Electronic component

Abstract

Electronic Component This description relates to an electronic component (100) comprising: – an integrated circuit chip (119); – a package (111, 113) surrounding the integrated circuit chip; and – at least one first conductive region (107) covering at least part of one face of the integrated circuit chip, the first conductive region comprising an alloy consisting mainly of bismuth. Figure for the abbreviation: Fig. 2

Description

Title of the invention: Electronic component technical field

[0001] This description relates generally to electronic components and their manufacturing processes, more particularly to electronic components comprising at least one integrated circuit chip packaged and the manufacturing processes of such components. Previous technique

[0002] Electronic components comprising at least one packaged integrated circuit chip have been proposed. In particular, there are components comprising a CSP (Chip-Scale Package) type package—a package with dimensions similar to those of the chip. These components are generally surface-mounted on a printed circuit board by a soldering process involving the melting and then solidification of a solder paste or flux based on a lead-free alloy, for example, a tin, silver, and copper alloy (Sn-Ag-Cu alloy), also known by the acronym SAC. To assemble the electronic component to the printed circuit board, a temperature above the melting point of the alloy, approximately 218 °C in the case of the SAC alloy, is applied to melt the solder material.The assembly is then cooled to solidify the soldering material, thus mechanically fixing the component to the board.

[0003] However, existing electronic components including a CSP package have several drawbacks. In particular, known manufacturing processes for electronic components using the SAC alloy give rise to problems of unintentional bridging, or interconnection, between adjacent integrated circuit chips during a reflow step of the solder material prior to a cutting step aimed at individualizing the integrated circuit chips.

[0004] Furthermore, in certain application areas such as automotive manufacturing, it would be desirable to have components with wettable sidewalls to facilitate post-soldering inspection steps. However, a reflow step of sidewalls coated with the SAC alloy during assembly would lead to an undesirable phenomenon of sagging or runoff of this alloy onto the printed circuit board.

[0005] Furthermore, in a case where the component package surrounds several integrated circuit chips, including, for example, an ASIC (Application-Specific Integrated Circuit) chip, stacked and interconnected by solder balls, these balls are generally composed of a metallic alloy, for example a gold and tin alloy, having a melting point higher than that of the alloy used for soldering, for example SAC alloy, to prevent remelting of the solder balls when soldering the component to the board. Since gold and tin alloy is particularly expensive, it would be desirable to find a substitute material with a lower cost. Summary of the invention

[0006] There is a need to overcome all or part of the drawbacks of known electronic components and their manufacturing processes.

[0007] To this end, one embodiment provides an electronic component comprising: - an integrated circuit chip; - a casing surrounding the integrated circuit chip; and - at least one first conductive region covering at least partially one face of the integrated circuit chip, the first conductive region comprising an alloy consisting mainly of bismuth.

[0008] According to one embodiment, the alloy has a bismuth content greater than 80%, preferably about 90%.

[0009] According to one embodiment, the alloy further comprises at least one additional element selected from silver, nickel and tin.

[0010] According to one embodiment, the alloy has a content of said at least one alloying element of less than 10%, preferably equal to about 5%.

[0011] According to one embodiment, the alloy has: - a bismuth content of approximately 90%; - a silver content of approximately 5%; and - a nickel content of approximately 5%.

[0012] According to one embodiment, the alloy has a melting point between 270 and 290 °C.

[0013] One embodiment provides an electronic device comprising: - a support and interconnection substrate; - at least one contact resumption element located on one face of the support and interconnection substrate; - at least one electronic component as described; and - at least one second conductive region interposed between said at least one contact resumption element and said at least one first conductive region of the electronic component.

[0014] According to one embodiment, the second conductive region covers a side of the electronic component.

[0015] According to one embodiment, the second conducting region is made of a tin, silver and copper alloy.

[0016] One embodiment provides for a motor vehicle comprising at least one device as described.

