Inductor and baking temperature control method thereof

Abstract

The present invention relates to the technical field of inductor preparation, it relates to a kind of inductor and baking temperature control method thereof, including an inductor formed by preparing a composite material, baking the sample to obtain the temperature range of interface cracks: copper wire and magnetic material are subjected to TMA test by TMA instrument, and the expansion data of copper wire and magnetic material are recorded respectively, and the expansion data of both are derived to draw a curve of temperature and expansion rate, in the linear region of material expansion behavior, the relationship between expansion rate and temperature is fitted using linear regression method to obtain a linear equation. The linear equation is calculated to obtain the temperature node corresponding to the same thermal expansion coefficient, so as to regulate the drying temperature and time of the product according to the temperature node. According to the TMA curves of different magnetic materials, a baking method can be formulated in a targeted manner to achieve the purpose of comprehensive improvement, and the improvement method is simple, without the need to improve from the material end and the mechanism end, and the execution difficulty is low.

Description

Technical Field

[0001] The present invention relates to the technical field of inductor preparation, and more particularly to an inductor and a baking temperature control method thereof. Background Art

[0002] As one of the three fundamental passive electronic components in electronic circuit boards, inductors are widely used in communications, industrial equipment, automotive, new energy, the Internet of Things, and other fields. With the rapid evolution of the market and the large-scale development of related industries such as the Internet of Things and smart cities, the inductor market is rapidly expanding, and market requirements for inductor quality are becoming increasingly stringent.

[0003] The common drawback of inductors currently used in manufacturing is interface cracking after baking, especially in inductors with a high proportion of copper wire and ultra-thin models. The specific pattern is as follows: Figure 1 and Figure 2 As shown,

[0004] The specific reason for the above is that the thermal expansion coefficients of copper wire and magnetic material are different during baking, which causes the magnetic material to be unable to support the expansion force of copper, resulting in interface cracks. To improve this problem, the industry usually increases the proportion of glue in the magnetic material to increase its strength.

[0005] However, this disadvantage will lead to the electrical properties of the product (the inductance will decrease proportionally), and it will also increase the risk of product surface cracking and mold damage during stamping. Summary of the Invention

[0006] In view of the shortcomings of the prior art, the present invention aims to provide an inductor with a structural temperature and a method for controlling the baking temperature of the inductor by precisely regulating the thermal expansion curves of the adhesive and copper in the magnetic material.

[0007] The present invention provides the following technical solutions:

[0008] An inductor, comprising an inductor formed by preparing a composite material,

[0009] The composite material comprises the following components:

[0010] Iron-based nanocrystalline alloy powder 40%~60%

[0011] Iron-silicon-aluminum alloy powder 40%~60%

[0012] Epoxy resin adhesive 5~7%

[0013] Coupling agent 0.4%~0.6%.

[0014] The present invention is further configured as follows: the iron-based nanocrystalline alloy powder specifically includes the following elemental components:

[0015] Fe: 70%~80%

[0016] Cu: 1%~3%

[0017] Nb: 2%~5%

[0018] Si: 10%~15%

[0019] B: 5%~10%.

[0020] The present invention is further configured as follows: the Sendust aluminum alloy powder specifically includes the following elemental components:

[0021] Fe: 83%~90%

[0022] Si: 8%~10%

[0023] Al: 5%~8%.

[0024] A method for controlling the baking temperature of an inductor comprises the following steps:

[0025] S1. The temperature range of the interface cracks obtained by baking the sample is:

[0026] S2. Perform TMA tests on copper wire and magnetic materials using a TMA instrument. Record the expansion data of the copper wire and the magnetic material respectively. Derive the expansion data of the two to plot a curve between temperature and expansion rate. In the linear region of the material expansion behavior, use a linear regression method to fit the relationship between the expansion rate and temperature to obtain a linear equation.

[0027] S3. Calculate the linear equation to obtain the temperature node corresponding to the same thermal expansion coefficient, so as to adjust the drying temperature and time of the product according to the temperature node.

[0028] The present invention is further configured as follows: Step S1 specifically includes the following steps:

[0029] S11. Observe the phenomenon: bake the inductor at different temperatures, observe the occurrence of interface cracks, record the temperature range where interface cracks occur, and determine the temperature at which the first crack occurs;

[0030] Based on the observed data, a possible interface crack temperature range is assumed;

[0031] S12, segmented baking curve detection: the entire baking temperature curve is divided into several segments, and the length of each segment is adjusted according to the hypothesis;

[0032] Full temperature curve detection: bake the sample according to the baking temperature curve and record the occurrence of interface cracks in the whole process.

[0033] Compare the segmented baking data with the full baking data to verify the accuracy of the segmented baking data;

[0034] S13. Data analysis: Draw a graph of the temperature range and the incidence rate of interface cracks to show the interface crack defect rate in different temperature ranges. By analyzing the graph, determine the temperature range where the interface cracks occur.

