Support entering into the fabrication of an electronic device, corresponding memory card connector, memory card read terminal and manufacturing method

Abstract

A support is provided for fabrication of an electronic device. The support includes at least one component to be protected and at least one three-dimensional element of a height at least equal to a height of the electronic component. The three-dimensional element is disposed laterally opposite the at least one component to be protected. The three-dimensional element is chiefly constituted of a permanent assembling material.

Claims

1. A support serving in the manufacture of an electronic device, said support comprising: at least one component to be protected; and at least one three-dimensional element with a height at least equal to the height of the electronic component, said three-dimensional element being disposed laterally relative to said at least one component to be protected, and wherein said three-dimensional element is constituted by a permanent brazing assembling material.

2. The support according to claim 1, wherein a section of said three-dimensional element along the height of said support, is shaped in the form of a disc with a flat portion, the flat portion of which rests on said support.

3. The support according to claim 1, wherein the height of said three-dimensional element is at least equal to 0.2 mm.

4. The support according to claim 1, wherein said three-dimensional element forms a broken line so as to protect at least two sides of said component to be protected.

5. The electronic device which comprises a support according to claim 1.

6. A terminal which comprises the electronic device according to claim 5.

7. A method for manufacturing a support serving in the manufacture of an electronic device, said support comprising at least one component to be protected, wherein said method for manufacturing comprises the following successive steps: positioning, on said support, a mask for deposition of at least one three-dimensional element with a height at least equal to said at least one component to be protected, the mask comprising at least one aperture positioned laterally relative to a location of said at least one component to be protected on said support, depositing a permanent brazing assembling material on said support through said at least one aperture, removing said deposition mask, forming said at least one three-dimensional element by reflow of said deposited permanent brazing assembling material.

8. The method for manufacturing according to claim 7, wherein the method comprises adjusting said height of said at least one three-dimensional element.

9. The method for manufacturing according to claim 7, wherein a ratio R between a width L.sub.DEP of said surface for depositing said permanent brazing assembling material and a width L.sub.o of said three-dimensional element is 2<R<4.

Description

5. FIGURES

(1) Other features and advantages of the technique described shall appear more clearly from the following description of a preferred embodiment, given by way of a simple, illustratory and non-exhaustive example and from the appended drawings of which:

(2) FIG. 1 already presented describes the classic architecture of a memory card reader;

(3) FIGS. 2A and 2B already presented respectively describe the architecture of another configuration of assembling of a memory card reader and a physical protection barrier for a component to be protected;

(4) FIGS. 3A to 3C respectively illustrate a support according to the technique described after deposition of a permanent assembling material to form a three-dimensional element physically protecting a component to be protected, this support finalized after the final step of manufacture of the method according to the described technique, and the assembling of a terminal according to the described technique;

(5) FIG. 4 illustrates the method of manufacture according to the described technique;

(6) FIGS. 5A and 5B respectively illustrate the step of deposition and the step of formation in the method of manufacture according to the technique described.

6. DETAILED DESCRIPTION OF THE INVENTION

(7) 6.1 Reminder of the Principle of the Invention

(8) The general principle of the technique described consists in modifying the constitution of a support comprising at least one component to be protected, in diverting a permanent assembling material from its classic use to form a three-dimensional element, the height of which is at least equal to the height of an electronic component, to act as a physical protection barrier for the component to be protected.

(9) Such three-dimensional protective elements are therefore formed chiefly by a permanent assembling material that costs little and is easily available because it is also used classically to fixedly attach an electronic component to the support.

(10) Thus, there is no obvious way to divert the function of a material classically used to fixedly attach two elements, namely for example a component and the support, in order to use it directly to form three-dimensional protection elements.

(11) The general principle of the technique described is described with reference to FIG. 3A representing the support after deposition of the permanent assembling material.

(12) Thus, this representation of the support according to the technique described corresponds to an image of the support between the deposition step and the formation step of the method for manufacturing the support as described in detail here below. Thus, this representation corresponds to the superimposition 30 of a mask (also called a stencil or a silkscreen print) on the support.

