DE102014016248B4 - Printed circuit board with at least one four-pole current measuring element - Google Patents

Abstract

Circuit board (1) with at least one (four-pole) current measuring element (20), which consists of at least one high-current conductor (5) which is connected to two spaced power connections (6, 7), between which two spaced measurement connections (3, 4) are arranged where the (four-pole) current measuring element (20) is designed as a shunt and is integrated into the structure of the printed circuit board (1), characterized in that the printed circuit board has at least one copper inner layer (2) which is at least in the area of the power connections (6, 7) and the measuring terminals (4, 5) are in contact with the high-current conductor (5).

Description

The invention relates to a circuit board with at least one four-pole current measuring element.

Printed circuit boards, ie Printed Circuit Boards (PCBs), Printed Wiring Boards (PWBs), circuit boards or printed circuits are used for wiring or electrical connection and for mechanically fastening electrical or electronic components (el. Components or el. Parts). For this purpose, the electrical components are mechanically fastened radially in the holes of the printed circuit board and electrically contacted. They can also be mounted on the surface (surface mount technology SMT or surface mount devices SMD) or buried in inner layers (burried components).

On the one hand, the progressive development of printed circuit boards shows that the electrical components are becoming smaller and more complex, which leads to high temperatures. Thus, the need to dissipate the heat loss of the electrical components is constantly increasing. Furthermore, higher and higher currents are provided or required on relatively small printed circuit board areas. The area of application for this can be, for example, a modern LED element in the EV (Electro Vehicle) sector or in power electronics in general. The copper cross-sections of the wiring structures on and in printed circuit boards must therefore be dimensioned for the planned currents so that the heating of the copper lines themselves remains within planned limits. Furthermore, the copper structures are actively used to dissipate heat loss from electrical components.

In addition to the thick copper technology with copper structures of typically 200 µm to 400 µm copper thickness (manufactured by etching and/or galvanically reinforced) and the integration of stamped copper structures in circuit boards, a high-current and heat management circuit board technology based on ultrasonic flat and semi-cold technology was developed contacted thick copper elements (profile laying technique) on conventional copper structures produced by etching.

A four-pole current measurement for printed circuit boards is known from the prior art. The four-pole current measurement essentially consists of a four-point or four-point measurement. A so-called shunt is used for this purpose, which is a low-impedance electrical resistance and is used to measure the electrical current. In general, the shunt has two current terminals and two terminals for measuring the voltage drop.

The shunt acts as a measuring resistor, whereby the current flowing through the shunt causes a voltage drop proportional to it, which can be measured. Usually, very small voltage drops are measured with suitable measuring devices and the current is determined according to Ohm's law.

Copper or copper alloys with, for example, manganese, nickel, aluminum and the like with preferably a low temperature coefficient can be used as the metal profile shunt material. In principle, however, with a selected shunt material, the temperature coefficient can be taken into account or corrected by measuring the temperature in the measurement result of the current.

Previously, when measuring current in printed circuit board technology, it was only known that a shunt was applied to the outer surface of the multi-layer printed circuit board and a current measurement took place there. Such an embodiment is, for example, with the WO 2014/099094 A1 shown. The problem with such shunts is that the shunt heats up in an undesired manner at high currents. Such warming should be prevented as far as possible. For this reason, copper profiles suitable for high currents are used as shunts, which allow currents in the range of > 30 amperes to flow through.

1. 1. Es fällt die Fläche, die der Shunt an der Oberfläche benötigt, für Bestückungszwecke weg;
2. 2. Es ist eine separate Bestückung der Leiterplatte notwendig;
3. 3. Die zusätzliche Anbringung des Bauteils auf der Leiterplatte verursacht zusätzliche Kosten, erhöht die Bauhöhe der Leiterplatte und verschlechtert die Bearbeitbarkeit der Leiterplatte.

Des Weiteren kann der Shunt nicht als integraler Bestandteil der Verschaltung an der Leiterplatte verwendet werden. Er ist jeweils immer nur ein isoliertes Messelement.However, the arrangement of a shunt on the surface of a printed circuit board has significant disadvantages:

1. 1. The area that the shunt requires on the surface is eliminated for assembly purposes;
2. 2. It is necessary to assemble the circuit board separately;
3. 3. The additional mounting of the component on the circuit board causes additional costs, increases the overall height of the circuit board, and deteriorates the workability of the circuit board.

