Electronic component package

Abstract

Provided is an electronic component package in which pads are disposed at a predetermined pitch in a lattice shape along an x direction and a y direction which is orthogonal to the x direction in an x-y plane. Signal electrode pads for inputting or outputting a high-frequency signal, which are disposed on the outer periphery of the electronic component, and ground electrode pads, which are adjacent in the x direction and y direction to the signal electrode pads, have a solder resist or ceramic coat suppression width and a pad size which are formed to be smaller than the solder resist or ceramic coat suppression width and the pad size of other pads.

Description

Technical Field

[0001] The present invention relates to an electronic component package such as an optical transceiver used in an optical communication system.

Background Art

[0002] In recent years, in the data center and optical communication industries, small optical transceivers that can achieve a higher transmission speed per unit volume have been put into practical use. For example, the form factor size of a transceiver for data communication and telecommunication called QSFP-DD is about 18.35 mm x 58.26 mm x 8.5 mm. In order to mount a high-speed optical communication transceiver in such a small form factor, not only ICs but also optical transceivers use high-frequency modules equipped with ball grid arrays (BGAs) and land grid arrays (LGAs) that can be mounted on a printed circuit board (PCB) by solder reflow. Both BGA and LGA are used in electronic component packages that use surface mount technology (SMT) to make electrical connections to a printed wiring board via solder bumps. Those with hemispherical solder provided on circular electrode pads arranged in a grid pattern on the bottom surface of the package are called ball grid arrays (BGAs), and those without solder are called land grid arrays (LGAs). Since LGA does not have solder mounted, when performing reflow mounting on a printed wiring board, electrical connection is made by applying paste solder or supplying spherical solder balls. There are various other names for surface mount technology that makes electrical connections via solder bumps based on detailed classifications, but in this specification, BGA, LGA, etc. will be collectively simply referred to as BGA.

[0003] Optical transceivers have terminals including a ground terminal, a DC terminal for supplying power, analog or digital control terminals, and signal terminals for inputting and outputting high-speed electrical signals. The number of DC terminals varies depending on the module. In contrast, the number of terminals for signal electrodes for inputting or outputting signals is usually eight pairs in total for coherent optical communication optical transceivers: four pairs for transmission and four pairs for reception in differential signal pairs. Furthermore, since the signal electrode terminals of an optical transceiver input and output signals to adjacent digital signal processing processors and devices that make up the optical communication system (host devices), they are generally often grouped at one end of the optical transceiver package.

[0004] To achieve a compact size while incorporating all the necessary terminals for the operation of these optical transceivers, the pads of the BGA used in the optical transceiver must be closely spaced. Furthermore, to ensure uniform mounting stress, the pads of the BGA are often arranged at equal intervals in the x and y directions within the plane of the BGA, and the size of each BGA pad is usually the same.

[0005] Figure 1 shows a conventional electronic component package having equally spaced BGA pads. As shown in Figure 1, one face 12 of the electronic component package 10 is formed of a resin such as glass epoxy or ceramic, and circular BGA pads 14 are arranged in a grid pattern on this face (xy face) at equal intervals in the xy direction at a predetermined pitch. Each BGA pad 14 is made of a metal such as aluminum or copper and is plated with gold, silver, or palladium so that it can be soldered.

[0006] Figure 2 shows two adjacent BGA pads 14a and 14b of the electronic component package shown in Figure 1. Figure 2(a) is a top view of the BGA pad, and Figure 2(b) is a cross-sectional view of the BGA pad. The BGA pads 14a and 14b are formed from a conductive metal such as aluminum or copper on one surface 12 of the electronic component package, which is made of a resin such as glass epoxy or ceramics. Each BGA pad is plated with gold, silver, or palladium to enable solder connections. The BGA pads shown in Figure 2 are circular, and their diameter is indicated by B. The pitch between the two adjacent BGA pads 14a and 14b is indicated by C. In this specification, the pitch of the BGA pads refers to the center distance as shown in Figure 2.

