Patent Description:
In motor vehicles and notably electric or rechargeable hybrid motor vehicles, the batteries of the vehicle are recharged using a cable. Thus, as shown schematically in <FIG>, electric or rechargeable hybrid motor vehicles <NUM> may comprise a connector socket <NUM> to which a charging plug <NUM>, supplied with electricity by an electric vehicle supply equipment <NUM> via an electrical cable <NUM>, may be connected. This charging plug <NUM> then allows one or more batteries mounted in the vehicle <NUM> to be charged.

The invention notably relates to connectors such as the connector socket <NUM>, or male power connectors. However, the invention may potentially also be used for charging plugs <NUM>, or female power connectors.

A power connector, whether male or female, includes a housing and power electrical contacts connected electrically to electrical wires, or conductive metal bars (busbars) forming a power electrical circuit. In this document, "contact" refers both to a male contact or electrical terminal (pin or plug) and to a female contact or electrical terminal (clip).

In some power electrical circuits, direct currents of <NUM> amperes, <NUM> amperes or even <NUM> amperes may be used. This creates a risk of the contacts heating up, for example, at the site of regions of contact with another contact and/or at the site of regions where the contact is crimped onto a cable. It is therefore desirable to be able to measure and monitor the temperature of the power contacts so as to decrease the amperage of the electric current flowing through them, or even to stop it by breaking the circuit, if the heating of the contact becomes too high. <CIT> and <CIT> disclose solutions wherein PCBs are used both for supporting a thermal sensor and for transmitting heat from a contact to this sensor.

One difficulty lies in accurately and reliably measuring the temperature of a contact while keeping same well isolated from any other electrical circuit.

An at least partial solution to this problem is proposed below.

Thus, what is proposed is a printed circuit board according to claim <NUM>. This printed circuit board includes a dielectric support in the form of a plate with two main faces and an edge face between the two main faces. At least a first and a second metal layers are rigidly connected to the dielectric support and run parallel to the main faces thereof. Additionally, a thermal conduction land is formed in each of the first and second metal layers. The respective thermal conduction lands of the first and second metal layers are electrically connected to one another at the site of a region of the edge face of the dielectric support. This region forms an area of thermal (and generally also electrical) contact with the outer peripheral surface of a power contact housed in the connector. Additionally, the printed circuit board includes a temperature sensor mounted on one of its main faces, this face being partially covered by the first metal layer and this sensor facing, through a thickness of the printed circuit board, the thermal conduction land formed in the second metal layer.

Thus, by virtue of these arrangements, there is a sensor to which heat may be conveyed along at least two thermal conduction paths, one of these paths going over the surface of the printed circuit board on which the sensor is mounted, and the other of these paths reaching the sensor from below. This arrangement makes it possible to significantly improve the accuracy of measurement of the temperature of a contact by minimizing the difference between its temperature and the temperature of the printed circuit board at the site of the sensor. Other arrangements presented below may allow this accuracy to be increased further.

This printed circuit board optionally includes one and/or another of the features recited in claims <NUM> to <NUM>, each considered independently of one another, or in combination with one or more others.

According to another aspect, what is proposed is a power connector according to claim <NUM>.

According to yet another aspect, what is proposed is a method for measuring the temperature of a contact housed in a power connector, according to claim <NUM>.

Further features, aims and advantages of the invention will become apparent from reading the following detailed description, and with reference to the appended drawings, which are given by way of non-limiting examples and in which:.

In the figures, the same references denote identical or similar elements.

A first embodiment example of a printed circuit board is described below with reference to <FIG>.

According to this example, the printed circuit board <NUM> is a multilayer circuit board with a dielectric support <NUM> or substrate and four conductive metal layers <NUM>, <NUM>, <NUM>, <NUM> separated by insulating material of the dielectric support <NUM>. The dielectric support <NUM> is for example composed, in a known manner, of an epoxy resin which may or may not be reinforced with glass fibres. The conductive metal layers <NUM>, <NUM>, <NUM>, <NUM> are for example composed of sheets of copper or of a copper alloy. The conductive metal layers <NUM>, <NUM>, <NUM>, <NUM> have for example a thickness of <NUM> micrometres, with <NUM>-micrometre layers of dielectric material intercalated between them. The printed circuit board <NUM> includes two outer conductive metal layers <NUM>, <NUM> and two inner conductive metal layers <NUM>, <NUM>. The outer conductive metal layers <NUM>, <NUM> run parallel to the main faces <NUM> of the dielectric support <NUM> on which they rest. The inner conductive metal layers <NUM>, <NUM> run parallel to the main faces <NUM> of the dielectric support <NUM> into which they are inserted.

