System with integrated circuit and printed circuit board, method for connecting an integrated circuit to a printed circuit board, control unit and vehicle

Abstract

System (200, 400) comprising an integrated circuit (205); a printed circuit board (215); and a sphere grid arrangement (210); wherein the integrated circuit (205) is mounted on the printed circuit board (215) by means of the sphere grid arrangement (210); and wherein the sphere grid arrangement (210) comprises at least one optical link (235) configured for transmitting optical signals (240); wherein the sphere grid arrangement (210) comprises a plurality of solder beads (220) for soldering to the printed circuit board (215); and wherein the optical link (235) is configured to melt under conditions similar to those of a solder bead (220).

Description

[0001] The present invention relates to a system comprising an integrated circuit, a printed circuit board, and a spherical grid arrangement by means of which the integrated circuit is arranged on the printed circuit board. In particular, the present invention relates to a control unit comprising such a system and to a vehicle comprising such a control unit.

[0002] Systems are known from the prior art in which integrated circuits (ICs) or packages containing integrated circuits are arranged on printed circuit boards (PCBs) using ball grid arrays (BGAs). The ball grid array electrically, mechanically, and thermally connects the integrated circuit or a surface-mounted device (SMD) located within it to the PCB. The BGA comprises a multitude of solder beads, typically arranged in a grid, which are melted during reflow soldering and, after cooling, form a permanent connection between the integrated circuit and the PCB or its contact pads.

[0003] US 2006 / 0208165 A1 discloses optical bumps for a low-loss connection and related methods. US 2017 / 0090129 A1 discloses a fiber optic connector device. US 2004 / 0057649 A1 discloses an electro-optical arrangement. US 2005 / 0196094 A1 discloses an optical bridge for a chip-to-board connection and manufacturing methods.

[0004] Spherical grid arrays (SGAs) allow for a high density of connections per unit area, making them advantageous compared to traditional pin grid arrays (PGAs). The steadily increasing density of connections between an integrated circuit and a printed circuit board (PCB) also raises the demands on signal integrity, EMC suppression, and data rates between the integrated circuit and the PCB.

[0005] The present invention is based on the objective of further developing a connection between the integrated circuit and the printed circuit board in such a way that the above-mentioned requirements can be met in an improved manner.

[0006] According to a first aspect of the present invention, a system is proposed comprising an integrated circuit, a printed circuit board, and a ball grating assembly. The integrated circuit is mounted on the printed circuit board by means of the ball grating assembly. The ball grating assembly includes at least one optical connection configured for transmitting optical signals.

[0007] The integrated circuit can include an interposer or be mounted on an interposer, such that the proposed mixed-electrical and optical sphere grating arrangement is located between the interposer and the printed circuit board. In this case, the integrated circuit can be connected to the interposer, for example, using microbumps, particularly copper pillars.

[0008] The present invention is therefore primarily directed to spherical grid arrangements which include at least one optical connection or optical connecting element. By using an optical connection in the spherical grid arrangement for transmitting optical signals between the integrated circuit and the printed circuit board, it is possible to connect an optical component in the integrated circuit to a corresponding optical component via the printed circuit board.

[0009] This enables the use of an optical communication system, which can be less susceptible to interference from electromagnetic fields (EMC) compared to conventional electrical circuits. Signal integrity can be improved compared to electrical transmission. Furthermore, the inventors have recognized that the use of optical communication systems allows for higher bandwidth transmission and reduces the power consumption of the integrated circuit. The use of optical components also enables a higher packing density for the integrated circuit.

[0010] According to a second aspect of the present invention, a method for connecting an integrated circuit to a printed circuit board (PCB) is shown using a ball grid arrangement, wherein the ball grid arrangement comprises at least one optical connection. The method comprises the following steps: placing the integrated circuit onto the PCB such that the solder beads of the ball grid arrangement and the optical connection are each in predetermined positions relative to the PCB; and heating the ball grid arrangement such that the solder beads are soldered to the PCB and the optical connection is metallurgically bonded to the PCB.

