JP2006073868A - Manufacturing method of micro power converter - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide the manufacturing method of a micro power converter, wherein when cutting it, the generations of its burrs, cracks, and peelings are so prevented as to enhance the fastening strength of its thin-film magnetic induction element and to improve its reliability. <P>SOLUTION: In the manufacturing method of the micro power converter after forming its coils and its terminal electrodes, each second groove 12 having a wide width and each first groove 11 contacting with each second groove 12 are formed in its ferrite base material 100 by a dicing saw. Consequently, burrs formed in its first and second terminal electrodes 5, 6 are made small so as to be able to prevent the generation of cracks of its ferrite base material 100 and the peeling of its protective resin 8. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to a method for manufacturing a micro power converter in which a coil is formed on a ferrite substrate and a semiconductor chip is fixed thereon.

In recent years, electronic information devices, in particular, various portable electronic information devices have been widely used. Many of these electronic information devices use a battery as a power source, and incorporate a power conversion device such as a DC-DC converter. Usually, the power conversion device is composed of functional elements such as switching elements, rectifier elements, control ICs, and passive components such as coils, transformers, capacitors, resistors, etc., on a printed circuit board such as a ceramic substrate or plastic. It is configured as a hybrid type module.
There is a strong demand for miniaturization of this power converter, and in recent years, a thin film magnetic induction element or the like is mounted as a coil to achieve ultra miniaturization.
FIG. 8 is a configuration diagram of a conventional thin-film magnetic induction element mounted on a micro power converter, in which FIG. 8 (a) is a plan view of an essential part, and FIG. 8 (b) is an X- The principal part sectional drawing cut | disconnected by the X-ray | X_line and the same figure (c) are the principal part sectional drawings cut | disconnected the same figure (a) by the YY line | wire.

In this thin film magnetic induction element, a first conductor 52 is formed on the surface of the ferrite substrate 51, a second conductor 53 is formed on the back surface, and the first conductor 52 and the second conductor 53 pass through the ferrite substrate 51. The conductor 54 is connected to form a solenoidal coil, and the first conductor 52 and the second conductor 53 are covered with a protective resin 58 such as a resist, and the first terminal electrode 55 is formed on the periphery of the first main surface of the ferrite substrate 51. The second terminal electrode 56 is formed on the periphery of the second main surface, and the second connection conductor 57 that connects the first terminal electrode 55 and the second terminal electrode 56 is formed.
Although not shown, a semiconductor chip (not shown) having an integrated circuit formed on the first main surface side of the ferrite substrate 51 of the thin film magnetic induction element is connected via a bump, and a second terminal electrode 56 formed on the second main surface is provided. Thus, an electronic component such as a multilayer ceramic capacitor array (not shown) is fixed to the second main surface to form a micro power converter.

The thin-film magnetic induction element used in this microminiature power converter is a large-area ferrite base material 200 (after being cut, becomes a ferrite substrate 51) shown in FIG. 8 (b) and FIG. 8 (c). A plurality of solenoidal coils are formed, and the first and second metal films 55a and 56a to be the first and second terminal electrodes 55 and 56 are formed so as to surround the coils. Formed on the surface and the second main surface, respectively. Further, the central portions of the metal films 55 a and 56 a are connected by a second connection conductor 57 formed in a through hole penetrating the ferrite base material 200. A dicing saw 71 cuts a straight line passing through the central portion of the second connection conductor 57. After cutting, the first and second metal films 55a and 56a become the first terminal electrode 55 and the second terminal electrode 56, respectively.
As described above, the protective resin 58 and the ferrite in which the large-area ferrite base material 200 is coated with the first and second metal films 55a and 56a on the first and second main surfaces on a straight line passing through the second connection conductor 57. Cutting the substrate 200 is disclosed in Patent Document 1 (however, in Patent Document 1, the coil is a toroidal endless solenoid). This cutting is usually performed by attaching the second main surface of the ferrite base material 200 to a dicing sheet, and connecting the first and second metal films 55a and 56a, the protective resin 58, and the ferrite base material 200 to the second connection. Cut along the straight line passing through the conductor 57 from the first main surface to the second main surface with the dicing saw 71 once.