A recess <NUM> is formed through the entire thickness of the printed circuit board <NUM>, through all of the conductive metal layers <NUM>, <NUM>, <NUM>, <NUM> and dielectric material. This recess <NUM> is suitable for insertion into a groove <NUM> formed in the outer peripheral surface <NUM> of a contact <NUM>. The recess <NUM> takes the shape of a "U" with a semicircular bottom and two mutually parallel guide edges <NUM>, corresponding to the arms of the U (see also <FIG>). This recess <NUM> includes an edge face <NUM>. This edge face <NUM> is at least partially covered by a layer of a conductive material <NUM>, for example by <NUM> micrometres of copper deposited by means of a chemical and electrolytic process. The layer of conductive material deposited on the edge face <NUM> extends all the way around the portion of the recess <NUM> which is intended to come into contact with the contact, via outer thermal conduction lands <NUM>, <NUM> formed respectively in the outer conductive metal layers <NUM>, <NUM>. Thus, the outer thermal conduction lands <NUM>, <NUM> are in electrical and thermal continuity with the edge face <NUM>. Similarly, inner thermal conduction lands <NUM>, <NUM>, formed respectively in the inner conductive metal layers <NUM>, <NUM>, are in electrical and thermal continuity with the edge face <NUM>. Thus, the outer and inner thermal conduction lands <NUM>, <NUM> and <NUM>, <NUM> are in electrical and thermal continuity with a contact <NUM> housed in the recess <NUM>. The inner thermal conduction lands <NUM>, <NUM> extend at least partially beneath a temperature sensor <NUM> deposited on one of the main faces <NUM> of the dielectric support <NUM>. The outer thermal conduction lands <NUM>, <NUM> extend until they are in proximity to the connection pads <NUM> to which the sensor <NUM> is connected. For example, a distance of about <NUM> millimetres separates the outer thermal conduction lands <NUM>, <NUM> from the connection pads <NUM>.

Connection lands <NUM> are also formed in the inner metal layers <NUM>, <NUM>. These connection lands <NUM> are suitable for forming an electrical connection between the connection pads <NUM> to which the sensor <NUM> is connected and an electrical measurement circuit (not shown). The connection pads <NUM> formed in the outer conductive layers <NUM>, <NUM> are electrically connected to the connection lands <NUM> formed in the inner conductive layers <NUM>, <NUM> by means of vias <NUM>.

The sensor <NUM> is therefore connected between two connection pads <NUM> located on one of the main faces <NUM> of the printed circuit board <NUM>. These connection pads <NUM> are connected, through thicknesses of the dielectric support <NUM>, to the connection lands <NUM> formed in the inner conductive metal layers <NUM>, <NUM>. These connection lands <NUM> are electrically isolated from the thermal conduction lands of the outer conductive metal layers <NUM>, <NUM> and are at least partially covered by the outer thermal conduction lands <NUM>, <NUM>.

Thus, the heat generated at the site of the contact <NUM> may be transmitted to the sensor <NUM> along at least two favoured conduction path types: a first thermal conduction path <NUM> at the level of the outer thermal conduction lands <NUM>, <NUM> and a second first thermal conduction path <NUM> at the level of the inner thermal conduction lands <NUM>, <NUM>.

A circuit such as described above may be used to measure the temperature of a single contact <NUM> (see <FIG>) or of a plurality of contacts 10a, 10b (for example two contacts 10a, 10b as shown in <FIG>).

