JPH09186021A - Thin laminated transformer and its manufacture - Google Patents

Abstract

PROBLEM TO BE SOLVED: To stabilize the coupling between windings by incorporating the magnetic cores constituting a closed magnetic path, from above and below the laminated coil where the lead wire of a spiral coil is led out from the space between the end face part provided with comb-toothed projections of a coil base and the inwall of a coil press cover. SOLUTION: Coil spacers 4 and spiral coils 2 are stacked alternately, while wiring the lead wires 2a among the comb-toothed projections 7a, on a coil base 7 which has comb-toothed projections 7a at both ends and a core guide wall 7b to pass a magnetic core 1 at the center. Then, insulating paper 3 is stacked, and from the topside, a coil press cover 8, which has a section 8a to oppose the the spiral coil 2 is put on it to constitute a stacked coil. At this time, the dimension of the lead wire 2a is set so that it may be drawn out from the space between the end face part provided with comb-toothed projections 7a and the inwall of the coil press cover 8. Then, magnetic cores 1 to constitute a closed magnetic path are set to it from above and below the laminated coil.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a thin laminated transformer using laminated coils used in various electronic devices and a method for manufacturing the same.

[0002]

2. Description of the Related Art In recent years, in order to meet the technical needs for higher frequency, smaller size and thinner transformer, a printed coil laminated transformer using a print etching technique, a transformer having a punched coil laminated structure formed by punching a copper plate,
Alternatively, a transformer having a spiral coil laminated structure in which electric wires are formed in a spiral shape has been developed.

In reality, in addition to the above technical needs, there is a strong demand for thorough cost reduction and high safety as a background of the times, and without this point, practical use is not possible. There is.

In order to provide a thin transformer at low cost, what laminated coil is formed and how is it. However, the printed coil manufactured by the etching method increases the cost and increases the current. Considering cost and versatility, it is necessary to adopt a transformer having a spiral coil laminated structure in which a coil or an electric wire is formed by a punching method in a spiral shape due to the limitation of capacity. Furthermore, in order to achieve high safety, resin filling, molding, etc. may be performed.

As a thin laminated transformer filled with a resin using a spiral coil, the one shown in FIGS. 9 to 10 is generally used.

A thin laminated transformer in which a conventional transformer is resin-filled with the spiral coil shown in FIGS. 9 and 10 will be described below.

FIG. 10 is a diagram for explaining the laminated structure of a conventional thin laminated transformer, and FIG. 9 is a sectional view.
Reference numeral 1 is a magnetic core, 2 is a winding wire, 3 is an insulating paper, 4 is a spacer, 5 is a coil case, and 6 is a filling resin.

The structure will be described with reference to FIG. 10. A winding 2 formed by spirally winding an electric wire alone, a spacer 4 for determining the position of the spiral coil, and an insulating paper 3 are alternately arranged in a coil case 5. After completing the laminated coil by stacking on
The thin laminated transformer main body is completed by incorporating the magnetic core 1 forming the closed magnetic circuit from the direction in which the coils are laminated. In this conventional technique, two sets of windings 2 are alternately laminated, but the same applies to two or more sets as long as the transformer has a primary winding and a secondary winding.

The transformer is completed by filling the resin 6 through the opening of the coil case 5 and then completing the transformer body.

[0010]

However, in the above-mentioned conventional structure, when the winding wire 2 is stacked in the coil case 5, the lead wire 2a comes into contact with the side wall of the coil case 5 and 2 moves, and the coupling between the windings becomes unstable.

Further, after the spiral coils are stacked, the coils are not pressed from above and below, so that the coil stack thickness varies and the coupling between the windings becomes unstable. Further, when the resin 6 is filled, the winding 2 is further moved by the filling resin 6, so that the coupling between the windings becomes further unstable.

The instability of the coupling between the windings due to the movement of the windings causes a variation in the electrical performance in practical use, which is a fatal defect in stacking spiral coils and providing them at low cost. It will be.

The present invention has been made to solve the above problems, and an object of the present invention is to provide a thin laminated transformer having stable electric performance by laminating windings using a spiral coil.

[0014]

In order to solve the above-mentioned problems, the present invention provides a comb-shaped projection on a coil base having a core guide wall having a comb-shaped projection formed at least on one end and a magnetic core passing through the center. From the upper surface of the laminated coil, which is formed by sequentially laminating the spiral coil while wiring the lead wire between the parts,
A laminated coil is formed by covering a coil pressing cover having at least a portion facing the spiral coil, and a spiral coil is formed from a gap between the end surface portion of the coil base provided with the comb-shaped projection and the inner wall of the coil pressing cover. A magnetic core forming a closed magnetic circuit is incorporated from above and below a laminated coil having a structure in which a lead wire of the coil is drawn out.

