A low-noise assembled chip inductor and its preparation method

Abstract

The present application relates to a low-noise assembled patch inductor and a preparation method thereof. The inductor includes a magnetic shield, a U-shaped inductor chip, and a magnetic core. An epoxy resin glue with a first hardness is provided between the inner wall of the bottom of the U-shaped inductor chip and the bottom surface of the magnetic core; an epoxy resin glue with a second hardness is provided at the air gap where the magnetic core directly cooperates with the magnetic shield; an epoxy resin glue with a third hardness is provided at the air gap between the top of the magnetic shield and the magnetic core; an epoxy resin glue with a fourth hardness is provided at the air gap between the magnetic core and the top of the U-shaped inductor chip; self-drying varnish is provided at the air gaps between the side surfaces of the magnetic core and the magnetic shield and between the side surfaces of the magnetic shield and the U-shaped inductor chip; the first hardness, the second hardness, and the fourth hardness are 40-50D, and the third hardness is 80-85D. The epoxy resin glue with the third hardness is harder and has a better fixing effect, effectively preventing the inductor from separating during reflow soldering; the three soft glues and the self-drying varnish are provided to offset vibration and reduce noise.

Description

Technical Field

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

[0002] With the increase in the main frequency and power of computer CPUs and graphics card GPUs, higher requirements are put forward for the inductors used. For example, they should have a high saturation current and be able to withstand a high peak current without entering the saturation state, which is very important for supporting rapidly changing loads (such as the switching of the processor between different tasks); they should have a low DC resistance (DCR), and a lower DC resistance means less energy loss converted into heat, which helps to improve the power supply efficiency and reduce heat generation; they should 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 operation ability, the inductor will cause magnetostriction in the magnetic core due to the change in the magnitude of the current when working under a large current (heavy load). Magnetostriction refers to the phenomenon that the length of the magnetic core repeatedly expands and contracts under the action of an alternating magnetic field when the magnetic core is under the action of a magnetic field, thereby generating vibration or sound waves. This vibration is the noise heard by the human ear (with a frequency in the range of 20 Hz - 20 KHz). The occurrence of noise is basically unsolvable or cannot be fundamentally eliminated. In the prior art, the noise is generally reduced by improving the magnetic materials (magnetic shields and magnetic cores) and the production process, but the satisfactory effect has not been achieved yet, and there is still room for improvement. Summary of the Invention

[0004] In order to solve the technical problem that the inductor in the prior art is prone to generate relatively large noise when working under a large 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 this application is as follows: A low-noise assembled chip inductor includes a magnetic cover, a U-shaped inductor chip, and a magnetic core. An embedded groove is provided inwardly on one side of the magnetic cover. The U-shaped inductor chip is arranged in the embedded groove, and the magnetic core is arranged within the U-shaped inductor chip and the magnetic cover. There is an epoxy resin glue with a first hardness between the inner bottom wall of the U-shaped inductor chip and the bottom surface of the magnetic core. There is an epoxy resin glue with a second hardness at the air gap where the magnetic core directly mates with the magnetic cover. There is an epoxy resin glue with a third hardness at the air gap between the top of the magnetic cover and the magnetic core. There is an epoxy resin glue with a fourth hardness at the air gap between the top of the magnetic core and the U-shaped inductor chip. The air gaps between the side surfaces of the magnetic cover and the magnetic core, and between the side surfaces of the magnetic cover and the U-shaped inductor chip are filled with self-drying varnish. 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. All the above hardness values are Shore A hardness values.

