Multilayer printed circuit board

Abstract

To provide a multilayer printed circuit board.SOLUTION: An embodiment of the present invention is a multilayer printed circuit board (10) that is intended to connect an electron component (304). The multilayer printed circuit board (10) comprises: a lamination body of a plurality of conductive layers (100). Each conductive layer (100) contains: two front surface layers (101); and one or a plurality of internal layers (102). A substrate (10) contains one or a plurality of end counterbore holes (202). Each of the end counterbore holes (202) contains: metalized part (2021) that is opened to one of the two front surface layers (101); and non-metalized part (2022) that is opened to the other front surface layer (101). Favorably, the multilayer printed circuit board (10) may include one or a plurality of metal pads (301), and each metal pad (301) is bound to one of the two front surface layers (101) so as to hide the non-metalized part (2022) of the corresponding end counterbore hole (202).SELECTED DRAWING: Figure 2

Description

Technical Field

[0001] The present invention generally relates to printed circuit boards for electronic systems, and more particularly to multilayer printed circuit boards and processes for manufacturing multilayer printed circuit boards.

Background Art

[0002] Electronic systems have conventionally implemented complex processing operations that affect the volume and power consumption of the system. For example, the operation of a radar-type electronic system generally is based on generated electromagnetic signals transmitted through space by a transmission module equipped with a dedicated antenna. The radar further includes a receiving module intended to detect electromagnetic signals reflected by a target and a processing module intended to determine information about the target, such as its position and the speed of its movement, based on the detected signals.

[0003] The radar can be fixed to the ground, mounted on a ground vehicle or ship or boat, or present in the air by an aircraft. In any case, the radar must meet many constraints, particularly related to volume. Specifically, for example, in the field of AESA radars (AESA represents an active electronically scanned array), the functions are being increasingly integrated within the antenna portion of the radar. Initially limited to microwave functions (signal transmission and reception and auxiliary functions), the antenna portion of the radar is now expected to host an increasing rate of digital processing operations applied to the signals. In addition, the radar must have the ability to implement more functions in order to adapt to targets that are becoming smaller and / or more mobile.

[0004] To satisfy volume constraints within a radar, it is known to use one or more single-layer printed circuit boards (SPCs), each containing multiple electronic components. The electronic components of a given SPC are electrically connected by electrical tracks and according to a given circuit diagram to perform electronic functions for various signals required by the radar's operation. Such electronic functions include, for example and without limitation, signal generation, filtering, modulation, and frequency transitions. Thus, the electrical signals carried by the electrical tracks of a SPC can have various forms (digital or analog), various frequencies (baseband and high-frequency signals), and / or various power levels. However, the dimensions of a SPC are strongly related to the number and length of electrical tracks connecting the various electronic components arranged on the SPC. As a result, SPCs are unsuitable for current radars that incorporate numerous electronic functions requiring a large number of electronic components.

[0005] To mitigate the limitations associated with the use of single-layer printed circuit boards in radar, it is known to use multilayer printed circuit boards, which consist of a laminate of multiple layers (two surface layers and one or more internal layers). In this case, electronic components can be connected to other electronic components by electrical tracks generated within one or more layers of the multilayer printed circuit board. To accomplish this, metallized holes are commonly used to ensure electrical connections between the various layers of the multilayer printed circuit board. For example, metallized through-holes can be used to electrically connect all layers of a multilayer printed circuit board. It is also known to use metallized bore holes to electrically connect one of two surface layers to one or more internal layers. Generally, bore holes are generated from metallized through-holes by removing unused or unhelpful metallization that causes certain phenomena resulting in useful signal reflection and / or distortion. However, in certain cases, bores can be a source of parasitic electromagnetic radiation that can locally degrade the operation of certain electronic components used in the multilayer printed circuit board.

[0006] Figure 1 shows one known solution for preventing parasitic electromagnetic radiation. Such a known solution involves the steps of filling each borehole with a non-conductive resin and then sealing the thus filled boreholes with metallization deposited using a process similar to that used to create metal interconnect tracks between surface mount electronic components. However, such known solutions are complex to implement and significantly reduce the yield of multilayer printed circuit boards. Specifically, the resin filler can easily penetrate into other types of metallized holes, such as metallized through-holes, thus requiring further steps to remove the resin from them. Furthermore, the creation of occluding metallization requires the deposition of an additional metal layer on the surface layer of the multilayer printed circuit board, in which case the final metallization thickness is consequently increased and reduces thinness and etching tolerances. [Overview of the project] [Problems that the invention aims to solve]

