Manufacturing process for a high-frequency compatible electronic module

Abstract

The invention relates to the manufacture of 3D electronic modules compatible with components operating above 1 GHz. The invention concerns a 3D electronic module having an interconnection between a horizontal conductor (31, 32; 33, 34) and a vertical conductor (30) to which it is connected, exhibiting a non-zero curvature in a vertical plane. It also relates to the associated manufacturing process. Figure 7 (for the abstract)

Description

Title of the invention: Method for manufacturing a high-frequency compatible electronic module

[0001] The present invention relates to the field of manufacturing 3D electronic modules compatible with components operating above 1 GHz. The invention relates to a 3D electronic module. It also relates to its manufacturing process.

[0002] In a 3D electronic module, there are several stacked levels of components. A printed circuit board (PCB) or a 3D module has several horizontal levels containing components and electrical conductors.

[0003] 3D interconnections can be classified into three groups: a. The stacking of bare chips or packages with an interconnection by means of a metal bus; b. The stacking of bare chips interconnected by holes passing through the silicon, also called TSV for the abbreviation of Thru Silicon Via; c. The stacking of bare chips interconnected by wiring wires, level upon level.

[0004] For the first group, in order to interconnect chips stacked one on top of the other, the vertical faces of the stack, which are metallized, are used to make the electrical connections between chips. As a result, the current technology is based on a so-called "T" interconnection. Each stacked layer contains conductors etched into a PCB that are connected vertically by a metal bus. In other words, the interconnections between the 2D layer (plane of a layer) and the 3D layer (stack of the different layers) are made perpendicularly, that is, at 90°.

[0005] For the second group, these electronic modules are generally equipped with vertically drilled holes, that is, holes drilled along the thickness of the module. Plated through holes, often referred to as vias, pass through these layers and thus allow these conductors to be connected vertically to each other by contact between the plated through holes and the sections of these conductors that are flush with the holes. Hereafter, a hole will be referred to as either a blind hole (non-through hole) or a through hole. Of course, an electronic module can have both blind and through holes. Here again, the conductors located on the different stacked layers intersect the holes orthogonally.

[0006] For the third group, the overlapping wiring harnesses lead to significant impedance variations and inductive interference. They cannot be used above 1 GHz.

[0007] For the first and second groups, it is therefore retained that the 3D interconnection is orthogonal, although TSVs are much smaller in size than metal bus interconnection.

[0008] For components operating above 1 GHz, orthogonal interconnection, or "T" interconnection, leads to reflections that are detrimental to signal integrity. In the microwave range of a 3D electronic module, since the connections are vertical on the stack faces, the "T" connections between electrical conductors (e.g., conductors from the chips and vertical conductors) are arranged at right angles. Electron reflection occurs at the connection, which disrupts and weakens the electrical connection.

[0009] Consequently, there remains to this day a need for a method of interconnecting stacked chips to ensure the integrity of signals at microwave frequencies.

[0010] The invention aims to overcome all or part of the problems mentioned above by proposing an interconnection through which the signal arriving via a conductor of the PCB, from a deposited redistribution layer called RDL or a via follows a curved path to reach the metal bus.

[0011] To this end, the invention relates to a 3D electronic module comprising, in a so-called vertical direction, a stack of at least two electronic housings, the module being capable of being assembled into an interconnection circuit, each of the at least two electronic housings comprising: a. components having interconnecting pads oriented towards a superior surface of the components, said components being at least partially surrounded by epoxy resin, the interconnecting pads of each component being connected by redistribution layers to vertical conductors themselves intended to be electrically connected to the interconnection circuit of the module, and b. horizontal conductors, a horizontal conductor and the vertical conductor to which it is connected forming an electrical conductor between an interconnection pad of a component and the interconnection circuit, the 3D electronic module being characterized in that the interconnection between a horizontal conductor and the vertical conductor to which it is connected presents in a vertical plane a non-zero curvature.

[0012] In one embodiment of the 3D electronic module according to the invention, the vertical conductors are buses.

[0013] In another embodiment of the 3D electronic module according to the invention, the vertical conductors are vias.

[0014] Advantageously, the curvature of the interconnection between the horizontal conductor and the vertical conductor to which it is connected forms a tangent with the vertical conductor.

