Thermal-mechanical coupling fatigue testing method for interface failure of bonding layer

Abstract

The invention discloses a thermal-mechanical coupling fatigue testing method for interface failure of a bonding layer. The method comprises the following steps: preparing a sample; carrying out displacement oscillation on the sample under a preset temperature condition according to a preset oscillation condition so as to carry out a thermal-mechanical coupling test 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. According to the method, the sample is subjected to displacement oscillation in the thickness direction while the periodically changing temperature is applied to the sample, so that the thermal-mechanical coupling environment of the sample in actual work is truly restored, and the accuracy of failure risk judgment is improved. By using harsh test conditions of thermal-mechanical coupling, the test period of the sample can be effectively shortened, and the test efficiency is improved.

Description

Technical Field

[0001] This invention relates to the field of electronic packaging reliability testing technology, and in particular to a thermal coupling fatigue testing method for adhesive layer interface failure. Background Technology

[0002] In microelectronic packaging, delamination at the epoxy resin adhesive interface with the device is a core failure mode that directly affects device lifespan. Traditional evaluation relies on thermal cycling tests (-55°C to 125°C) according to the JEDEC JESD22-A104 standard, which observe interface failure by inducing thermal expansion mismatch stress through temperature changes.

[0003] This method involves placing the packaged sample in an incubator for thousands of cycles and observing macroscopic failures through metallographic sections or X-rays. This method only observes the effect of thermal load on the packaged sample and cannot reproduce the thermo-mechanical stress coupling effect during chip service. Furthermore, it requires thousands of cycles (weeks to months), which cannot meet the needs for rapid material screening. At the same time, macroscopic observation is difficult to capture the initiation behavior of microcracks at the interface, resulting in a lag in risk assessment. Summary of the Invention

[0004] This invention provides a thermo-coupled fatigue testing method for adhesive layer interface failure, and at the same time, it adopts a rapid failure mechanism of thermo-coupled failure, which shortens the sample testing cycle and improves testing efficiency.

[0005] This invention provides a thermo-coupling fatigue testing method for adhesive layer interface failure, comprising:

[0006] Prepare a sample; the sample includes an upper substrate, a lower substrate, and an adhesive layer; the adhesive layer is located between the upper substrate and the lower substrate, the adhesive layer bonds the upper substrate and the lower substrate and forms an adhesive boundary on the sidewall of the sample;

[0007] The sample is subjected to displacement oscillation under preset temperature conditions and preset oscillation conditions to perform thermo-mechanical coupling testing on the sample; wherein, the temperature changes periodically under the preset temperature conditions.

[0008] Observe the final surface morphology of the sample at the bonding boundary and record the crack parameters of the cracks at the bonding boundary;

[0009] The interface failure risk level of the sample is determined based on the crack parameters of the cracks on the bonding boundary.

[0010] Optionally, the sample is subjected to displacement oscillation under preset temperature conditions and preset oscillation conditions to perform a thermo-coupling test on the sample, including:

[0011] The sample is subjected to displacement oscillation under preset temperature conditions and preset oscillation conditions, and a fixed compressive force in the thickness direction is applied to the sample to perform a thermo-mechanical coupling test.

[0012] Optionally, the sample is subjected to displacement oscillation under preset temperature conditions and preset oscillation conditions, and a fixed compressive force in the thickness direction is applied to the sample to perform a thermo-coupling test, including:

[0013] A periodic temperature change is performed within a preset temperature range using a preset temperature change rate. The sample is then subjected to displacement oscillation at a preset oscillation frequency, and a preset fixed extrusion force in the thickness direction is applied to the sample to perform a thermo-mechanical coupling test. The preset temperature change rate ranges from 10 to 20°C / min, the preset temperature range is from -55 to 125°C, the preset oscillation frequency ranges from 1 to 100 Hz, and the preset fixed extrusion force ranges from 5 to 15 N.

[0014] Optionally, the preset temperature conditions include a preset temperature change rate, a preset temperature change range, and a preset number of periodic temperature changes; the preset oscillation conditions include a preset oscillation displacement and a preset oscillation frequency.