Further, although different from the above, Patent Document 2 discloses a method of cutting from both sides of a semiconductor chip so that the end of the semiconductor chip is not chipped when the semiconductor chip is cut out from the semiconductor wafer.
Japanese Patent Laid-Open No. 2004-72815 FIG. Japanese Patent Laid-Open No. 6-89936 FIG. 1 and FIG.

However, as disclosed in Patent Document 1, when cut along a straight line passing through the second connection conductor 57, the first and second metal films are formed at the portion A in FIG. 8A as shown in FIG. 8B. 55a, 56b and the metal that is the second connection conductor 57 are cut by the dicing saw 71, while in the portion B of FIG. 8 (a), the protective resin 58 and the ferrite base material as shown in FIG. 8 (c). 200 is cut with a dicing saw 71. When the cutting conditions of the dicing saw 71 are matched to the ferrite base material 200, large burrs 72 are generated as shown in FIG. 9 on the cut surfaces of the first and second metal films 55a and 56b and the second connection conductor 57, Further, when combined with a metal, a crack 74 may be generated in the ferrite substrate 51 at the time of cutting as shown in FIG. 10, or peeling 75 may occur between the ferrite substrate 51 and the protective resin 58 as shown in FIG.
Moreover, when it is disclosed in Patent Document 2, it is necessary to form dedicated markers for matching the cut-out lines on the front surface and the back surface of the semiconductor chip.

  The object of the present invention is to solve the above-mentioned problems, prevent the occurrence of burrs, cracks and peeling at the time of cutting a dicing saw, increase the fixing strength of the thin-film magnetic induction element, and improve the reliability. An object of the present invention is to provide a manufacturing method of a micro power converter.

To achieve the above object, the magnetic insulating substrate and the first conductor formed on the first main surface of the magnetic insulating substrate or the second conductor formed on the second main surface of the magnetic insulating substrate. A first conductor formed on the first main surface of the magnetic insulating substrate, a second conductor formed on the second main surface of the magnetic insulating substrate, and a connection conductor formed in a through-hole penetrating the magnetic insulating substrate. A plurality of coil conductors connected to each other, and a plurality of outer peripheral portions of the first main surface and the second main surface of the magnetic insulating substrate, respectively, and connected to each other through a second connecting conductor penetrating the magnetic insulating substrate; An ultra-thin magnetic induction element comprising a first terminal electrode and a second terminal electrode facing each other across the magnetic insulating substrate, and a protective resin covering the first and second conductors and the magnetic insulating substrate. In the manufacturing method of the small power converter,
A step of forming a plurality of the thin-film magnetic induction elements on a magnetic insulating base material to be cut into a plurality of magnetic insulating substrates, a metal film to be the two adjacent second terminal electrodes, and the protective resin Forming a second groove on a straight line passing through the central portion of the metal film on the magnetic insulating substrate, and the adjacent first terminal electrode is formed to face each other with the protective resin interposed therebetween, and the protection And a step of separating the thin film magnetic induction element into a single piece by forming a linear first groove reaching the linear second groove on the magnetic insulating base material under the protective resin and the protective resin The method.