[0017] One embodiment provides a method for manufacturing an electronic component comprising an integrated circuit chip and a package surrounding the integrated circuit chip, the method comprising the step of coating at least partially one face of the integrated circuit chip with a first conductive region comprising an alloy consisting mainly of bismuth. Brief description of the drawings

[0018] These features and advantages, as well as others, will be described in detail in the following description of particular embodiments, given by way of non-limiting example, in relation to the accompanying figures, among which:

[0019] Figures [Fig. 1A], [Fig. 1B], [Fig. 1C], [Fig. 1D] and [Fig. 1E] are schematic and partial cross-sectional views illustrating successive stages of a manufacturing process for an electronic component according to one embodiment; and

[0020] [Fig.2] is a schematic and partial cross-sectional view of an electronic device comprising an electronic component according to an embodiment. Description of the implementation methods

[0021] The same elements have been designated by the same reference numerals in the different figures. In particular, structural and / or functional elements common to the different embodiments may have the same reference numerals and may have identical structural, dimensional and material properties.

[0022] For the sake of clarity, only the steps and elements necessary for understanding the described embodiments have been shown and are detailed. In particular, applications and systems in which electronic components may be used are not detailed, as the described embodiments and variants are compatible with common applications and systems comprising one or more electronic components, possibly subject to adaptations within the grasp of a person skilled in the art upon reading this description.

[0023] Unless otherwise specified, when referring to two elements connected together, this means directly connected without intermediate elements other than conductors, and when referring to two elements coupled together, this means that these two elements can be connected or linked through one or more other elements.

[0024] In the following description, when referring to absolute positional qualifiers, such as the terms "front", "back", "top", "bottom", "left", "right", etc., or relative positional qualifiers, such as the terms "above", "below", "superior", "lower", etc., or to orientational qualifiers, such as the term "horizontal", "Vertical", etc., refers, unless otherwise specified, to the orientation of the figures.

[0025] Unless otherwise specified, the expressions "approximately", "roughly", "about", and "in the order of" mean within 10%, preferably within 5%.

[0026] In the following description, the terms "insulating" and "conducting" mean, unless otherwise specified, electrically insulating and electrically conductive respectively.

[0027] Figs.1A, 1B, 1C, 1D and 1E are schematic and partial cross-sectional views illustrating successive stages of a manufacturing process for an electronic component 100 according to an embodiment.

[0028] Fig. 1A illustrates more precisely a structure obtained at the end of a step in which a mask 101 is placed on and in contact with a face 103T of a substrate 103 (the upper face of the substrate 103, in the orientation of Fig. 1A)).

[0029] In the illustrated example, the mask 101 forms a discontinuous layer extending laterally on and in contact with the face 103T of the substrate 103. In this example, the mask 101 comprises disjointed portions laterally defining openings. The mask 101 is, for example, a screen-printing mask. As an example, the mask 101 is made of an insulating material, for example, a resin.

[0030] The substrate 103 is, for example, a wafer or a piece of wafer made of a semiconductor material, for example silicon or germanium nitride (GaN). Although not detailed in [Fig. 1A], the substrate 103 comprises, for example, at least one unit electronic component, for example, at least one unit power electronic component. Each unit electronic component comprises, for example, at least one element selected from a diode, a thyristor, a triac, a transistor, a resistive, capacitive, or inductive load, etc.

[0031] In the example shown, contact elements 105 are located on and in contact with parts of the face 103T of the substrate 103 not coated with the mask 101. The contact elements 105 are for example connected to conduction and / or control electrodes of the unitary electronic component(s) formed in the substrate 103. By way of example, the contact elements 105 are conductive pads, for example pads made of a metal, for example copper, or of a metal alloy. The mask 101 is, for example, aligned with the position of the contact elements 105 on the face 103T of the substrate 103. In the example illustrated in [Fig.1A], two contact elements 105 are located in each opening of the mask 101. This example is not limiting, however; the number of contact elements 105 located in each opening of the mask 101 may, as an alternative, be different from two.

[0032] Figure [1B] illustrates more precisely a structure obtained from the structure of the [Fig.1A], at the end of a step in which conductive regions 107 are formed in the openings of the mask 101.

