WO2005122339A1

WO2005122339A1 - Electrical connector provided with at least one electrical contact and process for manufacture of such a connector

Info

Publication number: WO2005122339A1
Application number: PCT/EP2005/005951
Authority: WO
Inventors: Stéphane BARLERIN; Antoine Fares-Karam
Original assignee: Fci
Priority date: 2004-06-10
Filing date: 2005-06-02
Publication date: 2005-12-22
Also published as: FR2871621A1

Abstract

An electrical connector (1) according to the invention comprises an insulating case (3) and at least one electrical contact (4, 13). This electrical contact permits electrically coupling a smart card (2) to at least one electrically conductive track (8) printed on a support (7). In order to increase the performance of such an electrical connector, the invention also provides for increasing the elasticity of at least one electrical contact. To do this, the invention provides for making the electrical contact by forming at least one first curve (40, 41) made near an anchoring point of the contact on the case and at least one second curve (42, 43) made at an area distant from this same anchoring point.

Description

Electrical connector provided with at least one electrical contact and process for manufacture of such a connector. The invention concerns an electrical contact. The invention also pertains to an electrical connector provided with at least one such electrical contact, and more particularly to a connector to electrically connect a smart card to at least one electrically conductive track printed onto a support.

Document EP-B1-0 430,267, discloses a type of electrical contact manufactured of metallized plastic. This electrical contact is formed starting with an insulating case. This electrical contact has a convex end against which a circuit board is intended to be placed in a supported manner while being held against this contact and against a wall of the case from which this same contact extends. By being thus constrained, the circuit board is kept relatively fixed in the case. However, the elasticity of the contact can weaken over time and the circuit board can be dislodged from the connector. Weakening of the elasticity of the electrical contact can be the cause of a poor electrical connection between the connector and the circuit board. Weakening of the contact elasticity of the electrical contact can even involve an electrical break between the contact and the circuit board. In order to resolve this problem, the invention seeks to create an electrical contact according to claim 1. The electrical contact, according to the invention, can be made by a plastic- molding technique. This electrical contact can be made of plastic coated at least partially with a metal layer. Or this electrical contact can even be made of a plastic substance containing metal particles. In the case where the plastic is coated with the metal layer, this metal layer extends over the plastic so that an electrical connection is assured between, for example, a smart card and the pattern printed on the support by means of this metal layer during the positioning of said smart card in the electrical connector comprising a contact according to the invention. The electrical contact can be metallized by classical metallization techniques that will depend on the nature of the plastic used to form the electrical contact. The electrical contact can be metallized either by a pre-activation of the surface to be metallized and then immersion of this contact thus activated in a metallizing bath, or by direct immersion of the electrical contact in a metallizing bath when the electrical contact already comprises catalysts within it. The subject of the invention is therefore an electrical connector comprising such contacts, notably a smart card connector. The invention will be better understood upon reading the description that follows and examining the figures that accompany it. These are only given by way of indication and do not at all limit the invention. The figures show: - Figures 1a to 1b: schematic diagrams of the positioning of a smart card relative to an electrical connector comprising electrical contacts according to the