[0007] Therefore, there is a need for improved multilayer printed circuit boards. [Means for solving the problem]

[0008] For this purpose, the present invention provides a multilayer printed circuit board intended for connecting electronic components, comprising a laminate of a plurality of conductive layers, each conductive layer comprising two surface layers and one or more internal layers, wherein isolation between two adjacent conductive layers is ensured by an electrically insulating layer, and the printed circuit board comprises one or more boreholes, each borehole configured to electrically connect one of the two surface layers to one or more internal layers and comprising a portion having metallization that is open over one of the two surface layers and a portion not having metallization that is open over the other surface layer, wherein the portion having metallization and the portion not having metallization of the borehole extend in a direction perpendicular to the lamination plane. Advantageously, the multilayer printed circuit board further comprises one or more metal pads, each metal pad bonded to one of the two surface layers so as to conceal the corresponding portion not having metallization of the borehole, thereby providing a multilayer printed circuit board.

[0009] In one embodiment, parasitic electromagnetic radiation tends to form on the inside of the bore hole, and a metal pad may be selected to at least partially block the propagation of parasitic electromagnetic radiation from the bore hole.

[0010] In another embodiment, parasitic electromagnetic radiation tends to penetrate into the bore hole, and a metal pad may be selected to at least partially block the propagation of parasitic electromagnetic radiation into the bore hole.

[0011] Advantageously, the geometric properties of the metal pad can be selected in accordance with the properties of one or more parasitic electromagnetic radiations that tend to form within and / or penetrate the corresponding bore holes.

[0012] As one variation, the electrical properties of the metal pad may be selected according to the characteristics of one or more parasitic electromagnetic radiations that tend to form within and / or penetrate the corresponding bore hole.

[0013] In one embodiment, the metal pads may be identical.

[0014] In another embodiment, the metal pad may be a passive component that does not require a power source.

[0015] A process for manufacturing a multilayer printed circuit board and adding components to the multilayer printed circuit board is further provided, the process being intended for connecting electronic components. Advantageously, the process is - A step of producing a laminate of multiple conductive layers, wherein the conductive layers include two surface layers and one or more internal layers, and the isolation between two adjacent conductive layers is ensured by an insulating layer, - A step of creating an electrical connection between conductive layers by one or more metallized through-holes, - A step of converting at least one metallized through-hole into a bore hole, wherein the bore hole includes a metallized portion that is open onto one of two surface layers and a non-metallized portion that is open onto the other surface layer, and the metallized portion and the non-metallized portion of the bore hole extend in a direction perpendicular to the lamination plane, - Steps to generate an electric track and connection pad on at least one of two surface layers. Includes.

[0016] Advantageously, the process of manufacturing multilayer printed circuit boards and adding components is - A step of bonding one or more metal pads to one or both surface layers, wherein each metal pad is bonded in such a way that it conceals the portion of the corresponding bore hole that does not have metallization, - The step of connecting one or more electronic components to a connection pad belonging to one or both surface layers. It can further include:

[0017] Other features and advantages of the present invention will become apparent from the following description and the following figures. [Brief explanation of the drawing]

[0018] [Figure 1]Shows the end cut holes according to the prior art solution. [Figure 2] Shows a multilayer printed circuit board according to an embodiment of the present invention. [Figure 3] Shows the process of manufacturing a multilayer printed circuit board and adding components according to an embodiment of the present invention. [Figure 4A] Shows the steps performed to bond metal pads to the surface layer of a multilayer printed circuit board according to an embodiment of the present invention. [Figure 4B] Shows the steps performed to bond metal pads to the surface layer of a multilayer printed circuit board according to an embodiment of the present invention. [Figure 4C] Shows the steps performed to bond metal pads to the surface layer of a multilayer printed circuit board according to an embodiment of the present invention. [Figure 5A] Shows the steps used to generate end cut holes and through holes according to the prior art solution. [Figure 5B] Shows the steps used to generate end cut holes and through holes according to the prior art solution. [Figure 5C] Shows the steps used to generate end cut holes and through holes according to the prior art solution. [Figure 5D] Shows the steps used to generate end cut holes and through holes according to the prior art solution. [Figure 5E] Shows the steps used to generate end cut holes and through holes according to the prior art solution. [Figure 5F] Shows the steps used to generate end cut holes and through holes according to the prior art solution. [Figure 5G] Shows the steps used to generate end cut holes and through holes according to the prior art solution. [Figure 6A] Shows the steps used to generate end cut holes and through holes according to an embodiment of the present invention. [Figure 6B]The steps used to generate bored-out holes and through-holes according to embodiments of the present invention are shown. [Figure 6C] The steps used to generate bored-out holes and through-holes according to embodiments of the present invention are shown. [Figure 6D] The steps used to generate bored-out holes and through-holes according to embodiments of the present invention are shown. [Modes for carrying out the invention]

[0019] A multilayer printed circuit board 10 according to various embodiments of the present invention is intended to electrically connect electronic components 304 and to enable these electronic components to exchange electrical signals of various forms (digital or analog), various frequencies (baseband signals and high-frequency signals), and / or various power levels.