[0006] By adopting the above technical solution, this application basically does not modify the shapes and structures of the magnetic cover, the U-shaped inductor chip, and the magnetic core. An epoxy resin glue with a third hardness is provided at the air gap between the top of the magnetic cover and 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. To solve the technical problem of vibration noise generated by the magnetostriction phenomenon when the inductor operates at high current, first, an epoxy resin glue with a first hardness is provided between the bottom of the U-shaped inductor chip and the inner wall of the magnetic cover, and an epoxy resin glue with a fourth hardness is provided at the air gap between the top of the magnetic core and the U-shaped inductor chip (i.e., adjacent to the epoxy resin glue with a third hardness). The hardness of the glue at these two places is relatively soft, which can offset part of the vibration generated during the magnetostriction of the inductor and absorb part of the vibration energy, playing a role in reducing noise. Secondly, the current direction on the inductor chip is perpendicular to the magnetic force line direction of the magnetic core. Therefore, the magnetostriction phenomenon is particularly obvious in the direction of the magnetic force lines of the magnetic core. For this reason, an epoxy resin glue with a second hardness is particularly provided at the air gap where the magnetic core directly mates with the magnetic cover. The hardness is relatively soft, forming a good vibration damping surface, which can offset part of the vibration generated during the magnetostriction of the inductor, playing a role in further reducing noise. Thirdly, there will still be voids in some of the air gaps inside the magnetic cover, which is also one of the reasons for the noise generated by magnetostriction. This application fills the air gaps between the side surfaces of the magnetic cover and the magnetic core, and between the side surfaces of the magnetic cover and the U-shaped inductor chip with self-drying varnish. After the voids are filled, it plays a role in offsetting vibration and reducing noise for the third time.

[0007] After testing, when the inductor described in this application operates in the power circuits of the CPU and GPU on the computer motherboard, the generated noise is lower than 2.5acum, and the performance is excellent, indicating that the inductor structure and process have truly played a role.

[0008] Optionally, the epoxy resin glue with the second hardness is dispensed into a glue area of multiple dots by screen printing through a steel mesh, and is arranged in multiple rows and columns along the width direction of the magnetic core.

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

[0010] Optionally, the magnetic shield material and the magnetic core material are both ferrite manganese zinc materials; the material of the U-shaped inductive chip is tinned copper tape.

[0011] On the other hand, the present application also provides the following technical solution: a preparation method of the low-noise assembled surface-mount inductor described above, including the steps of:

[0012] S1, providing a magnetic shield, a U-shaped inductive chip and a magnetic core;

[0013] S2, dotting epoxy resin glue with the first hardness on the inner wall of the bottom of the U-shaped inductive chip, and then loading it into the slot of the magnetic shield;

[0014] S3, brushing epoxy resin glue with the second hardness on the two side surfaces where the magnetic core directly mates with the magnetic shield, and then loading it into the slot and the U-shaped inductive chip;

[0015] S4, dotting epoxy resin glue with the third hardness at the air gap between the top of the magnetic shield and the magnetic core;

[0016] S5, dotting epoxy resin glue with the fourth hardness at the air gap between the top of the magnetic core and the U-shaped inductive chip (i.e., adjacent to the epoxy resin glue with the third hardness);

[0017] S6, drying to cure all the glue;

[0018] S7, injecting air-drying varnish into the air gaps between the side surfaces of the magnetic shield and the magnetic core and between the side surfaces of the magnetic shield and the U-shaped inductive chip, so that the air-drying varnish fills the remaining air gaps.

[0019] Optionally, in step S3, six dots of glue areas are screen-printed through a steel mesh, and are divided into three rows and two columns along the width direction of the magnetic core, and the area of the glue area of each dot is greater than or equal to 1 square millimeter.

[0020] Optionally, in step S4, the width of the epoxy resin glue with the third hardness dotted at the air gap between the top of the magnetic shield and the magnetic core is between half and two-thirds of the width of the magnetic core.

[0021] Optionally, in step S5, the width of the epoxy resin glue with the fourth hardness dotted at the air gap between the top of the magnetic core and the U-shaped inductive chip is between half and two-thirds of the length of the magnetic core.

[0022] Optionally, in step S6, the drying temperature is 130 - 140 °C, and the drying time is 1H.

[0023] Optionally, in step S7, a dispensing syringe is used for the filling operation.

[0024] In summary, the present application includes at least one of the following beneficial technical effects:

[0025] 1. The present application is provided with an epoxy resin glue with a third hardness at 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, preventing the inductor from separating during reflow soldering.