[0035] The present invention is further configured as follows: the linear equation is specifically as follows:

[0036] Equations for magnetic materials:

[0037]

[0038] The equation for copper wire:

[0039]

[0040] Temperature Node

[0041]

[0042] The present invention is further configured such that the segments of the segmented baking curve in step S12 include the following:

[0043] Stage 1: baking at 25℃-85℃ for 40 minutes;

[0044] Stage 2: baking at 85℃-120℃ for 150 minutes;

[0045] Stage three, baking temperature 120℃-150℃, baking for 100 minutes;

[0046] Stage 4: baking temperature 150°C, baking for 200 minutes;

[0047] Stage 5: baking at 150℃-120℃ for 150 minutes;

[0048] The whole process temperature curve: baking temperature 25℃-150℃, baking time 540 minutes.

[0049] The present invention is further configured to obtain a linear equation based on data obtained by performing TMA tests on copper wire and magnetic materials:

[0050] =0.41T-25.75

[0051] =0.067T-2.0

[0052] Therefore, the temperature node 69.24℃.

[0053] The present invention is further configured as follows: based on the temperature node The magnetic material is kept at a constant temperature of 69.24°C for 60 minutes.

[0054] The present invention is further configured as follows: after the inductor is baked at 69.24° C. for 60 minutes:

[0055] a. After 10 minutes of heating and baking, raise the temperature to 85°C;

[0056] b. Bake at a constant temperature of 85°C for 120 minutes;

[0057] c. After 30 minutes of heating and baking, raise the temperature from 85°C to 120°C;

[0058] d. Bake at a constant temperature of 120°C for 60 minutes;

[0059] e. After 40 minutes of heating and baking, the temperature is raised from 120°C to 150°C;

[0060] f. Bake at a constant temperature of 150°C for 180 minutes;

[0061] g. After 90 minutes of cooling and baking, increase the temperature from 150°C to 120°C;

[0062] h. Cool the molded product to room temperature and store it.

[0063] Compared with the shortcomings of the prior art, the beneficial effects of the present invention are:

[0064] According to the TMA curves of different magnetic materials, a targeted baking method can be formulated to achieve the goal of comprehensive improvement. Moreover, the improvement method is simple, without the need to improve the material and mechanism ends, and the implementation difficulty is low.

[0065] This baking technology can greatly improve the appearance yield rate, thereby improving product efficiency while improving product quality. BRIEF DESCRIPTION OF THE DRAWINGS

[0066] Figure 1 is a schematic diagram of an existing inductor;

[0067] Figure 2 This is an enlarged view of the details of the existing inductor;

[0068] Figure 3 Schematic diagram for confirming the interface crack temperature range;

[0069] Figure 4 Export graph for TMA curve;

[0070] Figure 5 It is a baking curve diagram of the present invention. DETAILED DESCRIPTION

[0071] Reference Figures 1 to 5 The embodiments of the present invention are further described.

[0072] The specific content of this application is: including an inductor formed by preparing a composite material. The composite material includes the following components:

[0073] Iron-based nanocrystalline alloy powder 40%~60%, iron-silicon-aluminum alloy powder 40%~60%, epoxy resin adhesive 5~7%, coupling agent 0.4%~0.6%.

[0074] The iron-based nanocrystalline alloy powder specifically includes the following elemental components: Fe: 70%~80%, Cu: 1%~3%, Nb: 2%~5%, Si: 10%~15%

[0075] B: 5%~10%.

[0076] The iron-silicon-aluminum alloy powder specifically includes the following elemental components: Fe: 83%~90%, Si: 8%~10%, Al: 5%~8%.

[0077] The detailed contents of the components prepared in this application are as follows:

[0078] The proportion is: 40% iron-based nanocrystalline alloy powder, which contains 70% Fe, 1% Cu, 2% Nb, and 10% Si;

[0079] 40% of the iron-silicon-aluminum alloy powder. The iron-based nanocrystalline alloy powder specifically comprises the following elemental components: 83% Fe, 8% Si, and 5% Al;

[0080] Epoxy resin adhesive 5%; coupling agent 0.4%.

[0081] The above materials are mixed and pressed into a blank (hereinafter referred to as an inductor) through a mold.

[0082] Based on the inductor, the steps for baking it include:

[0083] Observe the phenomenon: bake the inductor at different temperatures, observe the occurrence of interface cracks, record the temperature range in which interface cracks occur, and determine the temperature at which the first crack occurs.

[0084] Based on the observed data, a possible interface crack temperature range is assumed.

[0085] The accuracy of the segmented baking data is verified by comparing the segmented baking curve test data with the full baking curve test data. The entire baking temperature curve is divided into several segments, and the length of each segment is adjusted according to the hypothesis.