[0020] Figure 2 shows a multilayer printed circuit board 10 according to an embodiment of the present invention. The multilayer printed circuit board 10 comprises a laminate of a plurality of conductive layers 100, in which separation between two adjacent conductive layers 100 is ensured by an electrical insulating layer 120 based on one or more insulating materials. The conductive layers 100 comprise two surface layers 101 and one or more internal layers 102. Furthermore, each of the conductive layers 100 includes a set of electrical tracks 302 intended for connecting electronic components 304 added, i.e., soldered, to one or more conductive layers 100 of the multilayer printed circuit board 10. The multilayer printed circuit board 10 further includes one or more connection holes 200, also referred to as vias, which allow electrical connections to be made between the various conductive layers 100 of the multilayer printed circuit board 10. For example, the electrical track 302, in cooperation with the connection hole 200, enables electrical connections to be made between two electronic components 304 added to a given layer of the multilayer printed circuit board 10 or added to two different layers. Furthermore, the multilayer printed circuit board 10 includes at least one borehole 202. The borehole 202 enables one of two surface layers 101 to be connected to one or more internal layers 102, and for this purpose includes a metallized portion 2021 that passes perpendicularly through the conductive layer 100 to be connected and is open on, i.e., terminates thereon, on the surface layer 101 of interest. The borehole 202 further includes a non-metallized portion 2022 that passes through the other conductive layer 100 and is open on the other surface layer 101. From an industrial perspective, a borehole 202 can be obtained by first generating a metallized through-hole 201 whose internal surface is completely metallized, i.e., covered with metal, before one portion of the internal metallization is removed in a direction perpendicular to the lamination plane. In embodiments of the present invention, the multilayer printed circuit board 10 further includes one or more metal pads 301. Each metal pad 301 is added to one of two surface layers 101 to conceal the portion 2022 that does not have metallization of the corresponding borehole 202. Each metal pad 301 is an insulating metal pad having the ability to block parasitic electromagnetic radiation.

[0021] Each layer of the multilayer printed circuit board 10 further includes, for example, a connection pad 303 corresponding to the termination of an electrical track 302 of the conductive layer 100 in question. The connection pad 303 may be perforated for the purpose of creating an electrical connection between two or more conductive layers 100 by vias, or for making an electrical connection between electronic components 304. Alternatively, the connection pad 303 may not be perforated and may rather be intended for soldering surface-mount electronic components 304.

[0022] In embodiments of the present invention, parasitic electromagnetic radiation tends to form inside the borehole 202. Sources of such parasitic electromagnetic radiation may be, for example and without limitation, portions 2021 having metallization of the borehole 202, which can function as antennas emitting electromagnetic waves passing through them. In such embodiments of the present invention, the metal pads 301 concealing the borehole 202 are selected to at least partially block the propagation of such parasitic electromagnetic radiation from the corresponding borehole 202. Advantageously, each metal pad 301 utilized within the multilayer printed circuit board 10 is selected to completely block the propagation of parasitic electromagnetic radiation from the corresponding borehole 202.

[0023] In other embodiments of the present invention, parasitic electromagnetic radiation tends to form outside the bore hole 202. In such embodiments of the present invention, the metal pad 301 concealing the bore hole 202 is selected to at least partially prevent such parasitic electromagnetic radiation from penetrating into the corresponding bore hole 202.

[0024] Advantageously, the metal pads 301 that conceal the bore holes 202 of the multilayer printed circuit board 10 can be identical, that is, the metal pads 301 can have the same geometric properties and specifically the same thickness, in which case the thickness is measured perpendicular to the layering plane.

[0025] In embodiments of the present invention, the geometric properties of the metal pad 301 concealing the bore hole 202 can be selected according to one or more properties of the parasitic electromagnetic radiation that tends to form inside or outside the corresponding bore hole 202. For example, the thickness of the metal pad 301 may be several times, and usually a hundred times, greater than the skin depth associated with the parasitic electromagnetic radiation in question, in which case the skin depth depends on the frequency of the parasitic electromagnetic radiation in question.

