Method for testing peel strength of thick copper foil copper-clad plate

Abstract

The invention relates to the technical field of electronic material testing, and discloses a method for testing the peel strength of a thick copper foil copper-clad plate, and the thickness of a copper foil layer of the copper-clad plate is greater than 105 microns. The testing method comprises the following steps: thinning a copper foil layer of a copper-clad plate; based on the thinned copper-clad plate, preparing a target test sample for peel strength test; and carrying out peel strength test on the target test sample piece. The copper foil layer of the copper-clad plate is thinned, so that the thickness of the copper foil on the finally obtained target test sample is relatively small. Therefore, when the peel strength of the target test sample is tested subsequently, the bending radius of the copper foil on the target test sample can be reduced, so that the influence of the bending of the copper foil on the force required by peeling is reduced or eliminated, and the peeling point of the copper foil on the target test sample and the direction of the tensile force borne by the copper foil are approximately on the same line; the accuracy of a peel strength test result of the thick copper foil copper-clad plate is improved, and the requirement for reliability evaluation of the thick copper foil copper-clad plate is met.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of electronic material testing, and in particular to a test method for peel strength of thick copper foil copper-clad plate. BACKGROUND

[0002] In the process of manufacturing printed circuit board (PCB), copper-clad plate as a key basic material, the bonding strength between its copper foil and insulating substrate directly affects the reliability and service life of the final PCB product. In order to evaluate the bonding strength between the copper foil and the insulating substrate, the industry generally adopts peel strength test method, that is, by measuring the force value required for the copper foil of unit width to peel off from the substrate, the adhesion quality between the copper foil and the substrate is characterized.

[0003] At present, in order to meet the design needs of high-power devices, thick copper foil copper-clad plates with more than 30Z (ounces) have been gradually used in PCB products. However, for the copper-clad plate with thick copper foil, when the peel strength test is carried out, due to the significant increase in the mechanical strength of the copper foil itself, during the peel pulling process, the copper foil strip will produce obvious bending deformation, forming a large bending radius, so that the direction of the actual applied pulling force deviates from the copper foil peeling point, which will cause the peel strength value recorded by the test equipment to be lower than the real adhesion strength. That is, for the copper-clad plate with thick copper foil, the test result is not accurate when the peel strength test is directly carried out, so that the test data cannot accurately reflect the real performance of the material, and further affect the judgment of the incoming quality of the copper-clad plate.

[0004] Therefore, there is an urgent need for a test method for peel strength of thick copper foil copper-clad plate to solve the above problems. SUMMARY

[0005] Based on the above problems, the purpose of the present application is to provide a test method for peel strength of thick copper foil copper-clad plate, which can improve the accuracy of the peel strength test result of the copper-clad plate with thick copper foil, and meet the demand for reliability evaluation of thick copper foil copper-clad plate.

[0006] To achieve the above purpose, the present application adopts the following technical solutions:

[0007] A test method for peel strength of thick copper foil copper-clad plate is provided, the copper-clad plate comprising a substrate and a copper foil layer provided on the substrate, the original thickness of the copper foil layer being greater than 105μm; the test method comprising the following steps:

[0008] (a) thinning the copper foil layer of the copper-clad plate;

[0009] (b) based on the copper-clad plate after thinning, preparing a target test sample for peel strength test;

[0010] (c) performing peel strength test on the target test sample.

[0011] As an alternative of the test method of the peel strength of the thick copper foil copper-clad plate of the present application, in step (a), the thinning treatment is to thin the copper foil layer of the whole copper-clad plate.

[0012] As an alternative of the test method of the peel strength of the thick copper foil copper-clad plate of the present application, in step (a), a preset pattern area is formed on the copper foil layer of the copper-clad plate first, then the copper foil of the area other than the preset pattern area is removed, and finally the copper foil of the preset pattern area is thinned.

[0013] As an alternative of the test method of the peel strength of the thick copper foil copper-clad plate of the present application, after the thinning treatment, the thickness of the copper foil on the target test sample obtained is D, and the value range of D is: 9 μm≤D≤105 μm.