Furthermore, the shunt cannot be used as an integral part of the wiring on the printed circuit board. It is always just an isolated measuring element.

With the DE 103 10 503 A1 discloses a device for measuring an electric current with a measuring resistor through which the current to be measured flows and a measuring device for measuring the voltage drop occurring at the measuring resistor as a result of the current flow.

the DE 103 10 498 A1 discloses a method and a device for integrating a measuring resistor on a ceramic circuit carrier.

With the U.S. 6,028,426 A discloses a method of manufacturing a printed circuit board with a four-pole current sensing element having a high current conductor connected to two spaced apart power terminals.

The invention is now based on the object of simplifying or improving a printed circuit board with a measuring element.

The invention is characterized by the technical teaching of claim 1 and claim 7 in order to solve the task at hand.

An essential feature of the invention is that the (four-pole current) measuring element is integrated as a shunt in the printed circuit board structure.

This arrangement of the measuring element has the advantage that the integrated circuit board is already provided with such a measuring structure during production. Thus, at least one (four-pole current) measuring element can be integrated into the circuit board structure.

In a preferred embodiment, the four-pole current measuring element is part of a printed conductor layout. This means that any circuit board trace that is suitable for a high current application can be repurposed as a four-pole current sensing element.

The four-pole current measuring element consists of two high-current connections, via which the current to be measured flows, and two measuring connections arranged in the area of this measuring element, between which the voltage drop is measured, with a defined resistance between the two measuring connections.

It is crucial that the measuring connections are always arranged at the same distance in order to achieve a constant resistance between the measuring connections.

The present invention provides several different embodiments, all of which fall within the scope of the present invention.

In a first embodiment of the invention, one or more (four-pole current) measuring elements are produced in a (separate) production process, which are integrated in a single or multiple form in the production of the circuit board in the circuit board structure. It is therefore a matter of defined four-pole current measuring elements that are integrated in addition to the other elements in the printed circuit board structure.

In a second embodiment of the invention, on the other hand, it is provided that a high-current-carrying conductor track is selected during the design and assembly of the printed circuit board and that the measuring connections required for the measurement are only arranged at certain, defined points. In this case, only the distance between the measuring connections in relation to other conductor tracks must always be the same.

This means that one can ad hoc define a specific, high-current-carrying trace as a four-pole current measuring element during development in the printed circuit board by arranging the measuring connections according to the invention for tapping off the measuring voltage in the inner area between the high-current-carrying connections.

It is thus possible in a simplified way to integrate a four-pole current measuring element next to any high-current-carrying printed circuit board structure.

For the formation of a four-pole current measuring element, only four locations or points on a high-current-carrying copper profile are necessary, which are preferably the external connection points for connecting a high-current and the precisely defined contacting on the high-current conductor by means of measuring connections. The contacting or attachment of measuring connections to this high-current conductor can take place in various embodiments.

In one embodiment, it is provided that the measuring connections themselves are designed directly on the high-current conductor as a contacting bore. The measuring connection or the measuring line can be connected directly to this contacting hole.

In a further embodiment of the invention, it is provided that only one contact point is arranged on the surface of the high-current conductor and the measuring lines are arranged at a distance from this contact point. Such a contact point can e.g. B. be designed as a contacting channel.

It is important that the contacts only have to be attached to the high-current conductor, but that the measuring lines can be routed on a different level of the multi-layer circuit board.

The contact can be made, for example, via ultrasound, friction welding, soldering, galvanic copper plating and the like.

The main advantage of the invention is that it is now possible for the first time to define a four-pole current measuring element in any high-current-carrying printed circuit board structure by simply providing a measuring distance for the attachment of measuring connections for measuring the voltage drop in this area in the space between two high-current-carrying connection points will.

With the given technical teaching, there is the essential advantage that the printed circuit board structure can now be kept very small, because no additional elements are necessary, because any high-current-carrying conductor track can be defined as a four-pole current measuring element.

