EP2948965A1

EP2948965A1 - Printed circuit board having a layer structure

Info

Publication number: EP2948965A1
Application number: EP14701333.8A
Authority: EP
Inventors: Peter Scholz
Original assignee: Phoenix Contact GmbH and Co KG
Current assignee: Phoenix Contact GmbH and Co KG
Priority date: 2013-01-22
Filing date: 2014-01-20
Publication date: 2015-12-02
Also published as: WO2014114584A1; DE102013100622A1; DE102013100622B4; CN105009235A; US20150357113A1; US9793042B2

Abstract

The invention relates to a printed circuit board having a layer structure, which accommodates a plurality of electric circuits (1, 2). The electric circuits are separated from each other by an insulating barrier layer (61) having a minimum thickness (Di) and a minimum distance (D0) between conducting components of the electric circuits.

Description

Printed circuit board in layer construction

The invention relates to a circuit board in a layer structure with transformer for galvanic isolation between individual circuits.

With US 2011/0095620 AI = DE 10 2007 034 750 AI an improved galvanic isolator with an inductive converter in a layer structure is known. On the top and bottom of a substrate plate, which has a barrier layer of sufficient thickness and with sufficient

Isolation characteristics forms, tracks are provided to form coil windings, which

Insulating cover layers are protected, on which run partially feeding traces, which are connected in a first embodiment via vias to a transmitting chip or a receiver chip. The vias pass through the insulation cover layers and partly also the

Substrate plate. The coil windings form the inductive converter, which in a second embodiment via

Wire connections to the transmission chip and the receiving chip is connected. The chips with the electrical or electronic components are thus arranged outside the galvanic isolator.

A broadband radio frequency transformer in layered construction is known from US 5,015,972, wherein primary winding and secondary winding between dielectric layers

are arranged, which in turn sit between ferrite cover plates. Electrical or electronic components are not included in the layer structure. A power supply unit for the transmission of

Auxiliary energy is known from EP 1 310 036 Bl and comprises mounted on support plates primary and

Secondary coils with air gap in between. To extend the air gap between the coils, one is the

Carrier plates overhanging insulating plate provided in the air gap. A layer structure of a printed circuit board is not formed thereby.

For electrical / electronic devices, high voltages sometimes have to be overcome, and to protect against overvoltages there is often a galvanic isolation between individual circuits or potential groups within the device. In order to avoid electrical flashovers in the devices, certain air and creepage distances must be between the circuits to be separated

Discharge currents are respected, or it must

Isolation material of predetermined quality and minimum thickness between the circuits can be arranged. There is thus a galvanic connection between the individual circuits

Trennstrecke, is to be exchanged over the electrical energy, which for energy supply or the

Data exchange or information exchange is useful. This electrical energy is hereinafter referred to as electrical signal.

Frequently used as a carrier for electrical / electronic components and assemblies and printed conductors (hereinafter referred to as "components") printed circuit boards, which are also referred to as printed circuit boards or boards, can be flexible or rigid and in as Layer structure called construction occur. to

galvanic isolation between different circuits or potential groups on the circuit board, it is known to provide a "trench" on the circuit board over which no component extends

Isolation trench corresponds to the minimum distance in air or the minimum creepage distance over the surface of the

Isolation trench, which must be adhered to in order to achieve sufficient electrical voltage protection. The wider the isolation trench is chosen on the circuit board, the less usable space is available for the accommodation of electrical / electronic components.

Galvanically separate circuits are interconnected by coupling components for signal exchange, and this purpose, inductive and capacitive transformers or operating in the electromagnetic near field antenna systems are useful, each having a first and at least second coupling element, between which solid

Insulation material extends. The dielectric strength of this insulating material determines the tolerable

Voltage difference between the potential groups or

individual circuits. The invention has for its object to provide a printed circuit board with galvanic isolation between individual circuits, in which relatively high voltages between the individual circuits can be tolerated without relatively large creepage distances and electrical

Discharge currents across the surface of the circuit board must be taken into account. The circuit board should also have a simple, cheap and space-saving design of the recorded components.

The invention is characterized in the claims.

For galvanic isolation between the individual

Circuits, the circuit board on at least one inductive and / or capacitive transformer, each consisting of a first and a second coupling element with the interposition of an insulating barrier layer.

This insulating barrier layer provides as much insulation as possible. As a result, isolation trenches for air or creepage distances on the printed circuit board can largely be dispensed with or their number can be greatly reduced. This is due to the fact that with regard to the same insulation values, the dimension of planar

Insulation regions for clearance and creepage distances is greater than the thickness of the insulating barrier layer. A flat insulation region is understood to mean a surface region which extends on the printed circuit board, also around the edge of the printed circuit board, and, measured as an air gap and creepage distance of electric flashovers or

Leakage currents, a minimum distance between galvanically isolated circuits or potential groups occupies. A precise definition of clearances and creepage distances as well as their requirements can, for example, the

Descriptions and figures of the standards DIN EN 60664-1, DIN EN 60079-11 / 15 and DIN EN 61010-1 are taken. Insulating attachments on the circuit board to extend the creepage distances and creepage distances or enlarge the

Dimension of the flat isolation region

accordingly considered as part of the circuit board, too if these attachments have no layer structure.