[0007] To prevent the BGA pads 14a and 14b from peeling off due to stress on the electronic components during soldering or use, a solder resist is applied to the edges of the BGA pads 14a and 14b if the electronic component package is made of resin, or a ceramic coating if it is made of ceramics, as shown in Figure 2(b). Note that Figure 2(a) shows only the portion (22) of the solder resist or ceramic coating 20 shown in Figure 2(b) that overlaps with the BGA pads 14a and 14b. The solder resist or ceramic coating defines the pad openings 24a and 24b, which are the area occupied by the solder bumps on the BGA pads, and in Figure 2, the diameter of the pad openings 24a and 24b is indicated by A. The distance D between adjacent BGA pads and the gap G between the BGA pads are shown in Figure 2. Although not shown in the diagram, the wiring from each pad of the BGA is done via inner layer wiring, called vias, which is formed inside the substrate that makes up one side of the package, which is made up of resin or ceramics.

[0008] The pad opening diameter A, BGA pad diameter B, and BGA pad pitch C are desirable to be large for ease of mounting electronic component packages with BGA pads onto printed circuit boards, etc. However, to increase pad density from the perspective of miniaturizing the device, these are desirable to be small. The extent to which they can be reduced is limited by constraints such as the difficulty of mounting the electronic components onto the printed circuit board, the difficulty of forming the electrodes, and the diameter of the vias of the inner layer wiring. Also, since the pad opening must be positioned without protruding from the BGA pad, the restraining width of the solder resist or ceramic coating (widths of 22a and 22b in Figure 2(a)) is important. (BA) / 2 To ensure the strength of the BGA pad, a thickness of approximately 40-100 μm is required.

[0009] Figure 3 is a table showing the relationship between BGA and LGA pad pitch and pad opening diameter, extracted from the "JEITA EDR-7316C, Integrated Circuit Package Design Guide," a guideline provided by the Japan Electronics and Information Technology Industries Association (JEITA). The value indicated by 'e' is the pad pitch C, and the values ​​indicated by min., nom., and max. are the minimum, standard, and maximum values ​​of the pad opening diameter A, respectively. The unit is (mm). Even international standard sizes have a range for the allowable pad opening diameter relative to the pad pitch, indicated by a minimum and maximum value. Furthermore, the solder formed on the BGA pad connects the printed circuit board etc. and the electronic component, and at the same time absorbs fluctuations in the gap of the joint surface due to warping of the two. The required solder height differs depending on the amount of warping to be absorbed, but the solder height after mounting to the printed circuit board etc. (the distance between the printed circuit board etc. and the BGA pad) will be about half the size of the pad opening diameter A. In Figure 3, F in FBGA and FLGA stands for fine pitch. Furthermore, in C-FLGA and P-FLGA, "C-" indicates that the substrate material is ceramic, while "P-" indicates that the substrate material is plastic, i.e., a resin such as glass epoxy.

[0010] Wiring from BGA pads is performed using internal layer wiring called vias, which are formed inside the substrate that constitutes one side of an electronic component package made of resin or ceramics, as shown in Figure 4(b). When constructing a transmission line that propagates high-frequency signals using internal layer wiring such as vias formed inside a laminated substrate as shown in Figure 4(b), it is necessary to adjust the characteristic impedance of the internal layer wiring. Characteristic impedance is the unique impedance (the ratio of voltage to current generated in the propagation medium) that a transmission line possesses, and in electronic components, it is usually set to 50Ω for single-phase transmission and 100Ω for differential transmission. To set the characteristic impedance of internal layer wiring using vias to 50Ω, the most effective method is to arrange vias that form signal electrodes for propagating high-frequency signals and vias that form ground electrodes for carrying return current in a concentric pattern, similar to a coaxial transmission line.