[0015] Optionally, the interface failure risk level of the sample is determined based on the crack parameters of the cracks at the adhesive boundary, including:

[0016] When the crack parameters are within a first preset range, the sample is determined to be of the first risk level;

[0017] When the crack parameters are within a second preset range, the sample is determined to be of the second risk level.

[0018] Wherein, 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.

[0019] Optionally, the crack parameters include at least one of crack length, crack width, and crack morphology complexity.

[0020] Optionally, the final surface morphology of the sample at the adhesive boundary is observed, and the crack parameters of the cracks at the adhesive boundary are recorded, including:

[0021] Observe the final surface morphology of the sample at the bonding boundary, and select the crack with a size larger than the resolution of the observation device as the target crack on the bonding boundary;

[0022] Record the crack parameters of the target crack.

[0023] Optionally, the final surface morphology of the sample at the adhesive boundary is observed, including:

[0024] The final surface morphology of the sample at the bonding boundary was observed using an electron scanning microscope or a laser confocal microscope.

[0025] Optionally, sample preparation includes:

[0026] The upper substrate and the lower substrate are provided;

[0027] The adhesive layer is coated on the first surface of the upper substrate and the second surface of the lower substrate;

[0028] The sample is formed by placing the first surface of the upper substrate and the second surface of the lower substrate opposite to each other and using a lamination and curing method.

[0029] Optionally, before performing thermo-coupling testing on the sample by displacing and oscillating the sample under preset temperature conditions according to preset oscillation conditions, the method further includes:

[0030] The sidewalls of the sample were mechanically polished and then nanopolished sequentially until the sidewalls of the sample were free of cracks.

[0031] The thermo-coupling fatigue testing method for adhesive layer interface failure provided by this invention applies a periodically changing temperature to the sample while simultaneously causing the sample to undergo displacement and oscillation in the thickness direction. This realistically replicates the thermo-coupling environment of the sample during actual operation, improving the accuracy of failure risk assessment. By using the stringent thermo-coupling testing conditions, the testing cycle of the sample can be effectively shortened, and testing efficiency can be improved. Attached Figure Description

[0032] Figure 1 A schematic flowchart of a thermo-coupling fatigue testing method for adhesive layer interface failure provided in an embodiment of the present invention;

[0033] Figure 2 This is a schematic diagram of the structure of a sample provided in an embodiment of the present invention;

[0034] Figure 3 A schematic flowchart of another thermo-coupling fatigue testing method for adhesive layer interface failure provided in an embodiment of the present invention;

[0035] Figure 4 A schematic flowchart of another thermo-coupling fatigue testing method for adhesive layer interface failure provided in an embodiment of the present invention;

[0036] Figure 5 A schematic flowchart of another thermo-coupling fatigue testing method for adhesive layer interface failure provided in an embodiment of the present invention;

[0037] Figure 6 A schematic flowchart of another thermo-coupling fatigue testing method for adhesive layer interface failure provided in an embodiment of the present invention;

[0038] Figure 7 This is a flowchart illustrating another thermo-coupling fatigue testing method for adhesive layer interface failure provided in an embodiment of the present invention. Detailed Implementation

[0039] The present invention will now be described in further detail with reference to the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are merely illustrative of the invention and not intended to limit it. Furthermore, it should be noted that, for ease of description, the accompanying drawings show only the parts relevant to the present invention, and not all of the structures.

[0040] The terminology used in the embodiments of this invention is for the purpose of describing specific embodiments only and is not intended to limit the invention. It should be noted that directional terms such as "upper," "lower," "left," and "right" described in the embodiments of this invention are used to describe the angles shown in the accompanying drawings and should not be construed as limiting the embodiments of this invention. Furthermore, in the context, it should be understood that when referring to an element being formed "on" or "below" another element, it can be formed not only directly on or below the other element, but also indirectly on or below it through intermediate elements. The terms "first," "second," etc., are used for descriptive purposes only and do not indicate any order, quantity, or importance, but are merely used to distinguish different components. Those skilled in the art can understand the specific meaning of the above terms in this invention based on the specific circumstances.

[0041] The term "comprising" and its variations as used in this invention are open-ended, meaning "including but not limited to". The term "based on" means "at least partially based on". The term "one embodiment" means "at least one embodiment".

