A copper clad ceramic substrate peel test method

Abstract

The present application relates to copper-clad ceramic substrate peeling test technical field, and relates to a copper-clad ceramic substrate peeling test method, and the present application comprises the following steps: copper-clad ceramic substrate front and back are carried out copper foil etching and solder etching to form a base material, the base material comprises a front copper foil layer, a substrate and a back copper foil layer, the front copper foil layer and the back copper foil layer all comprise A face copper foil sheet and B face copper foil sheet; the substrate surface contacted by B face copper foil sheet is carried out laser cutting; the cut base material is divided into test pieces through the splitting process, the test piece comprises A face copper foil sheet, substrate and B face copper foil sheet, and a tension strip is arranged on the A face copper foil sheet; the test piece is bent at right angles, so that the test piece forms a horizontal part and a vertical part; the horizontal part is inserted into the jig of a peeling tester for limiting, the vertical part is pulled upward by a holder, so that the tension strip is separated from the substrate, and the peeling strength tension is obtained; the solder removal process is omitted, the test cycle is shortened, and the peeling test data accuracy is improved.

Description

Technical Field

[0001] This invention relates to the field of copper-clad ceramic substrate peel testing technology, and to a method for peel testing copper-clad ceramic substrates. Background Technology

[0002] Copper-clad ceramic substrates are the superior packaging material for power modules in the power electronics field. Due to differences in manufacturing processes, they can be mainly divided into direct copper-clad ceramic substrates (DCB or DBC) and active metal brazed ceramic substrates (AMB). DCB involves directly bonding copper to the ceramic using an oxygen-containing eutectic solution, while AMB involves sintering the ceramic plate and copper foil together with solder. Comparatively, AMB copper-clad boards offer higher reliability and superior performance, but are more expensive. For both DBC and AMB products, product performance is crucial, primarily involving thermal cycling testing and peel strength testing.

[0003] AMB copper-clad laminates require copper foil, substrate, and solder in their sintering process for bonding to occur. Without solder, the copper foil and substrate cannot bond. In some areas, the copper foil bonds to the ceramic, making physical or chemical separation of the copper foil and substrate impossible. Before the peel test, the copper foil and substrate are separated by a certain distance. This is achieved by scraping off the solder to prevent bonding and allow separation. Vacuum sintering is then performed, followed by etching the desired pattern according to the designed film. The product is then cut along the designed cutting lines and split into smaller pieces for testing. The substrate is glued to an iron plate and pressed for 24 hours until firmly cured. Finally, the cured iron plate is placed in a peel tester for peel strength testing. The copper foil is held and pulled by the machine's clamps; the force required to separate the copper foil from the substrate is the peel strength test value.

[0004] Existing testing methods have the following shortcomings:

[0005] 1. In the printing and sintering process, the solder needs to be scraped off first to prevent the copper foil from bonding with the ceramic in some places, so that the copper foil and the substrate can be separated and the copper foil can be pulled up for peel strength testing. The operation process is complicated and increases the testing cycle. Moreover, since the substrate is glued to the iron plate, the fixture can only hold the copper foil for testing. The test data environment is different from the actual situation, which affects the actual test tensile strength.

[0006] 2. Since the existing peel tester does not have the relevant test fixtures, it is impossible to clamp the bottom substrate. Therefore, the traditional method is to first glue the substrate to the iron plate, fix the iron plate on the sample stage of the peel tester, and press the substrate for 24 hours to allow the glue to dry completely before subsequent testing can be carried out. This method is time-consuming and has a long testing cycle. Furthermore, changes in the glue's fixing strength will also affect the accuracy of the peel strength test.

[0007] In summary, to address the shortcomings of existing technologies, a simple method for peeling copper-clad ceramic substrates needs to be designed. Summary of the Invention

[0008] To address the problems of the prior art, this invention provides a method for peeling copper-clad ceramic substrates.

[0009] The objective of this invention can be achieved through the following technical solution: a method for peeling copper-clad ceramic substrates, comprising the following steps:

[0010] S1: The copper foil is etched and the solder is etched on the front and back sides of the copper-clad ceramic substrate using an etching solution to form a substrate. The substrate includes a front copper foil layer, a substrate and a back copper foil layer from top to bottom. Both the front copper foil layer and the back copper foil layer include A-side copper foil sheets and B-side copper foil sheets that are alternately connected in sequence.

[0011] S2: Laser cutting is performed on the substrate surface in contact with the copper foil sheet on side B in S1, and the depth of the laser-cut groove is 30%.

[0012] S3: The cut substrate is divided into several test pieces by a splitting process. The test pieces include a single A-side copper foil sheet, a substrate and a single B-side copper foil sheet arranged from top to bottom. The A-side copper foil sheet is provided with a tension strip.