[0026] In other embodiments of the present invention, the electrical properties of the metal pad 301 concealing the bore hole 202 may be selected in accordance with one or more properties of parasitic electromagnetic radiation that tends to form inside or outside the corresponding bore hole 202. Such electrical properties include, for example and without limitation, the conductivity of the metal pad 301.

[0027] Advantageously, the metal pad 301 that conceals the borehole 202 of the multilayer printed circuit board 10 is a passive component that does not require a power supply. Furthermore, the metal pad 301 added to one of the two surface layers 101 of the multilayer printed circuit board 10 can be electrically isolated from all other metal pads 301 added to the same surface layer 101.

[0028] In embodiments of the present invention, one or more metal pads 301 may be uniform in terms of chemical composition, i.e., they may be composed of a single chemical element, such as copper or aluminum. Alternatively, one or more metal pads 301 may be composed of an alloy of multiple chemical elements.

[0029] Figure 3 shows a process for manufacturing a multilayer printed circuit board 10 and adding components according to an embodiment of the present invention. The manufacturing process includes a first phase, which includes the step of manufacturing the multilayer printed circuit board 10, and a second phase, which includes the step of adding metal pads 301 and electronic components 304 to the multilayer printed circuit board 10 thus manufactured. The first phase includes steps 51 to 54, and the second phase includes steps 55 and 56, which will be described below. The manufacturing process according to various embodiments of the present invention is applicable to printed circuit boards having any number of conductive layers 100, which is usually four or more.

[0030] Step 51 generates a laminate of multiple conductive layers 100, in which case separation between two adjacent conductive layers 100 is ensured by an insulating layer 120 based on one or more insulating materials. The conductive layer 100 includes two surface layers 101 and one or more internal layers 102. Each conductive layer 100 and specifically each internal layer 102 may include a set of pre-generated electrical tracks 302 and a set of connection pads 303 according to a given circuit diagram. Step 51 may further include the steps of generating electrical connections between internal layers 102 by one or more embedded holes and generating electrical connections between the surface layers 101 and internal layers 102 by one or more blind holes. Generally, embedded holes or blind holes are obtained by generating metallized through-holes within the sub-laminated conductive layer 100. For example, a sub-laminated conductive layer 100 may include only the internal conductive layer 102 and its electrical insulating layer 120 of a multilayer printed circuit board 10.

[0031] In step 52, electrical connections between the conductive layers 100 are created by one or more metallized through-holes 201. The creation of the metallized through-holes 201 involves drilling holes through all of the mounted layers before depositing a layer of metal, such as copper, inside the holes. Specifically, the metallized through-holes 201 allow all of the mounted conductive layers 100 and specifically two surface layers 101 to be electrically connected.

[0032] In step 53, one or more metallized through-holes 201 are converted into one or more boreholes 202 by removing, i.e., eliminating the undesirable metallization in a direction perpendicular to the laminate plane. Thus, the boreholes 202 include a portion 2021 having metallization that passes perpendicularly through the connected conductive layer 100 and opens onto one of the two surface layers 101. The boreholes 202 further include a portion 2022 without metallization that passes through the other conductive layer 100 and opens onto the other surface layer 101. It should be noted that the boreholes 202 according to embodiments of the present invention are empty, i.e., they are not filled with any resin plugs as described with respect to prior art solutions.

[0033] In step 54, the electrical track 302 and the connection pad 303 are formed on one or both surface layers 101 of the multilayer printed circuit board 10.

[0034] In step 55, the metal pads 301 are bonded to, i.e., firmly fixed or added to, one or both surface layers 101 so as to conceal the portions 2022 of each bore hole 202 that do not have metallization. All of the metal pads 301 may be identical. Alternatively, at least two of the metal pads 301 may differ in terms of geometric properties and / or electrical properties.

[0035] In step 56, the electronic component 304 is coupled to a connection pad 303 formed on one or both of the surface layers 101. Those skilled in the art will understand that steps 55 and 56 may be performed in parallel or sequentially in time.