[0042] It should be noted that the concepts of "first" and "second" mentioned in this invention are only used to distinguish the corresponding contents and are not used to limit the order or interdependence.

[0043] It should be noted that the terms "a" and "a plurality of" used in this invention are illustrative rather than restrictive. Those skilled in the art should understand that, unless otherwise expressly indicated in the context, they should be understood as "one or more".

[0044] Figure 1 This is a flowchart illustrating a thermo-coupling fatigue testing method for adhesive layer interface failure provided in an embodiment of the present invention, as shown below. Figure 1 As shown, the test method includes:

[0045] S101. Prepare the sample.

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

[0047] Specifically, due to the different coefficients of thermal expansion of different materials, internal stress is generated at the interface between the two materials when the ambient temperature changes, causing interface delamination and affecting the reliability of the device. In addition, the device may be subjected to mechanical vibration 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, and the change of the adhesive boundary 20 formed on the sidewall of the sample is observed after the test. 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. The sample is subjected to displacement oscillation under preset temperature conditions and preset oscillation conditions to perform thermo-coupling tests on the sample.

[0049] The temperature undergoes periodic changes under preset temperature conditions. Specifically, in an optional embodiment, the preset temperature conditions include a preset temperature change rate, a preset temperature change range, and a preset number of periodic temperature changes. By changing the preset temperature change rate and the preset temperature change range, the speed of the sample fatigue failure test can be adjusted. A faster preset temperature change rate or a larger preset temperature change range can accelerate the sample fatigue failure test and correspondingly reduce the number of periodic temperature changes, thereby shortening the sample fatigue failure test time.

[0050] Furthermore, the prepared sample is placed on a thermo-coupling loading stage to perform thermo-coupling testing. A preset temperature condition for the thermo-coupling test is adjusted by a temperature controller. Based on this, a preset oscillation condition is controlled by a displacement generator, causing the sample to undergo thickness-direction displacement oscillation simultaneously with the thermal failure test, thereby accelerating the fatigue failure test and improving testing efficiency. Specifically, in an optional embodiment, the preset oscillation condition includes a preset oscillation displacement and a preset oscillation frequency. A larger preset oscillation displacement or a faster preset oscillation frequency results in a faster crack formation at the bond boundary 20 of the sample, and a shorter test time.

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

[0052] Specifically, after the sample undergoes a displacement oscillation test under preset temperature and oscillation conditions, cracks may appear at the bonding boundary 20 between the upper substrate 10 and the adhesive layer 12, or 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, ultimately causing sample failure. Therefore, after the test, the final surface morphology of the sample at the bonding boundary 20 is observed to check for cracks, and the crack parameters of the cracks at the bonding boundary 20 are recorded.

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

[0054] Specifically, when the upper substrate 10, lower substrate 11, and adhesive layer 12 use different materials, or when the test conditions are changed, inconsistent crack patterns will occur at the bonding boundary 20 after the test. If there are few cracks or no cracks appear, the sample can be considered to have not failed. If there are many cracks or obvious delamination occurs at the bonding boundary 20, the sample's interface can be considered to have failed. Furthermore, different crack parameters can be used to classify the sample's failure risk into multiple levels, perform a delamination risk level assessment, and generate a report.

[0055] This invention applies a periodically varying temperature to the sample while simultaneously causing the sample to oscillate and shift along its thickness, realistically replicating the thermo-mechanical coupling environment during actual operation and improving the accuracy of failure risk assessment. By using the stringent thermo-mechanical coupling testing conditions, the testing cycle for the sample is effectively shortened, and testing efficiency is improved.

[0056] Figure 3 This is a flowchart illustrating another thermo-mechanical coupling fatigue testing method for adhesive layer interface failure provided in an embodiment of the present invention. This embodiment is a refinement based on the above embodiment. Specifically, the step of: performing displacement oscillation on the sample under preset temperature conditions according to preset oscillation conditions to perform thermo-mechanical coupling testing on the sample can be further refined as follows:

[0057] The sample is subjected to displacement oscillation under preset temperature conditions and preset oscillation conditions, and a fixed compressive force in the thickness direction is applied to the sample to perform thermo-mechanical coupling test.