[0011] Figure 4 shows the structure of an electronic component package made of resin or ceramic, which has internal layer wiring that propagates high-frequency signals from the BGA pads through the inside of the substrate that constitutes one side of the package. Figure 4(a) shows one side 12 of the package, and Figure 4(b) shows the cross-sectional structure of the substrate that constitutes one side of the package. As shown in Figure 4(b), the substrate is a laminated substrate consisting of multiple layers 121 to 125. Lands 42 that receive vias 40 are formed on the surface of each layer of the laminated substrate, and vias 40 that penetrate the layers are formed within each layer. As is clear from the figure, electrodes that serve as propagation paths are wired from the substrate surface through the layers using vias 40 and lands 42.

[0012] Figure 4(a) shows vias 40a and lands 42a that constitute signal electrodes for transmitting high-frequency signals, and vias 46a to 46h that constitute ground electrodes arranged concentrically around them. In Figure 4(a), vias 40a to 40d and lands 42a to 42d that constitute four signal electrodes and four sets of ground electrodes arranged concentrically around them are shown, but for the sake of explanation, only vias 46a to 46h that constitute one set of ground electrodes are labeled. The ground electrodes consist of multiple vias 46a to 46h arranged concentrically around the signal electrodes and a connected land pattern 48 that concentrically surrounds via 40a and lands 42a that constitute the signal electrodes. The relative permittivity of the material of the electronic component package 12 is about 3 for resin and about 5 to 10 for ceramics. The lower the relative permittivity, the lower the loss of the transmission line that can be constructed. The gap between pads required to make the characteristic impedance of the coaxial transmission path configured in this way 50Ω is as follows. The gap between the signal electrode land 42 and the surrounding multiple vias 46a to 46h or land pattern 48 is approximately 1.5 times the diameter (pad diameter) of the signal electrode via or land in the case of a resin substrate, and approximately 2.5 to 6.5 times in the case of a ceramic substrate.

[0013] The increasing capacity of communication systems necessitates faster signal speeds. To achieve these speeds, the signal speeds exchanged between ICs and optical transceivers are increasing year by year. Currently, devices with baud rates ranging from 32 Gbaud to 64 Gbaud are being put into practical use, and research is underway to further increase speeds to 96 Gbaud and even 128 Gbaud. In the high-frequency range, communication devices generally require an operating frequency of approximately 0.7 times the baud rate, which corresponds to around 45 GHz for 64 Gbaud, 70 GHz for 96 Gbaud, and 90 GHz for 128 Gbaud. Thus, communication devices are required to operate across a wide frequency range, from several hundred kHz in the low-speed range to around 90 GHz in the high-speed range.

[0014] When miniaturizing electronic equipment such as optical transceivers with BGA pads and increasing signal speed, it is necessary to reduce the pitch of the BGA pads and appropriately set the distance between the signal electrode and the ground electrode.

[0015] In high-frequency signal propagation, impedance mismatch can be tolerated without problems if the length of the mismatched portion is kept to less than 1 / 20th of the wavelength. For example, the wavelength of a 45 GHz high-frequency signal is 6.7 mm in a vacuum. On a substrate made of resin or ceramic material, the refractive index of the resin or ceramic material is about 2 to 3, so the wavelength is about 3.3 mm to 2.2 mm. In that case, when a 45 GHz high-frequency signal is propagated through a substrate made of resin or ceramic material, the tolerable length of the mismatched portion is 0.11 mm to 0.16 mm. Since this length is small compared to the size of the BGA pad, impedance mismatch at the BGA connection becomes impossible to ignore in high-frequency signal propagation. Therefore, BGA pads used in electronic component packages used for propagating high-frequency signals must be designed to ensure impedance matching.