The width of the second groove may be wider than the width of the first groove.
The depth of the second groove may be less than half the thickness of the thin film magnetic induction element.
The first groove and the second groove may be formed with a dicing saw.
Further, the first main body of the magnetic insulating substrate comprising a magnetic insulating substrate and a first conductor formed on the first main surface of the magnetic insulating substrate or a second conductor formed on the second main surface of the magnetic insulating substrate. A coil conductor formed by connecting a first conductor formed on a surface, a second conductor formed on a second main surface of the magnetic insulating substrate, and a connection conductor formed in a through hole penetrating the magnetic insulating substrate. And a plurality of outer peripheral portions of the first main surface and the second main surface of the magnetic insulating substrate, which are connected to each other through a second connection conductor penetrating the magnetic insulating substrate and sandwiching the magnetic insulating substrate. Manufacturing method of micro power converter having thin-film magnetic induction element comprising first terminal electrode and second terminal electrode opposed to each other, and protective resin covering first and second conductors and magnetic insulating substrate In
A step of forming a plurality of the thin-film magnetic induction elements on a magnetic insulating base material that is cut into a plurality of parts and serving as the magnetic insulating substrate, and two adjacent first terminal electrodes are opposed to each other with the protective resin interposed therebetween The two adjacent second terminal electrodes are formed opposite to each other with the protective resin interposed therebetween, and the center of the protective resin is sandwiched between the adjacent first and second terminal electrodes. And cutting the protective resin and the magnetic insulating base material under the protective resin on a straight line passing through the section to separate the thin film magnetic induction element into a single unit.

According to this invention, cutting is performed in two steps from the first main surface side and the second main surface side, thereby reducing stress due to cutting and reducing the amount of burr protrusion of the terminal electrode to less than half the conventional amount. can do. At that time, it is not necessary to newly provide a marker necessary for the position at the time of cutting.
Also, cracks in the ferrite substrate and peeling between the protective resin and the ferrite substrate can be prevented.
In addition, by using protective resin and ferrite base material instead of the terminal electrode as a cutting point, no burrs are generated, and cracks generated in the ferrite substrate and peeling between the protective resin and the ferrite substrate are prevented. Can do.
As a result, the tensile breaking strength (shear strength: adhesion strength by solder or the like) of the thin film magnetic induction element is about 1.5 times that of the conventional one, and a highly reliable micro power converter can be manufactured.

  The best mode of implementation will be described with reference to the following examples.

1 to 4 are diagrams showing a method for manufacturing a micro power conversion device according to a first embodiment of the present invention, which are process diagrams shown in the order of steps, in which FIG. (B) is principal part sectional drawing cut | disconnected by the XX line of the figure (a). Here, the semiconductor chip fixed on the ferrite substrate is not shown, and only the thin film magnetic induction element is shown.
A plurality of coil conductors and a plurality of terminal electrodes are formed on the ferrite base material 100 (which becomes the ferrite substrate 1 after cutting) so as to surround the coil conductors on the ferrite base material 100 having a thickness of about 500 μm. The coil conductor includes a first conductor 2 formed on the first main surface of the ferrite base material 100, a second conductor 3 formed on the second main surface of the ferrite base material 100, and the first and second conductors 2, 3 and a first connection conductor 4 formed in a through hole opened in the ferrite base material 100 connecting the three. The terminal electrode includes a first terminal electrode 5 formed on the first main surface of the ferrite base material 100, and a second main surface of the ferrite base material 100 at a position facing the first terminal electrode 5 with the ferrite base material 100 interposed therebetween. The metal film 6a to be the second terminal electrode 6 and the second connection conductor 7 formed in the through-hole formed in the ferrite base material 100 connecting the first and second terminal electrodes 5 and 6 to each other. Is done. A protective resin 8 such as a resist is formed on the first conductor 2 and the first main surface of the ferrite base material 100, and on the second conductor 3 and the second main surface of the ferrite base material 100, respectively. The first terminal electrode 5 is separated from the adjacent first terminal electrode 5, and a protective resin 8 is coated on the separated portion. On the other hand, the second terminal electrode 6 is formed of one metal film 6a with the adjacent second terminal electrode 6 (FIG. 1).