With the above structure, the lead wire can be pulled out while pressing the laminated coil with the coil pressing cover, and the coil laminated thickness can be stabilized and the winding wire can be prevented from moving due to the influence of the lead wire. It is possible to provide a thin laminated transformer with stable performance.

[0016]

BEST MODE FOR CARRYING OUT THE INVENTION The invention according to claim 1 of the present invention is characterized in that a comb-shaped protrusion is formed on at least one end of the coil base having a core guide wall through which a magnetic core is inserted at the center. A coil pressing cover having at least a portion facing the spiral coil is covered from the upper surface of the multilayer coil, which is formed by sequentially stacking the spiral coil while wiring lead wires between the coil and the coil. A structure in which a magnetic core forming a closed magnetic path is incorporated from above and below a laminated coil in which a lead wire of a spiral coil is drawn out from a gap between an end face portion provided with a comb-shaped protrusion of a base and an inner wall of a coil pressing cover Therefore, stabilization of the coil laminated thickness and prevention of movement of the winding 2 due to the influence of the lead wire can be achieved at the same time, the coupling state between the laminated windings is stable, and the electrical property is improved. In which the variations can be reduced.

According to a second aspect of the present invention, in the structure according to the first aspect, a connecting terminal portion to the substrate is provided on at least a part of an outer peripheral portion of the coil pressing cover, and the outer peripheral end surface of the spiral coil extends to the substrate. The lead wire is laid out to the connection terminal provided on the outer circumference of the coil pressing cover while ensuring a predetermined lead length to the connection terminal, and the projected area of the transformer mounted on the board can be made extremely small. It is a thing.

According to a third aspect of the present invention, in the second aspect, the primary or secondary coil formed by a spiral coil is used.
At least one of the following windings is a three-layer insulation-coated electric wire, which can improve safety and contribute to downsizing of a thin laminated transformer.

According to a fourth aspect of the present invention, in the second or third aspect, a projecting collar portion is provided between the magnetic core and the connection terminal portion on the outer peripheral surface of the coil pressing cover, This makes it easier to secure the creepage distance between the magnetic core and the connection terminal portion, and further makes it possible to reduce the board mounting area.

According to a fifth aspect of the present invention, in the first to fourth aspects, the lead wire of the V-shaped concave lead is formed on at least a part of the inner and outer peripheral surfaces of the lead wire of the coil pressing cover. Since the guide grooves are provided, the lead wires can be positioned and the contact between the lead wires can be prevented.

According to a sixth aspect of the present invention, in the structure according to the fifth aspect, a protrusion is provided on the outer peripheral surface of the coil pressing cover to fix the lead wire to the protrusion and at least one of the lead wires. Since the coating removal portion is provided in the portion, the terminal for connecting to the substrate is not necessary and the connection points are reduced, so that the connection reliability is also improved.

The invention according to claim 7 is claim 5 or 6
In the structure described in (1) above, a concave horizontal groove is provided on the outer peripheral surface of the coil pressing cover to prevent the slack of the lead wire and prevent contact between adjacent lead wires.

According to an eighth aspect of the present invention, in the first to seventh aspects, the opening is left only on the coil base side surface, and the coil base and the coil retainer cover are fitted to each other without leaving a gap, With resin filled from this opening,
The heat generated by the coil can be increased and the safety can be improved.

According to a ninth aspect of the present invention, in the eighth aspect, the flange portion of the coil holding cover is provided, in which a convex flange portion is formed on the back surface of the coil base on which the spiral coil is laminated and an opening portion is formed. Are also formed to have substantially the same height, and when the resin is cast, the resin does not overflow and the casting operation is facilitated.

According to a tenth aspect, the first to ninth aspects are provided.
In the described one, a through hole is provided in the coil base surface on which the spiral coil is laminated, and the resin rotation speed is increased, so that the resin casting speed is increased, that is, the casting man-hour can be reduced. It is a thing. further,
Even if the resin is not cast, the effect of reducing the coil temperature can be obtained.

According to the eleventh aspect, the first to the first aspects are provided.
0, wherein the center core guide wall portion for passing the magnetic core through is provided in the central portion of the coil pressing cover, and the central core portion has a double fitting configuration, and the creepage distance between the winding and the magnetic core is The effect is that it can be secured without increasing the mounting area.

