DE102005019922A1 - Multilayer printed board for controller of electrical window lifter in motor vehicle has electrical resistance for measuring input power of electrical or electronic component - Google Patents

Abstract

A top layer, intermediate layers and a bottom layer include conductive strips and contact points, with at least one electrical resistance provided on the intermediate layers. The electrical resistance includes at least one intermediate layer that is printed or etched and serves as a measuring resistance for the measurement of the input power of an electrical or electronic component.

Description

The The invention relates to a multilayer printed circuit board with an integrated electrical resistance.

PCBs become common equipped with electrical and / or electronic components, which a high waste heat generate, which in turn from the device, from the circuit board and be kept away from adjacent components and removed must be to the component itself, the circuit board or the adjacent Do not damage components.

So For example, from DE-OS 27 43 647 known such devices with high waste heat up to mount a metal plate, which for electrical insulation coated with an electrically insulating film. The components are mounted on the metal plate, but with the insulating film the heat dissipation opposes a thermal resistance.

Out DE-A-38 29 117, a further printed circuit board is known which a Metal core which is enveloped by a dielectric material. The metal core is designed so that the heat loss from Components directly dissipated can be. Furthermore let yourself create a defined position of the metal core during injection molding and thus ensure a perfect connection of the enclosure with the metal core.

Out DE-A-43 26 506 is an electrical device with an electronic Circuit-carrying conductor foil known which with SMD power devices stocked is. The conductor foil is for mechanical stabilization and for heat dissipation the waste heat generated by the power components on a support plate applied. Below the power component is on the conductor foil a solderable surface layer formed, which has a large-scale recess limited. This recess is filled with a thermally conductive compound, so that a large-scale heat transfer from the power component to the carrier plate possible is.

Out DE-A-195 32 992 discloses a single-sided printed circuit board, on the back under insertion an intermediate layer applied to a cooling plate is. The circuit board carries at least one thermally highly resilient component. The bearing surface of this Component is by a Wärmeleitbrücke in shape a metal body or copper bolt with the cooling plate connected. The metal body sits in a recess that the bearing surface of the device by the intermediate layer connects to the cooling plate.

Out DE-A-196 01 649 is another arrangement for improving the heat dissipation in electrical and electronic components, in which one Component-carrying circuit board over an insulating layer cohesively with a metal plate connected, known. In the range of at least one component are introduced into the circuit board and in the insulating layer corresponding openings. The metal plate has elevations whose height is approximately the thickness of the circuit board and the insulation layer corresponds to or slightly exceeds this. The elevations are through the openings passed.

Finally is from DE-A-198 05 492 discloses a printed circuit board, which with at least a heat issuing electronic component is populated. Further she is with one of the heat dissipation serving metallic plate provided. A thermally conductive connecting element protrudes between the component and the metallic plate of a on both sides covered with insulating copper layer out. The Connecting element is an integral part of the copper layer etched out of this.

adversely in the known prior art is that on printed circuit boards increasingly Messanordungen be integrated, which, for example a current consumption of an electrical / electronic component or components. For this purpose, a measuring resistor used, which is made of temperature-stable material. Such resistances show over a constant resistance over a wide temperature range, so that a resistance drift due to self-heating of the resistor is not considered must become.

task The invention is a multilayer printed circuit board with an integrated Resistor and an arrangement for measuring the current consumption of a allow electrical / electronic component, wherein the measuring resistor implemented cost-effectively is and still a falsification the measurement because of the temperature drift of the measuring resistor avoided becomes.

These The object is achieved by the Arrangement according to claim 1 solved. Advantageous embodiments of the invention will become apparent from the Further description, the figures and the dependent claims.