invention; - Figures 2a to 2b: schematic diagrams of an electrical connector, according to the invention; - Figures 3a to 3b: schematic diagrams of an electrical connector, according to a variant of the invention; and Figure 4: a perspective schematic diagram of a connector case before insertion of the electrical contacts. Figure 1a shows a cross section of an electrical connector 1 for a smart card, the connector being positioned on a support 7 with a smart card 2 detached from connector 1. Figure 1 b shows smart card 2 positioned on an upper part 5 of a case This electrical connector comprises an insulating case 3, including an upper part 5 and a lower part 6, and at least one electrical contact 4. Case 3 is designed to be placed by its lower part 6 in contact with upper face 9 of support 7, which comprises at least one electrically conductive track 8. Support 7 can comprise several electrically-conductive tracks forming one or more patterns that may or may not be connected to one another. Smart card 2 is designed to be placed against upper part 5 of the case in a direction perpendicular to a plane formed by support 7. Electrical contact 4 permits electrically connecting smart card 2 to track 8 of support 7. According to the invention, the electrical contact is made so that it has the form of an elastic arm (Figures 1a, 1b, 2a and 2b). The invention provides that the electrical contact forms at least one first curve 40, 41 and a least one second curve 42, 43. A first curve such as 40 and 41 is shown by an arrow F1 in Figure 1a and a second curve such as 42 and 43 is shown by an arrow F2 in this same Figure 1a. The first curve and the second curve are created one following the other so that the concavity of the first curve is reversed relative to the concavity of the second curve. In this same preferred example, the electrical contact comprises two first curves 40 and 41 and two second curves 42 and 43. The first curve 40 is situated near an anchoring point for the contact on the case. The contact curves back at a first area near the anchoring point for the contact on the case in the direction opposite an area where the smart card is inserted onto the connector to form the first curve. The second curve 42 is created in an area distant from the anchoring point for the contact on the case. In order to form this second curve, the contact is curved back in a second area distant from the anchoring point of the contact on the case in a direction opposite that made to obtain the first curve. The anchoring point of the electrical contact corresponds to a crosspiece 14 that will be described below. The elasticity of the contact thus obtained by such curves 40, 41 , 42, 43 permits assuring a permanent contact of electrical contact 4 with smart card 2 and also permits compensating for the possible reduction in the quality of the plastic over time. In fact, this reduction in the quality of the plastic can be responsible for a permanent contact weakening of the electrical contact with the smart card. In addition, such a design of the curves also allows reducing the rate of wear of the contacts. In one variant, Figures 3a and 3b, an electrical contact 19 can form a tab folded along an angle at a stud 17 while also forming an elastic arm with a metallized surface 31. On an upper face 28 of this connector 18, as can be seen from the top view of Figure 3a, it is possible to visualize a first contact stud 17 for connection with smart card 2, which stud 17 is situated in the area of the fold of contact 19. On a lower face 29 of connector 18 viewed from the bottom of this same electrical connector 18 in Figure 3b, it is possible to visualize a second connection stud 20 of contact 19 to connect with track 8 of the support. Electrical contact 4 according to the invention is manufactured of plastic and is at least partially metallized so that it can electrically connect smart card 2 to track 8 of support 7 during the positioning of smart card 2 in case 3. Metallization can be carried out so that the electrical contact has a metal layer or metallized surface 30 that can correspond to at least one part of a surface bounding electrical contact 4. This metallized surface 30 is shown by bold lines in Figures 1a and 1 b and by dots in Figures 2a and 2b. This metallized surface 30 extends from a first end 15 of the contact up to a second end 16 of this same contact. The first end or first connection stud 15 is designed to come into contact with smart card 2. The second end or second connection stud 16 is designed to come into contact with track 8 of the support. The electrical contact can be metallized by classical metallization techniques that will depend on the nature of the plastic used to form the electrical contact. This metallization can consist either of a preliminary activation of the surface to be metallized and then immersion of this contact thus activated in a metallizing bath, or by direct immersion of the electrical contact in a metallizing bath when the electrical contact already comprises catalysts within its substance. Thus, one can use inert plastics, i.e., non-metallizable plastics that can only be rendered metallizable by activation of a surface 30 to be metallized after various chemical treatments. After chemical treatment, the contact is then immersed in a metallizing bath in order to obtain a surface 30 covered with a fine layer of metal. These chemical treatments can consist of rendering hydrophilic the surface to be metallized 30, or making it rough, or even by plasma etching the surface to be metallized. For example, the inert plastic employed can be a material classically used in the microconnector field such as polymers defined as high-temperature plastics, i.e., plastics of the semicrystalline and/or liquid crystal type, typically polyester, polybutylene-terephthalate PBT or LCP, the polyphenylene sulfide PPS type, or the syndiotactic polystyrene SPS type. These materials are defined as high- temperature plastic polymers because their melting point is 220 °C for PBT, and is greater than 350°C for the three others cited above. Plastics such as, for example, LCPs, the LCP Vectra E 820i Pd or LCP TitanLG431 type having catalysts incorporated within them that render these materials directly metallizable can also be used. These catalysts can be palladium. The incorporation of such catalysts into the plastic permits eliminating the initial step of sensitizing surface 30 of electrical contact 4 that is to be metallized and the electrical contact can be directly immersed in the metallizing bath. Case 3 can comprise at least one first contact such as 4 and at least one second contact such as 13, Figures 1a and 1b. In the example of Figures 2a and 2b, the case has three first contacts such as 4, 4.1 and 4.2, and three second contacts such as 13, 13.1 and 13.2. In order to attach these different contacts, the case can comprise a crosspiece 14. This crosspiece is preferentially centrally positioned relative to the case but could be positioned in another area of the case. The position of this crosspiece depends on the size of the electrical contacts that are placed in such a case. This central crosspiece 14 permits dividing case 3 into a first compartment 26 and into a second compartment 27. In the preferred example of Figures 1a, 1 b, 2a and 2b, from one side of crosspiece 14 to the other, the first contacts 4, 4.1 and 4.2 and the second contacts 13, 13.1 and 13.2 can extend perpendicularly relative to a plane formed by crosspiece 14. Thus, crosspiece 14 is preferentially centrally placed in a cavity 22 of case 3 so that it is possible to create electrical contacts of the same dimension relative to one another. The manufacturing cost of a connector provided with such identical contacts can thus be considerably

reduced. The contact 4 can be attached onto case 3 at the level of crosspiece 14. For this purpose, a notch 35 is hollowed out in crosspiece 14 and this notch is designed to receive corresponding electrical contact 4. This notch 35 is hollowed out perpendicularly to the plane formed by crosspiece 14 from a first area of the partition near a plane formed by upper part 5 of the case to a second area of crosspiece 14 near a plane formed by lower part 6 of case 3. The coated electrical contact with its metallized surface 30 can be inserted by embedding or by forcibly fitting it into notch 35 in a direction parallel to a plane formed by crosspiece 14 or in a direction perpendicular to the plane formed by support 7. Crosspiece 14 can be made over only part of height 38 of case 3 so as to define at least one space 39 between crosspiece 14 and the plane formed by lower part 6 of case 3 to permit the second end 16 of contact 4 to be housed therein. Height 38 is measured along an axis perpendicular to the plane formed by support 7. By creating crosspiece 14 over a part of height 38 of the case, it is possible to reduce the quantity of material necessary to create such a connector and therefore reduce manufacturing costs. Electrical contact 4 is inserted into notch 35 by a part 37 of contact 4. This part 37 is metallized and is shown by dashes in notch 35 in Figure 1 b. Inside notch 35, the electrical conduction between first connection stud 15 and second connection stud 16 is carried out along the part 37 of electrical contact 4 by means of metallized surface 30. In another variant, electrical contact 4 can be glued onto crosspiece 14 of case 3.