[0011] The method according to the invention offers the particular advantage that the electrical connections via the solder beads and the optical connection can be closed simultaneously, thus enabling more efficient packaging. Manufacturing a control unit with such a system can be carried out simply and reliably. Manufacturing costs can be kept low.

[0012] According to a third aspect, the present invention relates to a control unit with a system according to the first aspect of the present invention. According to a fourth aspect, the present invention relates to a vehicle, in particular a motor vehicle, with a control unit according to the third aspect of the present invention.

[0013] Although the first aspect mentions at least one optical connection, the sphere grid arrangement can include multiple optical connections that optically link the integrated circuit to different locations on the circuit board. This makes it possible for the integrated circuit to be optically connected to, for example, at least two other integrated circuits and to communicate with them.

[0014] In one embodiment of the invention, the sphere grid arrangement comprises a plurality of solder beads for soldering to the printed circuit board, wherein the optical connection is configured to melt under conditions similar to those of a solder bead. If the optical connection exhibits similar or identical thermal behavior to a solder bead, both the electrical contact via the solder beads and the optical contact via the optical connection between the integrated circuit and the printed circuit board can be established simultaneously. This eliminates the need to perform the reflow process for soldering the solder beads or for optically contacting the optical connection only once. Furthermore, reflow processes known from the prior art can also be used in this case. The optical connection can be used in conjunction with an electrical connection using lead-free or leaded solder.

[0015] The optical connection can be configured to form a metallurgical bond with the printed circuit board (PCB) during the melting process. This bond can involve, in particular, gluing or welding. This allows the use of liquid materials that can be joined using a simple reflow process known from the prior art. In this case, it can be advantageous if the material for the optical connection is already molten and bonded to a corresponding area of ​​the integrated circuit prior to the reflow process. This ensures that the material is already positioned correctly for bonding to the PCB during the reflow process.

[0016] The optical connection can be made of plastic. A plastic with a melting point similar to that of the solder used for the solder beads can be used. For example, a plastic with a melting point of approximately 180°C for leaded solder or approximately 194°C for lead-free solder can be used.

[0017] In a preferred embodiment, polycarbonate can be used as the plastic for the bonding. Polycarbonate is an amorphous plastic that has no melting point but can transition into a soft, rubbery state at approximately 150°C, in which it can be bonded to the printed circuit board. Alternatively, a thermoplastic polymer can be used, for example, of the type known as hot melt adhesive. The material can, for example, be polyamide-based.

[0018] The integrated circuit can include an electronic component for emitting and / or receiving light in the area of ​​the optical element. For example, the optical element could be an LED or a photodiode.

[0019] The optical connection can be made via a light guide that extends horizontally within the printed circuit board (PCB), i.e., along or parallel to the PCB surface facing the integrated circuit. This allows an optical signal to be guided horizontally into the PCB, enabling the use of a compact, low-profile integrated circuit design. This also allows communication between the integrated circuit and another integrated circuit connected to the PCB. The circuits can be located on the same or opposite surfaces of the PCB. The circuit density on the PCB can be high.

[0020] In yet another embodiment, the optical connection is permanently attached to the integrated circuit. For the purposes of the present invention, "permanently attached" means that the optical connection is permanently or irrevocably arranged on a surface of the integrated circuit facing the circuit board, such that the integrated circuit and the optical connection form a separately manageable unit. In particular, the optical connection can be bonded to the circuit by means of a material bond, for example by gluing or welding. This allows the optical connection to be bonded to the integrated circuit before the circuit is placed on the circuit board, similar to the solder beads of a sphere grid arrangement.

[0021] The optical link can be designed to prevent light from entering or exiting in a lateral direction. For example, the optical link can be made of a material with a high refractive index. Preferably, the refractive index is greater than approximately 1.5 and can be 2 or higher. This effectively prevents light from coupling in or out, thereby improving signal integrity.