[0033] In the example shown, the conductive regions 107 fill the openings in the mask 101, that is, they completely fill all the free spaces extending laterally between the parts of the mask 101. In this example, the conductive regions 107 are bordered by the mask 101, the sides of each conductive region 107 being covered by parts of the mask 101. In the example shown, the conductive regions 107 cover the contact elements 105 and parts of the face 103T of the substrate 103 not covered by the mask 101 or the contact elements 105. In the illustrated example, each conductive region 107 covers two contact elements 105. In the example shown, the conductive regions 107 are flush with the face of the mask 101 opposite the substrate 103 (the upper face of the mask 101, in the orientation of [Fig.1B]).

[0034] The conductive regions 107 are, for example, made of a brazing material, for example a brazing paste. At this stage of the process, the material of the conductive regions 107 comprises, for example, a metal alloy, for example in the form of metal alloy beads or microbeads dispersed in a viscous or pasty material.

[0035] According to one embodiment, the metallic alloy contained in the conductive regions 107 comprises predominantly bismuth (Bi). More specifically, the alloy has, for example, a bismuth content greater than 80%, for example, approximately 90%. The alloy also comprises, for example, at least one alloying element selected from silver (Ag), nickel (Ni), and tin (Sn). In this case, the alloy has, for example, a content of each alloying element less than 10%, for example, approximately 5%. By way of example, the metallic alloy of the conductive regions 107 has a bismuth content of approximately 90%, a silver content of approximately 5%, and a nickel content of approximately 5%. The alloy has, for example, a melting point between 270 and 290 °C.

[0036] [Fig.1C] illustrates more precisely a structure obtained, from the structure of [Fig.1B], at the end of a step in which the mask 101 is eliminated, the conductive regions 107 are subjected to remelting and trenches 109 are formed in the conductive regions 107 and the substrate 103.

[0037] In the example illustrated in [Fig.1C], mask 101 is completely removed.

[0038] In the example shown, the conductive regions 107 have been subjected to a remelting phenomenon, for example by implementing a heating operation aimed at exposing the structure to a temperature above the melting point of the metallic alloy contained in the conductive regions 107. In the case where the alloy is in the form of beads or microbeads dispersed in a flow, This operation leads to the melting of the beads or microbeads and the elimination of the flux. Following this operation, each conductive region 107 is essentially composed of the metallic alloy. In the example shown, the conductive regions 107 exhibit curved or rounded flanks after remelting. For example, the flanks of the conductive regions 107 exhibit a curvature that depends on the surface tension of the metallic alloy in the liquid state.

[0039] In the illustrated example, the trenches 109 are substantially aligned with respect to the center of the regions 107. In the orientation of [Fig.1C], each trench 109 extends vertically from the upper face of one of the conductive regions 107, through the region 107 and penetrates into the thickness of the substrate 103. In the example shown, the trenches 109 do not open out on the side of a face 103B of the substrate 103 (the lower face of the substrate 103, in the orientation of [Fig.1C]) opposite the face 103T. Each trench 109 is for example laterally interposed between two contact elements 105 initially coated by the same region 107. As an example, the trenches 109 are formed by cutting, for example by sawing, on the side of the face 103T of the substrate 103.

[0040] In the example shown, the unitary electronic component(s) formed in the substrate 103 and intended to be part of the same electronic component 100 are laterally delimited by the trenches 109. The trenches 109 have, for example, in top view, a grid pattern in which each square corresponds to a future electronic component 100. In the illustrated example, each contact element 105 is coated with a portion of one of the conductive regions 107 separate from the portions of the conductive regions 107 coating the other contact elements 105. In the example shown in [Fig. 1C], each future electronic component 100 comprises two contact elements 105 coated respectively with two portions of separate conductive regions 107.

[0041] [Fig.1D] illustrates more precisely a structure obtained, from the structure of [Fig.1C], at the end of a step in which an insulating layer 111 is deposited on the side of the face 103T of the substrate 103 and in which the structure is thinned on the side of the faces 103T and 103B of the substrate 103.

[0042] In the example shown, the insulating layer 111 fills, that is to say completely fills, the trenches 109 and all the free spaces extending laterally between the regions 107. By way of example, the insulating layer 111 is made of a resin, for example a molding resin intended to form a housing around each future electronic component 100.

[0043] In the illustrated example, the structure is thinned, for example by grinding, on the side of face 103T of the substrate 103 so as to reduce the thickness of the regions 107 and the insulating layer 111. In the example shown, the insulating layer 111 is flush with the face regions 107 opposite substrate 103 (the upper face of regions 107, in the orientation of [Fig.1D]).