According to a twelfth aspect of the present invention, in the first step of sequentially stacking the spiral coil on the coil base, and by covering the coil pressing cover from the upper surface of the laminated coil, the coil base end surface portion and the coil pressing cover are covered. This is a method for manufacturing a thin laminated transformer in which a magnetic core forming a closed magnetic circuit is incorporated through a second step of bending a lead wire of a spiral coil while pulling it out from a gap with a face wall. It is possible to provide a manufacturing method capable of preventing the winding from moving due to the influence of the lead wire.

According to a thirteenth aspect of the present invention, in the manufacturing method of the twelfth aspect, a step of covering the laminated coil with the coil pressing cover and then inverting the laminated coil upside down, and opening the coil pressing cover and the coil base after reversal This is a manufacturing method in which a magnetic core forming a closed magnetic circuit is incorporated through a step of filling a resin from a portion, and high heat dissipation and safety improvement of heat generation of a coil can be achieved.

Hereinafter, embodiments of the present invention will be described with reference to FIGS.
This will be described with reference to FIG. In the following description of the embodiments, the same parts as those in the related art will be designated by the same reference numerals, and the description will be omitted.

(Embodiment 1) FIG. 1 is a side sectional view,
FIG. 2 is an exploded perspective view with the magnetic core removed.

As shown in the figure, 7 is a coil base, 7a is a comb-shaped protrusion, 7b is a core guide flange, 8 is a coil pressing cover, 8a is a face facing the coil, and both ends are comb-shaped protrusions. A flat coil having a portion 7a formed and a convex portion having a predetermined width and height formed on at least a part of the inner and outer peripheral end faces on a coil base 7 having a center guide wall 7b through which a magnetic core passes. Spacers 4 and windings (spiral coils) 2 formed in a spiral shape are drawn out between the comb-shaped protrusions 7a and alternately stacked while wiring lead wires 2a, and then insulating paper 3 is stacked, Portion 8 facing the spiral coil 2
A laminated coil is constructed by covering the coil pressing cover 8 having a. At this time, the state of the lead wire 2a when the coil pressing cover 8 is covered is as follows: the gap between the end surface portion of the coil base 7 provided with the comb-shaped projection 7a and the inner wall of the coil pressing cover 8 as shown in FIG. The size of the gap between the coil base 7 and the coil pressing cover 8 is set so that the coil base 7 can be pulled out from. From the top and bottom of the laminated coil configured in this way,
Magnetic core 1 forming a closed magnetic circuit (not shown in FIG. 2)
To complete a thin laminated transformer.

According to the above structure, the lead wire 2a of the spiral coil 8 is laminated on the coil base 7 while being positioned between the comb-shaped protrusions 7a provided on the coil base 7, and then provided on the coil pressing cover 8. Face 8a facing the spiral coil 2
The spiral coil 2 is pressed by and the lead wire 2a is bent downward from the gap by the inner wall of the coil pressing cover 8 and pulled out, so that the coil stack thickness is stabilized and the lead wire 2a is affected by the lead wire 2a. Prevention of movement can be achieved at the same time. As a result, the coupling state between the laminated windings is stabilized, and variations in electrical performance can be reduced.

In order to obtain the above-mentioned structure, as a manufacturing method, the first step of sequentially stacking the spiral coil 2 on the coil base 7 and the coil pressing cover 8 covering the upper surface of the stacked coil are used to cover the coil base 7. Through the second step of bending and pulling out the lead wire 2a of the spiral coil from the gap between the end surface of the coil and the inner wall of the coil pressing cover 8, the magnetic core 1 forming the closed magnetic path is incorporated, and the thin laminated transformer is completed. I will let you.

