Low-noise assembled chip inductor and preparation method thereof

Abstract

The invention relates to a low-noise assembled chip inductor and a preparation method thereof, the inductor comprises a magnetic cover, an n-shaped inductor material sheet and a magnetic core, and epoxy resin glue with first hardness is arranged between the inner wall of the bottom of the n-shaped inductor material sheet and the bottom surface of the magnetic core; epoxy resin glue with second hardness is arranged at an air gap where the magnetic core is directly matched with the magnetic cover; epoxy resin glue with third hardness is arranged at an air gap between the magnetic cover and the top of the magnetic core; epoxy resin glue with fourth hardness is arranged in an air gap between the magnetic core and the top of the n-shaped inductance material sheet; air gaps between the magnetic cover and the side surface of the magnetic core and between the magnetic cover and the side surface of the n-shaped inductance material sheet are filled with self-drying varnish; the first hardness, the second hardness and the fourth hardness are 40-50 D, and the third hardness is 80-85 D. The epoxy resin glue with the third hardness is high in hardness, the fixing effect is better, and the inductor is effectively prevented from being separated during over-reflow soldering; and the three flexible glue and the self-drying varnish are arranged, so that the effects of offsetting vibration and reducing noise are achieved.

Description

Technical Field

[0001] The present application relates to the technical field of inductor manufacturing, and in particular to a low-noise assembled chip inductor and a preparation method thereof. Background Art

[0002] As the main frequency and power of computer CPUs and graphics card GPUs increase, higher requirements are placed on the inductors used. For example, they must have a high saturation current and be able to withstand high peak currents without entering a saturated state, which is very important for supporting rapidly changing loads (such as the switching of processors between different tasks); they must have a low DC resistance (DCR). Lower DC resistance means less energy loss converted into heat energy, which helps to improve power efficiency and reduce heat; they must also have the ability to operate at high frequencies. Modern CPUs and GPUs usually operate at very high frequencies, so the components in their power supply circuits also need to be able to support this high-frequency operation.

[0003] When the inductor meets the above three requirements of high saturation current, low DC resistance and high frequency working ability, the inductor will cause magnetostriction in the magnetic core of the inductor due to the change of current size when working at high current (heavy load). Magnetostriction refers to the repeated expansion and contraction of the length of the magnetic core under the action of the alternating magnetic field, thereby generating vibration or sound waves. This vibration is the noise heard by the human ear (frequency is in the range of 20Hz-20KHz). The occurrence of noise is basically unsolvable or cannot be fundamentally eliminated. In the existing technology, noise is generally reduced by improving magnetic materials (magnetic covers and magnetic cores) and production processes, but satisfactory results have not been achieved and there is still room for improvement. Summary of the invention

[0004] In order to solve the technical problem in the prior art that an inductor is prone to generate relatively large noise when operating at a high current, the present invention provides a low-noise assembled chip inductor and a preparation method thereof.

[0005] On the one hand, the technical solution provided by the present application is as follows: a low-noise assembled chip inductor, comprising a magnetic cover, an "X"-shaped inductor sheet and a magnetic core, wherein one side of the magnetic cover is provided with an embedding groove inwardly, the "X"-shaped inductor sheet is arranged in the embedding groove, and the magnetic core is arranged in the "X"-shaped inductor sheet and the magnetic cover; an epoxy resin glue of a first hardness is provided between the inner wall of the bottom of the "X"-shaped inductor sheet and the bottom surface of the magnetic core; an epoxy resin glue of a second hardness is provided at the air gap where the magnetic core and the magnetic cover directly cooperate; an epoxy resin glue of a third hardness is provided at the air gap between the magnetic cover and the top of the magnetic core; an epoxy resin glue of a fourth hardness is provided at the air gap between the magnetic core and the top of the "X"-shaped inductor sheet; self-drying varnish is provided in the air gap between the magnetic cover and the side of the magnetic core, and between the magnetic cover and the side of the "X"-shaped inductor sheet; the first hardness is 40-50D, the second hardness is 40-50D, the third hardness is 80-85D, and the fourth hardness is 40-50D. The above hardnesses are all Shore A hardness.