Another advantage of the invention is the inexpensive production and the favorable heat dissipation, because the surrounding components and components of the multi-layer printed circuit board are used as cooling elements for the high-current conductor that may heat up during operation, resulting in favorable heat dissipation.

The attachment of the power connections to the high-current conductor can be done in different ways.

In a preferred embodiment, it is provided that these connections are led out of the multi-layer printed circuit board on the face side and can thus be contacted directly with a live connection cable.

In another embodiment, it can be provided that these connections are bent up as connection lugs and thereby form contact elements for connecting power cables.

In a further refinement, provision can be made for the power connections for the high-current conductor to be integrated in the printed circuit board itself. Here z. B. current-carrying guide channels are provided, which have suitable holes for a press-in technique.

Another advantage of the invention is that the dimension and the geometry of the four-pole current measuring element can be defined arbitrarily, i. H. it can be redefined as a four-pole current measuring element any conductor path in the printed circuit board that affects a high-current conductor.

Due to the integration of the four-pole current measuring element in the printed circuit board, the outer surface of the printed circuit board is kept free of built-in components and can be used for additional equipment.

In a development of the invention, it is provided that an additional temperature compensation is integrated. This temperature compensation is based on the fact that the temperature of the high-current conductor increases in an undesirable manner when a high current flows through it, which in turn influences the voltage drop between the measuring influences. This influence should be compensated.

In a preferred embodiment of the invention, it is provided that temperature compensation takes place by measuring the temperature on or at the high-current conductor. Such a measurement of the temperature can, for. B. by any temperature measuring element such. a thermistor, a PT100 element or the like.

A preferred (manufacturing) process sequence can proceed as follows. The multi-layer printed circuit board is formed with the integrated metal profile in such a way that the metal profile is exposed from one side or from both sides of the multi-layer printed circuit board and can thus be electrically connected with low resistance. A part of the metal profile can also be exposed on one side or both sides and be angled so that one or two parts of the metal profile shunt can be electrically contacted by means of screws or clamps or soldering or pressing or welding.

With such a four-point or four-wire current measurement, the two contacts for measuring the generally very small voltage drop through the copper structure of a layer or contacting through at least one hole with any layer of the printed circuit board can be perceived and the corresponding components for current measurement are arranged on the printed circuit board.

The subject matter of the present invention results not only from the subject matter of the individual patent claims, but also from the combination of the individual patent claims with one another.

All information and features disclosed in the documents, including the abstract, in particular the spatial configuration shown in the drawings, are claimed to be essential to the invention insofar as they are new compared to the prior art, individually or in combination.

In the following, the invention is explained in more detail with reference to drawings showing only one embodiment. Here go from the Drawings and their description shows other features and advantages of the invention that are essential to the invention.

• 1: eine Anordnung einer Vierpolstrommessung nach dem Stand der Technik
• 2: die Draufsicht auf ein Vierpolstrommesselement, welches in einem Leiterplattenaufbau integriert ist
• 3: der Schnitt gemäß der Linie III-III in 2
• 4: Schnitt gemäß der Linie IV-IV in 2
• 5: schematisiert einen Schnitt durch eine Leiterplatte ähnlich der 2
• 6: der um 90° gedrehte Schnitt durch die Leiterplatte gemäß 5
• 7: eine schematisierte Darstellung der Anordnung von mehreren Vierpolstrommesselementen in einem Leiterplattenaufbau
• 8: eine ähnliche Darstellung wie 7 in gedrehter Form
• 9: eine Draufsicht auf einen aufgebrochenen Leiterplattenaufbau mit der Einbringung eines Vierpolstrommesselementes

Show it:

• 1 : an arrangement of a four-pole current measurement according to the prior art
• 2 : the top view of a four-pole current measuring element, which is integrated in a circuit board structure
• 3 : the cut according to line III-III in 2
• 4 : Section along line IV-IV in 2
• 5 : schematizes a section through a circuit board similar to that 2
• 6 : the section through the printed circuit board rotated by 90° according to 5
• 7 : a schematic representation of the arrangement of several four-pole current measuring elements in a circuit board structure
• 8th : a representation similar to 7 in twisted form
• 9 : a plan view of a broken circuit board structure with the incorporation of a four-pole current measuring element

In 1 the principle of four-pole current measurement is shown in general.