[0058] For details not covered in this embodiment, please refer to the foregoing embodiments. Figure 3 As shown, the test method provided in this embodiment includes:

[0059] S201. Prepare the sample.

[0060] S202. Under preset temperature conditions, the sample is subjected to displacement oscillation according to preset oscillation conditions, and a fixed compressive force in the thickness direction is applied to the sample to perform a thermo-mechanical coupling test.

[0061] Specifically, the sample is placed on a thermocoupled loading stage, and a fixed compressive force in the thickness direction is applied to the sample. This compressive force is perpendicular to the upper and lower surfaces of the sample and acts uniformly on both surfaces. This allows the upper substrate, lower substrate, and adhesive layer of the sample to adhere more tightly, reducing gaps between interfaces. Simultaneously, the uniform fixed compressive force does not cause bending deformation of the sample. Furthermore, under preset temperature conditions, applying a fixed compressive force in the thickness direction amplifies the thermal expansion coefficient mismatch effect between the substrate and adhesive layer, thereby further accelerating the interface failure rate of the sample.

[0062] S203. Observe the final surface morphology of the sample at the bonding boundary and record the crack parameters of the cracks at the bonding boundary.

[0063] S204. Determine the interface failure risk level of the sample based on the crack parameters of the cracks at the bonding boundary.

[0064] This invention, by adding a fixed compressive force to the sample based on preset temperature and vibration conditions, replicates the bonding pressure during chip packaging, making the test conditions more closely resemble actual application scenarios and improving the accuracy of interface failure risk level determination. Furthermore, applying a fixed compressive force along the sample thickness direction under preset temperature conditions amplifies the thermal expansion coefficient mismatch effect between the substrate and the adhesive layer, thereby further accelerating the interface failure rate.

[0065] Figure 4 This is a flowchart illustrating another thermo-mechanical coupling fatigue testing method for adhesive layer interface failure provided in this embodiment of the invention. This embodiment is a refinement based on the above embodiment. Specifically, the step of: displacing and oscillating the sample according to preset oscillation conditions under preset temperature conditions, and applying a fixed compressive force in the thickness direction to the sample to perform thermo-mechanical coupling testing, can be further refined as follows:

[0066] The sample is subjected to periodic temperature changes within a preset temperature range at a preset temperature change rate. The sample is then subjected to displacement oscillation at a preset oscillation frequency, and a preset fixed compressive force in the thickness direction is applied to the sample to perform a thermo-mechanical coupling test.

[0067] The preset temperature change rate ranges from 10 to 20℃ / min, the preset temperature change ranges from -55 to 125℃, the preset oscillation frequency ranges from 1 to 100Hz, and the preset fixed extrusion pressure ranges from 5 to 15N.

[0068] For details not covered in this embodiment, please refer to the foregoing embodiments. Figure 4 As shown, the test method provided in this embodiment includes:

[0069] S301. Prepare the sample.

[0070] S302. The sample is subjected to periodic temperature changes within a preset temperature change range using a preset temperature change rate. The sample is then subjected to displacement oscillation at a preset oscillation frequency, and a preset fixed compressive force in the thickness direction is applied to the sample to perform a thermo-mechanical coupling test.

[0071] The preset temperature change rate ranges from 10 to 20℃ / min, the preset temperature change ranges from -55 to 125℃, the preset oscillation frequency ranges from 1 to 100Hz, and the preset fixed extrusion pressure ranges from 5 to 15N.

[0072] Specifically, a preset temperature range can be set according to the sample's temperature resistance. The larger the temperature range, the greater the expansion or contraction of the substrate and adhesive layer due to temperature changes, resulting in greater stress between the substrate and adhesive layer. This, in turn, makes delamination more likely to occur at the adhesive interface 20. For example, the temperature range can be -55 to 125°C. Simultaneously, the temperature change rate can be set. A higher temperature change rate indicates a faster temperature change within the preset temperature range, further increasing the sample's failure rate. For example, the temperature change rate can be 20°C / min.

