Abstract
An electric module with a planar transformer has a housing with an interior having an internal length and an internal height. The electric module additionally has a main printed circuit board with a first thickness, the main printed circuit board being equipped with at least one electronic component. The planar transformer is arranged on an additional printed circuit board with a second thickness, and the main printed circuit board has a recess which receives the additional printed circuit board. Additionally, the main printed circuit board and the additional printed circuit board are connected together via a connection.
Claims
1. An electrical module comprising a planar transformer, said module comprising a housing having an interior m having an internal height; a main circuit board having a first thickness, at least one electronic component being arranged on the main circuit board; wherein the planar transformer is arranged on an add-on circuit board having a second thickness; the main circuit board comprising a recess that accommodates the add-on circuit board; and the main circuit board and the add-on circuit board being interconnected via a connection.
2. The electrical module according to claim 1, wherein the connection is step-like.
3. The electrical module according to claim 1, wherein the connection is formed by a step on the main circuit board.
4. The electrical module according to claim 1, wherein the connection is formed by a step on the add-on circuit board.
5. The electrical module according to claim 1, wherein the connection comprises an oblique contact surface.
6. The electrical module according to claim 1, wherein the connection is linear.
7. The electrical module according to claim 1, wherein the connection comprises a contact surface.
8. The electrical module according to claim 1, wherein the connection comprises a depth milling.
9. The electrical module according to claim 1, wherein the main circuit board is arranged centrally with respect to the internal height.
10. The electrical module according to claim 1, wherein the main circuit board is arranged so as to be asymmetric with respect to the internal height.
11. The electrical module according to claim 1, wherein the connection provides an electrical and mechanical connection.
12. The electrical module according to claim 1, wherein the main circuit board and the add-on circuit board comprises a common metallized contact surface.
13. The electrical module according to claim 1, wherein the first thickness of the main circuit board is smaller than the second thickness of the add-on circuit board.
14. The electrical module according to claim 1, wherein at least one component is mounted on either side of the main circuit board in each case.
15. The electrical module according to claim 1, wherein the electrical module provides an isolation amplifier.
Description
BRIEF DESCRIPTION OF THE DRAWINGS
(1) Further features and advantages of the invention can be found in the following description of preferred embodiments, which is given purely by way of example and with reference to the accompanying drawings, in which drawings:
(2) FIG. 1 is a cross-sectional view of a first embodiment of a design of an electronic module comprising a planar transformer, which module is within the scope of the invention;
(3) FIG. 2 is a cross-sectional view of a second embodiment of a design of an electronic module comprising a planar transformer, which module is within the scope of the invention;
(4) FIG. 3 is a cross-sectional view of a third embodiment of a design of an electronic module comprising a planar transformer, which module is within the scope of the invention;
(5) FIG. 4 is a plan view of an embodiment of an add-on circuit board that is integrated in a main circuit board;
(6) FIG. 5 is a plan view of the add-on circuit board of FIG. 4;
(7) FIG. 6 is a cross-sectional view of an embodiment of a main circuit board;
(8) FIG. 7 is a cross-sectional view of an embodiment of an add-on circuit board comprising depth milling;
(9) FIG. 8 shows the add-on circuit board of FIG. 7 comprising metal contacting;
(10) FIG. 9 is a table showing clearance and creepage distances and isolation distances with respect to particular levels of protection based on table 5 of the standard version EN 60079-11:2012 for the standard EN 60079-11;
(11) FIG. 10 is an embodiment of a connection having one oblique contact surface and one straight contact surface;
(12) FIG. 11 is an embodiment of a connection having two oblique contact surfaces;
(13) FIG. 12 is an embodiment of a connection having two step-like geometries; and
(14) FIG. 13 is an embodiment of a connection having one oblique contact surface and a step-like geometry.
DETAILED DESCRIPTION
(15) In the following, reference is made to FIG. 1, FIG. 2 and FIG. 3, which each show a preferred embodiment of the invention. FIGS. 1 to 3 are each cross-sections of an electrical module 100, the embodiments of FIGS. 1 to 3 differing in the arrangement of the circuit boards and the connection 150 thereof to one another. The electrical modules 100 each comprise a housing in which a main circuit board 110 and an add-on circuit board 120 are arranged in each case.