[0014] As an alternative of the test method of the peel strength of the thick copper foil copper-clad plate of the present application, the method for thinning the copper foil layer includes any one or at least two of chemical etching, chemical mechanical polishing, electrochemical polishing, laser ablation, and mechanical grinding.

[0015] As an alternative of the test method of the peel strength of the thick copper foil copper-clad plate of the present application, the method for thinning the copper foil layer includes chemical etching.

[0016] The etching solution used in the chemical etching is an alkaline etching solution or an acidic etching solution.

[0017] As an alternative of the test method of the peel strength of the thick copper foil copper-clad plate of the present application, the acidic etching solution includes at least one of a copper chloride system, a ferric chloride system, or a persulfate system.

[0018] As an alternative of the test method of the peel strength of the thick copper foil copper-clad plate of the present application, in the chemical etching process, the processing temperature is 25℃~55℃.

[0019] And / or, in the chemical etching process, the nozzle of the etching device is used to spray the etching solution to the copper foil layer, the spraying pressure of the nozzle is P, and the value range of P is: 1.0 kg / cm 2 ≤P≤3.0 kg / cm 2 .

[0020] As an alternative of the test method of the peel strength of the thick copper foil copper-clad plate of the present application, after the thinning treatment, the surface roughness of the copper foil on the target test sample prepared is Ra, and the value range of Ra is: 0.3 μm≤Ra≤0.8 μm.

[0021] As an alternative of the test method of the peel strength of the thick copper foil copper-clad plate of the present application, the width of the copper foil on the target test sample is W, and the value range of W is: 0.8mm≤W≤10mm.

[0022] The present application has the following advantages:

[0023] The test method of the peel strength of the thick copper foil copper-clad plate provided by the present application can reduce or eliminate the influence of the bending of the copper foil on the peel strength when the peel strength of the thick copper foil copper-clad plate (i.e., the thickness of the copper foil is large) is tested. The peel point of the copper foil on the target test sample and the direction of the pulling force of the copper foil perpendicular to the surface of the target test sample are approximately on a straight line, which improves the accuracy of the test result of the peel strength of the copper-clad plate with thick copper foil and meets the demand for the reliability evaluation of the thick copper foil copper-clad plate. Since only the copper foil layer on the copper-clad plate is thinned, the adhesion between the copper foil layer and the substrate of the copper-clad plate is not affected, which further ensures the accuracy of the test result of the peel strength of the copper-clad plate.

[0024] In addition, the present application first proposes the technical idea of first thinning the copper foil layer of the thick copper foil copper-clad plate with an original thickness greater than 105μm and then testing the peel strength, which fundamentally avoids the problem that the test result cannot truly reflect the interfacial adhesion between the copper foil and the substrate due to the large rigidity and large bending radius of the thick copper foil, and solves the industry problem of data distortion of the existing test method. BRIEF DESCRIPTION OF DRAWINGS

[0025] In order to more clearly illustrate the technical solutions in the embodiments of the present application, the drawings needed in the description of the embodiments of the present application will be briefly introduced. Obviously, the drawings in the following description are only some embodiments of the present application, and other drawings can be obtained by those skilled in the art without creative labor on the basis of the contents of the embodiments of the present application and these drawings.

[0026] Figure 1 is the first flowchart of the test method of the peel strength of the thick copper foil copper-clad plate provided by the present application;

[0027] Figure 2 is the second flowchart of the test method of the peel strength of the thick copper foil copper-clad plate provided by the present application;

[0028] Figure 3 is the third flowchart of the test method of the peel strength of the thick copper foil copper-clad plate provided by the present application;

[0029] Figure 4 is a fourth flow chart of the test method for the peel strength of the thick copper foil CCL provided by the embodiment of the present application;

[0030] Figure 5 is a schematic diagram of the peeling process of the copper foil strip on the target test sample by the peel strength test device provided by the embodiment of the present application;

[0031] Figure 6 is a comparison diagram of the peel strength test results of multiple target test samples of the same CCL provided by the embodiment of the present application.