Two spaced measuring connections 3, 4 are arranged on a high-current conductor 5. Furthermore, two spaced-apart power connections 6, 7 are connected to the high-current conductor 5, between which a current flows through the high-current conductor 5.

In the area of the high-current conductor 5, measuring connections 3, 4 are electrically conductively connected to the high-current conductor 5 and form a measuring distance 11 between them. It is now important that the voltage drop between the measuring connections 3, 4 is measured in the area of the measuring branch, in order to measure the current through to determine the high-current conductor 5.

Previously, it was only known to attach such a four-pole current measuring element, as shown in the prior art, outside of a printed circuit board structure, which is associated with increased effort. This has already been shown in the general introduction to the description.

According to the invention, a four-pole current measuring element 20 is now integrated in a printed circuit board structure. As a first embodiment shows the 2 a printed circuit board 1, which can consist of any material and which can have any number of layers.

It is now important that the four-pole current measuring element 20 according to the invention is integrated in the printed circuit board structure in the region of any layer, which can be an inner or outer layer. In the exemplary embodiment shown, it consists of a separate element, which essentially consists of a copper inner layer 2, which is designed as a flat copper track.

The copper inner layer has a thickness of about 35 µ to 150 µ. In one embodiment, the copper inner layer 2 is connected to the high-current conductor 5 designed as a shunt in the area of the current connections 6, 7 and the measuring connections 4, 5.

In the exemplary embodiment shown, the power connections 6 leading into the high-current conductor 5 are designed with a round profile and are shaped as contacting channels, as shown in FIG 5 and 6 is still shown.

Measuring lines are attached to the measuring terminals 4, 5 and lead to a measuring arrangement, not shown in detail, which is able to detect and evaluate the voltage drop between the two measuring terminals 3, 4.

Depending on how high the current is that flows between the current terminals 6, 7, there is a voltage drop between the measuring terminals 3, 4 and this voltage drop is tapped off at the measuring lines.

The copper inner layer 2 is contacted with the high-current conductor 5 according to the invention at the points mentioned. The high-current conductor itself is suitable for carrying a high current in the range of more than 30 amperes and is selected in terms of its size and dimensions so that it does not heat up significantly when a high current flows through it.

As an example, it is stated that such a high-current conductor has a width of 1 to 20 mm, a length of 10 to 100 mm and a thickness of 100 μm to 1.5 mm.

In the 3 and 4 it is shown that the dimensions of the high-current conductor 5 are smaller than the copper inner layer 2 attached thereto. However, the invention is not limited to this. However, this is not necessary for the solution; the copper inner layer 2 could also be dimensioned smaller than the dimension of the high-current conductor 5 in terms of length and width.

In other exemplary embodiments, which are not shown here, it is also possible to omit the copper inner layer because the corresponding connections 6, 7 and 3, 4 can also be attached directly to the high-current conductor 5 itself. The copper inner layer 2 can then be omitted.

the 5 FIG 3, 4 to be provided.

In the exemplary embodiment shown, the current is supplied via the connection cable 8 as a measuring current 12 and is introduced into the high-current conductor 5 via two contacting high-current contacts 11, which are designed in the form of channels, where it flows in the longitudinal direction of the high-current conductor 5 and causes a voltage drop to be detected.

On the opposite side, the power connection 7 is designed in the same way as the power connection 6, so that the current on the connection cable 9 flows out of the circuit again.

It is important that a measuring distance 11 is defined at the measuring terminals 3, 4, which are electrically conductively connected to the high-current conductor 5, at which there is a voltage drop. This voltage drop depends on a current flow through the high-current conductor and is therefore a direct measure of the current that is to be recorded.

In 6 is also shown that the copper inner layer 2 is again arranged on the underside of the high-current conductor 5 and only the high-current conductor is contacted with the high-current contacts 10 . Although it is possible to also supply the copper inner layer 2 with the high current, this is not necessary for the solution. The only decisive factor is that measuring connections 3, 4 are arranged at a precisely defined measuring distance 11 on the underside or at any point in the area between the power connections 6, 7 of the high-current conductor 5, between which the voltage drop is measured.

In the general description, it has already been pointed out that the copper inner layer 2 can also be omitted entirely if the measuring connections 3, 4 are arranged directly on the high-current conductor 5 as electrical contacts.