[0015] The invention also relates to a method for manufacturing a 3D electronic module suitable for assembly into an interconnection circuit, characterized in that it comprises the following steps: a. Transfer of components equipped with interconnecting pads onto a first surface of an adhesive skin, a lower surface of the components being in contact with the adhesive skin and the interconnecting pads being oriented towards a higher surface of the components; b. Deposition of a first epoxy resin in the space between the components and polymerization of the resin to obtain a panel; c. Creation of a groove of a first depth in the space filled with the first epoxy resin, said groove being flared towards the upper surface of the panel and having a laterally curved shape; d. Metallization of the grooved panel; e. Laser engraving of the grooved metallized panel so as to insulate horizontal conductors; f. Deposition of a second epoxy resin in the space formed by the groove; g. Creation of one or more photogravure redistribution layers on the upper surface of the panel; h. Removal of the sticky skin to obtain a plate; i. Deposition of a third epoxy resin on the upper surface of the plate; j. Stacking a second plate on top of the plate covered by the third epoxy resin; k. Creating a through groove in the space filled with the second epoxy resin; 1. Metallization of the through groove to obtain a vertical conductor.

[0016] According to one embodiment of the method according to the invention, the first depth is less than the thickness of the space filled with the first epoxy resin.

[0017] According to another embodiment of the process according to the invention, the first depth is equal to the thickness of the space filled with the first epoxy resin.

[0018] The invention will be better understood and other advantages will become apparent upon reading the detailed description of an embodiment given by way of example, a description illustrated by the accompanying drawing in which:

[0019] [fig. 1] [fig. 1] schematically illustrates the steps in the manufacturing process of the 3D electronic module according to the invention;

[0020] [fig.2]

[0021] [fig.3]

[0022] [fig.4]

[0023] [fig.5]

[0024] [fig.6]

[0025] [fig.7] Figures 2 to 7 schematically represent the sequence of steps of the manufacturing process of the 3D electronic module according to the invention;

[0026] [fig.7] Figure [fig.7] schematically represents a cross-sectional view of an electrical module 3D technology according to the invention;

[0027] [fig.8] the [fig.8] represents an embodiment in which the principle of the invention is applied to a via;

[0028] [fig.9] Fig.9 schematically represents a variant of the manufacturing process of the 3D electronic module according to the invention.

[0029] From one figure to another, the same elements are identified by the same references.

[0030] In the remainder of the description, the expressions "up", "down", are used in reference to the orientation of the figures described. Since the 3D electronic module can be positioned in other orientations, the directional terminology is given for illustrative purposes only and is not exhaustive.

[0031] Figure 1 schematically illustrates the steps in the manufacturing process of the 3D electronic module according to the invention. The manufacturing process of a 3D electronic module according to the invention comprises steps 100 to 112 carried out successively as explained in detail below.

[0032] Figures 2 to 7 schematically represent the sequence of steps in the manufacturing process of the 3D electronic module according to the invention.

[0033] As shown in [fig.2], the manufacturing process of a 3D electronic module includes a step 100 of transferring components 15, 16 equipped with interconnecting pads 19, 20 onto a first surface 50 of an adhesive skin 51. During this transfer, a lower surface 52 of the components 15, 16 is in contact with the adhesive skin 51 and the interconnecting pads 19, 20 are oriented towards an upper surface 23, 24 of the components 15, 16.

[0034] The manufacturing process according to the invention then includes a step 101 of depositing a first epoxy resin 25 in the space 53 between the components 15, 16 and a step 102 of polymerizing the resin 25 to obtain a panel 200.

[0035] The manufacturing process according to the invention comprises a step 103 of forming a groove 54 of a first depth 55 in the space 53 filled with the first epoxy resin 25. More particularly, the groove 54 is flared towards the upper surface of the panel 200 and has a lateral curvature. This groove 54 can be formed using a shaped saw having a form complementary to the groove 54 shown in [Fig. 3]. The groove 54 can also be formed using any other tool that removes a portion of the resin 25 so that the resulting groove has lateral walls with a curvature. Advantageously, the curvature is located in the area near the upper surfaces 23, 24. This area will be, once the manufacturing process is completed, the interconnection zone between a The horizontal conductor and its vertical conductor, to which the horizontal conductor is connected, result in a non-zero curvature in the vertical plane between the horizontal and vertical conductors. The advantage of this non-orthogonal interconnection in the microwave range of a 3D electronic module with vertical connections on the stack faces is that it prevents electron reflection at the connection point, which would disrupt and weaken the electrical connection. Thanks to the invention, the signal arriving via the horizontal conductor follows a curved path to reach the vertical conductor, as explained below.

[0036] Figure 4 shows step 104 of metallizing the grooved panel 200 obtained in step 103. The process then includes a step 105 of laser etching the metallized grooved panel 200 so as to isolate horizontal conductors 33, 34. This also applies to horizontal conductors 31, 32 (not shown in Figure 4 but visible in Figure 7). This step 105 is shown in Figure 5 by a top view of the horizontal conductors isolated from each other after the etching step 105.