[0032] In the figure:

[0033] 10, target test sample; 11, base material; 12, copper foil strip; 2, loading platform; 3, clamp. EMBODIMENT

[0034] In order to make the technical problems solved by the present application, the technical solutions adopted and the technical effects achieved more clear, the technical solutions of the embodiments of the present application will be further described in detail below with reference to the drawings. Obviously, the described embodiments are only part of the embodiments of the present application, not all. Based on the embodiments in the present application, all other embodiments obtained by those skilled in the art without creative labor fall within the scope of protection of the present application.

[0035] In the description of the present application, it should be noted that the terms "center", "upper", "lower", "left", "right", "vertical", "horizontal", "inner", "outer" and the like indicate the orientation or positional relationship shown in the drawings, and are only for the convenience of describing the present application and simplifying the description, and do not indicate or imply that the device or element referred to must have a particular orientation, be constructed and operated in a particular orientation, therefore it cannot be understood as a limitation of the present application. In addition, the terms "first", "second" are only for the purpose of description, and cannot be understood as indicating or implying relative importance. Among them, the terms "first position" and "second position" are two different positions.

[0036] In the description of the present application, it should be noted that unless otherwise explicitly specified and limited, the terms "mounting", "connecting", "connecting" should be understood broadly, for example, it can be fixedly connected, or it can be detachably connected; it can be mechanically connected, or it can be electrically connected; it can be directly connected, or it can be indirectly connected through an intermediate medium; it can be the communication inside two elements. For those skilled in the art, the specific meaning of the above terms in the present application can be understood according to the specific circumstances.

[0037] Example one

[0038] The embodiment provides a test method for peel strength of a copper-clad plate with thick copper foil, which can improve the accuracy of the peel strength test result of the copper-clad plate with thick copper foil, and meet the demand for reliability evaluation of the copper-clad plate with thick copper foil. The copper-clad plate comprises a base material and a copper foil layer arranged on the base material, and the original thickness of the copper foil layer is greater than 105 μm. That is, the copper foil with a thickness greater than 105 μm is defined as thick copper foil, and the test method is used for peel strength test of the thick copper foil.

[0039] For example, the thickness of the copper foil layer can be 140 μm, 175 μm, 210 μm, 280 μm, 350 μm, etc., as long as the test method is used for peel strength test of the copper-clad plate with a copper foil layer with a thickness greater than 105 μm.

[0040] As shown in FIG. 1, the test method for peel strength of the copper-clad plate with thick copper foil comprises the following steps: Figure 1

[0041] (a) performing thinning treatment on the copper foil layer of the copper-clad plate;

[0042] (b) based on the copper-clad plate after the thinning treatment, preparing a target test sample for peel strength test;

[0043] (c) performing peel strength test on the target test sample;

[0044] (d) comparing the result obtained by the peel strength test with a test standard, to determine whether the peel strength of the copper-clad plate meets the requirement.

[0045] The test method for peel strength of the copper-clad plate with thick copper foil provided by the embodiment can improve the accuracy of the peel strength test result of the copper-clad plate with thick copper foil, and meet the demand for reliability evaluation of the copper-clad plate with thick copper foil. When the peel strength test is performed on the copper-clad plate with thick copper foil (i.e., the copper foil has a large thickness), the thinning treatment is performed on the copper foil layer of the copper-clad plate during the preparation of the target test sample, so that the thickness of the copper foil of the finally obtained target test sample is small. Therefore, when the peel strength test is performed on the target test sample, the bending radius of the copper foil of the target test sample can be reduced, so that the influence of the bending of the copper foil itself on the force required for peeling can be reduced or eliminated, the peeling point of the copper foil of the target test sample and the direction of the pulling force of the copper foil perpendicular to the surface of the target test sample are approximately on a line, the accuracy of the peel strength test result of the copper-clad plate with thick copper foil is improved, and the demand for reliability evaluation of the copper-clad plate with thick copper foil is met. Since the thinning treatment is only performed on the copper foil layer of the copper-clad plate, the adhesion between the copper foil layer and the base material of the copper-clad plate is not affected, and the accuracy of the peel strength test result of the copper-clad plate is further ensured.