When a printed circuit board <NUM> such as described above is used to measure the temperature of a plurality of contacts 10a, 10b, it is advantageous to mount thereon at least one sensor <NUM> per contact. In other words, in this case the printed circuit board <NUM> comprises at least two measurement portions <NUM>, electrically isolated from one another. Each of these measurement portions <NUM> includes a region on the edge face <NUM> of the dielectric support <NUM> at the site of which thermal conduction lands <NUM>, <NUM>, <NUM>, <NUM>, formed in the inner and outer conductive metal layers <NUM>, <NUM> and <NUM>, <NUM>, are connected. Each region is suitable for being brought into contact with a contact <NUM>.

Additionally, this printed circuit board <NUM> may then comprise, between two measurement portions <NUM>, a flexible portion <NUM> suitable for accommodating a movement of one of the measurement portions <NUM> relative to the other, parallel to the plane of the main faces <NUM> of the dielectric support <NUM>. This flexible portion <NUM> is for example formed by means of a meander, or an "S" shape, or a "U" shape with each of the arms of the "U" in common with another "U", upside-down and connected to one of the measurement portions <NUM>.

<FIG> show, in greater detail, an example of shapes which may be given to the different connection lands <NUM> and thermal conduction lands <NUM>, <NUM>, <NUM>, <NUM>.

For example, the outer thermal conduction lands <NUM>, <NUM> are inscribed in a square or rectangular shape. One of the sides of this shape is open to the recess <NUM>. Additionally, one of the corners of this shape includes an indent <NUM>. This indent <NUM> includes two edges <NUM> that are substantially parallel to one another and each located respectively on either side of the indent <NUM>. The two connection pads <NUM> are each located respectively facing one of these edges <NUM>. The bottom <NUM> of the indent <NUM> is formed of a conductive metal strip in the shape of a circular arc extending for example over a width of <NUM> millimetres from the recess <NUM>. The sensor <NUM> is placed facing this conductive metal strip at a distance of <NUM> millimetres for example.

The two connection pads <NUM> of elongate shape extend from the outside to the inside of the indent <NUM>. These connection pads <NUM> each have one end connected to the sensor <NUM> and another end connected to inner connection lands <NUM>, and to the other outer metal layer <NUM>, by means of two vias <NUM>. The inner connection lands <NUM> are largely located beneath/between regions of the outer thermal conduction lands <NUM>, <NUM>, and run parallel to two of the edges of the square or rectangle shape of the outer thermal conduction lands <NUM>, <NUM> up to conductive vias <NUM> which go to the main faces of the dielectric support <NUM> in order to electrically connect them to a measurement circuit.

Claim 1:
Printed circuit board for a power connector, this printed circuit board (<NUM>) including a
dielectric support (<NUM>) in the form of a plate with two main faces (<NUM>) and an edge face (<NUM>) between the two main faces (<NUM>), a first (<NUM>) and a second (<NUM>) metal layers being rigidly connected to the dielectric support (<NUM>) and running parallel to the main faces (<NUM>) thereof,
wherein a thermal conduction land (<NUM> or <NUM>, <NUM> or <NUM>) is formed in each of the first (<NUM>) and second (<NUM>) metal layers, the respective thermal conduction lands (<NUM> or <NUM>, <NUM> or <NUM>) of the first (<NUM>) and second (<NUM>) metal layers being electrically connected to one another at the site of a region of the edge face (<NUM>) of the dielectric support (<NUM>), and wherein the second metal layer (<NUM>) is arranged in the thickness of the dielectric support (<NUM>),
including a temperature sensor (<NUM>) mounted on one of its main faces (<NUM>), this main face (<NUM>) being partially covered by the first metal layer (<NUM>), this sensor (<NUM>) facing, through a thickness of the printed circuit board (<NUM>), the thermal conduction land (<NUM>) formed in the second metal layer (<NUM>), the sensor (<NUM>) being connected to at least one connection pad (<NUM>) located on one of the main faces (<NUM>) of the printed circuit board (<NUM>),
characterized in that the connection pad (<NUM>) is connected in turn, through a thickness of the dielectric support (<NUM>), to a connection land (<NUM>) electrically connecting the connection pad (<NUM>) to a measurement electrical circuit, the connection land (<NUM>) being formed in the second metal layer (<NUM>), being electrically isolated from the thermal conduction lands (<NUM>, <NUM>) of the first (<NUM>) and second (<NUM>) metal layers and being at least partially covered by the thermal conduction land (<NUM>) of the first metal layer (<NUM>)