[0022] The optical connection can comprise a tube running between a semiconductor package of the integrated circuit and the printed circuit board, through whose interior light can be transmitted. This allows the optical signal to be transmitted without interference even over longer distances. Preferably, the interior of the tube is filled with a material that establishes the optical connection. The tube can be made of a flexible material so that it securely seals the interior, while the distance between the circuit and the printed circuit board decreases as the solder beads melt. In another embodiment, the tube is easily deformable and can, for example, comprise a film. In both cases, it is possible to prevent the material of the optical connection from flowing unintentionally or forming an unwanted connection, for example, with an adjacent solder bead.

[0023] The sphere grid arrangement can comprise solder beads of equal size, with the optical connection preferably occupying the same area as a solder bead. This allows the optical connection to be integrated into a grid of solder beads. The solder beads are arranged, for example, in columns and rows in a chessboard-like grid. The grid can be, for example, square or rectangular. For example, the grid can comprise 2, 3, 4 or more rows and 2, 3, 4 or more columns. In some embodiments, a sphere grid arrangement comprises a large number of elements, for example, more than 100 or several hundred.

[0024] Several sphere grid arrangements are known that can be used with the proposed system. For example, a 10 x 10 arrangement can be used, where the optical connection can occupy one cell of the known arrangement. Thus, instead of 100 electrical connections, only 99 electrical and one optical connection would be realized. In another embodiment, a known arrangement is extended by one cell that can be occupied by the optical connection. In the aforementioned example, approximately 9 rows of 10 columns each and one row of 11 columns could be provided. The sphere grid arrangement could thus comprise a total of 101 connections, one of which is optical and the others electrical. The electrical connections can remain in the known arrangement, and the optical connection can be adjacent to them.

[0025] The integrated circuit can include a processing unit, in particular a CPU or a GPU. The processing unit can be mechanically, thermally, and / or electrically connected to the printed circuit board by means of the sphere grid arrangement, and communication between the processing unit and the printed circuit board can be improved by means of the proposed optical connection.

[0026] The control unit according to the present invention can be used on board a motor vehicle and may, for example, comprise a control unit for processing a video data stream from an environmental sensor and / or a video camera for object detection or distance estimation. Furthermore, the control unit may be configured for processing a video data stream from a reversing camera or for controlling a navigation system.

[0027] The invention will now be described in more detail with reference to the attached figures, in which: Fig. 1 a motor vehicle with a control unit; Fig. 2 a side view of a system according to a first embodiment; Fig. 3 a bottom view of a sphere grid arrangement; Fig. 4 a system according to a second embodiment; and Fig. 5 shows a flowchart of a process.

[0028] It should be noted that in the following detailed description, features or components of different embodiments that are identical or at least functionally equivalent to the corresponding features or components of another embodiment are identified by the same reference numerals or reference numerals. To avoid unnecessary repetition, features or components already explained with reference to a previously described embodiment will not be explained in detail again later.

[0029] Furthermore, it should be noted that the embodiments described below represent only a limited selection of possible embodiments of the invention. In particular, it is possible to combine the features of individual embodiments in a suitable manner, so that a multitude of different embodiments are to be considered obviously disclosed to the person skilled in the art with the embodiments explicitly presented here.

[0030] Furthermore, it should be noted that spatial terms, such as "front" and "back," "top" and "bottom," "left" and "right," etc., are used to describe the relationship of one element to another, as illustrated in the figures. Accordingly, these spatial terms may apply to orientations that differ from those depicted in the figures. However, it goes without saying that, for the sake of simplicity, all such spatial terms refer to the orientations shown in the drawings and are not necessarily restrictive, since the device, component, etc., depicted, when in use, may assume orientations that differ from those shown in the drawing.

[0031] Fig. Figure 1 shows a control unit 100 on board a motor vehicle 105. The motor vehicle 105 can, in particular, comprise a motorcycle, a passenger car, a truck, or a bus. Other types of motor vehicles, for example, agricultural vehicles or construction machinery, are also included in the present invention.

