minutes to complete. The first underfill material exhibited a crack length exceeding 20% ​​of the total sample length, indicating a high risk. The second underfill material exhibited a crack width exceeding 2% of the total sample width, indicating a low risk. When the test results were compared with those from a conventional 1000-cycle thermal cycle test, the consistency was greater than 95%.

[0103] S503. Observe the final surface morphology of the sample at the bonding boundary, and record the crack parameters of the crack on the bonding boundary.

[0104] S504. Determine the interface failure risk level of the sample based on crack parameters of the crack on the bonding boundary line.

[0105] The embodiment of the present invention combines fixed temperature with programmed cyclic force loads to reproduce the thermomechanical coupling environment of the material in actual use, accurately simulates real working conditions, and can quickly evaluate the long-term performance of the sample through accelerated aging testing, clarify the crack initiation threshold and fatigue life. Finally, creep, fatigue and synergistic effect data can be simultaneously obtained through a single experiment, significantly reducing the sample quantity and testing time.

[0106] Figure 8 A flow chart of another method for testing bending fatigue of adhesive layer interface failure provided by an embodiment of the present invention is provided. This embodiment is a refinement of the above embodiment. Specifically, the step of preparing a sample can be further refined as follows:

[0107] providing an upper substrate and a lower substrate;

[0108] The flow filling method was used to fill the glue layer between the upper substrate and the lower substrate to form a sample.

[0109] Furthermore, under the preset temperature conditions, the following steps are added before applying a periodically changing external force to the sample according to the preset external force conditions to perform a bending deformation test on the sample:

[0110] The side wall of the sample is mechanically polished and nano-polished in sequence until there is no crack on the side wall of the sample.

[0111] For details not yet provided in this embodiment, please refer to the previous embodiment. Figure 8 As shown, the testing method provided in this embodiment includes:

[0112] S601 , providing an upper substrate and a lower substrate.

[0113] Specifically, refer to Figure 2 An upper substrate 10 and a lower substrate 11 are provided. Upper substrate 10 and lower substrate 11 may be made of silicon, silicon nitride, silicon oxide, or copper. Upper substrate 10 and lower substrate 11 are cut to meet the test device's dimensions. For example, when the test device is a DMA, upper substrate 10 and lower substrate 11 may have a length of 10 mm, a width of 10 mm, and a thickness of 0.75 mm.

[0114] S602: Using a flow filling method, fill a glue layer between the upper substrate and the lower substrate to form a sample.

[0115] Specifically, a flow-fill method was used to prepare an adhesive layer 12 between an upper substrate 10 and a lower substrate 11, forming a sandwich structure sample. For example, adhesive layer 12 can be made of epoxy resin adhesive, and its length and width match the dimensions of upper and lower substrates 10, 11, i.e., 10 mm in length and 10 mm in width. The thickness of adhesive layer 12 can range from 0.02 to 0.1 mm, resulting in a total sample size of 10 mm (length) × 10 mm (width) × 1.52-1.6 mm in total thickness (including the adhesive layer).

[0116] S603. Mechanically polishing and nano-polishing are sequentially performed on the side wall of the sample until there is no crack on the side wall of the sample.

[0117] Specifically, before performing a failure test on a sample, it is necessary to ensure that there are no cracks on the sidewalls of the sample, so that cracks can be more easily observed in the sidewalls of the sample after the failure test. Therefore, the sidewalls of the sample are first mechanically polished to remove protrusions on the sidewalls of the sample. For example, mechanical polishing can use sandpaper to grind the sidewalls of the sample, and then the sidewalls of the sample are nano-polished. For example, nano-polishing can use a 50nm Al2O3 suspension to polish to remove the initial cracks on the sidewalls of the sample and eliminate the interference of the initial cracks on the observation of cracks after the failure test. For example, an electron scanning microscope or a laser confocal microscope can be used to observe the initial cracks on the sidewalls of the sample. After determining that there are no initial cracks in a certain area of ​​the sidewalls of the sample, the same area should be observed when observing cracks on the sidewalls of the sample after the failure test.

[0118] S604 . Under preset temperature conditions, apply a periodically changing external force to the sample according to preset external force conditions to perform a bending deformation test on the sample.

[0119] S605. Observe the final surface morphology of the sample at the bonding boundary and record the crack parameters of the crack on the bonding boundary.

[0120] S606. Determine the interface failure risk level of the sample based on crack parameters of the crack on the bonding boundary line.

