Process for manufacturing a printed circuit board and printed circuit board

Abstract

One aspect of the invention relates to a process for manufacturing a printed circuit board (1), said process comprising a step of depositing a conductive material (5), by means of an additive-manufacturing device, on a first conductive track (3) that a first layer (2) of the printed circuit board initially has, said process further comprising steps of cutting beforehand, in a second layer (6) of the printed circuit board (1), a shape (7) complementary to the deposit of conductive material (5), and pressing the first layer (2) against said second layer (6).

Description

DESCRIPTION TITLE: METHOD FOR MANUFACTURED A PRINTED CIRCUIT BOARD AND PRINTED CIRCUIT BOARD TECHNICAL FIELD OF THE INVENTION

[0001] The present invention relates to a method for manufacturing a printed circuit board, in particular having a first layer comprising a first series of conductive tracks for the flow of power currents and a second series of conductive tracks for the flow of control currents. The invention thus falls within the field of printed circuit board manufacturing. TECHNOLOGICAL BACKGROUND OF THE INVENTION

[0002] Traditional electronic architectures consist of several interconnected circuit boards or boards connected via a motherboard. These traditional electronic architectures are gradually evolving towards simplified architectures with a single circuit board. This single circuit board integrates both power functions, such as power supply or actuation, and digital functions, such as signal processing and calculation.

[0003] However, merging digital and power functions onto a single circuit board presents some challenges. A major constraint lies with the printed circuit board, also known as the PCB. Combining digital and power functions requires the PCB to include, for the digital functions, thin conductive traces to allow for numerous thin tracks, and for the power functions, thick conductive traces to carry high currents.

[0004] Current manufacturing processes allow for the creation of conductive traces of uniform thickness within a single layer of the printed circuit board. The usual solution is to separate the digital and power functions by PCB layer. Thus, layers with thick conductive traces are used to carry high currents, while layers with thin conductive traces are used to carry low currents.

[0005] This solution has a significant limitation. Plated through-holes in the printed circuit board (PCB), which allow for the interconnection of the various superimposed layers, impose a limited PCB thickness due to the quality and reliability of the connections between the different trace layers, particularly the plated through-holes. This PCB thickness is typically limited to 3.2 mm. The thickness of the dielectrics separating the conductive traces then limits the number of conductive trace layers. SUMMARY OF THE INVENTION

[0006] The invention offers a solution to the problems mentioned above, by proposing a method for manufacturing a printed circuit board that allows for optimization of the routing of conductive tracks.

[0007] In this context, the invention thus relates, in its broadest sense, to a method for manufacturing a printed circuit board.

[0008] The process according to this aspect of the invention includes a step of depositing a conductive material, by means of an additive manufacturing device, onto a first conductive track which is initially present in a first layer of the printed circuit board.

[0009] Thanks to the manufacturing process according to this aspect of the invention, it is possible to locally deposit copper or another conductive material on top of a conductive trace produced using traditional methods. The process according to this aspect of the invention thus makes it possible to create, on a single layer of the printed circuit board, conductive traces of varying thicknesses: thin for low-current applications and thick for high-current applications. This facilitates the routing of the conductive traces and reduces the number of layers on the printed circuit board.

[0010] Furthermore, the process according to the invention makes it possible to contain the thickness of the printed circuit board and to obtain plated holes of moderate length exhibiting high quality and high reliability.

[0011] In addition to the characteristics mentioned in the preceding paragraph, the method according to this aspect of the invention may have one or more additional characteristics from the following, considered individually or according to all technically possible combinations.

[0012] According to a non-limiting aspect of the invention, the process comprises the steps of: Pre-cut, in a second layer of the printed circuit board, a complementary shape to the conductive material deposit. Press the first layer with the second layer so that the conductive material deposit is positioned in the pre-cut complementary shape.

[0013] According to a non-limiting aspect of the invention, the deposit of conductive material has a thickness of between 5 pm and 500 pm.

[0014] According to a non-limiting aspect of the invention, the conductive material deposited by the additive manufacturing device on the first conductive track is different from the conductive material that comprises the first conductive track initially present on the first layer of the printed circuit board.

[0015] Another aspect of the invention relates to a printed circuit board obtained by a manufacturing process according to any one of the aforementioned aspects of the invention.

[0016] According to a non-limiting aspect of the invention, the printed circuit board comprises an electronic component equipped with: First connection means for the flow of power current, said first connection means being connected to the first conductive track having received the deposit of conductive material, and Second means of connection for the circulation of control currents, said second means of connection being connected to a second conductive track comprising the first layer, said second conductive track having a thickness less than a thickness of said first conductive track having received the deposit of conductive material.