[0037] Fig. 4 also represents step 106 of depositing a second epoxy resin 45 in the space formed by the groove 54.

[0038] Figure 6 illustrates step 107 of producing one or more photogravure redistribution layers 28, 29 on the upper surface of the panel. This step makes it possible to create one or more horizontal interconnection levels.

[0039] Figure 7 illustrates the final stages of the manufacturing process of the invention. The process comprises a step 108 of removing the sticky skin 51 to obtain a plate 210, followed by a step 109 of depositing a third epoxy resin 35 onto the upper surface of the plate 210. Then comes a step 110 of stacking a second plate 211 on top of the plate 210, the plate 210 being coated with the third epoxy resin 35 to allow the plate 211 to bond to the plate 210.

[0040] Finally, the manufacturing process of the 3D electronic module 10 includes a step 111 of making a through groove 56 in the space filled with the second epoxy resin 45 and a step 119 of metallizing the through groove 56 to obtain a vertical conductor 30.

[0041] In variations of the manufacturing process according to the invention, during the step of forming the groove 54, the first depth 55 may be less than the thickness of the space 53 filled with the first epoxy resin 25. In this case, a so-called blind hole is obtained. Alternatively, the first depth 55 may be equal to the thickness of the space 53 filled with the first epoxy resin 25. This is then referred to as a through hole. Forming such a hole, blind or through, makes it possible to obtain an inter-level interconnection in the case of component stacking. By applying the principle of In this invention, the interconnection is also curved. On each of the levels before stacking, a suitable bore or hole is made with a shaped tool, allowing the desired curved shape to be obtained.

[0042] Figure 7 thus shows a cross-sectional view of a 3D electronic module 10 according to the invention. The 3D electronic module 10 comprises, along a so-called vertical direction Z, a stack of at least two electronic housings 11, 12. The module is suitable for assembly with an interconnection circuit (not shown). Each of the at least two electronic housings 11, 12 comprises: a. components 13, 14, 15, 16 provided with interconnecting pads 17, 18, 19, 20 oriented towards an upper surface 21, 22, 23, 24 of components 13, 14, 15, 16, said components 13, 14, 15, 16 being at least partially surrounded by epoxy resin 25, 35, 45, the interconnecting pads 17, 18, 19, 20 of each component 13, 14, 15, 16 being connected by redistribution layers 26, 27, 28, 29 to vertical conductors 30 themselves intended to be electrically connected to the interconnection circuit of the module, and b. horizontal conductors 31, 32, 33, 34, a horizontal conductor 31, 32, 33, 34 and the vertical conductor 30 to which it is connected forming an electrical conductor between an interconnection pad 17, 18, 19, 20 of a component 13, 14, 15, 16 and the interconnection circuit.

[0043] According to the invention, the interconnection between a horizontal conductor 31, 32, 33, 34 and the vertical conductor 30 to which it is connected exhibits a non-zero curvature in a vertical plane. The curved interconnection between the horizontal conductors and the metal bus 30 allows the signal arriving via the horizontal conductor to follow a curved path to reach the vertical conductor. As can be seen in [Fig. 7], the curvature of the interconnection between the horizontal conductor 31, 32, 33, 34 and the vertical conductor 30 to which it is connected forms a tangent with the vertical conductor 30. It follows that the invention ensures the interconnection of stacked chips while maintaining the integrity of microwave signals.

[0044] Generally presented as vertical conductors, the vertical conductors 30 can be buses or vias. The invention therefore corresponds to an interconnection between vertical and horizontal conductors with a curve.

[0045] Fig. 8 represents an embodiment in which the principle of the invention is applied to a via 36, ​​46. A via is a through hole, so the invention applies similarly to a vertical conductor or to a via.

[0046] At the top of [Fig. 8], the via 36 has a diameter of less than 200 micrometers. The reference 31 of the via 36 corresponds to copper, both as a horizontal conductor and also to fill the small-diameter via. The photo-etched layer 29 makes contact with the via in the conventional manner.

[0047] At the bottom of [Fig. 8], the via 46 has a diameter greater than 200 micrometers. The reference 31 of the via 36 corresponds to the copper, forming both the horizontal conductor and the vertical conductive part. The hole is filled with resin 45. The photo-etched layer 29 makes contact with the via in the conventional manner.