The reduction of the space requirement on the circuit board by eliminating or minimizing isolation trenches also leads to a reduction of the cost in the production of the circuit board. Further cost savings is made possible by structurally simple coupling elements on

Planar technology based. In this case, the coupling elements, for example, as conductor track loops or as

Capacitor plates made.

Specifically, with the insulating barrier layer, the circuit board material itself is used as the insulating medium between adjacent circuits. The two opposite sides of the layer structure for the different circuits or potential groups

used and the circuit board on both sides with the

equipped electrical / electronic components.

Through-connections through the printed circuit board via vias or through-risers are largely avoided or executed only at the lateral distance from the transformers.

Embodiments of the invention will be described with reference to FIGS

Drawing described. Showing:

1 shows an inductive transformer in exploded view of the various layers as a section of a printed circuit board, FIG. 2 shows a longitudinal section through a printed circuit board, with components mounted on both sides,

Fig. 3 shows a further longitudinal section through a

Circuit board in a schematic representation, and

Fig. 4 is a plan view of layer parts of another PCB.

Fig. 1 shows the layer structure of an inventive

Printed circuit board with the individual layers of the layer structure pulled apart in the Z direction. The ply structure comprises a first insulation spacer layer 71, an insulating barrier layer 61, and a second insulation layer

Insulation spacer layer 72. The first

Insulation spacer layer 71 provides a mounting surface for components, i. H. electrical / electronic components 13 and for printed conductors 14 (see FIG. 2). Also, the second insulating spacer layer 72 has a mounting surface for components, i. H. electrical / electronic components 23 and for printed conductors 24. Electrical contacts 8 pass through the respective insulating spacer layer 71 or 72, respectively, around the respective conductor tracks on the upper side with the underside of the relevant one

Insulation spacer layer to connect. On the upper side of the insulating spacer layer 71 extends a helical coil 11 which can be contacted with its terminal end 82 to electrical / electronic components, wherein the other terminal end 81 by means of

electrical contact 8 on the other side of the

Insulation spacer layer 71 leads over, from there also to electrical / electronic components

to be contacted. Below the insulating

Barrier layer 61 is also one

helical coil 21 with two terminal ends 83 and 84 on different sides of the second

Insulation spacer layer 72 are arranged, wherein the connection from top to bottom of the

Isolation distance layer in turn by an electric Contact 8 takes place. The coils 11 and 21 are separated from each other by the insulating barrier layer 61 and constitute the coupling elements of an inductive transformer 10. To increase the effectiveness of the inductive

Transformer 10 and to shield against interference ferrite plates 41 and 42 may be provided in spatial overlap with the coils 11 and 21. To one

To prevent shorting of coil windings by electrically conductive body, between the ferrite elements and the coil turns an additional, (not shown) insulating layer is present, for. B. in the form of a suitable paint.

2 shows a printed circuit board 100. The inductive transformer 10 formed by the coils 11, 21 has a

Cover and transfer area, which is the main area of propagation of the alternating magnetic fields, as shown in Fig. 2 with H. By means of the transformer 10 can energy between a first

Circuit 1 and a second circuit 2 are exchanged. This exchanged energy is referred to in the present application as a signal and can be used for data exchange, as it is known. in the

illustrated embodiment, the first circuit 1 and the second circuit 2 is still a capacitive

Transmitter 20 coupled together, the capacitor plates 12, 22 in a Überdeckungs- and transmission area contains and electric alternating fields E the

Signal transmission between the first and the second

Circuit allows. The first circuit 1 contains electrical / electronic components 13, which on the free top of the

Insulation spacer layer 71 are attached and which are supplied via tracks 14 with voltage / current. The conductor tracks 14 extend on both sides of the

Insulation spacer layer 71 and are connected via contacts 8, as shown. The second circuit 2 is on the top and bottom of the second

Insulation spacer layer 72 is arranged and includes

electrical / electronic components 23 and tracks 24 in a similar manner, as regards the

Components 13 and the tracks 14 has been described for the circuit 1. In the embodiment of Fig. 2, an additional inductive transformer 26 is still provided, which divides the circuit 2 into two sections 2a and 2b. This is intended to illustrate the various possibilities of equipping and subdividing the printed circuit board. In order to include the circuit board 100 in a device, it requires electrical connection lines 91, 92 for purposes of power supply and signal handling. Such

Lines may be attached to an insulating spacer layer 71 or 72. For attachment of such lines 91, 92 but can also anchorages in the form of electrical

Through holes 9 may be provided which extend through the layer structure of the printed circuit board 100 therethrough.

