JPH0653045A - Substrate transformer and its manufacture - Google Patents

Abstract

PURPOSE:To obtain a thinned substrate transformer and its manufacturing method wherein durability capable of mounting ordinary electronic parts for printed wiring on a substrate is ensured and massproductivity is excellent. CONSTITUTION:The transformer consists of the following; a comparatively durable substrate 1 of a ferrite single body or a magnetic metal foil laminate, a plurality of pairs of through holes 21-2n, 31-3n, formed in the substrate 1, and a plurality of printed wiring conductors 41-4n-1, 51-5n-1 which are formed on both sides of the substrate 1 and connect the through holes 21-2n with the corresponding through holes 31-3n. A pair of coil windings are formed by a plurality of the printed wiring conductors 41-4n-1, 51-5n-1 which are electrically connected in series via the through holes 21-2n, 31-3n. A pair of the coil windings are practically wound around the magnetic substance substrate 1, so that a small, thin, durable substrate transformer can be obtained. Further the substrate transformer is manufactured by a manufacturing process almost similar to usual thick film printed wiring.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a substrate transformer and a method of manufacturing the same, and in particular, a solid substrate made of a magnetic material is used as a base on which a coil winding is formed by printed wiring, and the whole structure is improved. BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a substrate transformer for obtaining a robust and thin transformer and a manufacturing method thereof.

[0002]

2. Description of the Related Art Conventionally, with the spread of portable personal computers (personal computers) and word processors (word processors), there has been an increasing demand for weight reduction and thinning of the personal computers and word processors (word processors). Research is underway to achieve weight reduction and thickness reduction for all electronic components. In particular, the transformer or reactor that constitutes the power supply unit inevitably becomes large, so There are strong expectations for thinning.

By the way, as a thinning means for a transformer or a reactor (hereinafter referred to as a first thinning means), one disclosed in JP-A-55-82412 is known. The one disclosed in JP-A-55-82412 forms a laminated transformer by a method called a sheet method or a printing method. In the sheet method, a magnetic paste is used to obtain a doctor beret degree or the like. To form a sheet, dry it, print a paste-like conductor on it, and then dry it, stack a sheet made of magnetic paste on it as a magnetic core, and print the conductor, The same process steps are repeatedly performed as necessary to obtain a laminated transformer, and the printing method is
Attach a polyester film to a flat support surface such as aluminum, print the magnetic paste on the support surface, then dry it, print a paste-like conductor on it, then dry it, and further magnetic core with magnetic paste. Is printed and then dried, and thereafter, the same processing steps are repeatedly performed as necessary to obtain a laminated transformer. And in either method, printing and drying of the magnetic paste,
Consists of printing and drying of the pasty conductor 1
The thickness of the layer formed by the single processing step is about ten and several tens of μm.

In addition to this, as a thinning means for a transformer or a reactor (hereinafter referred to as a second thinning means), the one disclosed in JP-A-59-39008 is known. In the one disclosed in JP-A-59-39008, a plurality of half coil patterns of primary windings and secondary windings are provided on one surface of an insulating substrate, and the primary winding is formed on the other surface of the insulating substrate. A plurality of remaining half-coil patterns of the wire and the secondary winding are provided, and the both half-coil patterns are connected by through holes provided in the insulating substrate, so that the primary winding and the secondary winding of the transformer are connected. A magnetic core is embedded inside an insulating substrate that is formed and corresponds to the center of the primary winding and the secondary winding.

[0005]

However, the known first thinning means is for printing the magnetic paste and the conductor paste and then sintering and drying to obtain the magnetic body and the conductor. Since the magnetic material and the conductor shrink significantly during sinter drying, it is difficult to obtain the required dimensional accuracy as a transformer, and there is a large difference in the degree of shrinkage between the magnetic material and the conductor during sinter drying. In addition, it is difficult to obtain the dimensional accuracy required for a transformer, and there is a problem that a precise and highly reliable transformer cannot be manufactured. Further, since the known first thinning means is adapted to manufacture the transformer by the printing laminating means,
The core has a large cross-sectional area, especially when trying to obtain a high output, robust transformer with sufficient thickness,
There is also a problem that mass productivity is poor because it is necessary to repeat similar processing steps many times.