[0026] 2. The present application is provided with an epoxy resin glue with a first hardness, an epoxy resin glue with a second hardness, and an epoxy resin glue with a fourth hardness. The hardness of the glue at these three places is relatively soft, which can offset part of the vibration generated during the magnetostriction of the inductor and absorb part of the vibration energy, playing a role in reducing noise.

[0027] 3. The present application fills the air gap between the side of the magnetic cover and the magnetic core, and between the magnetic cover and the side of the U-shaped inductor chip with self-drying varnish. After the voids are filled, it plays a role in offsetting vibration and reducing noise for the third time. Description of the Drawings

[0028] Figure 1 is a perspective view of the inductor according to the embodiment of the present application;

[0029] Figure 2 is a semi-sectional structural schematic diagram of the inductor according to the embodiment of the present application;

[0030] Figure 3 is a schematic diagram of the state of applying the epoxy resin glue with the first hardness on the U-shaped inductor chip in the method according to the embodiment of the present application;

[0031] Figure 4 is a schematic diagram of loading the U-shaped inductor chip into the magnetic cover in the method according to the embodiment of the present application;

[0032] Figure 5 is a schematic diagram of the state of scraping and printing the epoxy resin glue with the second hardness on the magnetic core in the method according to the embodiment of the present application;

[0033] Figure 6 is a schematic diagram of loading the magnetic core into the U-shaped inductor chip and the magnetic cover in the method according to the embodiment of the present application;

[0034] Figure 7 is a schematic diagram of the state after applying the epoxy resin glue with the third hardness in the method according to the embodiment of the present application;

[0035] Figure 8 is a schematic diagram of the state after applying the epoxy resin glue with the fourth hardness in the method according to the embodiment of the present application;

[0036] Figure 9 It is a schematic diagram of the state after filling with self-drying varnish in the method described in the embodiments of the present application.

[0037] Explanation of reference numerals: 1. Magnetic cover; 11. Embedded groove; 2. U-shaped inductor chip; 3. Magnetic core; 4. Epoxy resin glue with the first hardness; 5. Epoxy resin glue with the second hardness; 6. Epoxy resin glue with the third hardness; 7. Epoxy resin glue with the fourth hardness; 8. Self-drying varnish. Detailed implementation manners

[0038] The following further describes the present application in detail Figures 1 to 9 in conjunction with the accompanying drawings.

[0039] Referring to Figure 1 , Figure 2 and Figure 5 , an embodiment of the present application discloses a low-noise assembled chip inductor, which includes a magnetic cover 1, a U-shaped inductor chip 2 and a magnetic core 3. An embedded groove 11 is provided inwardly on one side of the magnetic cover 1. The U-shaped inductor chip 2 is arranged in the embedded groove 11, and the magnetic core 3 is arranged in the U-shaped inductor chip 2 and the magnetic cover 1. The U-shaped inductor chip 2 functions as an inductor coil. The above is the conventional structure of the inductor in the prior art. In the present application, an epoxy resin glue 4 with the first hardness is provided between the inner wall of the bottom of the U-shaped inductor chip 2 and the bottom surface of the magnetic core 3; an epoxy resin glue 5 with the second hardness is provided at the air gap where the magnetic core 3 is directly in contact with the magnetic cover 1; an epoxy resin glue 6 with the third hardness is provided at the air gap between the top of the magnetic cover 1 and the magnetic core 3; an epoxy resin glue 7 with the fourth hardness is provided at the air gap between the top of the magnetic core 3 and the U-shaped inductor chip 2 (i.e., adjacent to the epoxy resin glue 6 with the third hardness); self-drying varnish 8 is provided at the air gaps between the side surfaces of the magnetic cover 1 and the magnetic core 3, and between the side surfaces of the magnetic cover 1 and the U-shaped inductor chip 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.