[0073] Furthermore, under preset temperature variation conditions, the sample is induced to undergo displacement oscillation at a fixed frequency to simulate the mechanical vibration of the device in actual use. For example, the displacement oscillation frequency can be 50 Hz, and the oscillation displacement can be 30 μm. It is understood that the higher the displacement oscillation frequency and displacement, the faster the sample fails. Additionally, a fixed compressive force can be applied to the sample surface. This fixed compressive force value should be less than the maximum force the sample can withstand, and the higher the fixed compressive force value, the faster the sample fails. For example, the fixed compressive force value can be 10 N.

[0074] For example, in a urea-formaldehyde resin adhesive test experiment, the existing method of testing sample failure solely through heat load requires 500-1000 cycles to observe failure. However, using the testing method provided in this embodiment of the invention, only 10 cycles are needed to trigger the same failure mode, taking approximately 3.3 hours, representing an efficiency improvement of more than 20 times. Furthermore, the testing method provided in this embodiment of the invention can ensure that high-risk criteria samples experience 100% early failure in actual packaging tests.

[0075] S303. Observe the final surface morphology of the sample at the bonding boundary and record the crack parameters of the cracks at the bonding boundary.

[0076] S304. Determine the interface failure risk level of the sample based on the crack parameters of the cracks at the bonding boundary.

[0077] This invention simulates diurnal temperature variation or power cycling by cyclically varying the temperature within a set range at a preset rate; simulates vibration or mechanical fatigue by applying thickness-direction displacement at a set frequency and amplitude; and simulates packaging pre-tightening force or assembly constraints by maintaining a fixed compressive force. This makes the testing environment more closely resemble the actual operating environment of the device, improving the reliability of risk assessment results. The multi-physics coupled testing method effectively shortens the sample failure testing time and improves testing efficiency.

[0078] Figure 5 This is a flowchart illustrating another thermo-coupling fatigue testing method for adhesive layer interface failure provided in this embodiment of the invention. This embodiment is a refinement based on the above embodiment. Specifically, the step of determining the interface failure risk level of the sample based on the crack parameters of the cracks on the adhesive boundary can be further refined as follows:

[0079] When the crack parameters are within the first preset range, the sample is determined to be of the first risk level;

[0080] When the crack parameters are within the second preset range, the sample is determined to be of the second risk level;

[0081] Among them, 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.

[0082] For details not covered in this embodiment, please refer to the foregoing embodiments. Figure 5 As shown, the test method provided in this embodiment includes:

[0083] S401, Prepare the sample.

[0084] S402. The sample is subjected to displacement oscillation under preset temperature conditions and preset oscillation conditions to perform thermo-coupling tests on the sample.

[0085] S403. Observe the final surface morphology of the sample at the bonding boundary and record the crack parameters of the cracks at the bonding boundary.

[0086] S404. When the crack parameters are within the first preset range, the sample is determined to be of the first risk level.

[0087] S405. When the crack parameters are within the second preset range, the sample is determined to be of the second risk level.

[0088] Among them, 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.

[0089] Specifically, the minimum value in the first preset range can be determined by a first judgment threshold, and the maximum value in the second preset range can be determined by a second judgment threshold. In an optional embodiment, the crack parameters include at least one of crack length, crack width, and crack morphology complexity. When the crack parameter is crack length or crack width, the first judgment threshold can be expressed as the product of the sample size and a first percentage, that is, the first judgment threshold corresponding to crack length can be expressed as the product of the sample length and the first percentage, the first judgment threshold corresponding to crack width can be expressed as the product of the sample width and the first percentage, and the second judgment threshold can be expressed as the product of the sample size and a second percentage, that is, the second judgment threshold corresponding to crack length can be expressed as the product of the sample length and the second percentage, and the second judgment threshold corresponding to 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 judgment threshold is greater than the second judgment 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 parameters are within the first preset range, the length or width of the crack is greater than when the crack parameters are within the second preset range. Since the longer or wider the crack is after testing, the higher the probability of sample failure, 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.