Further, since the known second thinning means has a structure in which the magnetic core is embedded inside the insulating substrate, it is not easy to obtain an insulating substrate having such a structure, and There is a problem that it is difficult to form a closed magnetic circuit having a small magnetic resistance.

The present invention is intended to eliminate the above-mentioned problems, and its object is to have robustness to the extent that an ordinary electronic component for printed wiring can be mounted on a substrate and to have high mass productivity. (EN) A thinned substrate transformer and a method for manufacturing the same.

[0008]

To achieve the above object, the present invention provides a substrate in which a ferrite substrate or a magnetic metal foil is laminated, a plurality of pairs of through holes provided in the substrate, and both surfaces of the substrate. And a plurality of printed wiring conductors each of which is formed by connecting the corresponding through holes to each other, and a pair of coil windings is formed by the plurality of printed wiring conductors electrically connected in series through the through holes. A first means for forming a line is provided.

In order to achieve the above object, the present invention provides a step of obtaining a board in which a ferrite board or a magnetic metal foil is laminated, a step of forming a through hole in the board, and an insulating treatment in the through hole. A step of applying, a step of printing and wiring a conductor on one surface of the board, a step of printing and wiring a conductor on the other surface of the board, and a step of forming a board transformer by soldering necessary parts. The second means is provided.

[0010]

According to the first means, the magnetic substrate of the transformer in which the pair of coil windings is formed is made of a ferrite material or a laminated magnetic metal foil and is relatively robust. Since one substrate is formed from the beginning, the substrate has sufficient mechanical strength, like a normal printed substrate. Further, even in the formation of the pair of coil windings, since the ordinary printed wiring means is used on the robust substrate, the pair of coil windings can be easily formed with high dimensional accuracy and high reliability. It is also possible to form, and it is also possible to mount and arrange ordinary electronic components for printed wiring on the substrate together.

Further, according to the second means, when manufacturing this substrate transformer, it can be manufactured through substantially the same manufacturing process as the manufacturing process of the thick film printed wiring using the usual ceramic substrate. In particular, there is no need to prepare a line for a new manufacturing process, which is highly productive and
It is possible to manufacture and supply a substrate transformer having uniform quality.

[0012]

Embodiments of the present invention will be described below with reference to the drawings.

FIG. 1 is a constitutional view showing a first embodiment of the structure of a substrate transformer according to the present invention, (a) is a front view thereof, and (b) is a sectional view taken along the line AA. .

In FIGS. 1A and 1B, 1 is a ferrite substrate, 2 ₁ , 2 ₂ , ..., 2 _n , 3 ₁ ,
_{3 2, ... ... ..., 3} n -line-shaped through _{hole, 4 1, 4 2, ...} ... ..., 4 n-1 is the printed wiring conductors formed by printing wiring on one surface of the ferrite substrate 1, 5 ₁ , 5 ₂ , ..., 5 _n-1 are printed wiring conductors formed by printed wiring on the other surface of the ferrite substrate 1, and 6 ₁ , 6 ₂ , 7 ₁ , 7 ₂ are one of the ferrite substrates 1. Terminal pad formed by printed wiring on the surface, 8 ₁ ,
8 ₂ , 9 ₁ , and 9 ₂ are connection leads formed by printed wiring on the same surface, and 10 are through holes 2 ₁ , 2 ₂ , ...
_{..., 2 n, 3 1,} 3 2, ... ... ..., an insulating film is deposited on the ferrite substrate 1 side of the 3 _n.

The ferrite substrate 1 is, for example, a substrate made of Ni--Zn component ferrite having a plate thickness of about 2 mm, and the through holes 2 ₁ formed in the substrate ₁ ,
3 ₁ , through hole 2 ₂ , 3 ₂ , through hole 2 ₃ , 3
₃ , ..., Through holes 2 _n , 3 _{n make} a pair, and are formed and arranged at equal intervals in parallel positions in the vertical direction of the substrate 1, respectively.