(Second Embodiment) FIG. 3 (a) is a plan view of another embodiment, FIG. 3 (b) is a side sectional view, and FIG. 3 (c) is a view of FIGS. 3 (a) and 3 (b). It is a side sectional view showing a mode different from the embodiment, and according to the figure, 8b is a protrusion-shaped collar portion provided on the outer peripheral surface of the coil pressing cover 8, and 9a is a substrate provided on the outer peripheral portion of the coil pressing cover 8. 3b is an L-shaped terminal pin for connecting to a substrate provided on the outer peripheral portion of the coil pressing cover 8, and as shown in FIG. The spiral coil 2 is sequentially laminated while the lead wire 2a is laid on the coil base 7 having the shape-shaped protrusion 7a, and thereafter, as shown in FIG. 3B or FIG. While securing a predetermined lead length L from the outer peripheral end face to the connection terminal portion to the substrate, And routed to the terminal pins 9a or 9b for connection provided on the outer periphery of yl holding cover 8 is to wire the lead-out lead wire 2a. The length L of the lead wire 2a to be secured here varies depending on various design specifications, but the points to be considered are, firstly, the deterioration of the insulating film of the lead wire 2a due to the thermal influence from the connection terminal portion or the like. Therefore, it is possible to secure a distance sufficient to prevent a short circuit accident between the lead wire 2a and the internal spiral coil 2 or the spiral coil 2 and to secure the creepage distance according to the regulations of each country's safety standards. It can be done easily.

In order to secure the length L of the lead wire 2a, the coil pressing cover 8 is routed around the wiring, so that it can be used not only in the horizontal direction as in the prior art but also in the height direction. As a result, it can be secured in the vertical direction, and the projected area of the transformer on the board can be made extremely small.

In the case of using the three-layer insulation-coated electric wire for the primary or secondary winding, it is possible to provide a small-sized thin laminated transformer capable of further reducing the board mounting projected area of the transformer. To do.

Further, as shown in FIG. 3B, by providing a projecting flange portion 8b on the outer peripheral surface of the coil pressing cover 8 between the creeping surfaces of the magnetic core 1 and the connecting terminal portion, the magnetic core 1 and the connecting terminal portion are separated from each other. The creepage distance can be easily secured, and the board mounting area can be reduced. In this case, the position of the protruding collar portion 8b is ideally at an intermediate position where the magnetic core 1 and the connecting terminal portion are connected by a straight line, and the protruding core portion 8b is provided at a position at least 1 mm or more away from the magnetic core 1 and the connecting terminal portion. If this is done, the creepage distance can be defined as the distance along the surface of the projecting collar portion 8b as an interpretation in terms of safety standards. Therefore, the height dimension of the collar portion 8b can also be used, and the linear distance can be reduced, thus mounting the transformer on the substrate. The area can be further reduced.

When the thickness of the coil pressing cover 8 is large, the projection-like collar portion 8b is replaced by a concave-shaped portion 1m.
The same effect can be obtained by providing a groove of m or more.

(Third Embodiment) FIG. 4A is a plan view of still another embodiment, and FIG. 4B is a side sectional view.

For convenience of explanation, FIG. 4 (b) is shown upside down from that of the first and second embodiments.

The difference from the first or second embodiment is that
An approximately V-shaped concave lead lead guide groove 8c is formed on the inner peripheral surface of the coil pressing cover 8 for pulling out the lead wire 2a.
That is the point.

In the same drawing, since a substantially V-shaped concave lead lead guide groove 8c is provided on the inner peripheral surface for pulling the lead wire 2a of the coil pressing cover 8, the lead wire 2a is concave. The lead wire 2a is pulled out to the outside while being housed in the lead guide groove 8c, so that the lead wire 2a can be positioned and contact between the lead wires 2a can be prevented.

In FIGS. 4A and 4B, since the coil pressing cover 8 is also provided with a substantially V-shaped concave lead wire 8c, the coil pressing cover 8 has an outer periphery. When the surface-mounting terminal pin 9c for connection provided on the part is pulled around, the positioning accuracy is further improved and the connection work is facilitated.

Needless to say, the above-mentioned effects can be obtained even if the surface-mounting terminal pins 9c for connection are not particularly surface-mounting.

(Embodiment 4) FIG. 5 (a) is a partially enlarged sectional view of a coil pressing cover 8 which is a main part of still another embodiment, and has the same structure as that of the third embodiment. According to the figure, by providing the protrusion 8d on the outer peripheral surface of the coil pressing cover 8 to fix the lead wire 2a to the protrusion 8d and by providing the coating removal portion 9d on at least a part of the lead wire 2a, This coating removal portion 9d
Since the protrusion 8d having the above is inserted into the printed circuit board and mounted and connected to the printed circuit board, terminals for connecting to the printed circuit board are not required, and the number of connection points is reduced, so that the connection reliability is improved. It is a thing.

(Fifth Embodiment) FIG. 5 (b) is a partially enlarged sectional view of a coil pressing cover 8 which is a main part of still another embodiment, and the other parts have the same structure as the fourth embodiment. According to the figure, by providing the concave horizontal groove 8e on the outer peripheral surface of the coil pressing cover 8 and pushing the lead wire 2a into the concave horizontal groove 8e, the slack of the lead wire is prevented and the adjacent lead wire is prevented. It prevents contact between them.