[0090] For example, when the crack parameters are crack length or crack width, if the crack length or crack width of the sample at the bond boundary 20 is greater than the first judgment threshold, it indicates that the crack parameters are within the first preset range. In this case, the crack length or crack width is relatively large, and the sample can be determined to be at the first risk level, i.e., a high risk level. It is worth noting that the first percentages corresponding to crack length and crack width can be the same or different. For example, the first percentage corresponding to crack length can be 20%, and the first percentage corresponding to crack width can be 10%. If the crack length or crack width of the sample at the bond boundary 20 is less than the second judgment threshold, it indicates that the crack parameters are within the second preset range. The crack length or crack width is relatively small, and the sample can be determined to be at the second risk level, i.e., a low risk level. Similarly, the second percentages corresponding to crack length and crack width can be the same or different. For example, the second percentage corresponding to crack length can be 5%, and the second percentage corresponding to crack width can be 3%.

[0091] Furthermore, when the crack parameter represents 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 bond boundary 20 and is in the stage of network propagation or delamination, thus determining the sample as the first risk level, i.e., 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 bond boundary 20, thus determining the sample as the second risk level, i.e., low risk level.

[0092] In another optional embodiment, the crack parameters may also be within a third preset range. When the crack parameters are within the third preset range, the sample is determined to be at the third risk level. The minimum value in the third preset range is greater than the maximum value in the second preset range, but 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, but less than the severity of the first risk level.

[0093] For example, when the crack parameter is crack length or crack width, if the crack length 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 if the crack width 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 the crack parameter of the sample is determined to be within 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.

[0094] Furthermore, when the crack parameter is the complexity of the crack morphology, if the crack morphology value is less than or equal to the first judgment threshold and greater than or equal to the second judgment threshold, the crack parameter of the sample is determined to be within the third preset range, indicating that the crack morphology may have local micro-branching. Therefore, the sample is determined to be at the third risk level, i.e., the medium risk level.

[0095] This invention, by defining different preset ranges for crack parameters and classifying samples into multiple risk levels based on these preset ranges, avoids the waste of samples due to unclear risk level classification. This facilitates the subsequent development of more targeted solutions to address sample failure risks and improves the efficiency of sample failure risk analysis.

[0096] Figure 6 This is a flowchart illustrating another thermo-coupling fatigue testing method for adhesive layer interface failure provided in this embodiment of the invention. This embodiment is a refinement based on the above embodiment. Specifically, the step of observing the final surface morphology of the sample at the adhesive boundary and recording the crack parameters of the cracks at the adhesive boundary can be further refined as follows:

[0097] Observe the final surface morphology of the sample at the bonding boundary, and select cracks at the bonding boundary whose crack size is larger than the resolution of the observation device as target cracks;

[0098] Record the crack parameters of the target crack.

[0099] For details not covered in this embodiment, please refer to the foregoing embodiments. Figure 6 As shown, the test method provided in this embodiment includes:

[0100] S501. Prepare the sample.

[0101] S502. The sample is subjected to displacement oscillation under preset temperature conditions and preset oscillation conditions to perform thermo-coupling tests on the sample.

[0102] S503. Observe the final surface morphology of the sample at the bonding boundary, and select the cracks at the bonding boundary whose size is larger than the resolution of the observation equipment as target cracks.

[0103] S504. Record the crack parameters of the target crack.

[0104] Specifically, after the sample undergoes bending deformation testing, cracks may appear at the bonding boundary 20 due to thermal and mechanical loads, leading to delamination between the substrate and the adhesive layer and affecting the reliability of the device. Since the crack size may be submicron, a high-resolution observation device should be used when observing the final surface morphology at the bonding boundary 20. In an optional embodiment, an electron scanning microscope or laser confocal microscope is used to observe the final surface morphology of the sample at the bonding boundary 20 and to quantitatively measure and label the crack parameters. The accuracy of tracking crack parameter changes using an electron scanning microscope can reach 0.1 μm. Furthermore, when using an observation device to observe the final surface morphology at the bonding boundary 20, cracks with a size larger than the resolution of the observation device should be selected as target cracks on the bonding boundary 20. This allows the observation device to more clearly observe the crack parameters of the target cracks, thereby more accurately determining the interface failure risk level of the sample.

[0105] S505. Determine the interface failure risk level of the sample based on the crack parameters of the cracks at the bonding boundary.

[0106] This invention improves the accuracy of the target crack at the bonding boundary of the sample after failure testing by more accurately selecting the target crack size, which is larger than the resolution of the observation device. This improves the accuracy of the observation device in recording the crack parameters of the target crack, thereby further improving the accuracy of determining the interface failure risk level of the sample.