On one surface of the ferrite substrate 1, the first printed wiring conductor 4 is provided between the through holes 2 ₁ and 3 _2.
1 is the second printed wiring conductor 4 ₂ between the through holes 2 ₂ and 3 ₃ , the third printed wiring conductor 4 ₃ is between the through holes 2 ₃ and 3 ₄ , and so on. The n-2 printed wiring conductors 4 _{4 to} 4 _n-2 are respectively formed by printed wiring, and finally, the (n-1) th printed wiring conductor 4 _n-1 is printed between the through holes 2 _n-2 and 3 _n-1. Wiring is formed. On the other hand, the other surface of the ferrite substrate 1 has through holes 2 ₂ , 3 ₁
The first printed wiring conductor 5 ₁ is provided between the through holes 2 ₃ and 3
_{A second} printed wiring conductor 5 ₂ is provided between the two through holes 2 ₄ ,
3 between ₃ third printing wiring conductors 5 _3, and so on,
The fourth to n-2th printed wiring conductors 5 _{4 to} 5 _n-2 are formed by printed wiring respectively, and finally, the through holes 2 _n-1 and 3 are formed.
_{The n-} 1th printed wiring conductor 5 _n-1 is formed between the _n-2 printed wirings. In this embodiment, as the printed wiring conductor paste, for example, a Cu-based paste having a sheet resistance of tens of mΩ or less is used, but other printed wiring conductor pastes may be used. Of course.

Further, the terminal pads 6 ₁ , 6 ₂ , 7 ₁ , 7
₂ is printed wiring formed on the same line in the horizontal direction of the ferrite substrate 1. In this, the terminal pad 6 ₁ is connected to the through hole 2 via the connection lead 8 ₁ formed with printed wiring.
₁ , the terminal pad 6 ₂ is connected to the through hole 2 _n-1 via the similar connection lead 8 ₂ , the terminal pad 7 ₁ is connected to the through hole 3 _n-1 via the similar connection lead 9 ₁ , and the terminal pad 7
₂ is connected to each through hole 3 ₁ through the same connection lead 9 ₂ .

According to the above-mentioned structure, the odd-numbered printed wiring conductors 4 ₁ , 4 ₃ , ..., 4 _n-2 formed on one surface of the ferrite substrate 1 and the other of the substrate 1 are arranged. The even-numbered printed wiring conductors 5 ₂ formed on the surface of the
5 ₄ , ..., 5 _n-1 are through holes 2 ₁ , 3 ₂ , 2 ₃ , 3 ₄ , at both ends thereof, ...,
3 _n-1 , 2 _n are sequentially connected in series, for example, 1
The secondary coil winding is constructed, and the primary coil winding has one end connected to the terminal pad 6 ₁ via the connection lead 8 ₁ and the other end connected via the connection lead 8 _2. 8 ₂ and each of the connection leads 8
External connection is possible through ₁ and 8 ₂ . On the other hand, the odd-numbered printed wiring conductors 5 ₁ , 5 ₃ , ..., 5 _n-2 formed on the other surface of the substrate 1 and the even-numbered printing formed on one surface of the substrate 1 Wiring conductors 4 ₂ , 4
₄ , ..., 4 _n-1 are through holes 3 ₁ , 2 ₂ , 3 ₃ , 2 ₄ , at both ends thereof, ... 2 _n-1 ,
3 are sequentially connected in series via a _n, for example, become secondary coil winding is constructed, also in this secondary coil winding, the terminal pads ₇₁ one end via a connection lead 9 ₁
The other end through the connection lead 9 ₂ to the connection lead 7 ₂
To the outside, and a connection to the outside becomes possible in the same way, and the primary side coil winding and the secondary side coil winding constitute a substrate transformer.

In this case, the primary side coil winding and the secondary side coil winding are substantially wound around the substrate 1 made of a magnetic material and having a plate thickness of about 2 mm. It is possible to obtain a sufficient amount of inductance without increasing the number of each of the coil windings and the secondary side coil windings, and it is possible to configure a small and thin substrate transformer as a whole. Further, since this board transformer is formed by forming the primary coil winding and the secondary coil winding on the board 1 having a plate thickness of about 2 mm, it is small and thin. Instead, it is relatively robust, and it is possible to attach other printed wiring electronic components to the substrate 1 in addition to the substrate transformer.

Further, looking at the dimensional accuracy of the obtained substrate transformer, the already sintered ferrite substrate 1 is used as the substrate 1, and the substrate 1 is
For example, since it has a sufficient strength such as a plate thickness of 2 mm, printed wiring conductors 4 ₁ , 4 ₂ , ..., 4 _n-1 , 5 ₁ ,
5 _2, ... ... ..., 5 even when allowed to print form _n-1 and the like, the printed wiring conductors 4 _1, 4 _2, ... ... ..., 4
_It is sufficient to consider only the degree of shrinkage of _n-1 , 5 ₁ , 5 ₂ , ..., 5 _n-1, etc. during firing, which is extremely precise compared to known thin transformers of this type, and has dimensional accuracy. It is possible to obtain a substrate transformer that does not vary.