[0044] Furthermore, the structure is thinned, for example by grinding, on the side of face 103B of the substrate 103, so as to expose parts of the insulating layer 111 filling the bottom of the trenches 109. The parts of the insulating layer 111 located inside the trenches 109 thus become flush with face 103B of the substrate 103. By way of example, the structure is temporarily transferred to a support substrate, or handle, on the side of face 103T of the substrate 103 prior to thinning the structure on the side of face 103B, the support substrate then being removed after the thinning.

[0045] [Fig. 1E] illustrates more precisely a structure obtained, from the structure of [Fig.1D], at the end of a step in which another insulating layer 113 is deposited on the side of the face 103B of the substrate 103 and in which the substrate 103 is cut through its entire thickness to separate, or individualize, the electronic components 100.

[0046] In the example shown, the insulating layer 113 is located on and in contact with the face 103B of the substrate 103 and with the parts of the insulating layer 111 that are flush with the face 103B of the substrate 103. The layer 113 is, for example, made of a resin, for example a molding resin intended to be part of the housings of the electronic components 100. By way of example, the insulating layers 111 and 113 are made of the same material.

[0047] In the example shown, the structure comprises trenches 115 extending vertically through the thickness of the conductive regions 107 from the face of the conductive regions 107 opposite the substrate 103 (the upper face of the conductive regions 107, in the orientation of [Fig. 1E]). In this example, the trenches 115 have a height, or depth, less than the height, or thickness, of the conductive regions 107. In top view, the trenches 115 and 117 surround each electronic component 100.

[0048] In the illustrated example, the structure further comprises trenches 117 having a width less than that of the trenches 115. In the example shown, each trench 117 extends vertically from the bottom of one of the trenches 115 through the conductive region 107, the substrate 103 and the insulating layer 113. The trenches 117 thus have an end opening onto the side of the face 103B of the substrate 103. In the illustrated example, the trenches 117 have a width strictly less than that of the parts of the insulating layer 111 located inside the trenches 109.

[0049] Trenches 115 are for example made before trenches 117. As an example, trenches 115 and 117 are formed by sawing.

[0050] In the example shown, the trenches 117 delimit parts of the substrate 103, each of which, for example, forms part of an integrated circuit chip 119, or electronic chip. electronics, from one of the 100 electronic components.

[0051] The [Fig.2] is a schematic and partial cross-sectional view of an electronic device 200 comprising an electronic component 100 according to one embodiment.

[0052] In the example shown, the electronic device 200 comprises a support and interconnection substrate 203, for example, a printed circuit board. In the illustrated example, contact elements 205 are located on and in contact with one face of the support and interconnection substrate 203 (the upper face of the support and interconnection substrate 203, in the orientation of [Fig. 2]). The contact elements 205 are, for example, connected to conductive tracks formed on the substrate 203 and / or to conductive vias formed within the thickness of the substrate 203. By way of example, the contact elements 205 are conductive pads, for example, pads made of a metal, for example, copper, or of a metal alloy.

[0053] In the illustrated example, the electronic component 100 is fixed to the support and interconnection substrate 203 by conductive regions 207 interposed between the component 100 and the substrate 203. In this example, each conductive region 207 is more precisely interposed between one of the conductive regions 107 of the electronic component 100 and one of the contact elements 205 of the support and interconnection substrate 203. Each contact element 205 of the support and interconnection substrate 203 is thus connected to one of the contact elements 105 of the electronic component 100 via one of the conductive regions 207 and one of the conductive regions 107.

[0054] The conductive regions 207 are for example made of a metallic alloy, for example a metallic alloy having a melting point strictly lower than that of the metallic alloy of the conductive regions 107. By way of example, the conductive regions 207 are made of a lead-free alloy, for example a tin, silver and copper alloy (Sn-Ag-Cu alloy) also known by the acronym SAC.