[0107] Figure 7 This is a flowchart illustrating another thermo-coupling fatigue testing method for adhesive layer interface failure provided in an embodiment of the present invention. This embodiment is a refinement based on the above embodiment. Specifically, the step of preparing the sample can be further refined as follows:

[0108] Provide upper substrate and lower substrate;

[0109] An adhesive layer is coated on the first surface of the upper substrate and the second surface of the lower substrate;

[0110] The first surface of the upper substrate and the second surface of the lower substrate are placed opposite each other, and a sample is formed by lamination and curing.

[0111] Furthermore, before conducting thermo-coupling tests on the sample by displacing and oscillating it under preset temperature and preset oscillation conditions, the following steps are added:

[0112] The sidewalls of the sample were mechanically polished and then nanopolished sequentially until there were no cracks on the sidewalls.

[0113] For details not covered in this embodiment, please refer to the foregoing embodiments. Figure 7As shown, the test method provided in this embodiment includes:

[0114] S601 provides an upper substrate and a lower substrate.

[0115] Specifically, refer to Figure 2 The system provides an upper substrate 10 and a lower substrate 11, wherein the upper substrate 10 and the lower substrate 11 can be silicon, silicon nitride, silicon oxide, or copper. The upper substrate 10 and the lower substrate 11 are cut according to the testing equipment to meet the size requirements of the testing equipment. For example, the upper substrate 10 and the lower substrate 11 can be 60 mm in length, 10 mm in width, and 0.75 mm in thickness.

[0116] S602, Apply an adhesive layer to the first surface of the upper substrate and the second surface of the lower substrate.

[0117] S603. Place the first surface of the upper substrate and the second surface of the lower substrate opposite each other, and form a sample by lamination and curing.

[0118] Specifically, an adhesive layer is coated on the first surface of the upper substrate 10 and the second surface of the lower substrate 20, and the first surface of the upper substrate 10 and the second surface of the lower substrate 20 are placed opposite each other, forming a sandwich structure sample by lamination and curing. For example, the adhesive layer 12 can be an epoxy resin adhesive, and the length and width of the adhesive layer 12 are consistent with the dimensions of the upper substrate 10 and the lower substrate 11, i.e., the length can be 60 mm and the width can be 10 mm. The thickness of the adhesive layer 12 can be 0.02-0.1 mm, therefore the total sample size is 60 mm (length) × 10 mm (width) × total thickness 1.52-1.6 mm (including the adhesive layer).

[0119] S604. The sidewalls of the sample are mechanically polished and then nanopolished sequentially until there are no cracks on the sidewalls of the sample.

[0120] Specifically, before conducting failure testing on the sample, it is necessary to ensure that the sample sidewalls are free of cracks. This makes it easier to observe cracks in the sample sidewalls after the failure test. Therefore, the sample sidewalls are first mechanically polished to remove protrusions. For example, mechanical polishing can be performed using sandpaper to grind the sample sidewalls. Then, the sample sidewalls are nanopolished. For example, nanopolishing can be performed using a 50nm Al2O3 suspension to remove initial cracks in the sample sidewalls and eliminate interference from initial cracks in observing cracks after the failure test. For example, an electron scanning microscope or a laser confocal microscope can be used to observe the initial cracks in the sample sidewalls. Once it is determined that there are no initial cracks in a certain area of ​​the sample sidewall, the same area should be observed when observing cracks in the sample sidewalls after the failure test.

[0121] S605. The sample is subjected to displacement oscillation under preset temperature conditions and preset oscillation conditions to perform thermo-coupling tests on the sample.

[0122] S606. Observe the final surface morphology of the sample at the bonding boundary and record the crack parameters of the cracks at the bonding boundary.

[0123] S607. Determine the interface failure risk level of the sample based on the crack parameters of the cracks at the bonding boundary.

[0124] In this embodiment of the invention, a sandwich structure sample is prepared and the sidewalls of the sample are mechanically polished and nanopolished to ensure that there are no initial cracks on the sidewalls of the sample before the failure test. This makes it easier to observe the cracks after the failure test and avoids interference from the initial cracks.