[0032] The control unit 100 can, for example, be used for processing a video data stream from an environmental sensor and / or a video camera for object detection or distance estimation. The control unit can also be configured for processing a video data stream from a reversing camera or for controlling a navigation system or an infotainment system. The control unit 100 comprises at least one system according to the first aspect of the present invention.

[0033] Fig. Figure 2 shows a system 200. The system 200 comprises an integrated circuit 205, a ball grid arrangement 210, and a printed circuit board 215. The integrated circuit 205, which is, for example, a processing unit for processing a video data stream, is electrically and mechanically mounted on the printed circuit board 215 by means of the ball grid arrangement 210. The ball grid arrangement 210 is fixed to a surface 225 of the integrated circuit 205 and can be placed together with the integrated circuit 205 onto a surface 230 of the printed circuit board 215, such that the solder beads 220 are in predetermined positions relative to the printed circuit board 215 or relative to a surface 230 of the printed circuit board 215 facing the integrated circuit. The system 200 is then heated in a reflow soldering process so that the solder beads 220 fuse with the printed circuit board 215 or with the surface 230 of the printed circuit board 215 facing the integrated circuit.to whose surface 230 are soldered and a material-bonded electrical and thermal connection is created between the integrated circuit 205 and the circuit board.

[0034] According to the invention, the ball grid arrangement 210 of the system 200 has at least one optical connection 235, which is configured to transmit optical signals 240 between the integrated circuit 205 and the printed circuit board 215. An optical connection 235 can replace or extend a solder bead 220 of the ball grid arrangement 210.

[0035] In the embodiment according to Fig. Figure 2 shows two optical connections 235, which can transmit optical signals 240 between the integrated circuit 205 and the printed circuit board 215. The optical signals 240 are emitted and received by an LED 245 and a photodiode 250, respectively, which are integrated into the integrated circuit 205. Thus, the integrated circuit 205 can emit or receive light as an optical signal via the optical components 245 and 250. Light in the visible or invisible wavelength range can be used.

[0036] The optical connection 235 thus enables the exchange of data in the form of optical signals 240 between the integrated circuit 205 and the printed circuit board 215. A higher transmission rate can be achieved between the integrated circuit 205 and the printed circuit board 215 than with an electrical connection. Furthermore, the optical connection 235 allows the optical signal 240 to be transmitted in a noise-resistant manner and with very good electromagnetic compatibility (EMC), so that the quality of the transmitted signal can be improved compared to prior art sphere grid arrangements.

[0037] Preferably, the optical connection 235 is configured to melt at a similar temperature to a solder bead 220. This allows the optical connection 235 to be bonded to the printed circuit board 215 or its surface 230 in a single step during the reflow process, together with the solder beads 220. Furthermore, the optical connection 235 may be made of a material such as plastic, which forms a metallurgical bond with the printed circuit board when exposed to heat.

[0038] Furthermore, it can be provided that the optical connection 235 is applied to the lower surface 225 of the integrated circuit 205 before the integrated circuit 205 is placed on the printed circuit board 215, so that the optical connection 235 is permanently or indelibly connected to the surface 225 before the integrated circuit 205 is placed on the printed circuit board 215. In another embodiment, the optical connection can also be applied to the surface 230 of the printed circuit board 215 before the integrated circuit 205 is placed. The optical connection 235 can, for example, be produced by a thermal process.

[0039] In Fig. Figure 3 is a bottom view of an exemplary sphere lattice arrangement 210 according to Fig. 2 shown. As in the Fig. As can be seen in Figure 3, the ball grid arrangement 210 has two optical connections 235 and consists of a grid, which for example comprises seven rows 305 and eight columns 310. In this case, all solder beads 220 and the two optical connections 235 are of the same size, so that the optical connections 235 occupy the same area as the solder beads 220. This is particularly advantageous because the solder beads 220 can be replaced by further optical connections 235 without changing the grid of the ball grid arrangement 210, thus giving the ball grid arrangement 210 a high degree of flexibility. However, the invention also encompasses the case where the ball grid arrangement 210 has a different structure than an optical connection 235.