[0016] To miniaturize electronic components and optical transceivers used in optical communication systems while providing all the necessary terminals for their operation, BGA pads must be densely arranged. The pitch C of BGA pads has started to be used at intervals of 0.4 mm and 0.3 mm, from 0.5 mm, and the gap between BGA pads is tending to become narrower and narrower. As mentioned above, BGA pads need to be of a certain size to facilitate solder mounting. Therefore, the diameter of the BGA pads formed on the surface of the substrate is made larger than the diameter of the lands used in the inner layers of the substrate. As a result, it is becoming difficult to secure the gap between the PGA pads that make up the signal electrodes and the BGA pads that make up the ground electrodes located around the signal electrodes, in relation to the diameter of the BGA pads that make up the signal electrodes, in order to achieve the size necessary to achieve a characteristic impedance of 50 Ω. Also, as mentioned above, solder resist is placed on the edges of the BGA pads if they are made of resin, or ceramic coating if they are made of ceramics.

[0017] Figure 5 shows the solder resist or ceramic coating width for a typical BGA pad as shown in Figure 1. As described above, circular BGA pads 14 are arranged at equal intervals in a grid pattern with a predetermined pitch in the xy direction within the xy plane, which is one face of the electronic component package. As shown in Figure 2, the portion 22 where the solder resist or ceramic coating 20 and the pad overlap exists around the pad opening 24 for solder connection. The solder resist or ceramic coating 20 defines the size of the solder opening 24, which is the area occupied by the solder bump on the pad.

[0018] As described above, the BGA pad 14 needs to have a portion 22 that overlaps with the solder resist or ceramic coating 20 formed around it. For this reason, the diameter B of the BGA pad needs to be larger than the diameter A of the pad opening (24). Also, as described above, the restraining width of the solder resist or ceramic coating needs to be about 40 to 100 μm. In order to secure this restraining width, the pad diameter B must be larger than the required pad opening diameter A by the restraining width 22. As a result, the gap D between the BGA pad constituting the signal electrode and the BGA pad constituting the ground electrode becomes narrower by the restraining width 22 than when the required solder bump area (opening diameter A) is secured. Therefore, there was a problem in that the characteristic impedance of the transmission line composed of the signal electrode and the ground electrode became even lower. [Prior art documents] [Patent Documents]

[0019] [Patent Document 1] International Publication No. 2021 / 075035 [Overview of the project]

[0020] The present invention aims to provide an electronic component package, such as an IC or optical transceiver, that has pads, in which the gap between the signal electrode pads and the ground electrode pads can be appropriately set even when the pads are densely arranged, thereby preventing a decrease in the characteristic impedance of the high-frequency signal transmission path. Furthermore, the present invention aims to provide high-speed and high-performance electronic components such as ICs and optical transceivers without increasing the size of the electronic components, by preventing the transmission path for transmitting high-frequency signals from becoming low impedance even when the BGA pads of the electronic component package are densely arranged, thereby providing a compact, high-capacity, and high-function optical communication system.

[0021] To achieve this objective, the present invention has the following configuration.

[0022] (Configuration 1) An electronic component package in which pads are arranged in a grid pattern at a predetermined pitch in the x - direction and the y - direction orthogonal to the x - direction on the x - y plane, the suppression width of the solder resist or ceramic coat and the size of the pads of the pads for signal electrodes for inputting or outputting high - frequency signals arranged on one side of the outermost periphery and the pads for ground electrodes adjacent to the pads for signal electrodes in the x - direction and the y - direction are, smaller than the suppression width of the solder resist or ceramic coat and the size of the pads of the other pads, characterized in that it is an electronic component package.

[0023] (Configuration 2) An electronic component package in which pads are arranged in a grid pattern at a predetermined pitch in the x - direction and the y - direction orthogonal to the x - direction on the x - y plane, the suppression width of the solder resist or ceramic coat and the size of the pads of the pads for signal electrodes for inputting or outputting high - frequency signals arranged in the second row of one side of the outermost periphery and the pads for ground electrodes adjacent to the pads for signal electrodes in the x - direction and the y - direction are, smaller than the suppression width of the solder resist or ceramic coat and the size of the pads of the other pads, characterized in that it is an electronic component package.

