WO2004003947A1 - Method of producing planar transformers and planar transformer thus produced - Google Patents

Abstract

The invention relates to a planar transformer consisting of a series of windings which are disposed in a stack comprising a variable number of printed circuit winding panel plates and coil or die-cut laminar copper windings, with the insertion of insulating laminar elements which are in contact with all of the faces of the windings and which are of variable thickness, such that the spaces between windings can be adjusted. The aforementioned windings are interconnected by means of connecting pins which are solidly connected to said windings. The invention forms a single unit, whereby all of the stacked laminar elements are contained in a single mass of insulating resin which covers the exterior of all of the stacked elements and which is also inserted in the horizontal spaces between windings.

Description

 PROCEDURE FOR THE MANUFACTURE OF PLANAR TRANSFORMERS AND PT.ANAF TRANSFORMER. FAFÍF-TCADO OF A TTEPOO WITH THE MTBMΩ

MFMORTΆ DESCKTPTTVA

The present invention relates to a process for the manufacture of planar transformers and to the transformer manufactured by the application of said process.

The objective of the present invention is to achieve planar transformers with very small dimensions and with a high insulation capacity between layers, in particular between windings, also making it possible to manufacture them economically.

In order to achieve its objectives, the present invention relates to the manufacture of planar transformers composed exclusively of windings and insulating sheets of varying thickness in accordance with the insulation between integrated circuits and / or coils made by die-cutting of copper sheets or windings of copper, ensuring that the dielectric strength in the vertical direction is met.

The manufacturing process object of the present invention satisfactorily solves the insulation in the horizontal direction, in which the so-called "Creepage" distance is traditionally defined as the minimum distance between windings or winding and core on the insulating surface, through the air .

In accordance with the process object of the present invention, the manufacturing of the planar transformer by means of a series of successive operations that synthetically comprise: a) successive placement, by stacking, of the constituent laminar elements of the windings with interposition of insulating sheets on both sides and including the laminar elements of the multi-layer printed circuits or printed circuits with double printed or single-sided circuits; b) placement of the connecting pins inserted in aligned holes of the laminar elements that make up the windings and of the printed circuit board (PCB) panels, proceeding to fix the pins in both the winding or winding terminals of copper as in those of the printed circuits, simultaneously obtaining the electrical connection of said pins and the spatial fixation of the printed circuits, achieving a high rigidity in the whole; c) molding of a resin mass, for example using a recoverable mold or shell, forming a block, or, placing the assembly formed by the different stacked windings together with the insulating elements inside a box substantially adapted to the shape external of said set stacked and previously solidarity, proceeding to continuation to the pouring of the insulating resin, for example, polyurethane, with a very reduced speed, to allow its introduction between windings, until it reaches the desired height inside the box, which can be the flush height, after which and After hardening the resin, a completely compact assembly well insulated by the penetration of the resin between the winding layers is achieved, achieving high dielectric strength linked to small external dimensions.

To achieve a good penetration of the resin, for example, polyurethane, between the windings, it will be necessary for the insulation layers to be thick enough to allow such penetration, to leave a greater area of penetration of the insulating resin.

Finally, the assembly formed by the windings, separators, printed circuits and connecting pins will be incorporated, all embedded in a mass of insulating polyurethane resin, the externally coupled ferrites.

The molding box of the set of windings, insulation plates and printed circuits may be incorporated into the transformer with the mission of acting as an envelope of the assembly, although the transformer could also be manufactured, as indicated, inside a mold metal or shell, in which case there is no external molding box of polyurethane resin. For better understanding, representative drawings of the present invention are attached by way of explanatory but not limitative example.

Figure 1 shows the set of integral parts of a planar transformer made in accordance with the present invention, showing the relative position of a resin molding box and ferrite cores.

Figure 2 shows on a larger scale a cross section of the planar transformer itself in which the molding box is arranged as a protective envelope.

Figure 3 shows a second section of the planar transformer along a plane parallel to that of Figure 2.

Figure 4 shows a section in plan.