(16) Typically, at least one circuit board PCB1 or printed circuit board having a thickness of H0 is located in electrical modules or electrical devices of this kind having narrow housings, which circuit board is arranged more or less centrally in the available cavity of the housing, depending on the embodiment. Electronic components B1, B2 are mounted on the circuit board PCB1, which electronic components form the electronic functionality of the module or device. In order to make optimal use of the available space, the electronic components are often provided on both sides of the main circuit board 110. As shown in FIGS. 1 to 3, for example component B1 112 is arranged on the upper face and component B2 113 on the lower face of the main circuit board 110. Mounting on both sides means that the main circuit board PCB1 110 is often positioned more or less vertically in the center of the cavity, in order for the mounting heights P01 and P02 to be identical or approximately the same. Alternatively thereto, the main circuit board PCB1 110 can also be displaced in a slightly asymmetrical manner, in order that, for example, components 112, 113 of a greater height can be arranged on the upper face of the main circuit board 110, and components 112, 113 of a smaller height can be arranged on the lower face, with the result that different mounting heights are required. Furthermore, on the add-on circuit board 120 it is possible for components to also be arranged on the upper and/or lower face of the add-on circuit board. FIG. 1 shows a component 127 on the upper face of the add-on circuit board 120, by way of example.
(17) More or less symmetrical positioning of the main circuit board 110 within the cavity of the housing 101 is advantageous if external terminals of the main circuit board 110 are intended to be designed such that metallizations on the main circuit board 110 are intended to establish direct contact in the plug connector. In this case, it is possible, for example, for the metal contacts of the main circuit board 110 to be pushed into a plug connector, outside or inside the housing 101.
(18) The electrical modules shown in FIGS. 1 to 3 can be isolation amplifiers. Isolation amplifiers of this kind are provided in narrow housings.
(19) The electrical modules of FIGS. 1 to 3 each have an external width P1 of for example approximately 6.2 mm. A cavity having an internal height P0 of for example approximately 4.5 mm is provided within the device. The cavity is enclosed for example by two housing parts having a wall thickness of for example approximately 0.85 mm.
(20) In this case, it is possible for example for the main circuit board 110 to have a thickness H0 of for example approximately 0.8 mm. This results, in each case, in maximum mounting heights P01 and P02 within a cavity, of height P0, of the cuboid housing. The mounting heights P01 and P02 could be further increased if the thickness of the circuit board H0 were reduced. However, mechanical aspects, isolation requirements and the layer structure of the circuit board contradict this, with the result that a circuit board thickness of from approximately 0.5 mm to approximately 1.0 mm is typically selected. The mounting heights P01, P02 are for example each approximately 1.85 mm. In this case, manufacturing tolerances are generally also taken into account, and therefore individual values may be different.
(21) A central component of isolation amplifiers is the transformer. Accordingly, almost every isolation amplifier comprises at least one transformer which is dimensioned in accordance with the standards in order to have a particular level of protection. In the region of a transformer, for example galvanically isolated windings, in solid isolation, must maintain at least the measurement T0 with respect to one another. Furthermore, the transformer of an isolation amplifier is preferably designed as a planar transformer. According to the invention, the planar transformer is arranged on an add-on circuit board which may have a circuit board thickness H1 of for example 1.5 mm, the main circuit board 110 of the isolation amplifier being designed having a circuit board thickness H0 of for example 0.8 mm. Accordingly, the following correlation results: H1>H0 and H1>T0, T0 being the required minimum spacing for a specific level of protection, e.g. 1 mm according to table 5 of the standard DIN EN 60079-11, e.g. the version EN 60079-11:2012 (cf. FIG. 9).
(22) FIG. 1 is a cross-sectional view of a first embodiment of a design of an electronic module 100 comprising a planar transformer, which module is within the scope of the invention.