Next, the center portion of the metal film 6a is cut with a dicing saw to form the second terminal electrode 6, and the second groove 12 is formed so as to reach the ferrite substrate 100 with this dicing saw. At this time, the depth of the second groove 12 formed in the ferrite base material 100 is half the thickness of the ferrite base material 100 in order to ensure the strength of the ferrite base material 100 after the second groove 12 is formed. The following is recommended. Here, the depth of the second groove 12 is about 50 μm to 100 μm (1/10 to 1/5 of the thickness of the ferrite base material 100), and the width is about 120 μm to 150 μm. The cutting conditions of the dicing saw are matched to the metal (FIG. 2).
Next, a first groove 11 that reaches the second groove 12 is formed with a dicing saw at a location covered by the protective resin 8 between the adjacent first terminal electrodes 5, and the ferrite base material 100 is cut. To do. At this time, the width of the first groove 11 is made smaller than the width of the second groove 12 to be about 100 μm. The reason why the first groove 11 is narrowed is to ensure that the ferrite base material 100 can be separated by the first groove 11 and the second groove 12 even if a positional shift occurs. Further, the second groove 12 is widened by positioning the second terminal electrode 6 inside the ferrite substrate 1 so as to be fixed to the second terminal electrode 6 (the side surface of the second terminal electrode 6 is also used for soldering). This is because electronic parts such as a multilayer ceramic capacitor array (not shown) can be miniaturized. The cutting conditions of the dicing saw are matched with the ferrite base material 100 (FIG. 3).

Next, after cutting, a semiconductor chip or electronic component (not shown) is fixed to the first main surface and the second main surface, and the ferrite substrate 1 is composed of the first conductor 2, the second conductor 3, and the first connection conductor. An ultra-compact power conversion device having a thin film magnetic induction element on which a solenoid coil is formed is completed (FIG. 4).
The second groove 12 is formed on the ferrite base material 100 before fixing a semiconductor chip (not shown) to the ferrite base material 100 with bumps, and the first groove 11 is formed in the final step. The ferrite base material 100 may be separated.
By using such a cutting method, the amount of protrusion of burrs formed on the first and second terminal electrodes 5 and 6 can be reduced to less than half that of the prior art. Further, cracks generated in the ferrite base material 100 and peeling between the protective resin 8 and the ferrite base material 100 are also prevented.

As a result, the fixing strength of the thin-film magnetic induction element (fixing strength by solder or the like) is about 1.5 times that of the conventional one, and a highly reliable micro power converter can be manufactured.
Moreover, the side surface of the 2nd terminal electrode 6 is exposed by setting it as such a cutting method. By exposing the side surface of the second terminal electrode 6, it is possible to increase the fixing strength by soldering with an electronic component such as a multilayer ceramic capacitor array (not shown).
In addition, when a thin film magnetic induction element is cut out from the ferrite base material 100, a dedicated marker for matching a cut-out line required when cutting out a semiconductor chip from a semiconductor wafer is the same as the first terminal electrode 5 on the surface side. Since the metal film 6a on the back surface is formed so as to face each other with the ferrite base material sandwiched therebetween, the protective resin 8 sandwiched between the first terminal electrodes 5 and the central part of the metal film 6a are respectively on the surface. And acts as a dedicated marker on the back. Therefore, it is not necessary to form a marker for cutting required in the process of cutting out a semiconductor chip from a semiconductor wafer, and the process of cutting out a thin film magnetic induction element requires fewer man-hours and lowers costs compared to the case of a semiconductor chip. Can do.

  The shape of the coil conductor constituting the thin-film magnetic induction element is a solenoid shape, but it may of course be a spiral shape (not shown) formed on the ferrite substrate 100.