[0046] ​In addition, the present application first proposes a technical idea of performing thinning treatment on the copper foil layer of the thick copper clad plate with a raw thickness greater than 105 μm, and then testing the peel strength, thereby fundamentally avoiding the problem that the test result cannot truly reflect the interface bonding performance between the copper foil and the base material due to the large rigidity of the thick copper and the large bending radius of the copper foil, and solving the industry problem of data distortion of the existing test method.

[0047] Optionally, in step (a), the thinning treatment is to perform overall thinning on the whole copper foil layer of the copper clad plate. By performing overall thinning on the whole copper foil layer, the thickness of the copper foil layer after the thinning treatment can be uniform, thereby ensuring the consistency of the copper foil thickness on each target test sample, the stress is uniform during the peeling process, and the accuracy of the peel strength test result is improved.

[0048] Optionally, after the thinning treatment, the thickness of the copper foil on the target test sample is D, and the value range of D is 9 μm≤D≤105 μm. That is, the thickness of the copper foil of the target test sample after the thinning treatment is greater than or equal to 9 μm and less than or equal to 3 ounces. For the copper foil in this thickness range, it meets the vertical peeling test requirement specified in the IPC-TM-650 standard, can ensure that the included angle between the tensile direction of the copper foil during peeling and the plane of the base material of the copper clad plate is 90°±5°, and ensures the accuracy of the peel strength test result.

[0049] Exemplarily, D can be 9 μm, 10 μm, 12 μm, 15 μm, 18 μm, 20 μm, 23 μm, 27 μm, 30 μm, 35 μm, 40 μm, 45 μm, 50 μm, 55 μm, 60 μm, 65 μm, 70 μm, 80 μm, 90 μm, 95 μm, 100 μm, 105 μm, etc., but is not limited to the values listed above.

[0050] In some embodiments, after the thinning treatment, the thickness D of the copper foil on the target test sample is in the range of 18 μm≤D≤70 μm. The limitation of this size range makes the thickness of the copper foil on the target test sample neither too large nor too small, and the copper foil has sufficient strength to maintain the entire peeling process without obvious bending deformation. When performing the peel strength test, the copper foil is prevented from being too thin to cause breakage or tearing during the peeling process, which affects the judgment of the interface failure mode, and the result distortion problem caused by the large bending radius of the thick copper is also eliminated, thereby ensuring the accuracy of the peel strength test result.

[0051] Exemplarily, the thickness D of the copper foil on the target test sample can be 18 μm, 20 μm, 25 μm, 30 μm, 35 μm, 40 μm, 45 μm, 50 μm, 55 μm, 60 μm, 65 μm, 70 μm, etc., but is not limited to the values and value ranges listed above.

[0052] Optionally, the width of the copper foil on the target test sample is W, and the value range of W is 0.8 mm≤W≤10 mm. The calculation formula of the peeling strength is: peeling strength = average peeling force / copper foil width. If the width of the copper foil is too small, the edge sawtooth effect after etching will affect the test results and is easy to break, which is specifically manifested as: the stress concentrated on the edge will account for a large proportion of the total peeling force, resulting in that the measured average peeling force cannot truly reflect the performance of the entire bonding surface. If the width of the copper foil is too large, the clamp cannot uniformly clamp and synchronously bear force in the entire width direction during the peeling test, resulting in that some areas lag in peeling, which causes the problem of distorted test results. Therefore, limiting the width of the copper foil on the target test sample to the range of 0.8 mm to 10 mm can not only eliminate the influence of the edge sawtooth effect on the test results, ensure that the copper foil on the test sample is not easy to break during clamping and peeling, but also facilitate peeling and stretching operations, improve test efficiency, and avoid the problem of distorted test results caused by the lagging peeling of some areas.

[0053] For example, the width W of the copper foil on the target test sample is 3.2 mm. In other embodiments, the width W can also be 0.8 mm, 1.0 mm, 1.5 mm, 2.0 mm, 3.0 mm, 4.0 mm, 5.0 mm, 6.0 mm, 7.0 mm, 8.0 mm, 9.0 mm, 10.0 mm, etc., which can be selected according to actual needs and is not limited to the above-mentioned values.