Such electrical vias weaken the

Dielectric strength of the layer structure and in particular of the insulating barrier layer 61, in a certain radius, which is to be regarded as minimum distance DO to "foreign" or "neighboring" circuits. The Connecting lines 91 for power and signal supply of the circuit 1 can of course be arranged immediately adjacent to the elements 11, 12, 13, 14 of the circuit 1, while the minimum distance DO, which represents the creepage distance to the circuit 2, between the electrical via 9 and the nearest component of the circuit 2 must be maintained. In the same way connected to the connecting lines 92 electrical feedthrough 9 must

Maintain minimum distance DO to the nearest component of circuit 1. To protect flashovers between the circuits, it is also necessary to maintain a minimum thickness Di of the insulating barrier layer between the circuits. This minimum thickness Di depends on the quality of the insulating material and on the magnitude of the overvoltage to be tolerated. If, for example, the printed circuit board material FR4 is used as the insulating medium, it can be assumed that the withstand voltage is approximately 40 kV per millimeter. A minimum thickness of 0.2 mm would therefore a dielectric strength of 8 kV

while a minimum thickness of 0.5mm

correspondingly 20 kV could have dielectric strength. According to different standards and guidelines, increased security surcharges may reduce the

Dielectric strength or voltage class at a given minimum insulation thickness lead.

By these measures, the minimum thickness Di or the

Minimum distance DO, it is possible to provide the PCB designed in the layer structure for high voltage applications. Between the terminals 91 and 92 can thus handle voltage differences in the kV range become. The circuit board according to the invention can in

Measuring devices for measuring high voltages are used. So z. B. a high voltage to be measured in a

Measuring signal can be implemented, which can be evaluated with comparatively low voltages and currents. The circuit board can also be used in devices that are designed for low voltages, but can be exposed to high voltages in the event of a fault. Fig. 3 shows a printed circuit board construction 200 with three circuits 1, 2, 3. There are two insulating

Barrier layers 61 and 62 as well as three

Insulation spacers 71, 72, 73 and three groups of leads 91, 92, 93 used. The circuits 1 of FIGS. 2 and 3 are structurally identical. The circuit 2 is associated with parts of the insulating barrier layer 62 and the insulating spacer layer 72. The circuit 3 extends over portions of the insulating spacer layer 72, the insulating barrier layer 62 and the

Insulation distance layer 73. However, the inductive transformer 10 connects all three circuits together and the capacitive transformer 20 couples only the circuit 1 to the circuit 3. Between all circuits the necessary isolation distance is maintained, on the one hand by the minimum distance DO of the creepage distances between the circuits and the minimum thickness Di of

Insulation layers between the circuits. As a result, planar insulation regions extending over the surface of the printed circuit board are formed between the covering and transformer regions of the transformers 10, 20, whereby air gaps and creepage distances of sufficient length between conductive components of adjacent circuits are formed be created which exceed or exceed the minimum distances. The flat insulation regions can extend over the edge of the printed circuit board, as indicated on the right edge of the printed circuit board 200 in FIG. 3.

Fig. 4 shows a printed circuit board with a layer structure as in Fig. 2, but for three circuits 1, 2 and 3. Die

Top of the layer structure is shown with diagonal shading, while the underside is visualized with checkered hatching. There are three inductive transformers 10 used for coupling between the circuits, namely 10a for coupling the circuits 1 and 2, 10b for coupling the circuits 1 and 3 and 10c for coupling the

Circuits 2 and 3. The galvanic isolation path

with respect to the minimum thickness Di is formed in each case over the insulating barrier layer 61. The minimum distance DO as an air gap or creepage distance between the circuits is maintained everywhere, even in the case of the transformer 10b, since the creepage distance extends beyond the edge of the printed circuit board, as shown in FIG. 3 on the right-hand edge of the picture. So z. B. the transformer 10a from the first to the second circuit of an associated planar

Isolation region with distance D0 + X to the connecting lines 92 of the second circuit surrounded, the transformer 10b from the third to the first circuit is from an associated areal insulating region around the edge of the circuit board at a distance 2 D0 / 2 + Y to the connecting lines 91 of the first circuit surrounded and the transformer 10c of the second to the third circuit is of an associated areal isolation region with distance D0 + Z to the

Surrounding leads 92 of the second circuit. X, Y and Z indicate additional lengths to the minimum clearance and creepage distance DO.