[0013] S4: Bend the test piece in S3 at a right angle along the groove in S2 to form a horizontal and a vertical part of the test piece;

[0014] S5: Insert the horizontal part of the test piece from S4 into the slot in the fixture on the sample table of the peel tester for limiting. The gripper of the peel tester clamps and pulls the vertical part upward, so that the tension bar on the horizontal part separates from the substrate. The peel strength tensile force is obtained by testing the peel tester.

[0015] In a further improvement, the fixture includes a base plate, a fixing block one, and a fixing block two. The base plate is fixed on the sample table of the peeling test machine, and the fixing blocks one and two are fixed on the base plate. The slot is located between the fixing blocks one and two. The slot includes an upper pull groove and a lower locking groove that are interconnected. The upper pull groove is used to accommodate the tension strip in the copper foil sheet on side A, and the lower locking groove is used to accommodate the substrate and the copper foil sheet on side B.

[0016] In a further improvement, the right end of the slot is connected to an opening, and the vertical part is disposed within the opening.

[0017] As a further improvement, arc-shaped guide grooves are provided on both sides of the bottom right end of the opening.

[0018] As a further improvement, the lower slot has a height of 1.8mm and the upper pull slot has a width of 13.4mm.

[0019] Compared with the prior art, the beneficial effects of the copper-clad ceramic substrate peel test method of the present invention are as follows:

[0020] 1. The original method of separating the copper foil substrate by scraping off the solder is complicated and increases the testing cycle. The present invention uses etching solution to etch the copper foil on both sides of the copper-clad ceramic substrate and etch the solder, eliminating the solder scraping process. It also uses laser cutting to separate the copper foil substrate, reducing the number of operation steps and shortening the testing cycle.

[0021] 2. The original substrate was fixed to the iron plate with adhesive. After the substrate was subjected to pressure for 24 hours to allow the adhesive to dry completely, a peel test was performed. The adhesive strength and position changes also affected the accuracy of the experiment. Weak adhesive strength can easily lead to delamination, affecting the test results. This invention uses a fixture to insert the test piece and limit the substrate of the test piece. The test cycle is greatly shortened. It has the advantages of being able to test as needed and being easy to operate. At the same time, it can avoid the test influence caused by the adhesive itself.

[0022] 3. The original substrate was fixed to the iron plate with adhesive, and the clamp could only clamp a single copper foil for testing. The present invention can clamp the right end of the test piece, that is, clamp the bonding layer of the copper foil on side A, the substrate and the copper foil on side B, which is closer to the actual environment and improves the accuracy of the peel strength test data.

[0023] 4. Existing adhesive bonding methods require ensuring a flat surface at the contact point with the sample stage, without any protrusions. Therefore, the bottom surface of the substrate is fixed to the iron plate with adhesive. Only one side of the copper foil can be etched on the same substrate. When peeling tests are required for two different A-side copper foil sheets and B-side copper foil sheets, two substrates are needed. This invention uses a fixture to restrict the test piece, enabling double-sided etching of copper foil on the same substrate. Now, double-sided peeling tests can be performed. Attached Figure Description

[0024] Figure 1 This is a schematic diagram of the structure of the substrate in this invention.

[0025] Figure 2 This is a schematic diagram of the structure of the test piece in this invention.

[0026] Figure 3 This is a schematic diagram of the fixture in the present invention.

[0027] Figure 4 This is a schematic diagram of the structure of the fixture and test piece in this invention.

[0028] Figure 5 This is a schematic diagram of the fixture from another perspective in this invention.

[0029] In the figure, 1-substrate, 11-front copper foil layer, 12-substrate, 13-back copper foil layer, 14-A-side copper foil sheet, 141-tension bar, 15-B-side copper foil sheet, 2-test piece, 21-horizontal part, 22-vertical part, 3-fixture, 31-base plate, 32-fixing block one, 33-fixing block two, 34-groove, 35-upper pull groove, 36-lower slot, 37-opening, 38-arc guide groove, 4-groove. Detailed Implementation

[0030] In the description of this invention, it should be noted that the terms "center", "upper", "lower", "left", "right", "vertical", "horizontal", "inner", "outer", etc., indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings. They are only for the convenience of describing this invention and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation. Therefore, they should not be construed as limitations on this invention.

[0031] In the description of this invention, it should be noted that, unless otherwise explicitly specified and limited, the terms "installation," "connection," and "joining" should be interpreted broadly. For example, they can refer to a fixed connection, a detachable connection, or an integral connection. Those skilled in the art can understand the specific meaning of the above terms in this invention based on the specific circumstances.

[0032] The following is a description of the embodiments and appendices. Figures 1-5 The technical solution of the present invention will be further described below.