[0121] The embodiment of the present invention prepares a sandwich structure sample and mechanically polishes and nano-polishes the sidewall of the sample to determine that there are no initial cracks on the sidewall of the sample before the failure test, making subsequent observation of cracks after the failure test more intuitive and avoiding interference from the initial cracks.

[0122] In addition, the testing method of the embodiment of the present invention is not limited to the interface failure analysis between the substrate and the adhesive layer, but is also applicable to the bonding interface evaluation of chip stacking and the thermal fatigue life prediction between the ceramic substrate and the metal layer.

[0123] Note that the above are only preferred embodiments of the present invention and the technical principles employed. Those skilled in the art will appreciate that the present invention is not limited to the specific embodiments described herein, and that various obvious changes, readjustments, combinations, and substitutions are possible for those skilled in the art without departing from the scope of the present invention. Therefore, although the present invention has been described in detail through the above embodiments, the present invention is not limited to the above embodiments and may include many other equivalent embodiments without departing from the scope of the present invention. The scope of the present invention is determined by the scope of the appended claims.

Claims

1. A bending fatigue test method for adhesive layer interface failure, characterized in that: include: Prepare samples; The sample includes an upper substrate, a lower substrate and a glue layer; The adhesive layer is located between the upper substrate and the lower substrate, and the adhesive layer adheres the upper substrate and the lower substrate and forms an adhesive boundary on the side wall of the sample; Under preset temperature conditions, applying a periodically changing external force to the sample according to preset external force conditions to perform a bending deformation test on the sample; observing the final surface morphology of the sample at the bonding boundary, and recording crack parameters of the cracks at the bonding boundary; The interface failure risk level of the sample is determined according to the crack parameters of the crack on the bonding boundary line.

2. The method according to claim 1, characterized in that Determining the interface failure risk level of the sample according to the crack parameters of the crack on the bonding boundary line includes: When the crack parameter is within a first preset range, determining that the sample is at a first risk level; When the crack parameter is within a second preset range, determining that the sample is at a second risk level; The minimum value in the first preset range is greater than the maximum value in the second preset range, and the severity of the first risk level is greater than the severity of the second risk level.

3. The method according to claim 2, characterized in that The crack parameters include at least one of crack length, crack width and crack morphology complexity.

4. The method according to claim 1, wherein Observe the final surface morphology of the sample at the bonding boundary, and record the crack parameters of the crack at the bonding boundary, including: Observing the final surface morphology of the sample at the bonding boundary, and selecting a crack on the bonding boundary whose size is larger than the resolution of the observation equipment as a target crack; The crack parameters of the target crack are recorded.

5. The method according to claim 1, wherein Observe the final surface morphology of the sample at the bonding boundary, including: The final surface morphology of the sample at the bonding boundary is observed using an electron scanning microscope or a laser confocal microscope.

6. The method according to claim 1, wherein Under a preset temperature condition, applying a periodically changing external force to the sample according to a preset external force condition to perform a bending deformation test on the sample, including: At a fixed preset temperature or a periodically changing temperature, a periodically changing external force is applied to the sample according to a preset external force condition to perform a bending deformation test on the sample.

7. The method according to claim 1, characterized in that Under a preset temperature condition, applying a periodically changing external force to the sample according to a preset external force condition to perform a bending deformation test on the sample, including: At a preset fixed temperature, a periodically changing external force is applied to the sample according to a preset force value change frequency, a preset force value change range, and a preset number of periodic force value changes to perform a bending deformation test on the sample; wherein the preset fixed temperature range is -55-125°C, the preset force value change frequency range is 1-100Hz, the preset force value change range is 0-500N, and the preset number of periodic force value changes range is 10-100 times.

8. The bending fatigue testing method for adhesive layer interface failure according to claim 1, characterized in that: The preset temperature conditions include a preset temperature change rate, a preset temperature change range, and a preset number of temperature periodic changes; the preset external force conditions include a preset force value change frequency, a preset force value change range, and a preset number of force value periodic changes.

9. The bending fatigue testing method for adhesive layer interface failure according to claim 1, characterized in that: Prepare the sample, including: providing the upper substrate and the lower substrate; The sample is formed by filling the glue layer between the upper substrate and the lower substrate using a flow filling method.

10. The bending fatigue testing method for adhesive layer interface failure according to claim 1, characterized in that: Under a preset temperature condition, before applying a periodically changing external force to the sample according to a preset external force condition to perform a bending deformation test on the sample, the method further includes: The sidewall of the sample is subjected to mechanical polishing and nano-polishing in sequence until there is no crack on the sidewall of the sample.

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