[0040] Referring to Figure 5 , the epoxy resin glue 5 with the second hardness is dispensed into a glue area of multiple points by screen printing with a steel mesh, and is arranged in multiple rows and columns along the width direction of the magnetic core 3. The area of each point of the glue area is greater than or equal to 1 square millimeter. Vibration reduction with multiple points uses less glue material than vibration reduction of the entire surface, and has a better vibration reduction effect for high-frequency vibration. The area of each point of the glue area can also be designed differently and can be adjusted according to the actual situation of vibration.

[0041] In this embodiment, the materials of the magnetic cover 1 and the magnetic core 3 are preferably ferrite manganese zinc materials, which have the characteristic of high saturation power; the material of the U-shaped inductor chip 2 is tinned copper strip, which is first stamped and then electroplated to achieve a lower DCR (direct current resistance).

[0042] The preparation method of the low-noise assembled patch inductor described in this embodiment includes the following steps:

[0043] S1. Provide a magnetic shield 1, a U-shaped inductor chip 2, and a magnetic core 3;

[0044] S2. Refer to Figure 3 , apply epoxy resin glue 4 with the first hardness at the inner bottom wall of the U-shaped inductor chip 2, refer to Figure 4 , and then install it into the slot 11 of the magnetic shield 1;

[0045] S3. Refer to Figure 5 , brush epoxy resin glue 5 with the second hardness on two side surfaces where the magnetic core 3 directly mates with the magnetic shield 1. In this embodiment, six dot glue areas can be scraped out by using a stencil. Along the width direction of the magnetic core 3, they are arranged in three rows and two columns. The area of each dot glue area is greater than or equal to 1 square millimeter; refer to Figure 6 , and then install it into the slot 11 and the U-shaped inductor chip 2; The epoxy resin glue 5 with the second hardness is extruded by the magnetic core 3 and diffuses around to fill some of the surrounding voids, forming a soft glue layer between the magnetic shield 1, the magnetic core 3, and the U-shaped inductor chip 2;

[0046] S4. Refer to Figure 7 , apply epoxy resin glue 6 with the third hardness at the air gap between the top of the magnetic shield 1 and the magnetic core 3; In this embodiment, the width of the epoxy resin glue 6 with the third hardness applied at the air gap between the top of the magnetic shield 1 and the magnetic core 3 is between half and two-thirds of the width of the magnetic core 3. It should ensure sufficient dot glue mating length to avoid the problem of insufficient fixing force, but it cannot completely cover the air gap and cannot affect the subsequent dot glue of the soft glue and the filling of the self-drying varnish 8;

[0047] S5. Refer to Figure 8 , apply epoxy resin glue 7 with the fourth hardness at the air gap between the top of the magnetic core 3 and the U-shaped inductor chip 2 (i.e., adjacent to the epoxy resin glue 6 with the third hardness), which is also a soft glue and plays a role in vibration damping; In this embodiment, the width of the epoxy resin glue 7 with the fourth hardness applied at the air gap between the top of the magnetic core 3 and the U-shaped inductor chip 2 is between half and two-thirds of the length of the magnetic core 3. It is necessary to ensure sufficient glue amount to ensure the vibration damping effect, and at the same time, avoid completely blocking the air gap so that the gas inside the magnetic shield 1 cannot be released. Once there is gas inside, it will expand when heated during reflow soldering, which may cause poor floating of the magnetic shield 1.

[0048] S6. Perform drying to cure all the glues. In this embodiment, the drying temperature is 130 - 140 °C, and the drying time is 1H;

[0049] S7. Refer to Figure 9, pour injecter de la vernis auto - séchant 8 dans les fentes d'air entre la coque magnétique 1 et le côté latéral de la bobine magnétique 3, ainsi que dans les fentes d'air entre la coque magnétique 1 et le côté latéral de la lame d'inductance en forme de C 2. Le vernis auto - séchant a une bonne fluidité et peut remplir les fentes d'air restantes. Étant donné que la largeur de la fente d'air est très petite, il est préférable d'utiliser une seringue à colle pour effectuer l'opération de remplissage.