(Embodiment 6) FIG. 6 is a side sectional view of still another embodiment, and if only the difference from Embodiment 1 is explained, 10 is the coil base 7 and the coil pressing cover 8 fitted together. After that, the opening 11 is a fitting portion, and the coil pressing cover 8 and the coil base 7 are fitted in the fitting portion 11 so that there is no gap between them, and the coil base 7 side (upper side) in FIG. By forming the opening in the mold, the casting resin 6 is filled from the opening 10 to complete the thin laminated coil.

Therefore, by covering the coil base 7 with the coil pressing cover 8 and then reversing the laminated coil, the opening 10 can be directed upward, and the casting resin 6 can be extremely easily filled, and heat generation of the coil can be prevented. Higher heat dissipation and higher safety can be achieved.

If a highly adhesive resin is vacuum-cast and the voids in the coil are removed, the creepage distance and the like are alleviated, and further miniaturization is possible.

In order to have the above-mentioned structure, in addition to the first and second steps described in the first embodiment, after the coil pressing cover 8 is put on the laminated coil, the laminated coil is turned upside down. It is sufficient to use the manufacturing method in which the magnetic core 1 forming the closed magnetic path is assembled and completed through the step of (4) and the fourth step of filling the resin from the openings of the coil pressing cover 8 and the coil base 7 after reversal. .

(Embodiment 7) FIG. 7 is a side sectional view of still another embodiment. According to FIG. 7, 6a is a resin reservoir and 7c is provided on the back surface of a coil base 7 on which spiral coils are laminated. 7d is a through hole provided in the surface of the coil base 7 on which the spiral coil 2 is laminated, 8f is a flange portion of the coil pressing cover 8, and a convex flange portion is provided on the back surface of the coil base 7. 7c is formed, and the flange 8f of the coil pressing cover 8 forming the opening 10 is formed to have a height substantially equal to that of the flange 7c, and the resin reservoir 6a is provided. This has the effect that the resin does not overflow during molding and the casting operation becomes easier.

By providing the through hole 7d in the coil base 7, when the resin is cast, the through hole 7d can also be used as an opening, so that the resin can be swirled faster.
Resin casting speed becomes faster. In other words, it also has the effect of reducing the number of casting steps. Further, since the through hole 7d can also be used as a ventilation hole, the effect of reducing the coil temperature and the like can be obtained even when the resin is not cast.

As shown in FIG. 8, if a center core guide wall 8g for passing the magnetic core 1 is provided in the central portion of the coil pressing cover 8 and the center core guide wall 8g is used as the double fitting portion 12, the inner spiral is formed. Since the winding 2 forming the coil and the magnetic core 1 are separated by the double-fitting guide wall, the creeping distance between the winding 2 and the magnetic core 1 can be secured without increasing the board mounting area. I have.

[0054]

As described above, according to the present invention, a lead wire is provided between the comb-shaped protrusions on a coil base having a core guide wall having a comb-shaped protrusion formed at least at one end and a magnetic core passing through the central portion. A coil pressing cover having at least a portion facing the spiral coil is covered from the upper surface of the multilayer coil formed by sequentially stacking the spiral coil while wiring to form the multilayer coil, and the comb-shaped projection of the coil base is formed. The thickness of the coil stack is reduced by incorporating the magnetic cores that form the closed magnetic circuit from the top and bottom of the stacked coil in which the lead wire of the spiral coil is drawn out from the gap between the end surface where the section is provided and the inner wall of the coil pressing cover. Stabilization and prevention of movement of the winding due to the influence of the lead wire can be achieved at the same time, the coupling state between laminated windings is stable, and there is little variation in electrical performance. It is Kudekiru thing.

[Brief description of the drawings]

FIG. 1 is a side sectional view of an embodiment of a thin laminated transformer of the present invention.

FIG. 2 is an exploded perspective view of the same.

3A is a plan view of the other embodiment, FIG. 3B is a side sectional view of the same, and FIG. 3C is a side sectional view of the other embodiment.

FIG. 4A is a plan view of the other embodiment, and FIG. 4B is a side sectional view of the same.

5A is a partially enlarged cross-sectional view of a coil pressing cover, which is a main part of the other embodiment; FIG. 5B is a partially enlarged sectional view of a coil pressing cover, which is a main part of the other embodiment.