[0086] according to Figure 3 As shown, data analysis: draw a curve chart of temperature range and interface crack incidence rate, showing the interface crack defect rate in different temperature ranges, and determine the temperature range where interface cracks occur by analyzing the curve chart.

[0087] The segments of the baking curve will be divided into the following sections:

[0088] Stage 1: baking at 25℃-85℃ for 40 minutes;

[0089] Stage 2: baking at 85℃-120℃ for 150 minutes;

[0090] Stage three, baking temperature 120℃-150℃, baking for 100 minutes;

[0091] Stage 4: baking temperature 150°C, baking for 200 minutes;

[0092] Stage five: baking at 150℃-120℃ for 150 minutes.

[0093] The whole temperature curve is tested: the sample is baked according to the baking temperature curve, and the occurrence of interface cracks in the whole process is recorded. The whole temperature curve is: baking temperature 25℃-150℃, baking for 540 minutes.

[0094] By taking different sections of mapping verification, the interface crack occurrence interval is locked (it can be found that the first stage is the outbreak point of the interface crack (before 85°), and the subsequent stages are basically stable). Please refer to Table 1 for details.

[0095]

[0096] Table 1

[0097] like Figure 4 As shown: TMA tests are performed on copper wire and magnetic materials using a TMA instrument. The expansion data of the copper wire and the expansion data of the magnetic material are recorded respectively. The expansion data of the two are derived to draw a curve of temperature and expansion rate. In the linear region of the material expansion behavior, the linear regression method is used to fit the relationship between the expansion rate and temperature to obtain a linear equation.

[0098] The two tables in the figure represent the adhesive material and the coil, respectively, which represent the magnetic material and the copper wire.

[0099] According to the TMA temperature range (between 25 and 85°C) corresponding to the interface crack temperature, the linear function within the range is calculated to make the linear functions of the two equal, thereby calculating the temperature node corresponding to the same thermal expansion coefficient. The specific linear equation of the linear function is as follows:

[0100] Equations for magnetic materials:

[0101]

[0102] The equation for copper wire:

[0103]

[0104] Temperature Node

[0105]

[0106] The data obtained from TMA tests on copper wire and magnetic materials are based on the linear equation:

[0107] =0.41T-25.75

[0108] =0.067T-2.0

[0109] Therefore, = , and then the temperature node 69.24℃, Figure 4 Chinese use:

[0110] Represents magnetic materials, Indicates copper wire.

[0111] Based on temperature nodes The magnetic material is kept at a constant temperature of 69.24°C for 60 minutes.

[0112] When T < 69.24℃, the powder material expansion coefficient is less than the coil expansion coefficient. When 69.24℃ < T < 85℃, the powder material expansion coefficient is greater than the coil expansion coefficient.

[0113] Considering that the cause of interface cracks is the coil expansion force > the bonding strength of the powder material in the solidification range, the improvement plan is to keep the magnetic material glue at a constant temperature of 69.24°C for 60 minutes (increasing the solidification amount) at the temperature node with the same expansion coefficient. At this time, the copper expansion coefficient is constant, thereby increasing the bonding strength of the glue at this node and reducing the degree and probability of interface cracks.

[0114] The data for 60 minutes of constant temperature are based on the experimental data in Table 2:

[0115]

[0116] Table 2

[0117] According to the above data, when the constant temperature is set at 60 minutes, the defective rate of interface cracks is 0.

[0118] like Figure 5As shown: After the inductor is baked at 69.24℃ for 60 minutes: after 10 minutes of temperature rise baking, the temperature is raised to 85℃; after 120 minutes of constant temperature baking at 85℃; after 30 minutes of temperature rise baking, the temperature is raised from 85℃ to 120℃; after 60 minutes of constant temperature baking at 120℃; after 40 minutes of temperature rise baking, the temperature is raised from 120℃ to 150℃;

[0119] Bake at a constant temperature of 150℃ for 180 minutes; after 90 minutes of cooling and baking, increase the temperature from 150℃ to 120℃; cool the formed pieces to room temperature for storage.

[0120] Inductor performance test experimental data report:

[0121] Materials: Inductor samples (inductors after optimized baking process); Inductor samples (inductors produced by original process),

[0122] Equipment: LCR meter (for testing inductance and impedance), multimeter (for measuring voltage and current)

[0123] Sample preparation: Prepare inductor samples after optimized baking process and inductor samples produced by original process respectively.

[0124] Inductance and impedance testing:

[0125] The inductance (L) and equivalent series resistance (ESR) of the two inductor samples were measured using an LCR meter. The test was repeated three times for each sample and the average value was taken.

[0126]

[0127] Data Analysis:

[0128] Inductance (L): The inductance of the optimized process inductor samples is slightly higher, but within the allowable tolerance. The inductance of the original process samples fluctuates greatly.

