Method for testing fatigue resistance of bonding interface

Abstract

The invention provides a bonding interface fatigue resistance test method. The test method comprises the following steps: preparing a bending test sample with a prefabricated crack bonding layer by using a bonding material; performing a bending test on the bending test sample, and determining the maximum force value of the cyclic load; and performing a cyclic load test according to the maximum cyclic load force to determine the fatigue resistance of the bonding interface. According to the testing method, sample preparation is simple, consumed materials are few, sample defects and testing time are controllable, and the testing cost is greatly reduced.

Description

Technical Field

[0001] The present invention belongs to the field of bonding effect testing, and relates to a method for testing the fatigue resistance of a bonding interface. Background Art

[0002] Adhesives are widely used in industries such as electronic packaging, building materials, aerospace, automotive manufacturing, and medical and health. Their main functions include interfacial bonding, waterproofing, and enhancing reliability, etc. Their service environments are extremely complex. Affected by stress, environment, and other factors, the interfacial bonding strength of adhesives may change. Fatigue failure that occurs under the long-term action of external dynamic loads is one of the main forms of failure of the adhesive bonding interface. Therefore, the fatigue resistance of the bonding interface has a crucial impact on the reliability of the bonding structure.

[0003] Currently, there is still no reliable test method for the fatigue resistance of the bonding interface. For example, the piezoelectric ceramic driving method is used to measure the fatigue resistance of the bonding interface. An adhesive is used to bond a piezoelectric ceramic sheet to the adherend to be tested to form a sandwich structure, and a prefabricated crack is introduced at the interface between the adhesive and the adherend. By controlling the voltage input to the piezoelectric driving sheet to input cyclic stress to the bonding interface and recording the crack growth rate (da / dN) to evaluate the fatigue resistance of the interface. The defect of this method is that the complex specimen preparation method determines that the confidence level of its test results cannot be guaranteed; the tensile force provided by the piezoelectric driving sheet is relatively low, and the test time cannot be controlled; the piezoelectric driving sheet is a consumable, and the test cost is relatively high. Another example is the method of evaluating the fatigue resistance of the adhesive-metal bonding interface by preparing a compact tension (CT) specimen. A layer of adhesive with the same thickness is poured on the layered metal plate, and it is processed into a standard CT specimen in the cross-sectional direction, and a prefabricated crack is processed at the bonding interface. By marking the CT test to apply tensile cyclic stress to the interface and evaluating the fatigue resistance of the interface through the number of fracture cycles. In this method, the specimen is composed of half metal and half adhesive, so the amount of adhesive used is extremely large, which is not suitable for products in the fine chemical industry, and it is also impossible to ensure that there are no defects caused by the high viscosity of the adhesive at the bonding interface. Summary of the Invention

[0004] To solve the technical problems existing in the prior art, the present invention provides a method for testing the fatigue resistance of a bonding interface. The specimen preparation of this test method is simple, the material consumption is small, the specimen defects and the test time are controllable, and the test cost is greatly reduced.

[0005] To achieve the above technical effects, the present invention adopts the following technical solutions:

[0006] The present invention provides a method for testing the fatigue resistance of a bonding interface, and this test method includes:

[0007] Using a bonding material to prepare a bending test specimen with a prefabricated crack bonding layer;

[0008] Perform a bending test on the bending test specimen to determine the maximum force value of the cyclic load;

[0009] Perform a cyclic load test based on the maximum force of the cyclic load to determine the fatigue resistance of the bonding interface.

[0010] As a preferred technical solution of the present invention, the bonding material includes a bonding object and an object to be bonded; the bending test specimen includes the object to be bonded, and a bonding layer formed by bonding the bonding object and the object to be bonded; wherein, a prefabricated crack is formed at the unbonded part of the surfaces of the bonding object and the object to be bonded.

[0011] As a preferred technical solution of the present invention, the bonding layer of the bending test specimen includes a layer thickness control member, which is located at a position away from the tip of the prefabricated crack and is bonded to the object to be bonded.

[0012] As a preferred technical solution of the present invention, the bending test includes a three-point bending test and / or a four-point bending test.

[0013] As a preferred technical solution of the present invention, performing a bending test on the bending test specimen to determine the maximum force value of the cyclic load includes:

[0014] Perform a bending test on the bending test specimen to obtain the interfacial debonding force value corresponding to the bonding layer;

[0015] Determine the maximum force value of the cyclic load according to the interfacial debonding force value.

[0016] As a preferred technical solution of the present invention, the maximum force value of the cyclic load is 10-90% of the interfacial debonding force value.