The contact surface 14 after 6 between the high-current conductor 5 and the copper inner layer 2 does not have to be electrically conductive, but it can be designed to be electrically conductive. The contact point 15 is the contact point between the copper inner layer 2 and the high-current conductor 5.

In the exemplary embodiments shown 7 and 8th It is shown that several four-pole current measuring elements 20, 20a, 20b arranged separately from one another can also be integrated into any printed circuit board structure. They can be placed side by side or on top of each other, as shown in 8th is shown.

As another essential embodiment, however, shows the 9 that it is not necessary for the solution to integrate a four-pole current measuring element as a separate component in a printed circuit board. In another embodiment, it is provided that any high-current-carrying conductor track that is 9 is shown, is used as a high-current conductor 5. Here, as a first exemplary embodiment, the first four-pole current measuring element 20 would be designed as a U-shaped high-current conductor 5, and it can be seen that it is only essential to provide a defined measuring distance 11 between two measuring connections 3, 4 in order to measure the voltage drop between them. The measuring terminals 3, 4 can also be arranged at a different point of the high-current conductor, as is the case, for example, in FIG 9 as shown at 3a and 4a.

the 9 shows a four-pole current measuring element as a second exemplary embodiment, which consists directly of a high-current conductor 5, which is integrated into the printed circuit board structure and is intended for performing other electrical tasks. For example, a component 17 is supplied with the high current and further conductor tracks 16 are arranged on the printed circuit board 1 .

Thus, any high-current-carrying conductor track, such as the high-current conductor 5 here, can be used as a four-pole current measuring element, because in the area of this element there are again two spaced measuring connections 3, 4, between which there is a measuring distance 11, at which the voltage drop is measured.

It is thus possible in any printed circuit board structure to additionally design a high-current conductor 5 already used there and assigned for other circuit tasks as a four-pole current measuring element.

Reference List

1

circuit board

2

copper inner layer

3

measurement connections

4

measurement connections

5

high-current conductor

6

power connection

7

power connection

8th

connection cable

9

connection cable

10

high-current contacting

11

measuring distance

12

measuring current

13

14

contact surface

15

contact point

16

traces

17

component

18

measurement port

19

measurement port

20

four-pole current measuring element

Claims (7)

Circuit board (1) with at least one (four-pole) current measuring element (20), which consists of at least one high-current conductor (5) which is connected to two spaced power connections (6, 7), between which two spaced measurement connections (3, 4) are arranged where the (four-pole) current measuring element (20) is designed as a shunt and is integrated into the structure of the printed circuit board (1), characterized in that the printed circuit board has at least one copper inner layer (2) which is at least in the area of the power connections (6, 7) and the measuring terminals (4, 5) are in contact with the high-current conductor (5). Circuit board (1) after claim 1 , characterized in that the four-pole current measuring element (20) is part of a printed conductor guide. Printed circuit board (1) according to one of Claims 1 or 2 , characterized in that the printed circuit board (1) has at least two high-current contacts (10) which are connected to at least two connecting cables (8, 9) in order to feed current into and/or out of the high-current conductor (5). Printed circuit board (1) according to one of Claims 1 until 3 , characterized in that the measuring connections (3, 4) are conductively connected to the high-current conductor (5) at a defined measuring distance (11). Printed circuit board (1) according to one of Claims 1 until 4 , characterized in that only one contact point is arranged on the surface of the high-current conductor (5) and the measuring connections (3, 4) are arranged at a distance from this contact point. Printed circuit board (1) according to one of Claims 1 until 5 , characterized in that a temperature measuring element is arranged in the area of the high-current conductor (5). Method for producing a printed circuit board (1) with at least one (four-pole) current measuring element (20), which has at least one high-current conductor (5) which is connected to two spaced-apart power connections (6, 7), between which two spaced-apart measuring connections (3, 4) are arranged, characterized in that the four-pole current measuring element (20) is produced in a separate production process, which is then integrated into the circuit board structure during the production of the circuit board (1), the copper inner layer (2) being at least in the region of the power connections ( 6, 7) and the measuring connections (4, 5) are contacted with the high-current conductor (5).

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