Next, FIG. 2 is an equivalent circuit showing an electric circuit of the substrate transformer according to the first embodiment.

In FIG. 2, the same components as those shown in FIG. 1 are designated by the same reference numerals.

As shown in FIG. 2, the substrate transformer according to the first embodiment is functionally equivalent to a conventional bulk transformer using a bulk core and a copper wire coil, and is a power source for personal computers and word processors. It can be used as a transformer.

The substrate transformer according to the first embodiment is one in which the winding ratio of the transformer is 1: 1. For example, the width of each printed wiring conductor of one coil winding is If the width of each printed wiring conductor of the other coil winding is formed wider, or if each printed wiring conductor of any one coil winding is formed of a plurality of strips, the
It can be configured to have an arbitrary turns ratio without degrading the coupling between the secondary and the secondary.

Next, FIG. 3 is a flow chart showing an embodiment of a manufacturing process for manufacturing the substrate transformer according to the present invention.

However, in FIG. 3, description will be made assuming that the substrate transformer shown in the first embodiment is manufactured, but in the description of FIG. 3, the same components as the components shown in FIG. The same symbols are used for the elements.

First, in step S1, for example, a ferrite material having a Ni—Zn component is used to form the ferrite substrate 1 having a plate thickness of about 2 mm. Continued, step S
2, a plurality of through holes 2 ₁ , 2 ₂ , ...
2 _n , 3 ₁ , 3 ₂ , ... 3 _n are formed. Next, in step S3, the plurality of formed through holes 2 ₁ , 2 ₂ , ..., 2 _n , 3 ₁ ,
Insulation is performed on the peripheral portions of 3 ₂ , ..., 3 _n . Subsequently, in step S4, printed wiring conductors 5 ₁ , 5 ₂ , ..., 5 _n-1 are printed on the back surface (other surface) of the substrate 1 by using, for example, a Cu-based conductive paste. Let Succeedingly, in a step S5, the printed portion is dried and baked, and the substrate 1
The printed wiring conductors 5 ₁ , 5 ₂ , formed on the ...
Stabilize the state of _n-1 . Next, in step S6, the printed wiring conductor 4 is similarly formed on the surface (one surface) of the substrate 1 by using, for example, a Cu-based conductive paste.
₁ , 4 ₂ , ..., 4 _n-1 , terminal pad 6 ₁ ,
6 ₂ , 7 ₁ , 7 ₂ and connecting leads 8 ₁ , 8 ₂ ,
9 ₁ and 9 ₂ are formed by printing. Next, in step S7, the printed portion is dried and fired to form the printed wiring conductors 4 ₁ , 4 formed on the substrate 1.
₂ , ... ... 4 _n-1 , terminal pads 6 ₁ , 6 ₂ ,
7 ₁ , 7 ₂ and connection leads 8 ₁ , 8 ₂ , 9 ₁ , 9 ₂
Stabilize the state of. Subsequently, in step S8, terminals are provided on the substrate 1, or other printed wiring electronic components are mounted on the substrate 1 as necessary. Subsequently, in step S9, the substrate 1 is soaked in a solder bath and necessary portions are soldered. Finally, in step S10, the substrate 1 is washed with a washing liquid and inspected, and then shipped as a completed substrate transformer.

In this case, since the manufacturing process is generally the same as the manufacturing process of the thick film printed wiring using the ceramic substrate, a new manufacturing process line is used especially when manufacturing the substrate transformer. Therefore, it is possible to manufacture a substrate transformer which is not required to be provided and which is rich in mass productivity and has uniform quality.

Next, FIG. 4 is a constitutional view showing a second embodiment of the structure of the substrate transformer according to the present invention, (a) is a front view thereof, and (b) is a cross section taken along the line A--A. It is a figure.

In FIG. 4, reference numeral 11 denotes a substrate on which magnetic metal foils are laminated, and the same components as those shown in FIG. 1 are designated by the same reference numerals.