[0017] As a preferred technical solution of the present invention, the amplitude of the cyclic load test is determined according to the total test time of the cyclic load test.

[0018] As a preferred technical solution of the present invention, the frequency of the cyclic load test is determined according to the heat generation situation during the cyclic load test process.

[0019] As a preferred technical solution of the present invention, the cyclic load test includes a three-point bending test and / or a four-point bending test.

[0020] As a preferred technical solution of the present invention, the evaluation criteria for the fatigue resistance of the bonding interface include: any one or at least two combinations of the crack growth rate, the total number of cycles of bonding interface failure, or the interfacial debonding force value of the bonding layer after the cyclic load application ends.

[0021] Compared with the prior art, the present invention has at least the following beneficial effects:

[0022] (1) The present invention provides a method for testing the fatigue resistance of a bonding interface. The specimen preparation of this testing method is simple, without the need to use costly testing components such as piezoelectric ceramics. Moreover, the test results can be directly determined by the load applied by a bending testing machine, reducing the additional errors introduced by other testing components and making the test results more accurate.

[0023] (2) The present invention provides a method for testing the fatigue resistance of a bonding interface. The thickness of the bonding layer in this testing method is controllable, the amount of bonding material used is small, the specimen defects and testing time are controllable, and the testing cost is significantly reduced.

[0024] (3) The present invention provides a method for testing the fatigue resistance of a bonding interface. This testing method can complete the test at a relatively thin bonding layer thickness, which is closer to the bonding layer thickness and the amount of bonding material used in fine parts, and has a wider application range. Description of the Drawings

[0025] Figure 1 It is a schematic diagram of the bending test structure in the specific embodiment of the present invention.

[0026] Figure 2 It is a schematic flow diagram of the method for testing the fatigue resistance of a bonding interface provided by the present invention.

[0027] In the figure: (a) Four-point bending test specimen, (b) Three-point bending test specimen-I, (c) Three-point bending test-II, (1) Object to be bonded, (2) Adhesive layer, (3) Layer thickness control part.

[0028] The following further details the present invention. However, the following examples are only simple examples of the present invention and do not represent or limit the scope of the protection of the present invention. The scope of protection of the present invention is subject to the claims. Specific Embodiments

[0029] The technical solution of the present application will be further described below through specific embodiments.

[0030] The specific embodiment of the present invention provides a method for testing the fatigue resistance of a bonding interface, and this testing method includes:

[0031] Using a bonding material to prepare a bending test specimen with a prefabricated crack bonding layer;

[0032] Performing a bending test on the bending test specimen to determine the maximum value of the cyclic load;

[0033] Performing a cyclic load test according to the maximum value of the cyclic load to evaluate the fatigue resistance of the bonding interface.

[0034] In the present invention, there is no need to use costly test components such as piezoelectric ceramics, and the test results can be directly determined by the load applied by the bending test machine, reducing the additional errors introduced by other test components and making the test results more accurate. The thickness of the adhesive layer is controllable, and the amount of adhesive material used is small, further reducing the cost. Moreover, the test can be completed with a thinner adhesive layer thickness, which is closer to the adhesive layer thickness and the amount of adhesive material used in fine parts, and has a wider range of applications.

[0035] In a specific embodiment of the present invention, the adhesive material includes an adherend and an object to be adhered; the bending test specimen includes the object to be adhered and an adhesive layer formed by adhering the adherend to the object to be adhered. Among them, a prefabricated crack is formed at the non-adhered part of the surfaces of the adherend and the object to be adhered.

[0036] In a specific embodiment of the present invention, the method for forming the non-adhered part includes setting a low-affinity surface of the adhesive material at a position corresponding to the prefabricated crack on one side of the object to be adhered.

[0037] In a specific embodiment of the present invention, the method for forming the low-affinity surface includes adhering a material with low affinity to the adherend on one side of the object to be adhered. The low-affinity material refers to a material that is difficult or impossible for the adherend to adhere to, such as an ultra-thin Teflon tape or an inert metal coating.

[0038] In a specific embodiment of the present invention, the position where the low-affinity surface is set is the starting point of crack growth, and its position can be adjusted according to the specific crack growth situation to achieve the best crack growth effect, which will not be further limited here.