[0006] By adopting the above technical scheme, the present application has basically not made any changes to the shape and structure of the magnetic cover, the "J"-shaped inductor sheet and the magnetic core. An epoxy resin glue of the third hardness is provided in the air gap between the magnetic cover and the top of the magnetic core. The hardness is relatively hard and the fixing effect is better. The purpose is to fix the magnetic cover and the magnetic core well to prevent the inductor from separating during reflow soldering. In order to solve the technical problem that the inductor generates vibration noise due to magnetostriction when working at a large current, firstly, an epoxy resin glue of the first hardness is provided between the bottom of the "J"-shaped inductor sheet and the inner wall of the magnetic cover, and an epoxy resin glue of the fourth hardness is provided in the air gap between the magnetic core and the top of the "J"-shaped inductor sheet (i.e., adjacent to the epoxy resin glue of the third hardness). The hardness of the glue at these two places is relatively soft, which can offset part of the vibration generated by the magnetostriction of the inductor, absorb part of the vibration energy, and play a role in reducing noise; secondly, the current direction on the inductor sheet is perpendicular to the direction of the magnetic lines of force of the magnetic core, so in the magnetic field of the magnetic core, the epoxy resin glue of the fourth hardness is provided. The magnetostriction phenomenon is particularly obvious in the direction of the force line. For this reason, an epoxy resin glue with a second hardness is particularly arranged at the air gap where the magnetic core and the magnetic cover directly cooperate. The hardness is relatively soft, forming a good vibration damping surface, which can offset part of the vibration caused by the magnetostriction of the inductor, and further reduce the noise. Secondly, there will still be voids in some air gaps inside the magnetic cover, which is also one of the reasons why magnetostriction will generate noise. The present application fills the air gaps between the magnetic cover and the side of the magnetic core, and between the magnetic cover and the side of the "X"-shaped inductor sheet with self-drying varnish. After the voids are filled, it plays a third role in offsetting vibration and reducing noise.

[0007] After testing, the inductor described in this application generates noise less than 2.5acum when working in the power circuit of the computer motherboard CPU and the graphics card GPU, which performs well, indicating that the inductor structure and process really play a role.

[0008] Optionally, the epoxy resin glue of the second hardness is distributed into glue areas at multiple points by steel mesh scraping, and is arranged in multiple rows and columns along the width direction of the magnetic core.

[0009] Optionally, the glue area of ​​each point is greater than or equal to 1 square millimeter.

[0010] Optionally, the magnetic cover material and the magnetic core material are both ferrite manganese-zinc materials; and the material of the X-shaped inductor sheet is tinned copper strip.

[0011] On the other hand, the present application also provides the following technical solution: a method for preparing the low-noise assembled chip inductor described above, comprising the steps of: S1, provides magnetic cover, X-shaped inductor sheet and magnetic core; S2, applying epoxy resin glue of the first hardness on the bottom inner wall of the cross-shaped inductor sheet, and then installing it into the embedding groove of the magnetic cover; S3, apply epoxy resin glue of the second hardness on the two sides where the magnetic core and the magnetic cover directly match, and then install them into the embedding groove and the cross-shaped inductor sheet; S4, apply epoxy glue of the third hardness to the air gap between the magnetic cover and the top of the magnetic core; S5, apply epoxy resin glue of the fourth hardness to the air gap between the magnetic core and the top of the "X"-shaped inductor sheet (i.e., adjacent to the epoxy resin glue of the third hardness); S6, drying to cure all the glue; S7, injecting self-drying varnish into the air gap between the magnetic cover and the side of the magnetic core, and between the magnetic cover and the side of the "X"-shaped inductor sheet, so that the self-drying varnish fills the remaining air gap.