In the invention, a described temperature-independent resistor, ie, a resistor which has only a small and defined temperature drift of its electrical resistance, and serves as a measuring resistor for the current flow, replaced by at least one printed or etched resistor on the circuit board. This resistance consists, like the printed circuit board, of copper and therefore has a significantly lower temperature coefficient, which manifests itself in the form of a strong temperature drift due to the self-heating and the dependence on the ambient temperature.

for Compensation of this temperature drift of the value of the electric Resistance is achieved with the help of a microcomputer unit, in particular a microcontroller, a predefined temperature model of this Resistance calculated in parallel. In a preferred embodiment the invention is the microcomputer unit, arranged on the multilayer printed circuit board. The calculation is done in real time. The result of this real-time calculation is used to compensate for the temperature drift of the resistor. At the same time, about this Temperature model and the calculation of production-related tolerances of resistance to adjust an automatic adjustment on the final test. A corresponding calculation over However, the temperature model requires a special structure of the resistor on the circuit board, which will be described below.

Of the integrated in the multilayer PCB electrical resistance, hereinafter referred to as PCB shunt, the previous temperature-independent electrical resistance for measuring the current consumption of an electrical Replace module or component. Therefore, the circuit board shunt also approximate the same electrical resistance and also the same ampacity exhibit. To approximate these to achieve the same electrical properties, the width becomes the circuit board shunt running relatively narrow. But this is the current carrying capacity decreases and increases the power dissipation of the resistor, this leads to a reinforced self-heating and thus to an intensified Resistance drift of the PCB shunt.

Around To prevent the PCB shunt at high current load detached from the board and thus destroyed is, is the circuit board shunt as a conductor on or in one realized the middle layers of a multilayer printed circuit board. In this way becomes a possible replacement of the circuit board shunt of the multilayer printed circuit board or one of Layer of multilayer PCB prevented. An advantage of this Arrangement of the circuit board shunt is that the manufacturing tolerances the multilayer printed circuit board on the inner layers cheaper impact as on the outside layers, which due to the additional Coppering of the outer layers the case is.

Of the Circuit board shunt developed due to its resistance value Heat loss, which leads to an increase of its resistance value. Therefore, this is the so-called "hotspot" of the circuit board shunt thermally on copper surfaces, which are executed on the remaining layers around the circuit board shunt, tethered. These surfaces over and under the circuit board shunt serve as thermal energy storage, which is too fast increase prevent the resistance temperature. The thermal connection will with so-called thermovias and small bars from the middle of the circuit board shunt to these cooling surfaces realized.

The temperature-dependent Drift of the circuit board shunt equals the microcomputer unit computationally out. For this purpose, the microcomputer unit calculates from the measured Electricity the temperature increase the circuit board shunt opposite the ambient temperature. The ambient temperature is over a external sensor can be determined. Alternatively, it is also provided the temperature of the circuit board shunt with a temperature sensor directly on the circuit board shunt. With the temperature of Circuit board shunts in turn can affect the resistance of the circuit board shunt getting closed.

In An advantageous embodiment of the invention is the microcomputer unit designed as a microcontroller.

Besides that is the microcomputer unit capable of manufacturing tolerances of the PCB shunts in an automatic final test of the multilayer PCB match. Thus, too takes into account the manufacturing tolerances involved in each production and their influence over the microcomputer unit are compensated.

in the Further will be for better understanding the invention this with reference to a specific embodiment with reference to a Multilayer PCB for a control unit For use in a motor vehicle, in particular on a control unit of an electrical Windows for a motor vehicle, shown.

It shows:

1 a schematic structure of the multilayer printed circuit board according to the invention;

2 a schematic structure of the necessary for the compensation of the temperature drift elements;

3 a further schematic structure of the necessary for the compensation of the temperature drift elements.

Out 1 the structure of the multi-layer printed circuit board can be seen. In the embodiment of Mulitlayerleiterplatte off 1 this consists of four layers, a top layer 2 , a bottom layer 3 , an intermediate layer I 4 and an intermediate layer II 5 ,

All layers have cooling surfaces on their front sides 6 on, which preferably claim the entire width of the circuit board shunt.

Furthermore, those are on the layers 2 . 3 . 4 . 5 existing cooling surfaces 6 for the sake of clarity 1 only at the top layer 2 complete with the reference number 6 provided with the other layers 3 . 4 . 5 this was done only as an example and does not limit the invention to the embodiment in 1 represents.