The difference in structure between the first and second embodiments is that the first embodiment uses a sintered ferrite substrate 1 as the substrate 1. On the other hand, in the second embodiment, instead of the ferrite substrate 1, a metal laminated substrate (hereinafter, referred to as a metal laminated substrate) 11 in which amorphous magnetic foils are laminated and adhered with an epoxy adhesive is used. However, since there is no difference in structure between the first embodiment and the second embodiment except for that point, further detailed description of the structure of the second embodiment will be omitted. To do.

In this case, the second embodiment using the metal laminated substrate 11 has a higher impact strength than that of the first embodiment using the ferrite substrate 1. The advantage is that it is possible to reduce the risk of the metal laminated substrate 11 being damaged during use or during manufacturing, and to realize a thin substrate transformer as in the case of using the ferrite substrate 1. . In the second embodiment using the metal laminated substrate 10, each through hole 2 ₁ , 2 ₂ , ..., 2 _n , 3 is used.
_1, 3 _2, ... ... ..., it is 3 _n, and serves as rivets to the metal laminated substrate 11.

FIG. 5 is a block diagram showing a third embodiment of the structure of the substrate transformer according to the present invention.

In FIG. 5, the same components as those shown in FIG. 1 are designated by the same reference numerals.

The difference in structure between the first and third embodiments is that the first embodiment has two through-holes 2 arranged inline in two rows in the vertical direction of the ferrite substrate 1.
₁ , 2 ₂ , ... ... 2 _n , 3 ₁ , 3 ₂ , ...
.., 3 _n are formed, whereas in the third embodiment, the through holes 2 ₁ , 2 ₂ , ... are arranged in a zigzag pattern in the vertical direction of the ferrite substrate 1, 2 _n , 3 ₁ , 3 ₂ , ...
Forming 3 _n , that is, specifically, each through hole 2 ₁ , 2 ₃ , related to the coil winding on the primary side,
... 2 _n , 3 ₂ , 3 ₄ , ... 3 _n-1 inside, through holes 2 ₂ , 2 ₄ , associated with the coil winding on the secondary side ... 2 _{n- 1} , 3 ₁ , 3 ₃ , ...
The difference is that there is no difference in structure between the first embodiment and the third embodiment except that it is formed so that 3 _n is on the outside. The detailed description of the configuration of this embodiment will be omitted.

In the third embodiment, the through holes 2 ₁ , 2 ₂ , ... Are staggered in the vertical direction of the ferrite substrate 1.
... 2 _n , 3 ₁ , 3 ₂ , ... ... 3 _n are formed, so that each of these through holes 2 ₁ , 2 ₂ , ...
_{... ..., 2 n, 3 1} , 3 2, ... ... ..., 3 n and compared to that of the first embodiment which is formed in-line-shaped two rows in the longitudinal direction of the substrate 1, the substrate 1 There is an advantage that the reduction in mechanical strength is reduced. The third embodiment uses each through hole 2 associated with the coil winding on the primary side.
₁ , 2 ₃ , ... ... 2 _n , 3 ₂ , 3 ₄ , ... ...
... 3 _n-1 inward, through holes 2 ₂ , 2 ₄ , associated with the coil winding on the secondary side ... 2 _n-1 , 3 ₁ ,
Although 3 ₃ is an example in which 3 _n is arranged on the outer side, the through holes 2 ₁ , 2 ₃ , ..., 2 _n , 3 associated with the coil winding on the primary side are shown. ₂ , 3, ₄ , ...
... ..., 3 _n-1 to the outside, the through-holes 2 ₂ associated with the coil windings of the secondary side, 2 _4, ... ... ..., 2 _n-1, 3
₁ , 3 ₃ , ..., 3 _n may be placed inside.

Each through hole 2 ₁ , 2 ₂ , ...
_{..., 2 n, 3 1,} 3 2, ... ......, 3 to compensate for the reduction in the mechanical strength of the ferrite substrate 1 by providing the _n, printed wiring conductors _{4 1, 4 2, ... ...} ..., 4 n _-1 , 5
After printing and forming ₁ , 5 ₂ , ..., 5 _{n- 1} etc., these through holes 2 ₁ , 2 ₂ ,.
_{n, 3 1, 3 2,} ... ... ..., may be made to fill the filler such as epoxy resin and 3 _n.