[0012] Optionally, in step S3, six glue areas are printed using a steel mesh and arranged in three rows and two columns along the width direction of the magnetic core, and the glue area of ​​each point is greater than or equal to 1 square millimeter.

[0013] Optionally, in step S4, the width of epoxy resin glue with a third hardness is applied at the air gap between the magnetic cover and the top of the magnetic core to a value between half and two-thirds of the width of the magnetic core.

[0014] Optionally, in step S5, the width of epoxy resin glue with a fourth hardness is applied at the air gap between the magnetic core and the top of the X-shaped inductor sheet to be between half and two-thirds of the length of the magnetic core.

[0015] Optionally, in step S6, the drying temperature is 130-140° C., and the drying time is 1 hour.

[0016] Optionally, in step S7, a dispensing syringe is used for filling.

[0017] In summary, the present application includes at least one of the following beneficial technical effects: 1. The present application provides epoxy resin glue of the third hardness in the air gap between the magnetic cover and the top of the magnetic core, which has a harder hardness and a better fixing effect, thereby preventing the inductor from separating during reflow soldering; 2. The present application provides epoxy resin glue of the first hardness, epoxy resin glue of the second hardness and epoxy resin glue of the fourth hardness. The hardness of the three glues is relatively soft, which can offset part of the vibration caused by magnetostriction of the inductor, absorb part of the vibration energy, and play a role in reducing noise; 3. The present application fills the air gaps between the magnetic cover and the side of the magnetic core, and between the magnetic cover and the side of the "X"-shaped inductor sheet with self-drying varnish. After the voids are filled, they play a third role in offsetting vibration and reducing noise. BRIEF DESCRIPTION OF THE DRAWINGS

[0018] Figure 1 is a three-dimensional diagram of the inductor described in the embodiment of the present application; Figure 2 is a schematic diagram of a half-section structure of an inductor according to an embodiment of the present application; Figure 3 It is a schematic diagram of a state in which epoxy resin glue of a first hardness is applied to a cross-shaped inductor sheet in the method described in an embodiment of the present application; Figure 4 It is a schematic diagram of installing an X-shaped inductor sheet into a magnetic cover in the method described in an embodiment of the present application; Figure 5 It is a schematic diagram of the state of scraping the epoxy resin glue of the second hardness onto the magnetic core in the method described in the embodiment of the present application; Figure 6 It is a schematic diagram of installing a magnetic core into a cross-shaped inductor sheet and a magnetic cover in the method described in an embodiment of the present application; Figure 7 It is a schematic diagram of the state after the epoxy resin glue of the third hardness is applied at the midpoint of the method described in the embodiment of the present application; Figure 8 It is a schematic diagram of the state after the epoxy resin glue of the fourth hardness is applied in the method described in the embodiment of the present application; Fig. 9 It is a schematic diagram of the state after filling with self-drying varnish in the method described in the embodiment of the present application.

[0019] Explanation of the accompanying drawings: 1. Magnetic cover; 11. Embedding groove; 2. X-shaped inductor sheet; 3. Magnetic core; 4. Epoxy resin glue of the first hardness; 5. Epoxy resin glue of the second hardness; 6. Epoxy resin glue of the third hardness; 7. Epoxy resin glue of the fourth hardness; 8. Self-drying varnish. DETAILED DESCRIPTION

[0020] The following is combined with Figures 1 to 9This application is described in further detail.