[0017] According to a non-limiting aspect of the invention, the electronic component is a power transistor.

[0018] According to a non-limiting aspect of the invention, the electronic component is disposed in a cavity of a receiving layer of said electronic component, said receiving layer and said electronic component being covered by the first layer.

[0019] According to a non-limiting aspect of the invention, the first conductive track having received the deposit of conductive material has a thickness greater than or equal to 70 pm and the second conductive track has a thickness less than or equal to 35 pm.

[0020] The invention and its various applications will be better understood by reading the following description and examining the accompanying figures. BRIEF DESCRIPTION OF THE FIGURES

[0021] [Fig. 1] shows a step diagram of a non-limiting embodiment of a method for manufacturing a printed circuit board according to one aspect of the invention.

[0022] [Fig. 2] illustrates, schematically, a printed circuit board produced by implementing the process according to the invention.

[0023] [Fig. 3] shows, schematically, another example of a printed circuit board produced by implementing the process according to the invention. DETAILED DESCRIPTION

[0024] The figures are presented for illustrative purposes only and are in no way limiting to the invention.

[0025] Unless otherwise specified, the same element appearing on different figures has a unique reference.

[0026] Figure 1 illustrates a step diagram of a non-limiting embodiment of a method for manufacturing a printed circuit board according to one aspect of the invention. Figure 2 schematically shows a printed circuit board obtained using the method according to the invention. For the remainder of the description, reference will be made to Figures 1 and 2.

[0027] Starting from a printed circuit board 1 initially comprising a first layer 2 (made of a dielectric material whose function is to insulate and bond conductive tracks) equipped with a first conductive track 3 and a second conductive track 4 produced using a traditional method, the process 100 includes a step of depositing 101 of a conductive material 5, by means of an additive manufacturing device, onto the first conductive track 3 which is initially present in the first layer 2 of the printed circuit board 1.

[0028] This additive manufacturing device is also known as a three-dimensional printer. Examples, but not limited to, powder bed fusion or powder jetting additive manufacturing, include devices that utilize powder bed fusion.

[0029] This deposit of conductive material 5 increases the thickness e35 of the first conductive track 3. Thus, this first conductive track 3, having received the deposit of conductive material 5, can be used for the flow of power currents, in other words, high-intensity currents. In a non-limiting example, a current is considered high-intensity when it exceeds 5 A.

[0030] The second conductive track 4, which has not received the deposit of conductive material 5, can be used for the flow of control currents, in other words, low-intensity currents. In a non-limiting example, a current is considered low-intensity when it is less than 5 A.

[0031] In a non-limiting implementation, the material of the first conductive track 3 is copper and the conductive material 5 deposited by the additive manufacturing device is also copper.

[0032] In a different implementation, the material of the first conductive track 3 is copper and the conductive material 5 deposited by the additive manufacturing device is a conductive material other than copper.

[0033] In a non-limiting implementation, the deposited conductive material 5 has a thickness e5 between 5 pm and 500 pm, for example 182 pm.

[0034] In a non-limiting embodiment, the process 100 further includes a step of pre-cutting 102, in a second layer 6, formed of a dielectric material, of the printed circuit board 1, a complementary form 7 of the conductive material deposit 5.

[0035] Thus, the conductive material deposit 5 can be inserted into the complementary shape 7.

[0036] To this end, process 100 further includes a step of pressing 103 the first layer 2 with the second layer 6 so that the deposit of conductive material 5 is positioned in the complementary pre-cut shape 7.

[0037] In this non-limiting embodiment example, the second layer 6 of the printed circuit board 1 includes a third conductive track 8.

[0038] The printed circuit board 1 further includes a plated hole 9 through the first layer 2 and the second layer 6 to electrically connect the first conductive track 3 with the third conductive track 8.

[0039] Figure 3 schematically shows another example of a printed circuit board 1 according to a non-limiting aspect of the invention obtained via the process according to the invention.

[0040] The printed circuit board 1 according to this aspect of the invention comprises a first layer 2 having a first conductive track 3 covered with a deposit of conductive material 5 and a second conductive track 4. This first layer 2 also comprises a dielectric material 10 allowing electrical isolation of the first conductive track 3 covered with the deposit of conductive material 5 and the second conductive track 4. This dielectric material 10 may consist of a glass fabric and a resin that is not polymerized before the manufacture of the printed circuit board 1. After manufacture, this resin is polymerized.

[0041] Printed circuit board 1 also includes a second layer 6 with a third conductive track 8.

[0042] This second layer 6 also includes a dielectric material 11 for electrically insulating the third conductive track 8. This dielectric material 11 can also consist of a glass fabric and an unpolymerized resin before the printed circuit board is manufactured. After manufacturing, this resin is polymerized.