[0040] Fig. Figure 4 shows a system 400, which can be considered a further embodiment of a system 200. In contrast to the embodiments according to Fig. 2 and Fig. 3 indicates that the system 400 according to the Fig. Figure 4 shows a light guide 405 extending horizontally in the circuit board 215. The light guide 405 is configured to transmit an optical signal between the integrated circuit 205, for example, between an LED 245 of the integrated circuit 205, and another integrated circuit 410. This allows, for example, the further circuit 410 to be arranged on the circuit board 215 by means of another ball grid arrangement 415, preferably on a surface 420 of the circuit board 215 opposite the integrated circuit 215. Alternatively, another circuit board 215 can be used instead of the further circuit 410. The grid spacing of the ball grid arrangements 210 and 415 can be different.

[0041] However, it can also be provided that the additional circuit 410 is arranged on the same surface 230 as the integrated circuit 205 by means of the additional sphere grid arrangement 415. The additional sphere grid arrangement 415 is constructed similarly to the sphere grid arrangement 210 and has solder beads 230 and at least one optical connection 430, which is configured to transmit an optical signal between the light guide 405 and the additional integrated circuit 410. Thus, several integrated circuits 205, 410 arranged on the circuit board 215 can communicate with each other via optical signals through the light guide 405.

[0042] According to the embodiment in the Fig. Figure 4 further provides that the optical connection 235 comprises a vertically extending tube 425 between a semiconductor housing 406 of the integrated circuit 205 and the printed circuit board 215. The tube 425 can be filled with a transparent material. Preferably, the tube 425 is made of an opaque material so that light cannot pass laterally into or out of the tube 425. This allows for improved optical signal quality. The signal can be transmitted with less loss. The interference immunity of the optical connection can be improved.

[0043] In Fig. Figure 5 shows a schematic representation of a method 500 according to the invention for connecting an integrated circuit 205 to a printed circuit board 215 by means of a spherical grid arrangement 210, which can be used to connect a system 200, 400 as in the embodiments according to the Fig. 2, Fig. 3 to Fig. 4 to train.

[0044] In a first step 505, the sphere grid arrangement 210 can be connected to the integrated circuit 205 or to its surface 225, preferably in such a way that both the solder beads 220 and the optical connections 235 are permanently or indelibly bonded to the surface 225. For this purpose, for example, a thermal process can be used, which results in a metallurgical bond between the solder beads 220 and the optical connections 235 on the one hand and the surface 225 of the integrated circuit 205 on the other.

[0045] In a second step 510, the integrated circuit 205 can be placed on the printed circuit board 215, preferably such that the solder beads 220 and the optical connection 235 are located at predetermined positions relative to the printed circuit board 215. For example, it can be provided that the integrated circuit 205 is placed on the printed circuit board 215 such that the optical connection 235 is located relative to the light guide 405 of the printed circuit board 215.

[0046] In a third step 515, the ball grid arrangement 210 can be heated such that the solder beads 220 are soldered to the circuit board 215 and the optical connection 235 is metallurgically bonded to the circuit board 215. For this purpose, the entire system 100, 400 is typically heated. A reflow process can be used for this, for example, especially if the solder beads 220 and the optical connections 235 have similar or identical thermal behavior with regard to forming a connection to the circuit board 215.

[0047] The method 500 described above can also be used for connecting further integrated circuits 410 to the printed circuit board 215 by means of a spherical grid arrangement 210 according to the invention. Reference sign 100 control unit 105 motor vehicles 200 System 205 integrated circuit 210 sphere lattice arrangement 215 circuit board 220 Lotperle 225 surface 230 surface 235 optical connection 240 optical signal 245 LED 250 photodiode 305 series Column 310 400 System 405 Optical fibers 410 additional integrated circuit 415 further spherical grid arrangements 420 surface 425 pipe 430 optical connection 500 procedures 505 Connect ball lattice arrangement to circuit Mounting a 510 circuit on a printed circuit board 515 Heat the spherical lattice arrangement

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