[0039] In a specific embodiment of the present invention, the adhesive layer of the bending test specimen includes a layer thickness control member, which is located away from the tip of the prefabricated crack and adhered to the object to be adhered. The setting of the layer thickness control member facilitates the regulation of the adhesive layer thickness, and by adjusting the specimen specifications, a sufficiently high stress can be obtained at the crack tip; at the same time, the layer thickness control member is located away from the tip of the prefabricated crack, which can prevent the premature failure of the adherend.

[0040] In a specific embodiment of the present invention, when the adherend is a non-flowable adhesive material, after applying the adhesive material on one side of the object to be adhered, another object to be adhered can be buckled to obtain the bending test specimen.

[0041] In a specific embodiment of the present invention, when the adherend is a flowable adhesive material, the layer thickness control member can be used to pre-fix the two objects to be adhered on both sides, and then the adhesive material can flow into the gap formed by the two objects to be adhered on both sides through capillary action, and then be cured to obtain the bending test specimen.

[0042] In a specific embodiment of the present invention, the fatigue resistance test method for the bonding interface is applicable to any objects to be bonded and bonding materials, so no further limitation is imposed on the specific selection of the objects to be bonded and bonding materials.

[0043] In a specific embodiment of the present invention, the bending test includes a three-point bending test and / or a four-point bending test.

[0044] In a specific embodiment of the present invention, the span of the three-point bending test and the four-point bending test can be adjusted according to the size of the bending test specimen and the specific test conditions, and no specific limitation is made here.

[0045] In a specific embodiment of the present invention, in the four-point bending test, the upper support point of the four-point bending fixture is fixed on the upper surface of the upper object to be bonded, the lower support point is fixed on the lower surface of the lower object to be bonded, and the upper span is less than the lower span. At this time, the prefabricated crack can be set at the middle position of the bonding layer, such as Figure 1 (a).

[0046] In a specific embodiment of the present invention, in the three-point bending test, the support points of the three-point bending fixture can be simultaneously set on the object to be bonded above the bonding layer, that is, both ends of the upper object to be bonded are longer than the lower object to be bonded. The two lower support points of the three-point bending fixture are respectively fixed on the lower surfaces of both ends of the upper object to be bonded. At this time, the prefabricated crack can be set at a position close to both ends of the lower object to be bonded, such as Figure 1 (b).

[0047] In a specific embodiment of the present invention, in the three-point bending test, the upper support point of the support points of the three-point bending fixture can be fixed on the upper surface of the upper object to be bonded, one of the lower support points is fixed on the lower surface of the lower object to be bonded, a support plate is provided at one end of the lower object to be bonded away from this support point. The material and thickness of the support plate are the same as those of the lower object to be bonded, but it does not contact the lower object to be bonded. A layer thickness control member is provided between the support plate and the upper object to be bonded, and the other of the lower support points is fixed on the lower surface of the support plate. At this time, the prefabricated crack can be set at one end close to the lower object to be bonded and close to the support plate, such as Figure 1 (c).

[0048] In a specific embodiment of the present invention, performing a bending test on the bending test specimen to determine the maximum value of the cyclic load includes:

[0049] Performing a bending test on the bending test specimen to obtain the interfacial debonding force value corresponding to the bonding layer;

[0050] Determining the maximum value of the cyclic load according to the interfacial debonding force value.

[0051] In a specific embodiment of the present invention, the bending test determines the interfacial debonding force value of the adhesive layer, that is, the load applied by the testing machine when the object to be adhered above and / or below the adhesive layer is debonded from the adhesive layer.

[0052] In a specific embodiment of the present invention, the maximum value of the cyclic load is 10-90% of the interfacial debonding force value, such as 10%, 20%, 30%, 40%, 50%, 60%, 70%, 80% or 90%, etc., but is not limited to the listed values, and other unlisted values within this numerical range are equally applicable. The reason for determining the maximum value of the cyclic load by the interfacial debonding force value can make the method provided by the present invention applicable to more different types of materials.

[0053] In a specific embodiment of the present invention, the amplitude of the cyclic load test is determined according to the total test time of the cyclic load test. For example, increasing the amplitude can accelerate the failure speed of the adhesive layer, thereby shortening the total test time; decreasing the amplitude can slow down the failure speed of the adhesive layer, thereby prolonging the total test time.

[0054] In a specific embodiment of the present invention, the frequency of the cyclic load test is determined according to the heat generation situation during the cyclic load test process. Specifically, the cyclic load application frequency of the cyclic load test is based on the criterion that the heat generation of the specimen is not obvious. As an example, the heat generation not being obvious means that the temperature of the bending test specimen is within 5-10 °C higher than the test environment temperature.

