JPH01205509A - Radio frequency power transformer - Google Patents

Abstract

PURPOSE: To provide a small transformer which is easily manufactured by forming each coil on the primary and secondary sides on the first and second printed substrates and sandwiching these printed substrates between two ferrite cores for integration. CONSTITUTION: A primary side coil 26 of a transformer is formed on the first printed circuit board 20 and a secondary side coil 36 of the transformer on the second printed circuit board 30. With slot openings 24 and 34 formed on the circuit boards 20 and 30, respectively, forked ferrite pot cores 40 and 42 are combined so as to clamp the boards 20 and 30 through the openings, and the entire is integrated with fixing means 12a and 12b. In that case, the coils 26 and 36 contact to the cores 40 and 42, and by an insulation material layer generated at one of the coils, coil and core are insulated from each other.

Description

DETAILED DESCRIPTION OF THE INVENTION TECHNICAL FIELD This invention relates generally to power transformers, and more particularly to miniature high frequency printed circuit power transformers.

BACKGROUND OF THE INVENTION Conventional high frequency power transformers are typically relatively large devices that require wire-wound primary and secondary windings and customized core assemblies.

Such devices are often unusable in current printed circuit applications where size is a major factor in the design and manufacture of electronic devices. The high cost of winding and core formation in conventional transformers creates further problems.

Some attempts were made to reduce the size of the transformer. For example, in U.S. Pat. No. 4,507,640, a transformer formed with conductive ribbon windings positioned between halves of a magnetic core is small, but close in the manufacture of the core and ribbon. requires specific mechanical tolerances.

U.S. Patent No. 4. ．． No. 012,703, a transmission line matching transformer has primary and secondary windings separated by a plastic sheet covering and coupled to a printed circuit board. Transformers designed to change the characteristic impedance of a transmission line are relatively small, but expensive as a result of the customization that characterizes the transmission line impedance matching transformer.

It is therefore an object of the invention to provide a miniature high frequency power transformer that is compact and inexpensive to manufacture. Yet another object of the invention is to provide a miniature high frequency power transformer that exhibits excellent magnetic coupling and high voltage isolation. Other 1 of this invention
” is aimed at the primary and/or
or to eliminate the need for winding one or both of the secondary windings.

SUMMARY OF THE INVENTION The above and other objects of the present invention are to form the primary and primary windings of a transformer in accordance with a first embodiment, and to provide a structure in which the sides of the substrate holding the windings are separated very far apart. the first and second circuit boards being positioned facing each other. First and second halves of a bifurcated ferrite pot core that extend through a slot opening formed in the circuit board surround the winding. To maintain tight magnetic coupling between the windings, the windings are in contact with the core halves to avoid any high reluctance air gaps therein. The windings are insulated from the core and from each other by a layer of insulating material created on one of the windings. The first and second core halves are secured together by adhesive or by a non-metallic bolt extending through a central through hole in the first and second core halves.

According to a second embodiment of the invention, the primary or secondary winding of the transformer is formed on the motherboard of the electronic circuit, and the remaining windings are parallel to and in contact with the motherboard. It is formed on the second circuit board. The first and second core halves, extending through corresponding slot openings formed in the motherboard and the second circuit board, surround the windings. The windings on the outer surface of the substrate are insulated from the core halves and from each other by a layer of insulating material produced on at least one of the windings; The halves are fixed together to surround the winding.

In a third embodiment of the invention, the first and second annular circuit boards holding the primary and secondary windings, respectively,
and surrounded within the second core half. The windings on the outer surface of the substrate are insulated from the core halves through the core halves and from each other by a layer of insulating material created on at least one of the windings.

In a fourth embodiment of the invention, either the primary or secondary windings of the transformer are formed on the motherboard of the electronic circuit, and the remaining windings are parallel to and in contact with the motherboard. A second annular circuit board is formed on the surface of the second annular circuit board. 1st and 2nd
Half of the core surrounds the windings, and a layer of insulating material produced on one of the windings insulates the windings from the core and from each other.