[0054] In step (a), the method for thinning the copper foil layer includes any one or at least two of chemical etching, chemical mechanical polishing, electrochemical polishing, laser ablation, and mechanical grinding.

[0055] In some embodiments, the chemical etching method can be used to thin the copper foil layer. The etching solution used in chemical etching can be an alkaline etching solution or an acidic etching solution. The chemical etching method is suitable for large quantities and low cost scenarios, does not change the interface structure of the substrate, and does not cause mechanical stress and temperature impact on the substrate.

[0056] Optionally, the acid etching solution is used to etch the copper foil layer. The acid etching solution includes at least one of a copper chloride system, a ferric chloride system, or a persulfate system.

[0057] For example, the acid etching solution can include a copper perchloride system; or the acid etching solution includes a ferric chloride system. In other embodiments, the acid etching solution can include a copper chloride system and a persulfate system; or the acid etching solution includes a persulfate system. The appropriate acid etching solution can be selected according to actual needs, and is not limited to the above-mentioned combination methods.

[0058] Optionally, in the chemical etching process, the processing temperature is between 25℃ and 55℃. Below 25℃, the reaction is too slow and inefficient; above 55℃, the etching solution easily evaporates, reducing the reactivity. Therefore, controlling the temperature within the range of 25℃ to 55℃ can balance the etching rate and uniformity. By controlling the etching rate within a suitable range, the thickness of the copper foil layer is reduced uniformly throughout, improving the thickness uniformity of the thinned copper foil layer.

[0059] Furthermore, in the chemical etching process, the processing temperature is 45℃ to 55℃. Under this temperature condition, the active components of the acidic etching solution can be kept stable, the etching efficiency can be improved, and the etching effect can be guaranteed. For example, the processing temperature can be 45℃, 47℃, 50℃, 52℃, 55℃, etc.

[0060] In other embodiments, chemical mechanical polishing, electrochemical polishing, laser ablation, mechanical grinding, and other methods can also be used to thin the copper foil layer. Alternatively, two or more of these methods can be used in combination to thin the copper foil layer. The specific thinning method can be selected according to actual needs and is not limited to the thinning methods listed above.

[0061] like Figure 2 As shown, the following steps are included before the target test specimen is manufactured:

[0062] S01. Cut the copper-clad laminate to be tested to obtain a target test template that meets the test size requirements.

[0063] In step (a), the copper foil layer on the target test sample is thinned as a whole to ensure that the copper foil thickness on the final target test sample is uniform and consistent, thereby improving the accuracy of the peel strength test results.

[0064] like Figure 3 As shown, in step (a), the step of "thinning the entire copper foil layer of the copper-clad laminate" includes:

[0065] The target test sample is placed in an etching device for etching, so that the thickness of the copper foil layer on the target test sample is reduced to a preset thickness.

[0066] That is, the copper foil layer on the target test sample is thinned by chemical etching. Since etching is a chemical reaction process, the thick copper foil layer can be thinned uniformly by precisely controlling the concentration, temperature and other parameters of the etching solution, so as to ensure that the copper foil layer obtained after the thinning process has a uniform thickness.

[0067] Optionally, the etching apparatus can be an etching machine, wherein an etching machine using an acid etching system can be used to thin the copper foil layer, or an etching machine using an alkaline etching system can be used to thin the copper foil layer.

[0068] The preset thickness is the thickness of the copper foil on the target test sample. In the embodiment, the thickness of the copper foil on the target test sample is D, where 9 μm≤D≤105 μm. Further, the thickness of the copper foil on the target test sample is D, where 18 μm≤D≤70 μm. For example, the thickness of the copper foil on the target test sample is 45 μm. In other embodiments, the thickness of the copper foil on the target test sample is 18 μm, 20 μm, 25 μm, 30 μm, 35 μm, 40 μm, 50 μm, 55 μm, 60 μm, 65 μm, 70 μm, or the like, but is not limited to the above values and ranges.