[0033] Example 1

[0034] A method for peeling copper-clad ceramic substrates includes the following steps:

[0035] S1: The copper foil is etched and the solder is etched on the front and back sides of the copper-clad ceramic substrate using an etching solution to form a substrate 1. The substrate 1 includes a front copper foil layer 11, a substrate 12 and a back copper foil layer 13 from top to bottom. The front copper foil layer 11 and the back copper foil layer 13 each include an A-side copper foil sheet 14 and a B-side copper foil sheet 15 that are alternately connected in sequence.

[0036] S2: Laser cutting is performed on the substrate 12 surface that contacts the copper foil 15 on side B in S1, and the depth of the laser-cut groove 41 is 30%.

[0037] S3: The cut substrate 1 is divided into several test pieces 2 by a splitting process. The test piece 2 includes a single A-side copper foil 14, a substrate 12 and a single B-side copper foil 15 arranged from top to bottom. The A-side copper foil 14 is provided with a tension strip 141.

[0038] S4: Bend the test piece 2 in S3 at a right angle along the groove 41 in S2 so that the test piece 2 forms a horizontal part 21 and a vertical part 22;

[0039] S5: Insert the horizontal part 2 of the test piece 2 in S4 into the slot 34 in the fixture 3 on the sample table of the peel tester for limiting. The gripper of the peel tester clamps and pulls the vertical part 22 upward, so that the tension bar 141 on the horizontal part 21 is separated from the substrate 12. The peel strength tensile force is obtained by testing the peel tester.

[0040] like Figures 1-5 As shown, in step S1, copper foil etching and solder etching are performed on both sides of the copper-clad ceramic substrate using an etching solution to form substrate 1. This eliminates the original solder scraping step, as the solder is directly removed by the etching solution. Then, the copper foil sheet 15 on side B of test piece 2 in step S3 is laser-cut to a depth of 30%. During use, only slight force is needed to break substrate 12 in test piece 2 while the copper foil sheet 14 on side A remains intact. The copper foil sheet 14 on side A is then bent to form... Figure 2 The state shown will Figure 2 The test piece 2 is inserted into the fixture 3. The horizontal part 2 of the test piece 2 is located in the slot 31 of the fixture 3. The clamp holds and pulls the vertical part 22 vertically upward, so that the tension bar 141 on the horizontal part 21 is separated from the substrate 12. The peel strength tensile force is obtained by peel tester.

[0041] Compared with existing testing methods, the testing method of the present invention has the following advantages:

[0042] 1. The original method of separating the copper foil substrate by scraping off the solder was complex and involved numerous steps, increasing the testing cycle. This invention omits the solder scraping step by etching the copper foil and solder on both sides of the copper-clad ceramic substrate with an etching solution, and achieves separation of the copper foil substrate by laser cutting. This reduces the number of steps and shortens the testing cycle.

[0043] 2. The original substrate was fixed to the iron plate with adhesive. After the substrate was subjected to pressure for 24 hours to allow the adhesive to dry completely, a peel test was performed. The adhesive strength and position changes also affected the accuracy of the experiment. Weak adhesive strength can easily lead to delamination, affecting the test results. This invention uses a fixture to insert the test piece and limit the substrate of the test piece. The test cycle is greatly shortened. It has the advantages of being able to test as needed and being easy to operate. At the same time, it can avoid the test influence caused by the adhesive itself.

[0044] 3. The original substrate was fixed to the iron plate with adhesive, and the clamp could only clamp a single copper foil for testing. The present invention can clamp the right end of the test piece, that is, clamp the bonding layer of the copper foil on side A, the substrate and the copper foil on side B, which is closer to the actual environment and improves the accuracy of the peel strength test data.

[0045] 4. Existing adhesive bonding methods require ensuring a flat surface at the contact point with the sample stage, without any protrusions. Therefore, the bottom surface of the substrate is fixed to the iron plate with adhesive. Only one side of the copper foil can be etched on the same substrate. When peeling tests are required for two different A-side copper foil sheets and B-side copper foil sheets, two substrates are needed. This invention uses a fixture to restrict the test piece, enabling double-sided etching of copper foil on the same substrate. Now, double-sided peeling tests can be performed.

[0046] The table below shows the test data for the same batch of products on the new fixture and the old fixture. The test data shows that the average peel strength of the products on the new fixture is greater than that on the old fixture; for example: 52.1 > 48.9; 41.7 > 35.9; 46.7 > 41.6; 46.8 > 41.5. Using the new fixture makes the test data more accurate; the higher the peel strength value, the better the product performance.

[0047]

[0048]

[0049] As a further embodiment, the fixture 3 includes a base plate 31, a first fixing block 32, and a second fixing block 33. The base plate 31 is fixed on the sample table of the peeling test machine. The first fixing block 32 and the second fixing block 33 are fixed on the base plate 31. The slot 34 is located between the first fixing block 32 and the second fixing block 33. The slot 34 includes an upper pull groove 35 and a lower retaining groove 36 that are interconnected. The upper pull groove 35 is used to accommodate the tension strip 141 in the copper foil sheet 14 on the A side. The lower retaining groove 36 is used to accommodate the substrate 12 and the copper foil sheet 15 on the B side. The width of the lower retaining groove is set to be greater than the width of the upper pull groove.