[0043] The printed circuit board 1 further includes a receiving layer 12 for an electronic component 13. The material constituting this receiving layer 12 is also a dielectric material. This dielectric material may, for example, consist of a glass fabric and a polymerized resin.

[0044] In this embodiment example, the electronic component 13 is placed in a pre-cut cavity 14 in the receiving layer 12 of the electronic component 13.

[0045] In this embodiment example, the receiving layer 12 and the electronic component 13 are arranged between the first layer 2 and the second layer 6 of the printed circuit board 1.

[0046] In a non-limiting embodiment example, the electronic component 13 is a gallium nitride power transistor.

[0047] In this non-limiting example, the electronic component 13 is equipped with: First connection means 15 for the circulation of power currents, the first connection means 15 being connected to the first conductive track 3 having received the deposit of conductive material 5; to this end each of the first connection means 15 is, for example, connected to a metallized via or a hole filled with a conductive material passing through the first conductive track 3, and Second connection means 16 for the circulation of control currents, the second connection means 16 being connected to the second and third conductive tracks 4, 8 which respectively comprise the first layer 2 and the second layer 6; for this purpose, each of the second connection means 16 is for example connected to a metallized via or a hole filled with a conductive material passing through the second or third conductive tracks 4, 8.

[0048] It should be noted that the second conductive track 4 and the third conductive track 8 have a thickness less than the thickness of the first conductive track 3 which has received the deposit of conductive material 5.

[0049] In a non-limiting embodiment example, the first conductive track 3 having received the deposit of conductive material 5 has a thickness greater than or equal to 70 pm.

[0050] In a non-limiting embodiment example, the second conductive track 4 and the third conductive track 8 each have a thickness less than or equal to 35 pm.

[0051] Furthermore, in this non-limiting embodiment example, the printed circuit board has a thermal dissipation layer 17. This thermal dissipation layer is located below the second layer 6 and allows the heat emitted by the electronic component 13 to dissipate.

[0052] The various aspects of the aforementioned invention offer numerous advantages. Among these, we can mention: - Providing a significantly increased thickness of conductive material locally; To allow, on a single layer of a printed circuit board, conductive tracks of different thicknesses; Containing the thickness of the printed circuit board allows for moderately long plated holes.

[0053] It should be noted that a person skilled in the art is able to make different variations to the aforementioned aspects of the invention, for example by proposing a different thickness of deposit of a conductive material.

Claims

DEMANDS

1. A method (100) for manufacturing a printed circuit board (1) comprising a step of depositing (101) a conductive material (5), using an additive manufacturing device, onto a first conductive track (3) initially present in a first layer (2) of said printed circuit board (1), the deposition step (101) increasing the thickness (e35) of the first conductive track (3), said method being characterized in that it comprises the steps of: - Pre-cut (102), in a second layer (6) of the printed circuit board (1), a complementary shape (7) of the conductive material deposit (5), - Press (103) the first layer (2) with said second layer (6) so that the deposit of conductive material (5) is positioned in said pre-cut complementary shape (7).

2. A method (100) according to any one of the preceding claims characterized in that the deposit of conductive material (5) has a thickness (e5) between 5 pm and 500 pm. [Claims] A method (100) according to any one of the preceding claims characterized in that the conductive material (5) deposited by the additive manufacturing device on the first conductive track (3) is different from the conductive material that the first conductive track (3) initially presents on the first layer (2) of the printed circuit board (1).

4. Printed circuit board (1) obtained by a process (100) for manufacturing a printed circuit board (1) according to any one of the preceding claims comprising an electronic component (13) equipped with: - First connection means (15) for the flow of power currents, said first connection means (15) being connected to the first conductive track (3) having received the deposit of conductive material (5), and - Second connection means (16) for the circulation of control currents, said second connection means (16) being connected to a second conductive track (4), said second track conductive (4) having a thickness less than a thickness of said first conductive track (3) having received the deposit of conductive material (5), said printed circuit board being characterized in that the first layer (2) comprises the second conductive track (4). [Claims] Printed circuit board (1) according to the preceding claim characterized in that the electronic component (13) is a power transistor. [Claims] Printed circuit board (1) according to any one of claims 5 or 6 characterized in that the electronic component (13) is disposed in a cavity (14) of a receiving layer (12) of said electronic component (13), said receiving layer (12) and said electronic component (13) being covered by the first layer (2).

7. Printed circuit board (1) according to any one of claims 5 to 7 characterized in that the first conductive track (3) having received the deposit of conductive material (5) has a thickness greater than or equal to 70 pm and the second conductive track (4) has a thickness less than or equal to 35 pm.

Images