[0069] In step (b), the target test sample is prepared by forming a preset pattern region on the thinned copper foil layer and removing the copper foil outside the preset pattern region.

[0070] That is, the preset pattern region is left on the thinned target test sample, and the copper foil in other regions is removed. The copper foil in the preset pattern region is the copper foil for the subsequent peel strength test. The preset pattern region can be one or more, and the number of preset pattern regions is selected according to the test requirements.

[0071] The process sequence of “overall thinning first and patterning later” can ensure uniform thinning of the entire copper foil layer, good thickness consistency, uniform stress in the peeling process, and significantly improved repeatability and reliability of test data.

[0072] As shown in FIG. 4, the target test sample can be prepared by pasting a resist tape and etching. The method can include the following steps: Figure 3

[0073] The resist tape is pasted on the copper foil layer of the thinned target test sample to form a preset pattern region;

[0074] The target test sample with the pasted resist tape is placed in an etching device for etching;

[0075] After etching, the resist tape is removed, and the target test sample is cut to obtain the target test sample.

[0076] ​Specifically, according to the width requirement of the copper foil on the target test sample, the corresponding width of the resist tape is cut, and the resist tape is flatly pasted on the copper-clad plate (target test sample). Usually, multiple resist tapes are pasted on the copper-clad plate at intervals, and the position where each resist tape is pasted finally forms a copper foil strip that needs to be vertically peeled off. Then, the copper-clad plate with the pasted resist tape is placed in an etching solution, and the copper foil at the position where the resist tape is not pasted is etched off. After etching is completed, the target test sample is taken out, washed with clean water, and then dried. Finally, the resist tape is removed with tweezers or other tools, and a copper foil strip that needs to be tested is formed on the target test sample. Further, the target test sample is cut to obtain a target test sample that has a copper foil strip and meets the size requirements of the test standard, wherein the width of the substrate of the target test sample is greater than the width of the copper foil strip, ensuring that there is enough substrate area for clamping.

[0077] Illustratively, the resist tape is a special anti-etching tape that can tightly paste the copper foil, resist etching solution, and has no residue after being torn off.

[0078] Optionally, in the chemical etching process, the nozzle of the etching device sprays etching solution to the copper foil layer, and the spraying pressure of the nozzle is P, and the value range of P is: 1.0 kg / cm 2 ≤ P ≤ 3.0 kg / cm 2 If the spraying pressure is too low, the fluid flushing is insufficient, which is easy to produce "cloudy" residue, affecting uniformity; if the spraying pressure is too high, it will cause the resist tape to fall off during the patterning process. Therefore, by controlling the spraying pressure within the above range, sufficient fluid kinetic energy can be provided to ensure that the etching solution fully updates the reaction interface of the copper surface, maintains high and stable etching efficiency, and ensures that the entire copper-clad plate surface can be in contact with fresh and highly active etching solution, thereby achieving global uniform etching and making the copper foil thickness on the thinned copper-clad plate uniform.

[0079] Illustratively, the spraying pressure P can be 1.0 kg / cm 2 , 1.5 kg / cm 2 , 2.0 kg / cm 2 , 2.3 kg / cm 2 , 3.0 kg / cm 2 , etc. The spraying pressure can be adjusted according to actual conditions, and is not limited to the specific pressure values listed above.

[0080] Optionally, after the entire copper foil layer of the copper-clad plate is thinned, the method further comprises the steps of: cleaning the thinned copper-clad plate, and then polishing.

[0081] After etching, cleaning treatment is performed to wash away the residues and impurities after etching and ensure the cleanliness of the copper foil layer. Through polishing treatment, the surface of the copper foil layer after etching can be made flat to ensure that the surface roughness of the copper foil on the target test sample meets the requirements and does not affect the test result of the peel strength.