Next, FIG. 6 is a constitutional view showing a fourth embodiment of the structure of the substrate transformer according to the present invention.

In FIG. 6, reference numeral 12 is a first substrate transformer constituent portion, 13 is a second substrate transformer constituent portion, and other constituent elements that are the same as those shown in FIG. ing.

Then, the first substrate transformer component 12
And the second substrate transformer component 13 are formed on one common ferrite substrate 1. In this case, the primary and secondary coil windings of the first substrate transformer component 12 are arranged. And the coil windings on the primary side and the secondary side of the second substrate transformer constituting portion 13 are arranged so that their directions are different from each other by about 90 degrees. Part 12 and second substrate transformer component 1
Each of the substrate transformers formed in 3 is the first
The configuration is exactly the same as that shown in the embodiment.

As in the fourth embodiment, the coil windings on the primary and secondary sides of the first substrate transformer component 12 and the primary and secondary sides of the second substrate transformer component 13 are described. If the coil windings are arranged so that their orientations are different from each other by about 90 degrees, the first substrate transformer structure is formed even though the two substrate transformer constituent parts 12 and 13 are formed on one common ferrite substrate 1. Magnetic interference between the primary and secondary coil windings of the part 12 and the primary and secondary coil windings of the second substrate transformer component 13 can be minimized. Like

Next, FIG. 7 is a constitutional view showing a fifth embodiment of the structure of the substrate transformer according to the present invention.

In FIG. 7, reference numeral 14 is an additional through hole, 15 is a dummy pad, and the same constituent elements as those shown in FIG. 1 are designated by the same reference numerals.

The difference between the first embodiment and the fifth embodiment is that in the fifth embodiment, the through holes 2 ₁ , 2 ₂ , ... _n , 3
_The additional through holes 14 are provided separately from ₁ , 3 ₂ , ..., 3 _n, and the dummy pad 15 is formed around the additional through holes 14, while the first embodiment is used. The example is only that the additional through hole 14 and the dummy pad 15 are not provided, and other than that, there is no structural difference between the first embodiment and the fifth embodiment.

As shown in the fifth embodiment, by providing the additional through hole 14 and the dummy pad 15 having no wiring around the dummy pad 15, the dummy pad 15 becomes the terminal pad 6. Similar to ₁ , 6 ₂ , 7 ₁ and 7 ₂ , it can be used as a connection base for soldering wiring, which enables flexible wiring, and has a strong board transformer mounting strength. It can be handled as a normal chip component.

FIG. 8 is a block diagram showing an example of the mounting structure of the switching power supply using the substrate transformer according to the present invention.

In FIG. 8, 16 is a substrate transformer and 17
Is a substrate reactor having a configuration similar to that of the substrate transformer 16, 18 is an input connector, 19 is an output connector, 20 is a smoothing capacitor, 21 is a rectifying diode, 22 is a power transistor, 23 is a small signal transistor, 24 is a chip resistor, 25 Is a chip capacitor, 26 is a control IC,
Reference numeral 27 is a mounting hole, and other components that are the same as the components shown in FIG. 1 are denoted by the same reference numerals.

When manufacturing the switching power supply, first, the substrate transformer 16 and the substrate reactor 17 are formed on the ferrite substrate 1 by the above-described manufacturing process, and necessary circuit pattern wiring is performed. Wiring for components and component mounting pads, and then electronic components required as a switching power source, for example, a control IC 26,
The small signal transistor 23, the chip resistor 24, the chip capacitor 25, the power transistor 22, the rectifying diode 21, the smoothing capacitor 20, the input connector 18, the output connector 19 and the like are collectively arranged and mounted on the substrate 1, and thereafter, The board 1 is integrated with an upper system through the mounting holes 27.

FIG. 9 is a circuit diagram showing an actual circuit configuration of the switching power supply shown in FIG. 8. This circuit is a well-known device which generates a balanced output voltage composed of positive and negative voltages + Es and -Es. Of the DC / DC converter.

In FIG. 9, the same components as those shown in FIG. 8 are designated by the same reference numerals. In addition, FIG.
Since the operation of the DC / DC converter shown in Figure 1 is self-evident, further description of the operation will be omitted.