In each embodiment, the primary and secondary windings may be printed as variations on the sides of the circuit board facing each other, rather than on opposite sides as previously described. . A layer of insulating material is created on at least one of the windings between the substrates.

In either embodiment, the magnetic coupling between the transformer windings of the present invention is maximized since there is virtually no air gap between the windings and the core. This is particularly important for efficient high frequency power transformers and allows smaller transformers to be realized. Additionally, forming the windings directly on the circuit board in various embodiments of the invention eliminates manual or machine winding and reduces manufacturing costs.

Still other objects and advantages of this invention will emerge from the following detailed description, illustrated and described by way of illustration only of the preferred embodiments thereof, or merely the best mode contemplated for carrying out the invention. It will be apparent to those skilled in the art that this invention is capable of other and different embodiments as will be realized, and its several details depart from this invention. Modifications may be made in various obvious respects without limitation; accordingly, the drawings and description are to be regarded as illustrative in nature and not as restrictive.

BEST MODE FOR CARRYING OUT THE INVENTION Referring to Figure 1a, a miniature high frequency power transformer according to a first preferred embodiment of the invention
a circuit board 20 (see FIG. 2) having a printed circuit primary winding 26 formed on its side and a printed circuit secondary winding 36 formed on its second side. The circuit board 30 (FIG. 3) is positioned in facing relationship. The first circuit board 20 and the second circuit board 30 have identical arcuate slot openings 24 and 34, respectively, and circular central openings 22 and 32 formed therein.

The primary winding 26 faces the first core half 40 and the secondary winding 36 faces the second core half 42. 1st a
As shown in FIG.
6 is surrounded on opposite sides by core halves 40 and 42, respectively.

-]2- The core halves 40 and 42, commonly known as "bot cores", are manufactured from ferrite material and are conventional. As shown in Figures 4a and 4b,
Each of the identical core halves has an arcuate peripheral lip 44 extending axially from one surface of the core, and an annular spindle 48 projecting from the surface 43 therebetween, substantially forming a disc. It is in a state of A circular central through hole 46 is formed in the spindle half of each core. spindle 48
are disk-shaped openings 22 and 32 formed in the circuit board.
has a diameter equal to the diameter of. (See FIGS. 2 and 3) In the first preferred embodiment assembly of FIG. 1a, a primary winding 26 formed on a first circuit board 20 and a primary winding formed on a second circuit board 30 The first circuit board and the second circuit board 30 are positioned such that the secondary windings 36 are spaced apart and facing each other. Slot openings 24 and 34 in substrates 20 and 30 are aligned with each other and
and a first core half 40 and a second core half 42
The lip 44 of the disc-shaped openings 22 and 32 in the substrate
through the slot openings 24 and 34 so as to contact each other with the annular spindles 48 on the core halves of the pair. The lip 44 of each core half is positioned in mutual alignment with the primary winding 20 and secondary winding 30 facing and surrounding core halves 40 and 42, respectively (see FIG. 8). .

The depth of the lip 44 and spindle 46 on each core half is substantially equal to the thickness of each circuit board 20 and 30 so that the primary and secondary windings are located on the core surface 43 of the core halves 40 and 42. It should be understood that it abuts. This close fit between the windings and the core halves maximizes core-to-winding coupling and minimizes leakage flux (see Figure 1b).

High frequency power transformation is accomplished with the primary and secondary windings facing each other, separated by discrete layers of insulating material, as shown in the aforementioned U.S. Pat. No. 4,012,703. It is possible that the magnetic flux path with the lowest possible magnetic resistance is the highest level of efficient power transformation, i.e., the magnetic flux path with the lowest possible magnetic resistance. This is believed to be achieved by positioning the windings as close as possible to . "Standard Handbook for Electrical Engineers" 9th Edition (Standard Handb)
ook for Electrical Eng
McGraw Hill 1), 195
7, p. 321-. Thus, according to the invention, electrical isolation between the primary winding 26 and the secondary winding 36 is achieved by the creation of an insulating layer 13 on either or both of the two windings. Ru.