[0082] Optionally, after the thinning treatment, the surface roughness of the copper foil on the prepared target test sample is Ra, and the value range of Ra is 0.3 μm≤Ra≤0.8 μm. If the surface roughness is too low, the copper foil surface is too smooth, which can cause insufficient adhesion between the resist tape and the copper foil during the patterning process, and the resist tape is easy to fall off. If the surface roughness is too high, there are many micro peaks and valleys on the copper foil surface, which makes it difficult to completely and tightly bond with the resist tape. During the second etching process, the etching solution is easy to penetrate laterally, which damages the integrity of the edge of the target test sample. In addition, controlling the surface roughness of the copper foil within the above range can avoid the interference of the surface roughness on the peel strength test, ensure the true reflection of the adhesion between the copper foil and the substrate, and improve the accuracy of the test result of the peel strength of the copper-clad plate.

[0083] As shown in steps (c) and (d) in FIG. 1, the step of “performing peel strength test on the target test sample” in step (c) includes: Figure 4 Figure 5 As shown in steps (c) and (d) in FIG. 1, the step of “performing peel strength test on the target test sample” in step (c) includes:

[0084] The target test sample 10 is fixed on the stage 2 of the peel strength test equipment;

[0085] One end of the copper foil on the target test sample 10 is clamped by the clamp 3 of the peel strength test equipment, and the one end of the copper foil on the target test sample 10 is pulled vertically upward at a set speed.

[0086] The peel strength test can be performed according to the standard in IPC-TM-650 2.4.8 or an equivalent standard. During the test, the clamp 3 of the peel strength test equipment is used to pull the copper foil strip 12 on the target test sample 10 vertically until the copper foil strip 12 is peeled off from the substrate 11 of the target test sample 10. The pulling force value measured during this process is the peel force. The maximum peel force and the minimum peel force during the peeling process are obtained, and the average peel force is calculated. According to the peel strength calculation formula: peel strength = average peel force / copper foil width, the peel strength can be calculated.

[0087] Optionally, the peel strength test equipment can be a tensile testing machine. For example, the set speed can be 50.8 mm / min, which can be selected according to actual test requirements.

[0088] ​The following is an example of a 190 μm thick copper foil clad copper plate, the copper foil on the clad copper plate is thinned to different degrees, and the peel strength is tested. Among them, the peel strength testing equipment vertically pulls the copper foil strip on each test sample at a speed of 50.8 mm / min, and the test time is 45.85 s.

[0089] The following table is the peel strength data of the test samples of the five different thickness copper foils of the same clad copper plate:

[0090]

[0091] From the above table data, it can be seen that for the copper foil without thinning treatment, the measured peel force is small, and the obtained peel strength is also small. With the decrease of the thickness of the copper foil, the measured peel force gradually increases, and the peel strength also increases. When the thickness of the copper foil reaches 105 μm and below, the bending radius is basically eliminated, the measured peel force tends to be true, indicating that the bending of the copper foil itself reduces or eliminates the influence on the peel force after the copper foil is thinned, thereby ensuring that the measured peel force is closer to the true value, and further improving the peel strength test accuracy of the clad copper plate.

[0092] As shown in Figure 6 , it is the force and deformation relationship curve diagram of the test samples of the five different thickness copper foils of the same clad copper plate in the above table, from Figure 6 it can also be seen that with the decrease of the thickness of the copper foil, the peel force gradually increases, and the peel strength also increases. When the thickness of the copper foil reaches 105 μm and below, the bending radius is basically eliminated, the measured peel force tends to be true, and the peel strength also tends to be stable, indicating that the peel strength test after the copper foil is thinned can ensure the accuracy of the peel strength test results of the clad copper plate with thick copper foil.

[0093] Example Two

[0094] The embodiment provides a test method for the peel strength of a thick copper foil clad copper plate, which is different from the embodiment one in that:

[0095] In step (a), the step of thinning the copper foil layer of the clad copper plate includes: first forming a preset pattern area on the copper foil layer of the clad copper plate, then removing the copper foil in the area outside the preset pattern area, and finally thinning the copper foil in the preset pattern area.

[0096] That is, a preset pattern area is left on the clad copper plate, and the copper foil in other areas is removed. After the copper foil in the left preset pattern area is thinned, the obtained copper foil is used for subsequent peel strength test. Among them, the preset pattern area can be one or more, and the number of arranged preset pattern areas can be selected according to the test requirements.