[0048] A printed circuit board consists of stacked layers. To obtain a via according to the invention, it is necessary to drill one side of the circuit with a shaped drill bit, as explained previously, and then the other side of the circuit with the shaped drill bit to form the through hole 36, 46. In [Fig. 8], the vias 36, 46 have undergone the metallization step and, where applicable, the deposition of the epoxy resin 45. Thus, the via exhibits a curvature in its interconnection with the horizontal conductors.

[0049] Figure 9 schematically represents a variant of the manufacturing process for the 3D electronic module according to the invention with printed circuit boards 151, 161 (PCBs). In this variant, each PCB 151, 161 is considered as a component and the same process as described above applies.

[0050] Finally, it can be noted that the principle of the invention, according to which the interconnection between horizontal and vertical conductors has a certain curvature, also applies to TSVs (Thru Silicon Vias). The method for obtaining such a TSV with a non-orthogonal interconnection is carried out in a similar manner to that of a via as described above with vias 36, 46.

Claims

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5. Demands 3D electronic module (10) comprising, in a so-called vertical direction (Z), a stack of at least two electronic housings (11, 12), the module being capable of being assembled into an interconnection circuit, each of the at least two electronic housings (11, 12) comprising: a. components (13, 14; 15, 16) provided with interconnecting pads (17, 18; 19, 20) oriented towards an upper surface (21, 22; 23, 24) of the components (13, 14; 15, 16), said components (13, 14; 15, 16) being at least partially surrounded by epoxy resin (25, 35, 45), the interconnecting pads (17, 18; 19, 20) of each component (13, 14; 15, 16) being connected by redistribution layers (26, 27; 28, 29) to vertical conductors (30) themselves intended to be electrically connected to the interconnection circuit of the module, and b. horizontal conductors (31, 32; 33, 34), a horizontal conductor (31, 32, 33, 34) and the vertical conductor (30) to which it is connected forming an electrical conductor between an interconnection pad (17, 18; 19, 20) of a component (13, 14; 15, 16) and the interconnection circuit, the 3D electronic module (10) being characterized in that the interconnection between a horizontal conductor (31, 32; 33, 34) and the vertical conductor (30) to which it is connected has a non-zero curvature in a vertical plane and in that the curvature of the interconnection is covered with epoxy resin. 3D electronic module (10) according to claim 1, wherein the vertical conductors (30) are buses. 3D electronic module (10) according to claim 1, wherein the vertical conductors (30) are vias (36, 46). 3D electronic module (10) according to claim 1, wherein the curvature of the interconnection between the horizontal conductor (31, 32; 33, 34) and the vertical conductor (30) to which it is connected forms a tangent with the vertical conductor (30) A method for manufacturing a 3D electronic module (10) suitable for assembly into an interconnect circuit, characterized in that it comprises the following steps: a. Transfer (step 100) of components (15, 16) equipped with interconnecting pads (17, 18; 19, 20) onto a first surface (50) of a sticky skin (51), a lower surface (52) of the components (15, 16) being in contact with the sticky skin (51) and the interconnecting pads (19, 20) being oriented towards a higher surface (23, 24) of the components (15, 16); b. Deposition (step 101) of a first epoxy resin (25) in the space (53) between the components (15, 16) and polymerization (step 102) of the resin (25) to obtain a panel (200); c. Making (step 103) a groove (54) of a first depth (55) in the space (53) filled with the first epoxy resin (25), said groove (54) being flared towards the upper surface of the panel (200) and having a laterally curvature; d. Metallization (step 104) of the grooved (200) panel; e. Laser engraving (step 105) of the grooved metallized panel (200) so as to isolate horizontal conductors (31, 32; 33, 34); f. Deposition (step 106) of a second epoxy resin (45) in the space formed by the groove (54); g. Production (step 107) of one or more photogravure redistribution layers (28, 29) on the upper surface of the panel; h. Removal (step 108) of the sticky skin (51) to obtain a plate (210); i. Deposition (step 109) of a third epoxy resin (35) on the upper surface of the plate (210); j. Stacking (step 110) of a second plate (211) on the plate (210) covered with the third epoxy resin (35); k. Making (step 111) a through groove (56) in the space filled with the second epoxy resin (45); 1. Metallization (step 112) of the through groove (56) to obtain a vertical conductor (30).

6. A method for manufacturing an electronic module according to claim 5, wherein the first depth (55) is less than the thickness of the space (53) filled with the first epoxy resin (25).

7. Method of manufacturing an electronic module according to claim 5, wherein the first depth (55) is equal to the thickness of the space (53) filled with the first epoxy resin (25).

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