In this case, since the thickness of the substrate transformer 16 and the substrate reactor 17 used in the switching power source is extremely thin, the substrate transformer 16 and the substrate reactor 17 are used together with other electronic parts in the substrate 1.
When mounted on, the board transformer 16 and the board reactor 17 are thinner than the other electronic components, and the switching power supply can be mounted in a low state.
The effect of using surface-mounted parts becomes extremely large. In addition, conventionally,
Due to the layout, the transformer was an obstacle to miniaturization and thinning,
Since the reactor can be arbitrarily arranged on the substrate, it is not necessary to route the wiring, and the switching power supply can be compactly mounted on the substrate 1. Further, since the substrate 1 is entirely made of a magnetic material, the substrate 1 has a magnetic shield effect, and reduces mutual interference with other devices due to magnetic noise, which has been a problem in this type of switching power supply. And without using a bead core or the like,
It becomes possible to effectively attenuate the high frequency noise accompanying the wiring. In addition to this, the substrate 1 made of a magnetic material is
Since it has better thermal conductivity than a conventional substrate made of an organic material, the substrate 1 itself can be used as a radiator, and there is an advantage that the mounting can be made smaller than ever.

When the substrate 1 is provided with a large heat radiation characteristic, if a metal radiation fin is provided in a wide area on the back surface of the substrate 1, the heat radiation ability is remarkably enhanced as compared with that of the substrate 1 alone. Will be able to.

Next, FIG. 10 is a block diagram showing a large-sized substrate made of a magnetic material used in the substrate transformer according to the present invention.

In FIG. 10, 28 is a large-sized substrate made of a magnetic material, 29 is a vertical cut groove, 30 is a horizontal cut groove, and other components are the same as those shown in FIG. Are given the same symbols.

Then, a plurality of substrate transformers 16 are collectively formed on the large-sized substrate 28 made of a magnetic material by the above-described manufacturing process, and thereafter, the vertical cut groove 29 and the horizontal cut groove are formed. The large substrate 28 is divided into a plurality of individual substrates 1 along the line 30 to form the individual substrate transformers 16.

The substrate transformer 16 manufactured through the manufacturing process as shown in FIG. 10 is manufactured as compared with the case where the substrate transformers 16 are individually manufactured because a large number of substrate transformers 16 are efficiently manufactured at once. Since the cost is low and each board transformer 16 is used by being separated from each other, the problem of mutual interference due to good or bad arrangement is eliminated.

The substrate transformer 16 shown in FIG.
Since it is used by being mounted on another substrate as one electronic component, the thickness as a transformer is increased as compared with the substrate transformer 16 shown in FIG. 8, but the thickness is substantially only that of the substrate 1. Therefore, the thinning of the substrate transformer can be sufficiently achieved.

In each of the above embodiments, the substrate 1,
Although the plate thickness of 11 has been described as being about 2 mm, the plate thickness of the substrates 1 and 11 according to the present invention is not limited to the above, and may be about 1 to 2 mm which is thinner than the plate thickness. Depending on the thickness, the thickness may slightly exceed about 2 mm.

Further, in each of the above embodiments, the metal laminated substrate 11 is an example in which a metal foil made of an amorphous magnetic material is laminated and adhered with an adhesive, but the material according to the present invention is limited to amorphous. However, other magnetic materials can also be used.

In each of the above embodiments, the case where the laser processing method is used for the through hole processing of the substrate has been described, but the present invention is not limited to such a processing method, and an ultrasonic processing method, Needless to say, the same processing can be performed by using the die cutting method.

[0061]

As described above, according to the present invention,
Since a pair of coil windings are formed using ordinary printed wiring means on the magnetic substrates 1 and 11 having a relatively high mechanical strength and a plate thickness of about 1 to 2 mm, a small and thin substrate. A transformer can be realized, a pair of coil windings having high dimensional accuracy and high reliability can be easily formed, and other electronic components can be mounted on the boards 1 and 11. There is an excellent effect that you can also.

Further, according to the present invention, the substrates 1, 11 are
Form the core of the pair of coil windings, it is possible to obtain a sufficiently large reactance in spite of being small and thin, and to have a high output (several 10 W) compared to the conventional transformer of this type. ) There is also an effect that the degree can be processed.

Furthermore, according to the present invention, when manufacturing a substrate transformer, it can be manufactured through the same manufacturing process as a thick film printed wiring using a normal ceramic substrate, so that it is necessary to prepare a new manufacturing process line. In addition, there is also an effect that it is possible to manufacture a substrate transformer having high mass productivity and uniform quality.