FIG. 6 is a side sectional view of the other embodiment.

FIG. 7 is a side sectional view of the other embodiment.

FIG. 8 is a side sectional view of the other embodiment.

FIG. 9 is a side sectional view of a conventional thin laminated transformer.

FIG. 10 is an exploded perspective view of the same.

[Explanation of symbols]

 1 Magnetic Core 2 Winding (Swirl Coil) 2a Lead Wire 3 Insulating Paper 4 Spacer 5 Coil Case 6 Filling Resin 6a Resin Reservoir 7 Coil Base 7a Comb-Shaped Protrusion 7b Middle Guide Collar 7c Collar 7d Through Hole 8 Coil Pressing cover 8a Coil facing surface 8b Projection-shaped collar portion 8c Drawer lead guide groove 8d Projection portion 8e Recessed horizontal groove 8f Collar portion 8g Core guide wall 9a Terminal pin 9b L-shaped terminal pin 9c Surface mount terminal pin 9d Coating Removal part 10 Opening part 11 Fitting part 12 Double fitting part

Claims (13)

[Claims] 1. A spiral coil is formed on a coil base having a comb-shaped protrusion formed at least at one end and a core guide wall for passing a magnetic core in the center thereof while wiring lead wires between the comb-shaped protrusions. An end face of the coil base, on which the comb-shaped protrusions are provided, while a laminated coil is formed by covering a coil holding cover having at least a portion facing the spiral coil from the upper surface of the laminated coil that is sequentially laminated. A thin laminated transformer in which magnetic cores forming a closed magnetic path are incorporated from above and below a laminated coil in which lead wires of a spiral coil are drawn out from a gap between a coil portion and an inner wall of a coil pressing cover. 2. A coil pressing cover having a connecting terminal portion to a substrate on at least a part of an outer peripheral portion thereof, while securing a predetermined lead length from the outer peripheral end surface of the spiral coil to the connecting terminal portion to the substrate. 2. The thin laminated transformer according to claim 1, wherein the lead wire is extended to the connection terminal portion provided on the outer peripheral portion of the coil pressing cover and the lead wire is wired. 3. The thin laminated transformer according to claim 2, wherein a three-layer insulation-coated electric wire is used for at least one of the primary and the secondary. 4. The thin laminated transformer according to claim 2, wherein a protrusion-shaped collar portion is provided on the outer peripheral surface of the coil pressing cover between the magnetic core and the creeping surface of the connection terminal portion. 5. The thin laminated transformer according to claim 1, wherein a substantially V-shaped concave lead-out guide groove is provided on at least a part of the inner and outer peripheral surfaces of the lead-out lead of the coil pressing cover. 6. A protrusion is provided on the outer peripheral surface of the coil pressing cover to fix the lead wire to the protrusion,
The thin laminated transformer according to claim 5, wherein a coating removal portion is provided on at least a part of the lead wire. 7. The thin laminated transformer according to claim 5, wherein a concave horizontal groove is provided on the outer peripheral surface of the coil pressing cover. 8. The method according to claim 1, wherein the opening is left only on the surface on the side of the coil base, and the other part is fitted with the coil base and the coil pressing cover without any gap, and the resin is filled from the opening. Thin laminated transformer. 9. The coil base, on which the spiral coils are laminated, has a convex collar portion formed on the back surface thereof, and the collar portion of the coil pressing cover forming the opening is also formed at substantially the same height. The thin laminated transformer according to claim 8. 10. The thin laminated transformer according to claim 1, wherein a through hole is provided in a coil base surface on which the spiral coil is laminated. 11. The thin laminated transformer according to claim 1, wherein a center core guide wall portion through which a magnetic core is inserted is provided in a central portion of the coil pressing cover, and the center core portion has a double fitting structure. 12. A spiral coil is sequentially mounted on a coil base,
The first step of stacking and by covering the coil holding cover from the upper surface of the laminated coil, the coil lead cover is pulled out from the gap between the coil base end surface portion and the coil press cover inner surface wall while bending the lead wire of the spiral coil. A method of manufacturing a thin laminated transformer incorporating a magnetic core forming a closed magnetic circuit through the steps of. 13. A third step of covering the laminated coil with a coil pressing cover and then inverting the laminated coil up and down, and a fourth step of reversing the laminated coil after opening and inverting the coil pressing cover and the coil base. 13. The method for manufacturing a thin laminated transformer according to claim 12, wherein a magnetic core forming a closed magnetic circuit is incorporated via the above.