As shown in said figures, a planar transformer according to the present invention is composed of a set of windings and insulating layers interposed and stacked forming a set, being joined by a series of connecting pins, as seen in the figure 1, in which the winding laminar elements with printed circuit -1-and -2-and the intermediate coils -3-and -4-, stamped of copper sheet or winding of the same material, are disposed on each side of said elements the insulating material separators -5-, -6-, -7-, -8-and -9-, which have smaller surface dimensions than that of printed circuit windings -1-and -2- . The arrangement is the one that can be seen in figures 2 and 3, in which the arrangement of the coils, printed circuit panels and separators, being fixed in position by the through pins, in variable number, having been represented in the present example, as it is observed in figure 1, in which the pins have been represented with the numerals -10-, -10'-, -10 "-..., it should be understood that their number and arrangement will depend on the circuits involved. These pins are inserted in the corresponding holes of the printed circuit boards and the coils, as indicated, for example, on the printed circuit board -1-by the numerals -11-, -11'-, -11 "-... and on the coil -3- with the numerals -12- and -12'-.

The fixing of the pins in said panels and windings will be carried out in ways known in the art, for example, by means of cold welding, cementitious masses or others.

Once the assembly of the windings with its isolation separators and fixing pins is constituted, the assembly will be embedded in a mass of an insulating resin, for example, polyurethane, which can be done by molding with an external mold or " coquilla "or by means of an adapted structure box -13-, which has an external shape adapted to that of printed circuit boards, presenting lateral steps such as -14-and -15-to adapt to side recesses -16- and -17-of said printed circuit panels and an elongated central noi -18-intended to coincide in the central openings of said stacked elements, that is, printed circuit boards, insulating coils and separators.

To achieve a satisfactory result it is essential to adjust the thickness of the separators that gives rise to the steps for the resin.

Once the curing of the insulating resin, preferably polyurethane resin, is carried out, the ferrite cores -1 -and -20- will be coupled, being joined by means of insulating laminar elements adapted externally to them or any other means known in The technique.

Figure 4 shows a plan view of an example of a planar transformer made in accordance with the present invention, in which the enclosure -13-incorporated into the mass of polyurethane resin, which forms the elements extreme blocks -21 -and -34-that are interconnected by the zones -22-and -23-, of which only the beginning in Figure 4 bordering the central opening -25- can be seen. The ends of the connecting pins protrude from the polyurethane resin block, having been represented with the numbers -26-, -27-, -28-and -29-for the block -20- as well as the pins -30-, - 31-, -32-and -33-in block -21-, although it should be understood that the number and arrangement of said pins may vary with the specific design of the planar transformer.

Claims

 RETVTNDTr.Ar.τONES 1. Planar transformer, characterized by comprising a succession of stacking windings consisting of a variable number of printed circuit winding panel plates and copper windings, stamped or winding laminations, with interposition of insulating laminar elements in contact with all the faces of the windings and of variable thickness to adjust the interstices between windings, said windings being connected to each other by means of connecting pins jointly joined to them, and constituting a single block because all the laminar elements are embedded stacked in a single mass of insulating resin that externally covers the set of stacked elements and that is introduced into the horizontal interstices between the windings, being coupled on the pre-assembled block and embedded in the polyurethane mass, the outer ferrite cores, joined by an external insulator that extends to its entire exterior surface. 2. Planar transformer, according to claim 1, characterized in that the resin block containing the windings, separators and pins of the transformer is incorporated inside an open insulating box that adapts to the base, to the side profile of said block and its central opening 3. Procedure for the manufacture of planar transformers according to claims 1 and 2, characterized by proceeding in a first phase to the vertical stacking of the panels of printed circuit winding and laminar or winding coils with arrangement of intermediate laminar separators, as well as in the upper or lower part of the stack, making their solidarity by introducing connection pins mounted in the aligned holes of the windings, making their solidarity with said windings and finally pouring a mass of polyurethane resin into a mold that wraps the previously assembled block formed by the windings, separators and joining pins, making the pouring at a suitable speed to allow the penetration of the insulating resin in the interstices between windings. 4. A method according to claim 3, characterized in that the pouring of the polyurethane resin mass is carried out inside a closed and open-top enclosure that is externally adapted to the shape of the pre-assembled block of windings and separators , filling the resin until it flush with the upper face to form a block.