(23) The planar transformer is manufactured as a component on an add-on circuit board PCB2 of thickness H1, which complies with all isolation requirements, such that the planar transformer can be used as an intrinsically safe planar transformer. Furthermore, the planar transformer comprises a ferrite core which comprises two ferrite core parts. The ferrite core parts of the planar transformer F1 and F2 protrude from the add-on circuit board in both directions, by the distance K1 and K2 in the vertical direction, resulting in an overall thickness of the transformer of K1+H1+K2. The overall thickness of the planar transformer may typically be for example approximately 4 mm. As a result, the planar transformer fits in the cavity P0 of for example approximately 4.5 mm.
(24) The add-on circuit board has terminals on the outer layers thereof which are electrically and mechanically contacted with the main circuit board PCB1 110, for example via a connection 150 in the form of a solder connection. The planar transformer 122 is therefore an independent component that can be mounted for example in an SMT process, and essentially comprises, as a main component, the add-on circuit board PCB2 120, which also contains windings, as well as the two ferrite core parts F1 124 and F2 125. In this case, the two ferrite core parts 124 and 125 can be designed as carry-over parts, i.e. be of the same height, but this is not essential. Furthermore, in addition to the planar transformer the add-on circuit board can also accommodate further components B3, such as protective components (fuses, resistors, semiconductors, etc.) which are in particular likewise based on SMT technology. There may be many reasons for this. This measure thus makes it possible, for example, to make even better use of the available installation space, and in addition components B3 can be better thermally coupled to the transformer than if they were arranged on the main circuit board 110. This can be expedient for example for thermal monitoring of the transformer in the event of a malfunction.
(25) The main circuit board PCB1 110 comprises a recess 111 for being able to receive the add-on circuit board via a connection. Furthermore, the add-on circuit board 120 comprises a recess 121 in the region of the transformer 122, through which recess one or both core halves can protrude, for example the lower core halves F2 125.
(26) In the embodiment of FIG. 1, the main circuit board PCB1 110 is, however, not positioned vertically in the center of the cavity P0, but rather displaced downwards to such an extent that the mounting height P02 is smaller than the mounting height P01. Depending on the specific dimensioning, P02 can be so small that even the component B2 113, having a very small height, e.g. smaller than one millimeter (<1 mm), possibly can no longer be mounted at all.
(27) In order to avoid this, a second embodiment according to FIG. 2 is furthermore proposed. In this case, the main circuit board PCB1 110 remains vertically centered or at least approximately vertically centered in the cavity or the interior of the housing 101 having the internal height P0, such that the mounting heights P01 and P02 are identical or at least approximately the same size, and there is sufficient space for both component B1 and component B2.
(28) In this case, according to FIG. 2 what is known as a depth milling 151 is expediently made in the add-on circuit board PCB2 120, as a connection 150, which depth milling is dimensioned such that the electrical and mechanical connection between the two circuit boards 110, 120 is retained, e.g. by edge metallization, and at the same time is designed with respect to the tolerances such that the transformer body (of thicknesses H1+F1+F2) still fits in the cavity P0.
(29) The design according to the second embodiment in FIG. 2 is advantageous inter alia in that it can be expediently produced using a machine, and also in that the circuit board PCB1 110 can remain more or less in the center of the cavity, which has advantages for the components B1 and B2 on either side of the circuit board.
(30) FIG. 3 is a cross-sectional view of a third embodiment of a design of an electronic module 100 comprising a planar transformer 122, which module is within the scope of the invention. In this embodiment, the main circuit board PCB1 110 remains in a more or less central position, as does the add-on circuit board PCB2 120. However, the add-on circuit board PCB2 120 now no longer rests on the circuit board PCB1 110, as is the case in the embodiments of FIG. 1 and FIG. 2, but rather “floats” in a recess 111 of the main circuit board PCB1 110. This can be achieved for example by means of temporary retainers in the manufacturing process. In this position, the two circuit boards 110, 120 (PCB1 and PCB2) are mechanically and electrically interconnected, which can be achieved for example by means of solder connections. In the third embodiment, the add-on circuit board PCB2 120 may be more cost-effective compared with the second embodiment, since the depth milling 151 can be omitted.