[0050] like Figures 2-5 As shown, the horizontal part 21 is inserted into the slot 34. Specifically, the substrate 12 and the copper foil sheet on the B side below are inserted into the lower slot 36, and the upper tension bar 141 is inserted into the upper pull groove 35. Then, the clamp of the peel tester clamps the vertical part 22 and the clamp continues to lift upward, so that the tension bar 141 located in the upper pull groove 35 is peeled off from the substrate 12. The peel tester measures the tension of the tension bar 141 being peeled off from the substrate.

[0051] The width of the lower slot is greater than the width of the upper pull slot so that during the separation of the pull bar from the substrate, the substrate is limited in the lower slot and cannot move upward, while the pull bar can be pulled out along the upper pull slot.

[0052] Meanwhile, the upper pull groove 35 in the fixture 3 ensures that the tension bar is always pulled horizontally upward along the direction of the upper pull groove during the peeling process. Combined with the clamp, this ensures that the tension bar can only be peeled in a fixed direction, improving the accuracy of the test.

[0053] As a further embodiment, the right end of the slot 34 is connected to an opening 37, and the vertical part 22 is disposed within the opening 37. The opening 37 is provided so that after the L-shaped test piece 2 is inserted into the slot 34, the vertical part 22 contacts the end face of the opening 37, preventing the test piece 2 from being pushed in further, thus serving as a limiting function.

[0054] As a further embodiment, the bottom right side of the opening 37 is provided with arc-shaped guide grooves 38. The arc-shaped guide grooves 38 facilitate the insertion of the horizontal part 2 of the test piece 2 into the opening 37.

[0055] As a further embodiment, the lower slot 36 has a height of 1.8mm, and the upper pull slot 35 has a width of 13.4mm. The 1.8mm high lower slot can accommodate copper-clad laminates of all thicknesses currently available, thus having a wider range of applications; the 13.4mm wide upper pull slot adapts to the width design of the copper-clad laminates to be tested.

[0056] The preferred embodiments of the present invention have been described in detail above. It should be understood that those skilled in the art can make numerous modifications and variations based on the concept of the present invention without creative effort. Therefore, all technical solutions that can be obtained by those skilled in the art based on the concept of the present invention through logical analysis, reasoning, or limited experimentation on the basis of existing technology should be within the scope of protection defined by the claims.

Claims

1. A method for peeling copper-clad ceramic substrates, characterized in that, Includes the following steps: S1: The copper foil is etched and the solder is etched on the front and back sides of the copper-clad ceramic substrate using an etching solution to form a substrate. The substrate includes a front copper foil layer, a substrate and a back copper foil layer from top to bottom. Both the front copper foil layer and the back copper foil layer include A-side copper foil sheets and B-side copper foil sheets that are alternately connected in sequence. S2: Laser cutting is performed on the substrate surface in contact with the copper foil sheet on side B in S1, and the depth of the laser-cut groove is 30%; S3: The cut substrate is divided into several test pieces by a splitting process. The test pieces include a single A-side copper foil sheet, a substrate and a single B-side copper foil sheet arranged from top to bottom. The A-side copper foil sheet is provided with a tension strip. S4: Bend the test piece in S3 at a right angle along the groove in S2 to form a horizontal and a vertical part of the test piece; S5: Insert the horizontal part of the test piece in S4 into the slot in the fixture on the sample table of the peel tester for limiting. The gripper of the peel tester clamps and pulls the vertical part upward to separate the tension bar on the horizontal part from the substrate. The peel strength tensile force is obtained by testing the peel tester. The fixture includes a base plate, a fixing block one, and a fixing block two. The base plate is fixed on the sample table of the peeling test machine. The fixing blocks one and two are fixed on the base plate. The slot is located between the fixing blocks one and two. The slot includes an upper pull slot and a lower locking slot that are interconnected. The upper pull slot is used to accommodate the tension strip in the copper foil sheet on side A. The lower locking slot is used to accommodate the substrate and the copper foil sheet on side B. The width of the lower slot is set to be greater than the width of the upper slot. The lower slot has a height of 1.8 mm, and the upper slot has a width of 13.4 mm.

2. The method for peeling copper-clad ceramic substrates according to claim 1, characterized in that, The right end of the slot is connected to an opening, and the vertical part is disposed in the opening.

3. The method for peeling copper-clad ceramic substrates according to claim 2, characterized in that, The bottom right end of the opening is provided with arc-shaped guide grooves on both sides.

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