[0055] In the example shown, the conductive regions 207 cover a face of the conductive regions 107 located on the side of the support and interconnection substrate 203 (the lower face of the conductive regions 107, in the orientation of [Fig. 2]). Furthermore, in this example, the conductive regions 207 cover a portion of the flank of the conductive regions 107, i.e., they wet the flanks of the conductive regions 107.

[0056] Figure 2 illustrates an example in which the electronic device 200 comprises a single electronic component 100. This example is not, however, limiting; the electronic device 200 may, alternatively, comprise any number of electronic components of the type of component 100. By way of example, the electronic device 200 is integrated into a motor vehicle, the electronic component 100, for example, implementing a protection function against electrostatic discharges to which the electronic device 200 may be exposed.

[0057] One advantage of the electronic component 100 lies in the fact that the presence of the high-bismuth conductive regions 107 allows for wettable edges. This facilitates the implementation of solder joint inspection operations of the component 100 on the support and interconnection substrate 203. Another advantage of using high-bismuth conductive regions 107 is that it prevents unintentional bridging, or interconnection, between adjacent integrated circuit chips during the reflow soldering step of the conductive regions 107 material prior to the cutting step aimed at individualizing the integrated circuit chips.This stems in particular from the fact that the high-bismuth metal alloy, in its liquid state, exhibits a surface tension higher than that of known alloys, notably the SAC alloy.

[0058] Furthermore, the high-bismuth alloy has the advantage of being usable as a replacement for expensive alloys, for example, the gold-tin alloy, for making solder joints in a material having a melting point strictly higher than that of the SAC alloy. In this case, the high-bismuth alloy, for example, covers at least part of the underside of an integrated circuit chip superimposed on another integrated circuit chip, for example, a chip of the type of chip 119 previously described in connection with [Fig. 1E].

[0059] Various embodiments and variations have been described. A person skilled in the art will understand that certain features of these various embodiments and variations could be combined, and other variations will become apparent to a person skilled in the art.

[0060] Finally, the practical implementation of the described embodiments and variants is within the reach of a person skilled in the art, based on the functional indications given above. In particular, the bismuth content in the metallic alloy of the conductive regions 107 can be adjusted according to the application, for example, in order to obtain a compromise between an increase in the surface tension of the alloy in the liquid state, obtained by increasing the bismuth content in the alloy, and an increase in the wettability of the flanks of the electronic components 100, obtained by decreasing the bismuth content in the alloy.

Claims

Claims

1. Electronic component (100) comprising: - an integrated circuit chip (119); - a housing (111, 113) surrounding the integrated circuit chip; and - at least a first conductive region (107) at least partially coating one face of the integrated circuit chip, the first conductive region comprising an alloy comprising mainly bismuth.

2. Component (100) according to claim 1, wherein the alloy has a bismuth content greater than 80%, preferably equal to about 90%.

3. A component (100) according to claim 1 or 2, wherein the alloy further comprises at least one addition element selected from silver, nickel and tin.

4. Component (100) according to claim 3, in which the alloy has a content of said at least one addition element of less than 10%, preferably equal to approximately 5%.

5. Component (100) according to any one of claims 1 to 4, wherein the alloy has: - a bismuth content equal to approximately 90%; - a silver content equal to approximately 5%; and - a nickel content equal to approximately 5%.

6. A component (100) according to any one of claims 1 to 5, wherein the alloy has a melting point of between 270 and 290°C.

7. Electronic device (200) comprising: - a support and interconnection substrate (203); - at least one contact recovery element (205) located on one face of the support and interconnection substrate; - at least one electronic component (100) according to any one of claims 1 to 6; and - at least one second conductive region (207) interposed between said at least one contact recovery element and said at least one first conductive region (107) of the electronic component.

8. Device (200) according to claim 7, wherein the second conductive region (207) covers a side of the electronic component (100).

9. A device (200) according to claim 7 or 8, wherein the second conductive region (207) is made of an alloy of tin, silver and copper.

10. Motor vehicle comprising at least one device (200) according to claim 7, 8 or 9.

11. A method of manufacturing an electronic component (100) comprising an integrated circuit chip (119) and a package (111, 113) surrounding the integrated circuit chip, the method comprising the step of at least partially coating one face of the integrated circuit chip with a first conductive region (107) comprising an alloy comprising predominantly bismuth.

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