(31) FIG. 4 to FIG. 8 show further possible embodiments according to the invention. In this case, FIG. 4 shows a main circuit board PCB1 110 in an embodiment which is based on the second embodiment of FIG. 2. FIG. 5 to FIG. 8 furthermore show additional details.
(32) FIG. 4 is a plan view of the interior of an electrical module 100, comprising a main circuit board 110 and an add-on circuit board 120. An add-on circuit board PCB2 120 comprising two planar transformers 130, 140 is attached to the main circuit board PCB1 110 of FIG. 4, which planar transformers each comprise a ferrite core pair F1 and F2, only the ferrite core part 131, 141 being visible in the plan view of FIG. 5. The main circuit board PCB1 110 has the layer structure 114 shown in FIG. 6, comprising four electrically conductive layers and intermediate isolating layers.
(33) The add-on circuit board PCB2 120 of FIG. 4 and FIG. 5 comprises depth millings 151, in each case, on two edges. The depth millings 151 serve as the connection 150 between the main circuit board 110 and the add-on circuit board 120. Copper contacts or copper pads (optional edge metallizations) which can be soldered to the main circuit board PCB1 are provided on the depth millings 151.
(34) Windings of the planar transformers 130, 140 are shown on an inside layer on the add-on circuit board PCB2 120 of FIG. 5. Further conducting tracks, which are also part of the individual windings and complete these, are provided on a further inside layer that is not shown in FIG. 5. Copper surfaces can be arranged on the outer layers, which surfaces can be used for shielding.
(35) FIG. 6 shows a layer structure of the main circuit board PCB1 which has a maximum thickness of approximately 0.9 mm for example. The individual layers, alternately copper and an isolating layer, have a thickness in the millimeter range, for example 35 μm in each case for a copper layer, and 200 μm in each case for an isolating layer, measured in the vertical direction of FIG. 6.
(36) FIG. 7 shows a layer structure, by way of example, of the add-on circuit board of FIG. 4. The add-on circuit board PCB2 120 according to FIG. 7 has a layer structure 126, comprising four electrically conductive layers and intermediate isolating layers. The dimensions of the individual layers are similar to that in FIG. 6, specifically 35 μm in each case for a copper layer, and 200 μm to 600 μm in each case for an isolating layer, measured in the vertical direction of FIG. 7, it also being possible for vias to furthermore be provided between the individual layers, for the planar transformer. In this case, the layer structure comprising the four layers for example has a maximum thickness of approximately 1.45 mm, without the outer copper layers being taken into account. Furthermore, the add-on circuit board has a step-like geometry 152, on the lower face of which a metal contact surface in the form of edge metallization 153 is arranged, which surface is shown in FIG. 8.
(37) FIG. 8 shows an embodiment comprising edge metallization 153, the metal in this case being copper (edge plated pads). The edge metallization 153 makes it possible in particular to provide electrical connections between the main circuit board and the add-on circuit board.
(38) FIGS. 10 to 13 are cross-sectional views of further embodiments of an electrical module 100, in addition to FIGS. 1 to 3, FIGS. 10 to 13 showing only some of the components provided, and for example the housing 101 and the electronic components 112, 113 not being shown. FIGS. 10 to 13 each schematically show a main circuit board 110 and an add-on circuit board 120, the add-on circuit board 120 being surrounded, at least in part, by two core parts 124 and 125. In this embodiment, the main circuit board 110 has a smaller thickness in comparison with the add-on circuit board 120 which has a larger thickness or height.
(39) FIGS. 10 to 13 show various variants of a type of the connection 150 between a main circuit board 110 and an add-on circuit board 120. In this case, each embodiment of FIGS. 10 to 13 in each case comprises two connections 150 which are each designed in an identical or similar manner. It is also possible, however, to combine different variants, such that for example a first connection 150 is formed in an electrical module 100 according to FIG. 10, and a second connection 150 is formed in an electrical module according to FIG. 12. Any desired variants are possible within the scope of the invention.