On the intermediate layer II 5 is an electrical resistance 8th arranged, which replaces a previously used because of its low temperature drift power resistance. The electrical resistance 8th must have approximately the same electrical resistance as well as the same ampacity which had the power resistor replaced and which was made of isotan. The electrical resistance 8th is as a track on the middle layer of the intermediate layer II 5 realized. In this way, the electrical resistance 8th be produced in a process step together with the interconnects.

A further advantage is that the manufacturing tolerances of the layer 2 . 3 . 4 . 5 to have a better effect on the inner layers than on the outer layers. The reason for this is the additional coppering of the outer layers.

The electrical resistance 8th developed due to its electrical resistance at current flow loss heat, which leads to an increase in the resistance value, just to the so-called temperature drift. It is therefore the so-called "hotspot" of electrical resistance 8th thermally on copper surfaces, on the remaining layers around the electrical resistance 8th and the other layers 2 . 3 . 4 are executed around, tethered. These copper surfaces above and below the resistor serve as thermal energy storage, and cooling surfaces 6 which causes too rapid a rise in the temperature of the electrical resistance 8th prevent. The thermal connection is made with so-called thermovias 7 and small bars from the center of electrical resistance 8th to the cooling surfaces 6 realized. It must be ensured that the cooling surfaces are electrically at the same potential.

In a particular embodiment of the invention, the width of the electrical resistance 8th executed relatively narrow. This reduces the current carrying capacity and at the same time increases the power loss of the electrical resistance 8th , which in turn increases the resistance drift due to self-heating.

To avoid measurement errors, the electrical resistance 8th is used for current measurement, in particular for measuring the current consumption of an electrical / electronic component / component, the temperature drift of the electrical resistance 8th , which is caused by its heating, compensated. The type of compensation and the procedure will be explained in more detail below.

In 2 a schematic structure of the essential components and their input signals and processing stages is shown.

The drift of the resistance value of the electrical resistance 8th is using a microcomputer unit 20 or a microcontroller, balanced. For this purpose, the microcomputer unit determines 20 from the measured current consumption, that of the current measuring unit 26 is made and which for measuring the current electrical resistance 8th used in 2 not shown, but part of the current measuring unit 26 is, the temperature increase of the electrical resistance 8th opposite to the ambient temperature. The ambient temperature is given to the microcomputer unit 20 via a data bus 21 to which a sensor is connected. Advantageously, it is the data bus 21 to a vehicle data bus, since the multilayer printed circuit board is used in a motor vehicle. Furthermore, the sensor for determining the ambient temperature is a sensor already present in the motor vehicle, for example an outside temperature sensor. The vehicle data bus is advantageously a CAN bus, a MOST bus or a Firewire bus.

The microcomputer unit 20 uses a model, a resistance temperature drift model, to calculate the change in the value of the electrical resistance 8th depending on its temperature change.

In order to obtain a slight deviation of the actual resistance value and of the calculated resistance value, in a further advantageous embodiment of the invention a look-up table with the changes in the resistance value of the electrical resistance is provided 8th about the temperature in a memory the microcomputer unit 20 stored. This look-up table is made during the final test after the multilayer PCB has been manufactured and stored in memory.

The calculation of the change in the resistance value of the electrical resistance 8th depending on its heating takes the microcomputer unit 20 in a separate process 24 true. This process 24 is as a circuit board shunt temperature 24 designated. Based on this calculation, the microcomputer unit calculates 20 the actual current resistance of the electrical resistance 8th and corrects the measured current of the current measurement 26 and gives this value of the corrected measured value as the measured current correct 25 from, in which case the actual current exception of the electrical component as a corrected current 23 will spend.

In 3 an alternative embodiment of the invention is shown. Across from 2 is a temperature sensor 31 present, which is directly on the electrical resistance 8th is arranged and the temperature of the electrical resistance 8th determined directly.