[0036] Figures 4A, 4B, and 4C illustrate the steps (step 55 described above) performed to bond the metal pad 301 to one of the two surface layers 101 of the multilayer printed circuit board 10. More precisely, Figure 4A shows a first step, which includes depositing solder paste onto the metal portion of the surface layer 101, intended to accommodate the metal pad 301, in this case the metal portion is, for example and without limitation, a connecting pad 303. Figure 4B shows a second step, which includes placing the metal pad 301 onto the pre-prepared metal portion of the surface layer 101. The second step can be performed manually or automatically using a surface mount component (SMC) placement machine. Figure 4C shows a third soldering step, which includes firmly fixing the metal pad 301 to the surface layer 101 of the multilayer printed circuit board 10. The soldering step can be performed using a reflow soldering technique. Furthermore, the deposition of solder paste (first step) and reflow (third step) can be performed simultaneously for the metal pad 301 and the electronic component 304.

[0037] Figures 5A, 5B, 5C, 5D, 5E, 5F, and 5G illustrate the generation of boreholes 202 and metallized through-holes 201 within a multilayer printed circuit board 10 by a prior art solution. The prior art solution includes the step of filling the boreholes 202 with a non-conductive resin before closing the boreholes 202 by metallization. Figures 6A, 6B, 6C, and 6D illustrate the steps required to generate boreholes 202 and metallized through-holes 201 according to embodiments of the present invention.

[0038] Figures 5A and 6A specifically correspond to drilling and metallization steps that enable the preparation of the bore hole 202 by generating a metallized through hole 201. More precisely, Figure 6A shows that the generation of the bore hole and the generation of the metallized through hole 201 can be initiated in the same manufacturing step having the generation of two metallized through holes 201, according to embodiments of the present invention. Furthermore, Figure 5A shows that prior art solutions do not provide such parallelism in the generation of the metallized through hole 201 and the bore hole 202.

[0039] Figures 5B and 6B correspond to a boring step that includes the step of generating a bored hole 202 from the metallized through-hole 201. This results in a step of removing a portion of the metallization of the metallized through-hole 201 in a direction perpendicular to the lamination plane.

[0040] Figure 5C corresponds to the filling step implemented in the prior art solution, in which the filling step includes completely filling the bore hole thus obtained with a non-conductive resin.

[0041] Figure 5D corresponds to the planarization step implemented in the prior art solution, in which case the planarization step includes the step of planarizing two surface layers 101 of the multilayer printed circuit board 10.

[0042] Figure 5E shows a deposition step implemented in the prior art solution, in which case the deposition step includes depositing a conductive layer 100 on two pre-planarized surface layers 101. Specifically, the deposition step allows the borehole 202 to be concealed in order to prevent parasitic electromagnetic radiation from propagating from and / or penetrating into the borehole 202. Figure 5E further shows another implementation of the drilling and metallization step (a similar step is described with reference to Figure 6A) for producing a metallized through-hole 201. According to the prior art solution, the metallized through-hole 201 can only be produced after the borehole 202 has been filled and sealed. This makes it possible to avoid filling the metallized through-hole 201 with a non-conductive resin.

[0043] Figure 5F shows an etching step implemented in a prior art solution, in which the etching step includes generating electrical tracks 302 and / or connecting pads 303 on one or both surface layers 101. Specifically, the etching step allows the metallization concealing each bore hole 202 to be electrically insulated.

[0044] Figure 5G shows the step of adding an electronic component 304 as implemented in the prior art solution, in which case the step of adding the electronic component 304 includes the step of bonding the electronic component 304 to one or both surface layers 101. More precisely, each electronic component 304 can be bonded to two or more dedicated connection pads 303.

[0045] Figure 6C corresponds to an etching step that includes generating electrical tracks 302 and / or connection pads 303 on one or both surface layers 101, in which case this etching step directly follows a previous manufacturing step according to an embodiment of the present invention.

[0046] Figure 6D corresponds to the step of adding an electrical component, which includes the step of bonding the electronic component 304 to one or both surface layers 101. The electronic component 304 bonded in this step includes a metal pad 301 intended to conceal the bore hole 202. Thus, the metal pad 301 can be bonded to the surface layer 101 in a manner similar to any other surface mount electronic component 304.

[0047] Accordingly, embodiments of the present invention enable the electrical isolation of the borehole 202 to be achieved with fewer manufacturing steps than prior art solutions, and thus ensure a relatively good manufacturing yield. Furthermore, embodiments of the present invention enable the electrical insulation of such borehole 202 without requiring the borehole 202 to be filled with a non-conductive resin. This enables, for example, weight reduction. Moreover, unlike prior art solutions that require the additional step of depositing a conductive layer 100 (Figure 5E) on one or more surface layers 101 to conceal the borehole 202, embodiments of the present invention enable the initial thickness of the conductive surface layer 100 to be maintained, which enables improvements in terms of etching accuracy and weight.