(13) In FIG. 3A, the components to be protected are represented by rectangles 31 on the superimposition 30 of the mask and the support corresponding to a printed circuit board (PCB) also called an electronic board.

(14) According to the embodiment represented in FIG. 3A, eight rectangles corresponding to the zones for soldering active components are shown. These eight rectangles 31 correspond for example to the eight connection pins 21 of the memory card connector 22 as represented in FIG. 2B. Among these eight pins, there are especially a pin on which the I/O signal to be protected is accessible.

(15) In addition, the superimposition 30 of the mask and of the support comprises, after deposition of the permanent assembling material, layers also called surfaces of deposition of this permanent assembling material. These layers or surfaces of deposition are situated at the apertures 32 of the silkscreen mask superimposed on the zones 33 of the support that correspond to the surface of fixed joining, with the support, of the three-dimensional elements obtained after reflow process. Such layers of permanent material, which in this case is preferably a brazing material (also called a brazing cream or paste), have a greater width after deposition, and preferably a width that is about three times greater than the width of the zone 33 of the support covered with the three-dimensional element obtained after the reflow process according to the technique described here, these layers being deposited on the three-dimensional element in order to prevent the generation of conductive beads during the reflow process since these conductive beads could impair the working of the components within the support.

(16) After removal of the silkscreen print mask and reflow process, the support 38, finalized according to the technique described as shown in FIG. 3B, is obtained. Thus, the support 38 according to the technique described comprises three-dimensional elements 34, 35 and 36 for the physical protection of the components to be protected. These components to be protected correspond, according to the illustration of FIG. 3C, to the connection pins 21.sub.H of the independent memory card connector 39 of the memory card reading terminal 390 obtained after assembling of the memory card reader body 3900 with the support 38 obtained according to the technique described.

(17) The connection between these two elements is obtained by means of an elastomer connector which sets up permanent pressure, for example a connector of the Zebra type (Registered Mark) (3901) as shown in FIG. 3C.

(18) In addition, the memory card reader body also comprises apertures for the insertion of metal anchoring protruding tips 3902 fixing the support according to the technique described in the memory card reader body 3900. These metal protruding tips are soldered with the brazing paste (also called brazing cream). Such metal anchoring protruding tips hold the connector during repeated insertions of a memory card into the memory card reader. These metal anchoring protruding tips can also have a particular shape suited firstly to fulfilling a function of guiding the memory card in the reader and secondly, if need be, obtaining an electrostatic discharge of the ridges of the inserted card.

(19) Each of these three-dimensional elements 34, 35, 36 are laid out laterally relative to the component to be protected, namely the connection pins 21.sub.H of the memory card connector so as to physically defend at least one side, as if it were as a wall or a rampart, against any malicious intrusion.

(20) The advantage of the composition of the three-dimensional element based on permanent assembling material is that it enables high flexibility of shape and length of the protective three-dimensional elements.

(21) Thus, it is possible to have three-dimensional elements in the form of a broken line such as the element 36 which enables the protection, along an angle, of the components to be protected but also elements of various lengths such as the great length of the three-dimensional element 34 which replaces four fictitious components of the prior art or again the small length of the three-dimensional element 35 which gives a protection barrier capable of being inserted in the housings of the metal spring blades 37 which get positioned on the surface of the chip.

(22) The three-dimensional elements 34 to 36 have the characteristic shape of a cylinder with a flat portion, this flat portion resting on the support. In other words, the heightwise section of the three-dimensional element has the shape of a disk with a flat portion.

(23) Indeed, this characteristic shape of the three-dimensional protection element according to the technique described is obtained during the reflow process. Indeed, the capillarity of the permanent assembling material corresponding, according to the example illustrated in FIGS. 3A and 3B, to a brazing material produces a grouping of this material at the level of the support zones 33 and possibly a shrinking of its volume. In particular, with respect to the width of the deposition of the layer of permanent assembling material in the aperture 32 of the deposition mask in FIG. 3A representing the support after deposition of the permanent assembling material, the three-dimensional element obtained after reflow process has a width substantially close to the width of the zones 33 of the support.