[0055] In a specific embodiment of the present invention, the cyclic load test includes a three-point bending test and / or a four-point bending test. In the cyclic load test, the fixing method of the three-point bending fixture or the four-point bending fixture is the same as that of the bending test, except that the testing machine applies a cyclic load to the specimen.

[0056] In a specific embodiment of the present invention, the evaluation criteria for the fatigue resistance of the bonding interface include any one or at least two combinations of the crack growth rate, the total number of cycles of bonding interface failure, or the interfacial debonding force value of the adhesive layer after the cyclic load application ends.

[0057] In a specific embodiment of the present invention, the method of characterizing the fatigue resistance of the bonding interface by the crack growth rate can be: using a macro camera to photograph the pre-cracked area, recording the crack growth situation at a fixed frequency, and determining the crack growth rate.

[0058] In a specific embodiment of the present invention, the method of characterizing the fatigue resistance of the bonding interface by the total number of cycles of bonding interface failure can be: continuously applying a cyclic load to the specimen until the bonding surface is debonded from the object to be adhered, and then stopping the application of the cyclic load and recording the total number of cycles of the cyclic load application.

[0059] In a specific embodiment of the present invention, the method for characterizing the fatigue resistance of the bonding interface by the interfacial debonding force value of the bonding layer after the cyclic load application ends may be as follows: Continuously apply a cyclic load to the specimen until a specified cyclic test is reached. At this time, perform a bending test on this experiment to obtain the interfacial debonding force value, and compare it with the interfacial debonding force value before the cyclic load test to determine the attenuation amplitude of the interfacial debonding force value.

[0060] To better illustrate the present invention and facilitate understanding of its technical solutions, the typical but non-limiting embodiments of the present invention are as follows:

[0061] Embodiment 1

[0062] This embodiment provides a method for testing the fatigue resistance of a bonding interface, and its process is as Figure 1 shown. This testing method includes:

[0063] S1. Use a polyimide (PI) double-sided tape with a thickness of 50 mm as the layer thickness control piece, two silicon wafers with a thickness of 750 mm and a size of 50 mm * 10 mm (after plasma cleaning) as the objects to be bonded, and bottom fill adhesives A and B as adhesives to prepare two Figure 1 four-point bending test specimens in (a). A prefabricated crack is prepared using a Teflon tape with a thickness of 30 mm and a width of 10 mm.

[0064] S2. Use a fatigue testing machine equipped with a four-point bending fixture (lower span: 40 mm, upper span: 30 mm) to measure that at a load of 35 N, the interfacial crack begins to stably expand.

[0065] S3. According to the above test results, perform a fatigue test on the four-point bending specimen using cyclic load parameters of 10 N to 30 N and 5 Hz. Use a macro camera to photograph the prefabricated crack area, and record the crack growth rate at a frequency of 10 s / frame.

[0066] S4. After 300,000 cycles, the specimens using the two bottom fill adhesives did not fail. By analyzing the photographed photos, it was found that the interfacial crack growth rate of bottom fill adhesive A was 110 mm / 10,000 cycles, and the interfacial crack growth rate of bottom fill adhesive B was 90 mm / 10,000 cycles. Therefore, the conclusion was drawn that bottom fill adhesive B has higher fatigue resistance.

[0067] Embodiment 2

[0068] This embodiment provides a method for testing the fatigue resistance of a bonding interface. This testing method includes:

[0069] S1. Use a polyimide (PI) double-sided tape with a thickness of 50 mm as the layer thickness control piece, a 50 mm * 10 mm silicon wafer with a thickness of 750 mm and a 40 mm * 10 mm silicon wafer with a thickness of 750 mm (after plasma cleaning) as the objects to be adhered, and bottom fill adhesives A and B as adhesives to prepare two Figure 1 Three-point bending test specimens in (b), and a prefabricated crack is prepared using a 30 mm thick and 10 mm wide Teflon tape;

[0070] S2. Use a fatigue testing machine equipped with a three-point bending fixture (span 45 mm) to measure that at a load of 45 N, the interfacial crack begins to stably propagate;

[0071] S3. According to the above test results, perform fatigue testing on the three-point bending specimens using cyclic load parameters of 20 N to 40 N and 10 Hz;

[0072] S4. After 15,000 cycles and 27,000 cycles, the specimens using the two bottom fill adhesives both failed. The number of cycles at which bottom fill adhesive B failed was greater than that of bottom fill adhesive A, and the conclusion was that bottom fill adhesive B has higher fatigue resistance.