[Brief description of drawings]

FIG. 1 is a configuration diagram showing a first embodiment of the structure of a substrate transformer according to the present invention.

FIG. 2 is a circuit diagram showing an equivalent circuit of the substrate transformer of the first embodiment shown in FIG.

FIG. 3 is a flow chart showing an example of a manufacturing process when manufacturing a substrate transformer according to the present invention.

FIG. 4 is a configuration diagram showing a second embodiment of the structure of the substrate transformer according to the present invention.

FIG. 5 is a configuration diagram showing a third embodiment of the structure of the substrate transformer according to the present invention.

FIG. 6 is a configuration diagram showing a fourth embodiment of the structure of the substrate transformer according to the present invention.

FIG. 7 is a configuration diagram showing a fifth embodiment of the structure of the substrate transformer according to the present invention.

FIG. 8 is a configuration diagram showing an example of a mounting structure of a switching power supply using a substrate transformer according to the present invention.

9 is a circuit diagram showing an actual circuit configuration of the switching power supply shown in FIG.

FIG. 10 is a configuration diagram showing a large-sized substrate made of a magnetic material used in the substrate transformer according to the present invention.

[Explanation of symbols]

1 Ferrite substrate 2 ₁ , 2 ₂ , ..., 2 _n , 3 ₁ , 3 ₂ , ..., 3 _n
Through holes 4 ₁ , 4 ₂ , ..., 4 _n-1 Printed wiring conductors formed on one surface 5 ₁ , 5 ₂ , ..., 5 _n-1 Printed wiring conductors formed on the other surface 6 ₁ , 6 ₂ , 7 ₁ , 7 ₂ Terminal pads 8 ₁ formed on one surface 8 ₁ , 8 ₂ , 9 ₁ , 9 ₂ Connection leads 10 formed on one surface 10 Insulating film 11 Substrate laminated with magnetic metal foil ( Metal laminated board) 12 First board transformer constituent part 13 Second board transformer constituent part 14 Additional through hole 15 Dummy pad 16 Board transformer 17 Board reactor 18 Input connector 19 Output connector 20 Smoothing capacitor 21 Rectifying diode 22 Power transistor 23 Small signal transistor 24 Chip resistor 25 Chip capacitor 26 Control IC 27 Mounting hole 28 Large substrate made of magnetic material 29 Vertical notch 3 The transverse direction of the cut groove

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Takashi Sase Inventor Takashi Sase 4026 Kuji-cho, Hitachi City, Ibaraki Prefecture Hitachi Research Laboratory, Hitachi, Ltd.

Claims (7)

[Claims] 1. A ferrite substrate or a substrate on which a magnetic metal foil is laminated, a plurality of pairs of through holes provided in the substrate, and a plurality of through holes formed on both surfaces of the substrate and having corresponding through holes coupled to each other. And a plurality of printed wiring conductors electrically connected in series through the through holes to form a pair of coil windings. 2. The substrate transformer according to claim 1, wherein the substrate has a thickness of about 1 to 2 mm. 3. The substrate of claim 1, wherein the substrate comprises one or more additional through holes, and dummy pads are electrically coupled to the additional through holes. Trance. 4. The substrate transformer according to claim 1, wherein various electronic components for printed wiring are mounted and arranged on the substrate in addition to the substrate transformer including the pair of coil windings. 5. A substrate transformer including one pair of coil windings and a substrate transformer including another pair of coil windings are formed on the substrate. The substrate transformer according to claim 1, wherein the substrate transformers are arranged and formed so as to be orthogonal to each other on the substrate. 6. A step of obtaining a ferrite board or a board in which a magnetic metal foil is laminated, a step of forming a through hole in the board, a step of subjecting the through hole to an insulating treatment, and a conductor on one surface of the board. A method for manufacturing a substrate transformer, comprising: a step of performing a printed wiring of the substrate; a step of performing a printed wiring of a conductor on the other surface of the substrate; and a step of forming a substrate transformer by soldering necessary portions. . 7. The board according to claim 6, further comprising a step of mounting terminals and other printed wiring electronic components on the board after the step of printing and wiring a conductor on the other surface of the board. Method of manufacturing transformer.