(24) The shape resulting from this shrinkage by reflow process characteristically has a section along the height of the support having the shape of a disk with a flat portion and a height H at least equal to that of the electronic component of the order of 0.2 mm to 0.3 mm in order to provide physical protection while at the same time enabling integration into an ultra-flat connector. For example, a height H of 0.5 mm to 0.6 mm is obtained for a three-dimensional element, the length of which is perpendicular to the sense of passage of a scraper for depositing assembling material. Obtaining such a height of 0.5 mm to 0.6 mm is especially associated with the formation of beads of brazing paste described here above.

(25) Thus, a protection barrier corresponding to the three-dimensional element chiefly constituted by a brazing material is easily identifiable with respect to the fictitious components used according to the prior art.

(26) 6.2 Description of the Method of Manufacture

(27) Referring to FIG. 4, we present the method of manufacture 40 of a support according to the technique described.

(28) Such a method comprises the following successive steps:

(29) Positioning 41, on the support, a mask for deposition of a three-dimensional element with a height at least equal to the height of an electronic component, the mask comprising at least one aperture 32 positioned laterally relative to the location of said at least one component to be protected on said support,

(30) Depositing 42 a permanent assembling material on the support through the aperture 32,

(31) removing 43 said deposition mask,

(32) forming 44 at least one three-dimensional element with a height at least equal to said at least one component to be protected by reflow of said permanent assembling material deposited on said aperture 32.

(33) More specifically, the method is one of manufacturing barriers for the physical protection of components to be protected by deposition of a permanent assembling material preferably brazing paste, according to a screen-printing method and also over-printing method corresponding to the fact that the deposition of a brazing cream is about three times wider than the width of the support covered with the three-dimensional element which will be obtained after reflow process according to the technique described herein.

(34) Thus, first of all on the support that is to be improved, a mask is placed 41 also called a screen-printing screen or stencil.

(35) This mask comprises apertures 32 such as those represented with reference to FIG. 3A. These apertures 32 correspond to the deposition areas.

(36) The masks also called stencils or again silk-screen printing screens are sometimes prepared from polyester sheets or copper alloys.

(37) These materials are used to an increasingly smaller extent because they are less reliable and more easily damaged.

(38) As an alternative, it is possible to use specific stainless sheets whose cost is reasonable while at the same time providing high stability and long service life.

(39) Sometimes, it can be necessary to resort to other materials, especially if the apertures are truly very small or if it is necessary to have a greater deposit than that which would be permitted with stainless steel sheets of this kind. In this case, the invention uses for example a nickel sheet which has much lower adhesion to the walls and therefore provides for a smaller surface-to-thickness ratio. The flip side here is the high cost of these nickel sheets which limits their use.

(40) There also exist adhesive point stencils which are less complicated but have drawbacks similar to those of the above stencils. The essential difference is the thickness of the sheet which is generally 250 m.

(41) The cutting out of apertures 32 in the silkscreen stencil is done for example by laser rays. These laser rays are generated, for example, by means of laser diodes which enable very fine cutting and very swift implementation.

(42) The outline of the aperture 32 is often trapezoidal, with the base of the trapezoid being in contact with the circuit, in order to favor the demolding process.

(43) During the deposition 42 and as illustrated by FIG. 5A, the brazing paste is pushed into the apertures of the mask (not shown in FIG. 5A) by a scraper so that it can be deposited on the surface of the support 53. The support 53 is coated with a varnish 52 and has a support zones with a thickness L.sub.o, free of varnish, receiving the permanent assembling material and corresponding to the surface for the fixed attachment, with the support, of the three-dimensional elements obtained after reflow process once the soldering is done.

(44) The volume of a brazing paste to be deposited is for example determined by the surface of the receiving zone and the thickness of the stencil which is generally 150 m. If the deposit is not enough, the protective three-dimensional element will not be accurately attached. If it is excessive, the paste can overflow and cause bridges between the zones.