(40) FIG. 10 shows an embodiment of a connection 150 between one straight contact surface of the main circuit board 110 and one oblique contact surface of the add-on circuit board 120. In this case, the contact surface in FIG. 10 extends upwards from the bottom, approximately at an angle of 45 degrees with respect to a horizontal orientation of the main circuit board 110. A blunt side of the connection surface rests on the lower edge of the add-on circuit board, and a tip of the connection surface rests on the upper edge of the add-on circuit board 120. In this case, the height of the add-on circuit board 120 exceeds the height of the main circuit board 110.
(41) FIG. 11 shows an embodiment of a connection 150 having a common oblique contact surface of the main circuit board 110 and of the add-on circuit board 120. In this case, the main circuit board 110 also has an oblique edge surface, which corresponds to the oblique edge surface of the add-on circuit board, such that the two edge surfaces mechanically contact one another over the entire surface. In addition to the mechanical connection 150, an electrical connection 150 is provided, which is linear and is shown as a point in the cross-sectional view in FIG. 11.
(42) FIG. 12 shows an embodiment of a connection 150 comprising a step-like mechanical contact surface and a linear electrical connection 150 at the step, which is shown as a punctiform connection in the cross-sectional view of FIG. 12. In this case, the edge region of the main circuit board 110 comprises a step which forms a contact surface upwards. The edge region of the add-on circuit board 120 furthermore comprises a step which forms a contact surface downwards. The two step-like geometries correspond to one another. In this case, the add-on circuit board 120 rests on the main circuit board 110, at the connection 150. Reversal of the support would also be possible, with the result that the main circuit board 110 rests on the add-on circuit board 120.
(43) FIG. 13 shows an embodiment of a connection 150 in which the main circuit board 110 comprises an oblique contact surface in the edge region thereof. Furthermore, the add-on circuit board 120 has a step-like geometry at the edge region thereof. In this case, the two edge geometries of the two circuit boards 110, 120 are in mechanical contact only at one point or on one line, when the depth of the circuit boards 110, 120 is considered. At this point in the cross-sectional view, a connection 150 between the two circuit boards 110, 120 is provided, which connection acts both mechanically and electrically.
(44) Overall, an electrical module 100 can be provided which comprises a main circuit board 110 and at least one add-on circuit board 120, it being possible for the main circuit board 110 and the add-on circuit board 120 to be electrically and mechanically interconnected. This connection 150 is advantageous in that the electrical module 100 can have a low design height overall, and at the same time can also be operated in an intrinsically safe manner, within the meaning of standard DIN EN 60079-11 or, at the international level, version EN 60079-11:2012.
LIST OF REFERENCE SIGNS
(45) 100 electrical module
(46) 101 housing
(47) 102 wall thickness
(48) 110 main circuit board PCB1
(49) 111 recess in the main circuit board
(50) 112 electronic component B1
(51) 113 electronic component B2
(52) 114 layer structure of the main circuit board comprising the layers C01, C02, C03, C04
(53) 120 add-on circuit board PCB2
(54) 121 recess in the add-on circuit board
(55) 122 first planar transformer
(56) 123 ferrite core
(57) 124 first ferrite core part F1 of the first planar transformer
(58) 125 second ferrite core part F2 of the first planar transformer
(59) 126 layer structure of the add-on circuit board comprising the layers C01, C02, C03, C04
(60) 127 electronic component B3
(61) 130 second planar transformer
(62) 131 ferrite core part of the second planar transformer
(63) 132 primary winding of the second planar transformer
(64) 133 secondary winding of the second planar transformer
(65) 140 third planar transformer
(66) 141 ferrite core part of the third planar transformer
(67) 142 primary winding of the third planar transformer
(68) 143 secondary winding of the third planar transformer
(69) 150 connection
(70) 151 depth milling
(71) 152 step-like geometry
(72) 153 edge metallization
(73) H0 thickness of the circuit board or circuit board thickness
(74) H1 thickness of the circuit board or circuit board thickness
(75) K1 height of the ferrite core part F1
(76) K2 height of the ferrite core part F2
(77) P0 cavity height in the interior of the housing
(78) P1 outside width of the housing
(79) P01 mounting height in the interior of the housing
(80) P02 mounting height in the interior of the housing
(81) T0 required minimum spacing with respect to a level of protection