FIGS. 5 to 7 are views showing a manufacturing method of the micro power converter according to the second embodiment of the present invention, which are process drawings shown in the order of steps, in which FIG. (B) is principal part sectional drawing cut | disconnected by the XX line of the figure (a). Here, the semiconductor chip fixed on the ferrite substrate is not shown, and only the thin film magnetic induction element is shown.
A plurality of coil conductors and a plurality of terminal electrodes are formed on the ferrite substrate 100 so as to surround the coil conductors on the ferrite substrate 100 having a thickness of about 500 μm. The coil conductor includes a first conductor 2 formed on the first main surface of the ferrite base material 100, a second conductor 3 formed on the second main surface of the ferrite base material 100, and the first and second conductors 2, 3 and a first connection conductor 4 formed in a through hole opened in the ferrite base material 100 connecting the three. The terminal electrode includes a first terminal electrode 5 formed on the first main surface of the ferrite base material 100, and a second main surface of the ferrite base material 100 at a position facing the first terminal electrode 5 with the ferrite base material 100 interposed therebetween. And the second connection conductor 7 formed in the through-hole formed in the ferrite base material 100 connecting the first and second terminal electrodes 5 and 9. A protective resin 8 such as a resist is formed on the first conductor 2, the first main surface of the ferrite base material 100, the second conductor 3, and the second main surface of the ferrite base material 100. The first terminal electrode 5 is separated from the adjacent first terminal electrode 5, and the second terminal electrode 9 is separated from the adjacent second terminal electrode 9. Protective resins 8 are respectively coated on the separation portions separating these terminals. The locations where these protective resins 8 are coated are at positions facing each other with the ferrite base material 100 sandwiched between the first main surface side and the second main surface side (FIG. 5).

Next, a portion covered with the protective resin 8 between the first terminal electrodes 5 adjacent on the first main surface is cut with a dicing saw, and the ferrite base material 100 is separated by the cutting portion 13. At this time, the cutting conditions of the dicing saw are matched to the ferrite base material 100 (FIG. 6).
Next, after cutting, a semiconductor chip or an electronic component (not shown) is fixed to the first main surface and the second main surface, and the ferrite substrate 1 is constituted by the first conductor 2, the second conductor 3, and the first connection conductor. An ultra-compact power conversion device having a thin film magnetic induction element formed with a solenoid coil is completed (FIG. 7).
In this cutting method, since the portions to be cut are the protective resin 8 and the ferrite base material 100, naturally there are no metal burrs, and by matching the cutting conditions to the ferrite base material 100, there is no crack in the ferrite base material 100. The introduction and the peeling of the protective resin 8 can be prevented.

In this case, since the metal is not cut, it is not necessary to change the cutting conditions of the dicing saw, and the cutting by the dicing saw is performed once from the first main surface to the second main surface.
This cutting may be performed in two steps as in the first embodiment. If it is performed twice, the introduction of cracks and the peeling of the protective resin are less likely to occur than in the case of one time.

BRIEF DESCRIPTION OF THE DRAWINGS It is process drawing of the micro power converter device of 1st Example of this invention, (a) is a principal part top view, (b) is principal part sectional drawing cut | disconnected by the XX line of (a). It is process drawing of the micro power converter of 1st Example of this invention following FIG. 1, (a) is a principal part top view, (b) is the principal part cut | disconnected by the XX line of (a). Cross section FIG. 3 is a process diagram of the micro power converter according to the first embodiment of the present invention, following FIG. 2, wherein (a) is a plan view of the main part, and (b) is a main part cut along line XX of (a). Cross section FIG. 4 is a process diagram of the micro power converter according to the first embodiment of the present invention, following FIG. 3, wherein (a) is a plan view of the main part, and (b) is a main part cut along line XX of (a). Cross section It is process drawing of the micro power converter of 2nd Example of this invention, (a) is a principal part top view, (b) is principal part sectional drawing cut | disconnected by the XX line of (a). FIG. 6 is a process diagram of the micro power converter according to the second embodiment of the present invention, following FIG. 5, wherein (a) is a plan view of the main part, and (b) is a main part cut along the line XX of (a). Cross section FIG. 7 is a process diagram of the micro power converter according to the second embodiment of the present invention, following FIG. 6, wherein (a) is a plan view of the main part, and (b) is a main part cut along line XX of (a). Cross section It is a block diagram of the conventional thin film magnetic induction element mounted in a micro power converter, (a) is a principal part top view, (b) is principal part sectional drawing which cut | disconnected (a) by the XX line, (C) is the principal part sectional drawing which cut | disconnected the same figure (a) by the YY line. Figure with large burrs generated during cutting A crack occurs in the ferrite substrate during cutting. Figure of separation between ferrite substrate and protective resin during cutting