[0048] The present invention is not limited to the embodiments described above as non-limiting examples. Specifically, the present invention is not limited to the examples of electronic systems mentioned in this description. The present invention encompasses any modified embodiments that can be conceived by those skilled in the art. [Explanation of symbols]

[0049] 10 Multilayer printed circuit board 100 conductive layer 101 Surface layer 102 Inner layer 120 Electrical insulation layer 200 connection holes 201 Through Hole 202 End bore hole 301 Metal Pad 302 Electric Truck 303 Connection Pad 304 Electronic Components 2021 Parts having metallization 2022 Non-metallized portion

Claims

1. A multilayer printed circuit board (10) intended for connecting electronic components (304), comprising a laminate of a plurality of conductive layers (100), the conductive layers (100) comprising two surface layers (101) and one or more internal layers (102), wherein isolation between two adjacent conductive layers (100) is ensured by an electrical insulating layer (120), and the printed circuit board comprises one or more boreholes (202), each borehole (202) configured to electrically connect one of the two surface layers (101) to one or more internal layers (102), and having a metallized portion (2021) that is open over one of the two surface layers (101). The multilayer printed circuit board (10) further includes a non-metallized portion (2021) and a non-metallized portion (2022) of the bore hole (202) which are open on another surface layer (101), and the metallized portion (2021) and the non-metallized portion (2022) of the bore hole (202) extend in a direction perpendicular to the layer stacking plane, and further includes one or more metal pads (301), each metal pad (301) bonded to one of the two surface layers (101) such that it conceals the non-metallized portion (2022) of the corresponding bore hole (202), and the metal pads (301) do not fill the internal space of the corresponding bore hole (202).

2. The multilayer printed circuit board (10) according to claim 1, characterized in that the parasitic electromagnetic radiation tends to form inside the bore hole (202), and the metal pad (301) is selected to at least partially block the propagation of the parasitic electromagnetic radiation from the bore hole (202).

3. The multilayer printed circuit board (10) according to claim 1 or 2, characterized in that the parasitic electromagnetic radiation tends to penetrate into the bore hole (202), and the metal pad (301) is selected to at least partially block the propagation of the parasitic electromagnetic radiation into the bore hole (202).

4. The multilayer printed circuit board (10) according to claim 2, characterized in that the geometric properties of the metal pad (301) are selected according to one or more properties of the parasitic electromagnetic radiation that is formed in and / or tends to penetrate into the corresponding bore hole (202).

5. The multilayer printed circuit board (10) according to claim 2, characterized in that the electrical properties of the metal pad (301) are selected according to one or more properties of the parasitic electromagnetic radiation that is formed in and / or tends to penetrate into the corresponding bore hole (202).

6. The multilayer printed circuit board (10) according to claim 1, characterized in that the metal pad (301) is identical.

7. The multilayer printed circuit board (10) according to claim 1, characterized in that the metal pad (301) is a passive component that does not require a power supply.

8. A process for manufacturing a multilayer printed circuit board (10) and adding components, wherein the multilayer printed circuit board (10) is intended to connect electronic components (304), - Step (51) of generating a laminate of multiple conductive layers (100), wherein the conductive layers (100) include two surface layers (101) and one or more internal layers (102), and separation between two adjacent conductive layers (100) is ensured by an insulating layer (120), - Step (52) of creating an electrical connection between the conductive layers (100) by one or more metallized through-holes (201), - Step (53) of converting at least one metallized through-hole (201) into a bore hole (202) without filling the bore hole (202) with a resin plug, wherein the bore hole (202) includes a metallized portion (2021) open onto one of the two surface layers (101) and a non-metallized portion (2022) open onto the other surface layer (101), wherein the metallized portion (2021) and the non-metallized portion (2022) of the bore hole (202) extend in a direction perpendicular to the lamination plane, - Step (54) of generating an electric track (302) and a connecting pad (303) on at least one of the two surface layers (101) Includes, - Step (55) of bonding one or more metal pads (301) to one or both surface layers (101), wherein each metal pad (301) is bonded such that it conceals the non-metallized portion (2022) of the corresponding bore hole (202), and the metal pads (301) do not fill the internal space of the corresponding bore hole (202), Step (55), - Step (56) of connecting one or more electronic components (304) to a connecting pad (303) belonging to one or both surface layers (101) A process characterized by further comprising the following.

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