For the construction of printed circuit boards with four or more circuits to be separated from each other, the surfaces of the circuit board are split even more intelligently and / or there are several insulating

Barrier layers used. As in the case of FIG. 4, the components and traces for some circuits will be on both the top and bottom of the circuit

Layer structure attached. To be compliant with the

required clearances and creepage distances according to the

Minimum distance DO, certain requirements are met. Within a range with the distance DO around the transducers 10, there are no openings or plated-through holes of the insulation layers. Also

Components of adjacent circuits maintain this distance DO to the transmitter. The circular areas in Fig. 4 illustrate this fact. The circuit 3 is distributed on two sides of the circuit board by means of

Through holes 9 are connected to each other, which are located outside the flat isolation regions around the transformer 10b and 10c. The described method thus makes it possible to equip even several circuits to be isolated by as few vias as possible and only one or a few insulating ones

To use barrier layers in the layer structure.

The structure of the printed circuit board described can be modified. So it is possible two or more

Isolation spacers to provide one above the other, within which the components of the circuits are housed. In this case, electrical / electronic components by means of SMD technology (Surface Mounting Devices) attached and optionally also included. For the high dielectric strength of the circuit board, however, the insulating barrier layer or

Barrier stories responsible.

With three or more circuits to be separated, the values Di and DO can also be individually selected differently depending on the requirements of the withstand voltages to the individual circuits. Thus, for example, three can be used for three circuits to be separated

different values D012 are used for the separation of circuits 1 and 2, D013 for the isolation of circuits 1 and 3 and D023 for the isolation of circuits 2 and 3. The same applies to Di.

Claims

claims

1. Circuit board in a layer structure with galvanic isolation between individual circuits, comprising:

a first coupling element associated with a first circuit (1),

- A first insulating spacer layer (71) for the spatial separation of components (13, 14) of the first circuit

(1) ,

- A second coupling element, the second circuit

(2) is assigned,

- A second insulating spacer layer (72) for the spatial separation of components (23, 24) of the second circuit (2), and

- A (first) insulating barrier layer (61) with a minimum thickness (Di) to achieve a high

Dielectric strength between the circuits (1, 2),

- Wherein the first and the second coupling element interpose the insulating barrier layer (61)

cover and in a cover and

Transmission area form a transformer (10; 20),

- Wherein each transformer (10; 20) with respect to the first coupling element, or an associated ferrite plate (41), is surrounded by a first sheet-like insulation region extending across the surface of the circuit board with an air and creepage distance D0 + X or D0 + Y or D0 + Z too

conductive components of the second circuit (2)

and each transmitter (10; 20) with respect to the second coupling element, or an associated ferrite plate (42), is surrounded by a second laminar isolation region extending across the surface of the circuit board with an air gap or creepage distance D0 + X or D0 + Y or D0 + Z too conductive components of the first circuit (1)

wherein DO means a minimum distance and X, Y, Z additional lengths, and

- Where electrical vias (9), if such are provided for power and signal supply of the first or second circuit and are also anchored in the insulating barrier layer (61), comply with the minimum distance (DO) to conductive components of the respective adjacent circuit.

2. Printed circuit board according to claim 1,

wherein the insulating barrier layer (61) is provided on both sides with printed conductors (14, 24) adjacent to the first and second insulating spacer layers (71, 72), respectively.

3. Printed circuit board according to claim 1 or 2,

wherein the dielectric strength of the barrier layer (61) is designed for at least 1000 V.

4. Printed circuit board according to claim 1 or 2,

wherein the withstand voltage of the barrier layer (61) is designed to be at least 10000V.

5. Printed circuit board according to one of claims 1 to 4, wherein the insulating barrier layer has a minimum thickness (Di) of 0.2 mm.

6. Printed circuit board according to one of claims 1 to 4, wherein the insulating barrier layer has a minimum thickness (Di) of 0.5 mm.

7. Printed circuit board according to one of claims 1 to 4, wherein the insulating barrier layer has a minimum thickness (Di) of 1 mm.

8. Printed circuit board according to one of claims 1 to 7, wherein the first and / or the second circuit two

Sections (2a, 2b) which are coupled together via a transformer.

9. A printed circuit board according to any one of claims 1 to 8, wherein a second insulating barrier layer (62) is provided adjacent to a third insulation spacer layer (73) and on its free side the second insulation spacer layer (72) and components such as electrical / electronic components (33). and conductor tracks (34) of a third circuit (3).

10. Printed circuit board according to claim 9,

wherein the third circuit (3) of conductive components of the first and second circuits by planar

Isolation regions (DO + X, DO + Y, DO + Z) is arranged separately, which are equal to or greater than the minimum distance (DO).

11. Printed circuit board according to claim 9 or 10,

wherein the second insulation spacer layer (72) carries parts of the second circuit and the third circuit.

12. Printed circuit board according to one of claims 1 to 11, wherein a plurality of circuits (1, 2, 3) are distributed on the top and bottom of the circuit board and each circuit via the flat isolation region a Minimum distance (DO) and in case of coverage over the insulating barrier layer (61)

Minimum voltage resistance applies.