In a further advantageous embodiment of the invention by means of the microcomputer unit 20 Manufacturing tolerances in the production of electrical Widertandes 8th balanced. For this purpose, the temperature of the electrical resistance at the automatic final test 8th at a respective temperature of electrical resistance 8th measured and stored in a look-up table.

1

scythe connections

2

toplayer

3

bottom layer

4

between layer I

5

between layer II

6

cooling surfaces

7

Thermovias

8th

PCB shunt

9

thermal connection

20

Microcomputer unit

21

Motor vehicle data bus

22

temperature signal

23

corrected electricity

24

temperature Calculate printed circuit shunt

25

measured Correct current

26

current measurement

31

temperature sensor

Claims (13)

Multi-layer board consisting of several layers ( 2 . 3 . 4 . 5 ), namely a top layer ( 2 ), at least one intermediate layer ( 4 . 5 ) and a bottom layer ( 3 ), where the layers ( 2 . 3 . 4 . 5 ) Conductor tracks and contact points and at least one conductor as electrical resistance ( 8th ) on one or more intermediate layers ( 4 . 5 ), characterized in that the electrical resistance ( 8th ) one or more intermediate layers ( 8th ) is printed or etched resistance and the electrical resistance ( 8th ) serves as a measuring resistor for measuring the current consumption of an electrical and / or electronic component and / or component. Multilayer printed circuit board according to claim 1, characterized in that the electrical resistance ( 8th ) is made of the same material and in the same step together with the conductor tracks. Multilayer printed circuit board according to claim 1 or 2, characterized in that the layers ( 2 . 3 . 4 . 5 ) are made of copper-clad PCB material. Multilayer printed circuit board according to one or more of the preceding claims, characterized in that the electrical resistance ( 8th ) is a circuit board shunt. Multilayer printed circuit board according to one or more of the preceding claims, characterized in that on the bearings ( 2 . 3 . 4 ) Cooling surfaces ( 6 ) are arranged which of the heat dissipation from the electrical resistance ( 8th ) and the electrical resistance ( 8th ) with the cooling surfaces ( 6 ) about Thermovias ( 7 ) connected is. Multilayer printed circuit board according to one or more of the preceding claims, characterized in that a microcomputer system ( 20 ), which is based on a current measurement on the electrical resistance ( 8th ) determines the current consumption of the electrical and / or electronic component and / or component, the microcomputer system ( 20 ) based on the ambient temperature and the result value of the current measurement, the temperature of the electrical resistance ( 8th ) and the temperature drift of the value of the electrical resistance ( 8th ) in the measurement of the current and corrects the measured value of the current measurement on the basis of these values. Multilayer printed circuit board according to one or more of the preceding claims, characterized in that the electrical resistance ( 8th ) on one or more intermediate layers ( 4 . 5 ) is arranged. Multilayer printed circuit board according to one or more of the preceding claims, characterized in that the intermediate storage ( 4 . 5 ) Sense connectors ( 1 ) having. Multilayer printed circuit board according to one or more of the preceding claims, characterized in that a sensor ( 31 ) the temperature of the electrical resistance ( 8th ) and the microcomputer unit ( 20 ) this temperature value to compensate for the temperature drift of the electrical resistance ( 8th ) and corrects the measured current value as a function of this temperature value. Multilayer printed circuit board after one or more of the preceding claims, characterized in that it is the multilayer printed circuit board um a circuit board for use in a motor vehicle is. Multilayer printed circuit board according to one or more of the preceding claims, characterized in that the microcomputer unit ( 20 ) is a microcontroller. Multilayer printed circuit board after one or more of the preceding claims, characterized in that the thermal connection of the electrical Resistance is done at least once. Multilayer printed circuit board according to one or more of the preceding claims, characterized in that the microcomputer unit ( 20 ) Manufacturing tolerances of the whole arrangement in the correction of the measured current value taken into account and these correction values the microcomputer unit ( 20 ) from a memory in which these values are stored during the automatic adjustment in the final test or taken from a look-up table.