(45) The quality of the deposition depends on numerous factors, namely the grain of the paste, its viscosity, the quality of the support, its thickness and the strength of retention on its walls, the dimensions of the aperture, the temperature curves during the passage into the oven inter alia.

(46) In addition, the thickness of the stencil is also decisive. The adhesion of the paste to the walls depends on the ratio between the surface of the aperture and the thickness of the material.

(47) Thus, it is optionally possible to act on these factors to adjust (410) the height of the three-dimensional element of the support.

(48) The adjusting REG 410 of this height consists for example in adjusting the ratio between the width of the aperture 42 in the silk-screen printing stencil corresponding to the width of deposition L.sub.DEP of the permanent assembling material and the width L.sub.o of the zone of the support covered by the three-dimensional element obtained after reflow process.

(49) Advantageously, the width of the deposition L.sub.DEP of the permanent assembling material is three times greater than the width L.sub.o, the zone on the support covered by the three-dimensional element obtained after the reflow process.

(50) Such a ratio provides for a height of the three-dimensional element (for example between 0.2 mm and 0.3 mm, for a deposition width L.sub.DEP of the permanent assembling material equal to 3 mm and a width L.sub.o of 1 mm for the zone of the support covered by the three-dimensional element obtained after reflow process) that is sufficient for it to fulfill the role of protecting sensitive components.

(51) Then, the deposition mask is removed (43) (or again demolded).

(52) Once the brazing paste has been deposited, the components to be protected are placed COMP (411) according to one option. Positioning the components to be protected after depositing the brazing paste prevents any splashing of the brazing paste on these components and therefore prevents them from undergoing potential deterioration because of this material. Such a deposition of the components to be protected can be done optionally before or after the removal of the deposition mask.

(53) Finally, the method of manufacture implements the formation (44) of the three-dimensional elements by reflow process in a reflow oven, to obtain the support capable of being used to manufacture an electronic device such as a memory card reading terminal (390), an example of which is shown in FIG. 3B.

(54) Optionally, it is possible to again adjust the height of the three-dimensional element mechanically. Indeed, it is possible to touch up the brazing by hand, with a brazing iron, to increase the volume of cream and therefore the height.

(55) The advantage of using a brazing material to form the three-dimensional protective elements is that the temperatures needed so that it joins with the support and form the three-dimensional element is below the melting temperature of the support but also below that of the component to be protected. A deterioration of the component to be protected is therefore prevented because during the reflow process, only the brazing paste reaches its melting temperature, while that of the component is not reached.

(56) Such a reflow process causes a loss in the volume of the brazing paste as shown in FIG. 5B. After reflow process, a three-dimensional element is then obtained, the section of which along the height of the support (53) has the shape of a disk (55) with a flat portion (54), the flat portion (54) lying on the zone of the support.

(57) It must be noted that an excessive width of deposition that does not comply with the recommended ratio, according to which the width of deposition L.sub.DEP of the permanent assembling material is about three times greater than the width L.sub.o of the aperture defining the deposition area, would generate conductive beads that are not soldered to the support and therefore devoid of any protective functions.

(58) We therefore obtain a three-dimensional element 55, the height H of which is for example 0.2 mm to 0.3 mm for a deposition width L.sub.DEP of permanent assembling material equal to 3 mm and a width L.sub.o of 1 mm for the zone of the support covered by the three-dimensional element obtained after reflow process. The width L.sub.o of the zone of the support is therefore equal to the width of the surface of the three-dimensional element lying on the support (53). This height, which is of the same order as that of an electronic component, therefore fulfills the role of a protection wall.

(59) It must be noted that the three-dimensional elements for protecting a support are also capable of protecting the components 14 of a classic architecture such as that shown in FIG. 1.

(60) Although the present disclosure has been described with reference to one or more examples, workers skilled in the art will recognize that changes may be made in form and detail without departing from the scope of the disclosure and/or the appended claims.