[0125] Furthermore, the testing methods of this invention are not limited to interface failure analysis between the substrate and the adhesive layer, but are also applicable to interface evaluation of die mounting materials (DAF) and interface reliability testing of redistribution layers (RDL) in wafer-level packaging (WLP).

[0126] Note that the above description is merely a preferred embodiment of the present invention and the technical principles employed. Those skilled in the art will understand that the present invention is not limited to the specific embodiments described herein, and various obvious changes, readjustments, combinations, and substitutions can be made without departing from the scope of protection 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 concept of the present invention, the scope of which is determined by the scope of the appended claims.

Claims

1. A thermo-coupling fatigue testing method for adhesive layer interface failure, characterized in that, include: Sample preparation; The sample includes an upper substrate, a lower substrate, and an adhesive layer; The adhesive layer is located between the upper substrate and the lower substrate, and the adhesive layer bonds the upper substrate and the lower substrate and forms an adhesive boundary on the sidewall of the sample; The sample is subjected to displacement oscillation under preset temperature conditions and preset oscillation conditions to perform thermo-mechanical coupling testing on the sample; wherein, the temperature changes periodically under the preset temperature conditions. Observe the final surface morphology of the sample at the bonding boundary and record the crack parameters of the cracks at the bonding boundary; The interface failure risk level of the sample is determined based on the crack parameters of the cracks on the bonding boundary.

2. The method according to claim 1, characterized in that, The sample is subjected to displacement oscillation under preset temperature conditions and preset oscillation conditions to perform a thermo-coupling test on the sample, including: The sample is subjected to displacement oscillation under preset temperature conditions and preset oscillation conditions, and a fixed compressive force in the thickness direction is applied to the sample to perform a thermo-mechanical coupling test.

3. The method according to claim 2, characterized in that, The sample is subjected to displacement oscillation under preset temperature conditions and preset oscillation conditions, and a fixed compressive force in the thickness direction is applied to the sample to perform a thermo-mechanical coupling test, including: A periodic temperature change is performed within a preset temperature range using a preset temperature change rate. The sample is then subjected to displacement oscillation at a preset oscillation frequency, and a preset fixed extrusion force in the thickness direction is applied to the sample to perform a thermo-mechanical coupling test. The preset temperature change rate ranges from 10 to 20°C / min, the preset temperature range is from -55 to 125°C, the preset oscillation frequency ranges from 1 to 100 Hz, and the preset fixed extrusion force ranges from 5 to 15 N.

4. The method 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 periodic temperature changes; the preset oscillation conditions include a preset oscillation displacement and a preset oscillation frequency.

5. The method according to claim 1, characterized in that, Based on the crack parameters of the cracks at the adhesive boundary, the interface failure risk level of the sample is determined, including: When the crack parameters are within a first preset range, the sample is determined to be of the first risk level; When the crack parameters are within a second preset range, the sample is determined to be of the second risk level. Wherein, 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.

6. The method according to claim 5, characterized in that, The crack parameters include at least one of crack length, crack width, and crack morphology complexity.

7. The method according to claim 1, characterized in that, Observe the final surface morphology of the sample at the adhesive boundary and record the crack parameters of the cracks at the adhesive boundary, including: Observe the final surface morphology of the sample at the bonding boundary, and select the crack with a size larger than the resolution of the observation device as the target crack on the bonding boundary; Record the crack parameters of the target crack.

8. The method according to claim 1, characterized in that, Observe the final surface morphology of the sample at the adhesive boundary, including: The final surface morphology of the sample at the bonding boundary was observed using an electron scanning microscope or a laser confocal microscope.

9. The method according to claim 1, characterized in that, Sample preparation; including: The upper substrate and the lower substrate are provided; The adhesive layer is coated on the first surface of the upper substrate and the second surface of the lower substrate; The sample is formed by placing the first surface of the upper substrate and the second surface of the lower substrate opposite to each other and using a lamination and curing method.

10. The method according to claim 1, characterized in that, Before performing a thermo-coupling test on the sample by displacing and oscillating the sample under preset temperature conditions and preset oscillation conditions, the method further includes: The sidewalls of the sample were mechanically polished and then nanopolished sequentially until the sidewalls of the sample were free of cracks.

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