[0073] Example 3

[0074] This example provides a method for testing the fatigue resistance of a bonding interface. The testing method includes:

[0075] S1. Use a polyimide (PI) double-sided tape with a thickness of 50 mm as the layer thickness control piece, a 50 mm * 10 mm silicon wafer with a thickness of 750 mm and a 45 mm * 10 mm silicon wafer with a thickness of 750 mm (after plasma cleaning) as the objects to be adhered, and bottom fill adhesives A and B as adhesives to prepare two Figure 1 Three-point bending test specimens in (c), and a prefabricated crack is prepared using a 30 mm thick and 10 mm wide Teflon tape;

[0076] S2. Use a fatigue testing machine equipped with a three-point bending fixture (span 45 mm) to measure that at a load of 40 N, the interfacial crack begins to stably propagate;

[0077] S3. According to the above test results, perform fatigue testing on the three-point bending specimens using cyclic load parameters of 16 N to 32 N and 10 Hz;

[0078] S4. After 300,000 cycles, the specimens using the two bottom fill adhesives did not fail. The three-point bending test in S2 was respectively performed on the specimens of the two fill adhesives. After the cyclic load test, the interfacial debonding force value of the specimen of fill adhesive A was 19 N, and the interfacial debonding force value of the specimen of fill adhesive B was 23 N. The conclusion was that bottom fill adhesive B has higher fatigue resistance.

[0079] The applicant declares that the detailed structural features of the present invention are illustrated by the above embodiments, but the present invention is not limited to the above detailed structural features, that is, it does not mean that the present invention must rely on the above detailed structural features to be implemented. Those skilled in the art should understand that any improvement to the present invention, the equivalent replacement of the components selected for the present invention, the addition of auxiliary components, and the selection of specific methods, etc., all fall within the protection scope and the disclosure scope of the present invention.

[0080] The preferred embodiments of the present invention have been described in detail above. However, the present invention is not limited to the specific details in the above embodiments. Within the scope of the technical concept of the present invention, various simple modifications can be made to the technical solution of the present invention, and these simple modifications all belong to the protection scope of the present invention.

[0081] In addition, it should be noted that, in the case of no contradiction, the various specific technical features described in the above specific embodiments can be combined in any suitable way. To avoid unnecessary repetition, the present invention will not separately describe various possible combination methods.

[0082] Furthermore, any combination can be made between various different embodiments of the present invention, as long as it does not violate the idea of the present invention, and it should also be regarded as the content disclosed by the present invention.

Claims

1. A method for testing fatigue resistance of bonding interface, characterized in that: The test method includes: preparing a bending test specimen having a prefabricated crack bonding layer using a bonding material; Performing a bending test on the bending test specimen to determine a maximum force value of a cyclic load; A cyclic load test is performed according to the maximum cyclic load force to determine the fatigue resistance of the bonding interface.

2. The testing method according to claim 1, characterized in that: The bonding material includes an adhesive and an object to be bonded; the bending test specimen includes an object to be bonded and an adhesive layer formed by bonding the adhesive and the object to be bonded, wherein prefabricated cracks are formed at the unbonded portion between the adhesive and the surface of the object to be bonded.

3. The testing method according to claim 2, characterized in that: The bonding layer of the bending test specimen includes a layer thickness control member, the layer thickness control member is away from the tip of the prefabricated crack and is bonded to the object to be bonded.

4. The testing method according to claim 1, characterized in that: The bending test includes a three-point bending test and / or a four-point bending test.

5. The testing method according to claim 1, characterized in that: The performing a bending test on the bending test specimen to determine the maximum force value of the cyclic load comprises: Performing a bending test on the bending test specimen to obtain an interface debonding force value corresponding to the bonding layer; The maximum force value of the cyclic load is determined according to the interface debonding force value.

6. The testing method according to claim 6, characterized in that: The maximum force value of the cyclic load is 10 to 90% of the interface debonding force value.

7. The testing method according to claim 1, characterized in that: The amplitude of the cyclic load test is determined according to the total test time of the cyclic load test.

8. The testing method according to claim 1, characterized in that: The frequency of the cyclic load test is determined according to the heating condition during the cyclic load test.

9. The testing method according to claim 1, characterized in that: The cyclic load test includes a three-point bending test and / or a four-point bending test.

10. The testing method according to claim 1, characterized in that: The evaluation criteria for the fatigue resistance of the bonding interface include: any one of the following, or a combination of at least two, crack growth rate, total number of bonding interface failure cycles, or interface debonding force value of the bonding layer after the cyclic load application is completed.

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