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Ferrite board | substrate 2 1st conductor 3 2nd conductor 4 1st connection conductor 5 1st terminal electrode 6 2nd terminal electrode 6a Metal film 7, 9 2nd connection conductor 8 Protection resin 11 1st groove | channel 12 2nd groove | channel 13 Cutting Part 100 Ferrite base material

Claims (5)

On the first main surface of the magnetic insulating substrate comprising a magnetic insulating substrate and a first conductor formed on the first main surface of the magnetic insulating substrate or a second conductor formed on the second main surface of the magnetic insulating substrate A coil conductor formed by connecting the formed first conductor, the second conductor formed on the second main surface of the magnetic insulating substrate, and the connection conductor formed in the through hole penetrating the magnetic insulating substrate; A plurality of outer peripheral portions of the first and second main surfaces of the magnetic insulating substrate are connected to each other via second connection conductors that penetrate the magnetic insulating substrate, and face each other with the magnetic insulating substrate interposed therebetween. In a method for manufacturing a micro power converter having a first terminal electrode and a second terminal electrode, and a thin film magnetic induction element comprising a protective resin covering the first and second conductors and the magnetic insulating substrate,
A step of forming a plurality of the thin-film magnetic induction elements on a magnetic insulating base material to be cut into a plurality of magnetic insulating substrates, a metal film to be the two adjacent second terminal electrodes, and the protective resin Forming a second groove on a straight line passing through the central portion of the metal film on the magnetic insulating substrate, and the adjacent first terminal electrode is formed to face each other with the protective resin interposed therebetween, and the protection Forming a linear first groove reaching the linear second groove in the magnetic resin and the magnetic insulating base material under the protective resin, and separating the thin film magnetic induction element into a single unit. The manufacturing method of the micro power converter characterized by these. The method for manufacturing a micro power converter according to claim 1, wherein a width of the second groove is wider than a width of the first groove. 3. The method for manufacturing a micro power converter according to claim 1, wherein a depth of the second groove is equal to or less than half of a thickness of the thin film magnetic induction element. 4. The method for manufacturing a micro power converter according to claim 1, wherein the first groove and the second groove are each formed by a dicing saw. 5. On the first main surface of the magnetic insulating substrate comprising a magnetic insulating substrate and a first conductor formed on the first main surface of the magnetic insulating substrate or a second conductor formed on the second main surface of the magnetic insulating substrate A coil conductor formed by connecting the formed first conductor, the second conductor formed on the second main surface of the magnetic insulating substrate, and the connection conductor formed in the through hole penetrating the magnetic insulating substrate; A plurality of outer peripheral portions of the first and second main surfaces of the magnetic insulating substrate are connected to each other via second connection conductors that penetrate the magnetic insulating substrate, and face each other with the magnetic insulating substrate interposed therebetween. In a method for manufacturing a micro power converter having a first terminal electrode and a second terminal electrode, and a thin film magnetic induction element comprising a protective resin covering the first and second conductors and the magnetic insulating substrate,
A step of forming a plurality of the thin-film magnetic induction elements on a magnetic insulating base material that is cut into a plurality of parts and serving as the magnetic insulating substrate, and two adjacent first terminal electrodes are opposed to each other with the protective resin interposed therebetween The two adjacent second terminal electrodes are formed opposite to each other with the protective resin interposed therebetween, and the center of the protective resin is sandwiched between the adjacent first and second terminal electrodes. A step of cutting the protective resin and the magnetic insulating base material under the protective resin on a straight line passing through the portion to separate the thin film magnetic induction element into a single unit, Device manufacturing method.

Images