[0097] Optionally, the copper foil in the area outside the preset pattern area can be removed by pasting the etching-resistant tape and etching. Specifically, the etching-resistant tape is pasted on the copper foil layer of the copper-clad plate to form the preset pattern area; the copper-clad plate with the pasted etching-resistant tape is placed in an etching device for etching; after the etching is completed, the etching-resistant tape is removed, and then the copper foil in the remaining preset pattern area is subjected to thinning treatment. The thinning treatment method can be any one or at least two of chemical etching, chemical mechanical polishing, electrochemical polishing, laser ablation and mechanical grinding, which can be selected according to actual requirements.

[0098] It should be noted that the above are only the preferred embodiments of the present application and the principles of the technology applied. Those skilled in the art will understand that the present application is not limited to the specific embodiments herein, and those skilled in the art can make various obvious changes, readjustments and substitutions without departing from the scope of the present application. Therefore, although the present application has been described in more detail through the above embodiments, the present application is not limited to the above embodiments, and can include more other equivalent embodiments without departing from the concept of the present application, and the scope of the present application is determined by the scope of the appended claims.

Claims

1. A method of testing the peel strength of a thick copper foil copper clad laminate, characterized by, The copper-clad plate comprises a substrate and a copper foil layer provided on the substrate, and the original thickness of the copper foil layer is greater than 105 μm; the test method comprises the following steps: (a) performing a thinning treatment on the copper foil layer of the copper-clad plate; (b) based on the copper-clad plate after the thinning treatment, preparing a target test sample for peel strength test; (c) performing a peel strength test on the target test sample.

2. The test method for peel strength of thick copper foil-coated copper plate according to claim 1, characterized by, In step (a), the thinning treatment is a whole-body thinning treatment on the whole copper foil layer of the copper-clad plate.

3. The test method for peel strength of thick copper foil-coated copper plate according to claim 1, characterized by, In step (a), a preset pattern area is first formed on the copper foil layer of the copper-clad plate, then the copper foil in the area outside the preset pattern area is removed, and finally the copper foil in the preset pattern area is subjected to a thinning treatment.

4. The test method for peel strength of thick copper foil-coated copper plate according to claim 1, characterized by, After the thinning treatment, the thickness of the copper foil on the target test sample obtained is D, and the value range of D is: 9 μm≤D≤105 μm.

5. The test method for peel strength of thick copper foil-coated copper plate according to claim 1, characterized by, The method for performing the thinning treatment on the copper foil layer comprises any one or at least two of chemical etching, chemical mechanical polishing, electrochemical polishing, laser ablation and mechanical grinding.

6. The test method for peel strength of thick copper foil-coated copper plate according to claim 1, characterized by, The method for performing the thinning treatment on the copper foil layer comprises chemical etching. The etching solution used in the chemical etching is an alkaline etching solution or an acidic etching solution.

7. The test method for peel strength of thick copper foil-coated copper plate according to claim 6, characterized by, The acidic etching solution comprises at least one of a copper chloride system, a ferric chloride system or a persulfate system.

8. The test method for peel strength of thick copper foil-coated copper plate according to claim 6, characterized by, In the chemical etching process, the treatment temperature is 25-55°C. And / or, in the chemical etching process, the nozzle of the etching device is used to spray etching liquid to the copper foil layer, the spraying pressure of the nozzle is P, the value range of P is: 1.0kg / cm 2 ≤P≤3.0kg / cm 2 .

9. The test method for the copper foil peel strength of a thick copper foil-coated copper plate according to any one of claims 1 to 8, characterized in that, After the thinning treatment, the surface roughness of the copper foil on the target test sample prepared is Ra, and the value range of Ra is: 0.3 μm≤Ra≤0.8 μm.

10. The test method for the copper foil peel strength of a thick copper foil-coated copper plate according to any one of claims 1 to 8, characterized in that, The width of the copper foil on the target test sample is W, and the value range of W is: 0.8 mm≤W≤10 mm.

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