[0021] Reference Figure 1 , Figure 2 and Figure 5 The embodiment of the present application discloses a low-noise assembled chip inductor, including a magnetic cover 1, an "X"-shaped inductor sheet 2 and a magnetic core 3. A groove 11 is provided inwardly on one side of the magnetic cover 1. The "X"-shaped inductor sheet 2 is arranged in the groove 11. The magnetic core 3 is arranged in the "X"-shaped inductor sheet 2 and the magnetic cover 1. The "X"-shaped inductor sheet 2 acts as an inductor coil. The above is a conventional structure of an inductor in the prior art. In the present application, an epoxy resin glue 4 of a first hardness is provided between the inner wall at the bottom of the "X"-shaped inductor sheet 2 and the bottom surface of the magnetic core 3; an epoxy resin glue 5 of a second hardness is provided at the air gap where the magnetic core 3 and the magnetic cover 1 directly cooperate; an epoxy resin glue 6 of a third hardness is provided at the air gap between the magnetic cover 1 and the top of the magnetic core 3; an epoxy resin glue 7 of a fourth hardness is provided at the air gap between the magnetic core 3 and the top of the "X"-shaped inductor sheet 2 (i.e., adjacent to the epoxy resin glue 6 of the third hardness); self-drying varnish 8 is provided in the air gap between the magnetic cover 1 and the side of the magnetic core 3, and between the magnetic cover 1 and the side of the "X"-shaped inductor sheet 2; the first hardness is 40-50D, the second hardness is 40-50D, the third hardness is 80-85D, and the fourth hardness is 40-50D.

[0022] Reference Figure 5 The epoxy resin glue 5 of the second hardness is distributed into glue areas at multiple points by steel mesh scraping, and arranged in multiple rows and columns along the width direction of the magnetic core 3, and the glue area of ​​each point is greater than or equal to 1 square millimeter. Compared with the whole surface vibration reduction, multi-point vibration reduction uses less glue material, and has a better vibration reduction effect against high-frequency vibrations. The glue area of ​​each point can also be designed to be different, which can be adjusted according to the actual vibration situation.

[0023] In this embodiment, the material of the magnetic cover 1 and the material of the magnetic core 3 are preferably ferrite manganese zinc material, which has the characteristic of high saturation power; the material of the X-shaped inductor sheet 2 is tinned copper strip, which is first stamped and then electroplated to achieve a lower DCR (direct current resistance).

[0024] The method for preparing the low-noise assembled chip inductor described in this embodiment includes the following steps: S1, providing a magnetic cover 1, a cross-shaped inductor sheet 2 and a magnetic core 3; S2, reference Figure 3 , apply epoxy resin glue 4 of the first hardness on the inner wall of the bottom of the "X"-shaped inductor material 2, refer to Figure 4 , and then installed into the embedding groove 11 of the magnetic cover 1; S3, refer to Figure 5, brush the epoxy resin glue 5 of the second hardness on the two sides where the magnetic core 3 and the magnetic cover 1 directly match. In this embodiment, the steel mesh can be used to scrape out six glue areas, which are arranged in three rows and two columns along the width direction of the magnetic core 3. The glue area of ​​each point is greater than or equal to 1 square millimeter; refer to Figure 6 , and then loaded into the embedding groove 11 and the cross-shaped inductor material 2; the epoxy resin glue 5 of the second hardness is squeezed by the magnetic core 3, diffused to the surrounding, and filled the surrounding gaps, so that a soft glue layer is formed between the magnetic cover 1, the magnetic core 3 and the cross-shaped inductor material 2; S4, ref. Figure 7 , apply epoxy resin glue 6 of the third hardness at the air gap between the magnetic cover 1 and the top of the magnetic core 3; in this embodiment, the width of the epoxy resin glue 6 of the third hardness at the air gap between the magnetic cover 1 and the top of the magnetic core 3 is between half and two-thirds of the width of the magnetic core 3, and sufficient glue-application matching length should be ensured to avoid the problem of insufficient fixing force, but the air gap cannot be completely covered, and the glue-application of the soft glue and the filling of the self-drying varnish 8 cannot be affected; S5, refer to Figure 8 , epoxy resin glue 7 of the fourth hardness is applied to the air gap between the magnetic core 3 and the top of the "X"-shaped inductor sheet 2 (i.e., adjacent to the epoxy resin glue 6 of the third hardness), which is also soft glue and plays a vibration reduction role; in this embodiment, the width of the epoxy resin glue 7 of the fourth hardness applied to the air gap between the magnetic core 3 and the top of the "X"-shaped inductor sheet 2 is between half and two-thirds of the length of the magnetic core 3. It is necessary to ensure that there is enough glue to ensure the vibration reduction effect, and to avoid completely blocking the air gap so that the gas inside the magnetic cover 1 cannot be released. Once there is gas inside, it will expand due to heat during reflow soldering, which will cause poor floating height of the magnetic cover 1.