(The insulating layer 13 is produced on the secondary winding 36 of FIG. 1a). As shown in FIG. 7, the insulating layer 3 is manufactured by Dynachem Company, Tustin, California, USA.
ted in Tustin, CA)
5-Film solder mask (Dry Film S.

(Ider Mask) or, preferably, by using vacuum lamination, on one of the circuit boards. However, any other permanent insulation producing material exhibiting high its thin film properties may be used as well.

As will be readily appreciated, forming the printed circuit primary and secondary windings on the first circuit board 20 and the second circuit board 30 eliminates windings and reduces cost. .

The first and second circuit boards 30 of the preferred embodiment include fiberglass impregnated with epoxy resin. However, other suitable materials can also be used.

Once assembled, the transformers 14 can be glued together by any suitable adhesive (not shown) applied to the core lip 44. Alternatively, as shown in FIG. 1a, bonding is preferred, but the non-metallic hole 12a passes through the first core half 40 and the second core half 42 through the through hole 46. and 16 one nonmetallic nara l-: ], held by 2 b,
The transformer assembly may be fixed together.

It should be understood that the nineteen windings of the transformer can be formed directly on a circuit board carrying components of a composite electrical circuit rather than on a dedicated circuit board. Thus, in FIG. 9, either primary winding 26 or secondary winding 36 of transformer 90 is]. The remaining transformer windings are formed on a second circuit board 94, with the remaining transformer windings being formed on a second circuit board 94.

In another preferred embodiment of the invention, shown in FIG.
A primary winding 64 and a secondary winding 66 of transformer 50 are formed in a first annular circuit board 60 and a second annular circuit board 62, each having a disc-shaped central opening 68 formed therein. (Figures 6a and 6b). As shown in Figures 4a and 4b and Figures 6a and 6b, the diameter of the opening 68 is the same as that of the annular spindle 48 formed in one half of the ferrite core. Both of the annular circuit boards conform to the surface 4B on each half of the Ferrai I core, and a layer of insulating material is produced on one or both of the windings.

In the assembly of transformer 50, first annular circuit board 60
and a second annular circuit board 62 are brought together with the circuit boards oriented such that the primary winding 64 and the secondary winding 66 are spaced apart and facing each other. Substrates 60 and 62
are located within core halves 40 and 42 because they are assembled around the core halves or substrate, with primary winding 64 and secondary winding 66 facing each core half. . A layer of insulating material 13 is created on one or both of windings 64 and 66.

(Only 19 generated layers are shown). Then the entire assembly or each core half 40 and 42
The spindle 48 and lip 44 are interfitted with each other with any suitable adhesive material (not shown).
(See Figure 5). As shown in the embodiment of FIG. 1a, there is no air cap between the transformer windings and the core halves, thereby optimizing the gravity switching capacity of the device.

Referring now to FIG. 10, in yet another preferred embodiment of the present invention, one of the primary windings 104 or the secondary windings 106 of the transformer 100 is formed on the motherboard 92, and The remaining transformer windings are connected to the second annular circuit board 10.
11- is formed.

As shown in other embodiments of the invention, to fit completely within the first core half 40 and the second core half 42 and to contact the surface 43 of the core half; A circular circuit board 101 is formed.

In the assembly of transformer 100, two substrate primary windings 104 and a secondary winding 106 or each core half 4
0 and 42, and is positioned in contact with the annular circuit board 101 or the mother board 92. In a manner similar to the embodiment of FIG. 1a, the core halves 40 and 42 are arranged such that one core half surrounds the annular circuit board 101;
The other half of the core is inserted into the mother board 92, and the two cores are integrated together. The entire assembly is secured in place by gluing them together or otherwise joining the core's 13 minutes 40 and 42 by other means.