[0129] Impedance (ESR): The optimized process significantly reduced the impedance of the inductor samples (averaging approximately 26.1 mΩ). The existing samples had a higher impedance (averaging approximately 28.9 mΩ), indicating that the original process may have electrical instability caused by interface cracks.

[0130] Quality Factor (Q): The quality factor of the inductor samples after the optimized process has been significantly improved, with an average value of around 91.3. The quality factor of the samples with the original process is lower, with an average value of around 74.6.

[0131] By optimizing the baking process (maintaining a constant temperature at the calculated temperature node and increasing the adhesive bonding strength), the inductor samples showed significant improvements in electrical performance. Specifically:

[0132] The inductance value is more stable, indicating better product consistency. The quality factor (Q) is significantly improved, meeting high-quality requirements.

[0133] The optimized baking process effectively improves the overall performance of the inductor and is suitable for applications requiring high quality and high reliability.

[0134] The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. Common changes and substitutions made by those skilled in the art within the scope of the technical solution of the present invention should be included in the protection scope of the present invention.

Claims

1. A method for controlling the baking temperature of an inductor, characterized in that: Including inductors made from composite materials, The composite material comprises the following components: Iron-based nanocrystalline alloy powder 40%~60% Iron-silicon-aluminum alloy powder 40%~60% Epoxy resin adhesive 5~7% Coupling agent 0.4%~0.6%; The iron-based nanocrystalline alloy powder specifically includes the following elemental components: Fe: 70%~80% Cu: 1%~3% Nb: 2%~5% Si: 10%~15% B：5%~10%； The Sendust aluminum alloy powder specifically includes the following elemental components: Fe: 83%~90% Si: 8%~10% Al：5%~8%； The inductor baking temperature control method includes the following steps: S1. Baking the sample to obtain the temperature range of the interface crack; S2. Perform TMA testing on the copper wire and the magnetic material using a TMA instrument, record the expansion data of the copper wire and the magnetic material respectively, and derive the expansion data of the two to plot a curve of temperature and expansion rate. In the linear region of the material expansion behavior, use the linear regression method to fit the relationship between the expansion rate and temperature to obtain a linear equation; S3. Calculate the linear equation to obtain the temperature node corresponding to the same thermal expansion coefficient, so as to adjust the drying temperature and time of the product according to the temperature node. The step S1 specifically includes the following steps: S11. Observe the phenomenon: bake the inductor at different temperatures, observe the occurrence of interface cracks, record the temperature range where interface cracks occur, and determine the temperature at which the first crack occurs; Based on the observed data, a possible interface crack temperature range is assumed; S12, segmented baking curve detection: the entire baking temperature curve is divided into several segments, and the length of each segment is adjusted according to the hypothesis; Full temperature curve detection: bake the sample according to the baking temperature curve and record the occurrence of interface cracks in the whole process; Compare the segmented baking data with the full baking data to verify the accuracy of the segmented baking data; S13. Data analysis: Draw a graph of temperature range and interface crack incidence rate, showing the interface crack defect rate in different temperature ranges. By analyzing the graph, determine the temperature range where interface cracks occur. The linear equation is as follows: Equations for magnetic materials: ; The equation for copper wire: ; Temperature Node: ; The segments of the segmented baking curve in step S12 include the following: Stage 1: baking at 25℃-85℃ for 40 minutes; Stage 2: baking at 85°C-120°C for 150 minutes; Stage three, baking temperature 120℃-150℃, baking for 100 minutes; Stage 4: baking temperature 150°C, baking for 200 minutes; Stage 5: baking at 150℃-120℃ for 150 minutes; The whole process temperature curve: baking temperature 25℃-150℃, baking time 540 minutes.

2. The method for controlling the baking temperature of an inductor according to claim 1, wherein: Based on the data obtained from TMA tests on copper wire and magnetic materials, a linear equation is derived: ; ; Therefore, the temperature node T=69.24℃.

3. The method for controlling the baking temperature of an inductor according to claim 2, wherein: Based on the temperature node T=69.24℃, the inductor is temperature-controlled for 60 minutes.

4. The method for controlling the baking temperature of an inductor according to claim 2, wherein: After the inductor is baked at 69.24°C for 60 minutes: a. After 10 minutes of heating and baking, raise the temperature to 85°C; b. Bake at a constant temperature of 85°C for 120 minutes; c. After 30 minutes of heating and baking, raise the temperature from 85°C to 120°C; d. Bake at a constant temperature of 120°C for 60 minutes; e. After 40 minutes of heating and baking, the temperature is raised from 120°C to 150°C; f. Bake at a constant temperature of 150°C for 180 minutes; g. After 90 minutes of cooling and baking, increase the temperature from 150°C to 120°C; h. Cool the molded product to room temperature and store it.

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