[0025] S6, drying to solidify all the glue. In this embodiment, the drying temperature is 130-140° C. and the drying time is 1 hour; S7, reference Fig. 9 , inject the self-drying varnish 8 into the air gap between the magnetic cover 1 and the side of the magnetic core 3, and between the magnetic cover 1 and the side of the "X"-shaped inductor sheet 2. The varnish has good fluidity and can fill the remaining air gap with the self-drying varnish 8. Because the width of the air gap is very small, it is preferred to use a dispensing syringe for filling.

[0026] After the inductor is manufactured, it is generally required to undergo reflow testing and electrical testing. If the tests are qualified, it will be packaged.

[0027] The present application has not made any basic changes to the shape and structure of the magnetic cover 1, the "J"-shaped inductor sheet 2 and the magnetic core 3. An epoxy resin glue 6 of the third hardness is provided in the air gap between the magnetic cover 1 and the top of the magnetic core 3. The hardness is relatively hard and the fixing effect is better. The purpose is to fix the magnetic cover 1 and the magnetic core 3 well to prevent the inductor from separating during reflow soldering. In order to solve the technical problem that the inductor generates vibration noise due to magnetostriction when working with a large current, firstly, an epoxy resin glue 4 of the first hardness is provided between the bottom of the "J"-shaped inductor sheet 2 and the inner wall of the magnetic cover 1, and an epoxy resin glue 7 of the fourth hardness is provided in close proximity to the epoxy resin glue 6 of the third hardness. The hardness of the glue at these two places is relatively soft, which can offset part of the vibration generated by the magnetostriction of the inductor, absorb part of the vibration energy, and play a role in reducing noise; secondly, the current direction on the inductor sheet is perpendicular to the direction of the magnetic lines of force of the magnetic core 3, so the magnetostriction phenomenon in the direction of the magnetic lines of force of the magnetic core 3 It is particularly obvious that, for this reason, an epoxy resin glue 5 of the second hardness is set in the air gap where the magnetic core 3 and the magnetic cover 1 directly cooperate. The hardness is relatively soft, forming a good vibration damping surface, which can offset part of the vibration caused by the magnetostriction of the inductor, and play a role in further reducing noise; thirdly, there will still be voids in some air gaps inside the magnetic cover 1, which is also one of the reasons why magnetostriction will generate noise. The present application fills the air gaps between the magnetic cover 1 and the side of the magnetic core 3, and between the magnetic cover 1 and the side of the "X"-shaped inductor sheet 2 with self-drying varnish 8. After the voids are filled, it plays a third role in offsetting vibration and reducing noise.

[0028] After testing, the inductor described in this application generates noise less than 2.5acum when working in the power circuit of the computer motherboard CPU and the graphics card GPU, which performs well, indicating that the inductor structure and process really play a role.

[0029] The above are all preferred embodiments of the present application, and the protection scope of the present application is not limited thereto. Therefore, any equivalent changes made according to the structure, shape, and principle of the present application should be included in the protection scope of the present application.