As a variation of embodiments of the invention, as previously mentioned, the primary and secondary windings are formed on sides 1- of the circuit board facing each other rather than on opposite sides. Insulation +
A layer of material is formed on at least one of the windings between the substrates. Thus, in FIG. 11, the circuit (the primary wire 26 on the board 20 faces the secondary winding 36 on the circuit board 30,
An insulating layer ] 3 is produced on the secondary winding 36 .

(7) first and second circuits having primary and secondary windings of the transformer formed thereon (7) and positioned such that the sides of the substrate holding the windings face each other apart. A miniature high frequency power transformer has been described which includes a substrate, the substrates being insulated from each other by a layer of electrically insulating material formed on at least one side of the windings. 1') of the bifurcated core extending through the apertures provided surround the windings without any air gaps existing between the core and the windings. Both side boards can be used exclusively for transformers, or one board can be the mother board for an electronic circuit. Furthermore, one or both substrates can be shaped so that they are surrounded by one or both core halves.

As a variation of each embodiment, the primary and secondary windings may be printed on sides of the circuit board facing each other rather than on opposite sides. A layer of insulating material is created on at least one of the windings between the substrates.

In this disclosure, only preferred embodiments of the invention are shown and described; however, as noted above, the invention can be used in various other combinations and environments. , and it is to be understood that changes or modifications may be made within the scope of the inventive concept described herein.

[Brief explanation of the drawing]

FIG. 1a is an exploded view of a transformer according to a nineteenth embodiment of the invention. Figure 1b is a side view of the assembled transformer of Figure 1a showing virtually no air gaps between the primary and secondary windings and between the windings and the ferrite core halves; be. FIG. 2 is a plan view of a first circuit board carrying the primary winding of the transformer of FIG. 1a. FIG. 3 shows a second
FIG. 3 is a plan view of the circuit board of FIG. FIG. 4a is a front view of one half of the first ferrite core shown in FIG. 1a, and FIG. 4b is a rear view thereof. FIG. 5 is an exploded view of a transformer according to a second embodiment of the invention. FIG. 6a shows a first circuit board carrying a primary winding according to the embodiment of FIG. FIG. 6b shows a second winding carrying a secondary winding according to FIG.
printed circuit board. 7 is a side view of a portion of the transformer of FIG. 5 showing the insulation layer on one winding of the substrate; FIG. FIG. 8 is a perspective view of an assembled miniature high frequency power transformer according to the present invention. FIG. 9 is a perspective view of a transformer according to the invention assembled on a 1':J board. FIG. 10 is a modification of the embodiment of FIG. FIG. 11 is a variation of the preferred embodiment of the invention showing the primary and secondary windings facing each other with a produced layer of insulating material therebetween. In the figure, 14 is a miniature high frequency power transformer;
0 is a first printed circuit board, 30 is a second printed circuit board,
26.64 is the primary printed circuit winding, 36.66 is the secondary printed circuit winding, 40 is the first core half, 42 is the second core portion, 43 is the surface of the core, 24.34 is the Arc-shaped slot opening, 22.32.68 is a disk-shaped central opening, 46
60 is a circular center through hole, 60 is a first annular circuit board, and 62 is a circular central through hole;
is a second annular circuit board,] 3 is an insulating layer, and 12a is a non-metallic bolt. (Left below) Procedural amendment (method) 1. Description of the case 1986 Patent Application No. 303891 2 Title of the invention High frequency power transformer 3 Person making the amendment Relationship to the case Patent applicant Address Everitt Seaway Poolehard, Washington State, United States of America, 6920 people John Flug Manufacturing
Company Incorporated Representative Deuda Matsufnight 4, Agent address 1-29, 2-1 Minamimorimachi, Kita-ku, Osaka, Sumitomo Bank Minamimorimachi Building 6, 4. of the application subject to amendment. Column for the representative of the patent applicant, all drawings, power of attorney and translation 7, and contents of the amendment as shown in the attached sheet. There are no changes to the contents of the drawing. that's all