[0050] Après la fabrication de l'inductance, il est généralement nécessaire de procéder à des tests de soudage au four à convection et des tests électriques. Si les tests sont tous réussis, l'inductance est emballée.

[0051] Dans la présente demande, les formes et les structures de la coque magnétique 1, de la lame d'inductance en forme de C 2 et de la bobine magnétique 3 ne sont pas sensiblement modifiées. Il y a de la colle d'époxy de troisième dureté 6 dans la fente d'air entre le sommet de la coque magnétique 1 et la bobine magnétique 3. Elle est assez dure et a un meilleur effet de fixation. Le but est de bien fixer la coque magnétique 1 et la bobine magnétique 3 pour empêcher la séparation de l'inductance lors du soudage au four à convection. Pour résoudre le problème technique du bruit de vibration généré par le phénomène de magnétostriction lorsque l'inductance fonctionne à forte intensité de courant, tout d'abord, il y a de la colle d'époxy de première dureté 4 entre le fond de la lame d'inductance en forme de C 2 et la paroi interne de la coque magnétique 1, et il y a de la colle d'époxy de quatrième dureté 7 à proximité immédiate de la colle d'époxy de troisième dureté 6. Les deux colle sont assez molles et peuvent annuler une partie des vibrations générées par la magnétostriction de l'inductance et absorber une partie de l'énergie de vibration, ce qui joue un rôle dans la réduction du bruit. Deuxièmement, la direction du courant sur la lame d'inductance est perpendiculaire à la direction des lignes de force magnétiques de la bobine magnétique 3. Par conséquent, le phénomène de magnétostriction est particulièrement évident dans la direction des lignes de force magnétiques de la bobine magnétique 3. Pour cela, il y a spécifiquement de la colle d'époxy de deuxième dureté 5 dans la fente d'air où la bobine magnétique 3 est directement en contact avec la coque magnétique 1. Elle est assez molle et forme une bonne surface antivibratoire, qui peut annuler une partie des vibrations générées par la magnétostriction de l'inductance et joue un rôle supplémentaire dans la réduction du bruit. Troisièmement, il y aura toujours des cavités dans une partie des fentes d'air à l'intérieur de la coque magnétique 1, ce qui est également l'une des raisons pour lesquelles le magnétostriction produit du bruit. Dans la présente demande, on remplit les fentes d'air entre la coque magnétique 1 et le côté latéral de la bobine magnétique 3, ainsi que les fentes d'air entre la coque magnétique 1 et le côté latéral de la lame d'inductance en forme de C 2 avec de la vernis auto - séchant 8. Après que les cavités sont remplies, cela joue un troisième rôle dans l'annulation des vibrations et la réduction du bruit.

[0052] Après des tests, le bruit généré par l'inductance décrite dans la présente demande est inférieur à 2,5 acum lors du fonctionnement dans les circuits d'alimentation du processeur CPU et de la carte graphique GPU de la carte mère d'ordinateur, ce qui indique de bonnes performances et montre que la structure et le procédé de l'inductance ont réellement joué leur rôle.

[0053] Tout ceci sont les exemples de réalisation optimaux de la présente demande, et ne limitent pas la portée de protection de la présente demande. Donc : toutes les variations équivalentes faites selon la structure, la forme et le principe de la présente demande devraient être incluses dans la portée de protection de la présente demande.

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 magnetic cover (1) and the magnetic core (3) are both made of ferrite manganese-zinc material; and 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 the 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 the six glue areas are arranged in three rows and two columns along the width direction of the magnetic core (3), and the area of ​​the glue area of ​​each point is 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, at the air gap between the magnetic cover (1) and the top of the magnetic core (3), the epoxy resin glue (6) of the third hardness is applied with a glue length between half and two thirds of the length 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, at the air gap between the magnetic core (3) and the top of the cross-shaped inductor sheet (2), the epoxy resin glue (7) of the fourth hardness is glued to a length between half and two thirds of the width 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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