Claims

1. A low-noise assembled chip inductor, comprising a magnetic cover (1), an "X"-shaped inductor sheet (2) and a magnetic core (3), wherein one side of the magnetic cover (1) is provided with an embedding groove (11) inwardly, the "X"-shaped inductor sheet (2) is arranged in the embedding groove (11), and the magnetic core (3) is arranged in the "X"-shaped inductor sheet (2) and the magnetic cover (1), characterized in that: An epoxy resin glue (4) of a first hardness is provided between the inner wall at the bottom of the "X"-shaped inductor sheet (2) and the bottom surface of the magnetic core (3); an epoxy resin glue (5) of a second hardness is provided at the air gap where the magnetic core (3) and the magnetic cover (1) directly cooperate; an epoxy resin glue (6) of a third hardness is provided at the air gap between the magnetic cover (1) and the top of the magnetic core (3); an epoxy resin glue (7) of a fourth hardness is provided at the air gap between the magnetic core (3) and the top of the "X"-shaped inductor sheet (2); and self-drying varnish (8) is provided in the air gap between the magnetic cover (1) and the side of the magnetic core (3), and between the magnetic cover (1) and the side of the "X"-shaped inductor sheet (2); the first hardness is 40-50D, the second hardness is 40-50D, the third hardness is 80-85D, and the fourth hardness is 40-50D.

2. The low-noise assembled chip inductor according to claim 1, characterized in that: The epoxy resin glue (5) of the second hardness is distributed into glue areas at multiple points by means of steel mesh scraping, and is arranged in multiple rows and columns along the width direction of the magnetic core (3).

3. The low-noise assembled chip inductor according to claim 2, characterized in that: The glue area of ​​each point is greater than or equal to 1 square millimeter.

4. The low-noise assembled chip inductor according to claim 1, characterized in that: The material of the magnetic cover (1) and the material of the magnetic core (3) are both ferrite manganese-zinc materials; the material of the X-shaped inductor sheet (2) is tinned copper strip.

5. A method for preparing the low-noise assembled chip inductor according to any one of claims 1 to 4, characterized in that: Includes steps: S1, providing a magnetic cover (1), a cross-shaped inductor sheet (2) and a magnetic core (3); S2, applying epoxy resin glue (4) of the first hardness on the bottom inner wall of the "X"-shaped inductor sheet (2), and then inserting it into the embedding groove (11) of the magnetic cover (1); S3, brushing epoxy resin glue (5) of the second hardness on the two sides of the magnetic core (3) and the magnetic cover (1) that directly match each other, and then inserting them into the embedding groove (11) and the cross-shaped inductor sheet (2); S4, applying epoxy resin glue (6) of the third hardness at the air gap between the magnetic cover (1) and the top of the magnetic core (3); S5, applying epoxy resin glue (7) of the fourth hardness at the air gap between the magnetic core (3) and the top of the X-shaped inductor sheet (2); S6, drying to cure all the glue; S7, injecting self-drying varnish (8) into the air gap between the magnetic cover (1) and the side of the magnetic core (3), and between the magnetic cover (1) and the side of the "X"-shaped inductor sheet (2), so that the self-drying varnish (8) fills the remaining air gap.

6. The method for preparing the low-noise assembled chip inductor according to claim 5, characterized in that: In step S3, six glue areas are printed using a steel mesh and arranged in three rows and two columns along the width direction of the magnetic core (3), with the area of ​​the glue area at each point being greater than or equal to 1 square millimeter.

7. The method for preparing the low-noise assembled chip inductor according to claim 5, characterized in that: In step S4, epoxy resin glue (6) of the third hardness is applied at the air gap between the magnetic cover (1) and the top of the magnetic core (3) to a width between half and two thirds of the width of the magnetic core (3).

8. The method for preparing the low-noise assembled chip inductor according to claim 7, characterized in that: In step S5, epoxy resin glue (7) of the fourth hardness is applied to the air gap between the magnetic core (3) and the top of the cross-shaped inductor sheet (2) to a width between half and two-thirds of the length of the magnetic core (3).

9. The method for preparing the low-noise assembled chip inductor according to claim 5, characterized in that: In step S6, the drying temperature is 130-140°C and the drying time is 1H.

10. The method for preparing the low-noise assembled chip inductor according to claim 5, characterized in that: In step S7, a dispensing syringe is used to perform a filling operation.

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