Claims (19)

[Claims] (1) A high frequency power transformer comprising: first and second printed circuit boards;
primary and secondary printed circuit windings of the transformer respectively formed on substrates, the first and second substrates having surfaces thereof carrying the primary and secondary windings spaced apart from each other. and further comprising first and second core halves, wherein the first and second printed circuit boards are formed therein to partially connect the primary and secondary windings. a slot aperture surrounding the substrate, the apertures in the substrate being aligned with each other, the first and second core halves each including a portion extending through the slot aperture; said primary and secondary windings are in contact with their respective core halves so as to substantially surround said primary and secondary windings and provide close magnetic coupling between said windings; the printed circuit primary and secondary windings to hold the first and second printed circuit boards together and further electrically isolate the one winding from the core half and the other winding; a layer of electrically insulating material produced on one of the transformers. 2. The transformer of claim 1, wherein the other of the electrical printed circuit windings is not insulated. 3. The transformer of claim 1, wherein the core halves together form a pot core. (4) the axially extending portion of the core half;
and the slot opening formed in the printed circuit board is arcuate. (5) One of the first and second printed circuit boards,
2. The transformer of claim 1, wherein the transformer is larger in surface area than the other and carries at least one electrical component in circuit with the transformer. (6) half of the core is formed from ferrite;
A transformer according to claim 1. (7) said core halves each having a circular central passage hole therein, and means extending through said passage hole of said core halves for securing said core halves together; The transformer of claim 1, comprising: (8) Claim 7, wherein the fixing means includes a non-metallic bolt.
Transformer described in. (9) Claim 1, wherein the core halves are glued together.
Transformer described in. (10) A high frequency power transformer, comprising: first and second printed circuit boards;
primary and secondary printed circuit windings of the transformer respectively formed on substrates of the transformer, the first and second substrates having sides thereof carrying the primary and secondary windings spaced apart from each other. first and second core halves positioned facing each other and further substantially surrounding the primary and secondary windings; and connecting one of the printed circuit windings from the core half and the other winding. an electrically insulating material produced in one of the printed circuit primary and secondary windings to electrically insulate the first and second printed circuit boards, the first and second printed circuit boards being aligned with each other and having an electrically insulating material formed therein; a central opening formed in the first and second core halves, the first and second core halves having portions each extending through the central opening in contact with each other; the primary and secondary windings are in contact with their respective core halves to hold the two printed circuit boards together and provide close magnetic coupling between the windings and the core halves; Transformer. 11. The transformer of claim 10, wherein the other of the printed circuit windings is not insulated. 12. The transformer of claim 10, wherein the core halves together form a pot core. 13. The transformer of claim 10, wherein half of the core is formed from ferrite. (14) said core halves each having a circular central through-hole therein and means extending through said through-hole of said core halves for securing said core halves together; 11. The transformer of claim 10, comprising: (15) The transformer of claim 10, wherein the securing means includes a non-metallic bolt. 16. The transformer of claim 10, wherein the core halves are glued together. (17) The transformer according to claim 10, wherein at least one of the circuit boards is annular. (18) at least one of the first and second printed circuit boards, a first of which is annular and the other printed circuit board is larger in surface area than the first, and in circuit with the transformer; 11. A transformer as claimed in claim 10, holding three electrical components. (19) A high frequency power transformer comprising first and second circuit boards and planar primary and secondary circuit windings of the transformer formed on the first and second boards, respectively. the first and second substrates are positioned such that sides thereof carrying the primary and secondary windings face each other, and the substrates are aligned with each other and have openings formed therein. and further comprising: a layer of electrically insulating material between the facing sides of the substrate for electrically insulating the primary and secondary windings from each other; and the first and second core halves each have a portion extending through the opening, and the primary and secondary windings are magnetically coupled in close proximity to each other. As in, the first
and a transformer holding together a second circuit board, the core half substantially surrounding the primary and secondary windings.