Electrical contacts such as 4 and 13 are designed to come into contact with at least one electrically conductive strip 11 printed on a lower surface 25 of smart card 2. This strip 11 can be the same for all the electrical contacts, or several strips such as 11 and 12 can be printed on smart card 2. There can be as many electrically conductive strips as there are contacts. In the example of Figures 1a to 1 b, the smart card has a first electrically conductive strip 11 and a second electrically conductive strip 12, first strip 11 being designed to be in contact with all the first contacts 4, 4.1 , 4.2, and the second strip 12 being designed to be in contact with all the second contacts 13, 13.1 and 13.2. Thus, the first and the second electrical contacts permit making an electrical connection between first strip 11 and second strip 12, respectively, and track 8 coated on support 7, Figure 1 b. At rest, contact 4 is positioned relative to case 3 in such a way that end 15 of the contact is positioned above the plane formed by upper part 5 of case 3 and outside cavity 22, along height 21 , Figure 1a. End 15 of contact 4 at rest has a tendency to project from cavity 22 of case 3. The first end is slightly raised relative to the plane formed by upper part 5. When smart card 2 is placed against first end 15 of contact 4, first end 15 passes from this first position towards a second position in which the first end tends to be aligned on the plane formed by upper part 5. By being aligned with the plane formed by upper part 5, a permanent contact is made between the contact and the smart card thus assuring a stable and durable electrical connection. The stability and durability of this electrical connection is proportional to the number of zigzags that the electrical contact comprises. The manufacturing process for such an electrical connector can be carried out in the following manner. In a first example, an inert plastic is molded or cast-molded to form insulating case 3. Then a second molding of another plastic is produced so as to form at least one electrical contact 4. This other plastic can be inert or this other plastic can even be metallizable or comprise catalysts in its substance. Depending on the nature of the plastic molded to form the electrical contact, the electrical contact is metallized

before or after insertion in the case. In particular, when the second molding is made from an inert plastic, such a plastic is metallized before insertion of the electrical contact. When the second molding is made from a metallizable plastic, the electrical contact is metallized before or after its insertion in the case, since the case is made of a plastic that cannot be directly metallized. In a second example, a metallizable plastic is molded or cast-molded to form insulating case 3. Then another plastic is molded so as to form at least one electrical contact 4. This other plastic can be inert or this other plastic can even be metallizable or comprise catalysts in its substance. In this example, the electrical contact is metallized before insertion of the contact in the case. The contact formed by an inert plastic is metallized by activating the surface to be metallized 30 by various chemical treatments so as to graft catalysts onto the surface to be metallized 30. Then the electrical contact which has first been activated is immersed in a metallizing bath. The electrical contact is inserted into the casing after at least one notch 35 of the partition has been formed. This notch is made on at least one of the sides of a plane formed by crosspiece 14. In another variant of the invention, a first molding and a second molding of a plastic are conducted to respectively form the contact and the case. The case and the electrical contact are metallized. Then a mask is applied, which is designed to cover the metallized surface 30 of the electrical contact. And finally, the metal is scoured (except for surface 30 covered by the mask) by means of a laser technique,

or by a chemical method.

Claims

1. An electrical contact (4) comprising first and second ends, the first end (15) being connected to the second end (16) by a part alternatively including at least one first curve (40, 41 ) extended directly by at least one second curve (42, 43), first curve (40, 41) comprising a concavity that is inverted relative to that of second curve (42, 43).

2. The contact (4) according to claim 1 , further characterized in that it has two first curves (40, 41 ) and two second curves (42, 43).

3. The contact according to claim 1 or 2, further characterized in that it is made of plastic which is at least partially metallized by a layer of metal (30) to form electrical contact zones.

4. The contact (4) according to claim 3, further characterized in that the plastic material is a high-temperature plastic.

5. The contact (4) according to claims 3 or 4, further characterized in that the

plastic is of the semicrystalline and/or liquid crystal type.

6. An electrical connector for a smart card (2) comprising: a case (3) that can be positioned on a support (7) including at least one

electrically conductive track (8), and at least one electrical contact (4) according to any one of the preceding claims in which one of the ends is designed to be in contact with an electrically conductive strip (11) of smart card (2) and the other end is designed to be in contact with at least one electrically conductive track (8) of support (7).

7. The connector according to claim 6, further characterized in that case (3) comprises a crosspiece (14) including at least one notch (35) able to receive electrical contact (4).