[0024] (Configuration 3) An electronic equipment package in which pads are arranged in a grid pattern at a predetermined pitch in the x - direction and the y - direction orthogonal to the x - direction on the x - y plane, comprising pads for signal electrodes for inputting or outputting high - frequency signals arranged on one side of the outer periphery of the electronic component and pads for ground electrodes adjacent to the pads for signal electrodes in the x - direction, and the pads between the pads for signal electrodes and the pads for ground electrodes adjacent to the pads for signal electrodes in the x - direction are deleted, and the interval between the pads for signal electrodes and the pads for ground electrodes adjacent to the pads for signal electrodes in the x - direction is larger than the interval between the other pads, characterized in that it is an electronic component package.

[0025] According to the electronic component packages such as the ICs and optical transceivers of the above-described configurations 1 to 3, impedance matching can be achieved without reducing the characteristic impedance of the pad connection portion, so that a small-sized, large-capacity, and high-functional optical communication system can be provided.

Brief Description of the Drawings

[0026] [Figure 1] FIG. 1 is a diagram showing an electronic component package having BGA pads arranged at equal intervals, which is a prior art. [Figure 2] FIG. 2 is a diagram showing two adjacent BGA pads of the electronic component package of FIG. 1. [Figure 3] FIG. 3 is a diagram showing a table indicating the relationship between the pad pitch and the pad opening diameter of BGA and LGA, excerpted from JEITA EDR-7316C, Integrated Circuit Package Design Guide. [Figure 4] FIG. 4 is a diagram showing the structure of a substrate formed of resin or ceramic provided with an inner layer wiring for propagating a high-frequency signal passing through the inside of the substrate constituting one surface of the package from the BGA pad. [Figure 5] FIG. 5 is a diagram showing BGA pads in a state where a general BGA solder resist or a ceramic coat is seen through. [Figure 6] FIG. 6 is a diagram showing an electronic component package having BGA pads according to Example 1 of the present invention. [Figure 7] FIG. 7 is a diagram showing an electronic component package having BGA pads according to Example 2 of the present invention. [Figure 8] FIG. 8 is a diagram showing an electronic component package having BGA pads according to Example 3 of the present invention. [Figure 9] FIG. 9 is a diagram showing an electronic component package having BGA pads according to Example 4 of the present invention.

Modes for Carrying Out the Invention

[0027] Embodiments of the present invention will be described in detail below with reference to the drawings. [Examples]

[0028] Figure 6 shows an electronic component package having BGA pads according to Embodiment 1 of the present invention. Similar to Figure 5, Figure 6 shows the solder resist or ceramic coating width for each BGA pad in Embodiment 1. The electronic component shown in Figure 6 has circular BGA pads 61 arranged in a grid pattern in the xy direction at a predetermined pitch on one surface 60 of a package made of a resin such as glass epoxy or ceramic. Each BGA pad is made of a metal such as aluminum or copper. It is desirable to plate the BGA pads with gold, silver, or palladium to enable solder connections.

[0029] In the figure, BGA pads S for signal electrodes, which are used to input or output high-speed electrical signals, are indicated by pads with the letter S in the pad opening. Similarly, BGA pads G for ground electrodes are indicated by pads with the letter G in the pad opening. These BGA pads S for signal electrodes and BGA pads G for ground electrodes are arranged close together on one side of one face 60 of the electronic component package. In this embodiment, the BGA pads S for signal electrodes are located in the first row of BGA pads from the left, which forms the outermost edge of the pads. The difference from the conventional design shown in Figure 1 is that the retaining width 66a of the BGA pads S64a and S64b for signal electrodes, and the retaining width 66b of the solder resist or ceramic coating of the BGA pads G65a to G65d for ground electrodes, which are adjacent to the BGA pads S64a and S64b in the x and y directions, are smaller than the retaining width 62a of the other BGA pads 61. In Figure 6, for the sake of clarity, only the BGA pads S for the signal electrodes and BGA pads G for the ground electrodes that constitute a differential pair are typically labeled. The following explanation will focus on this differential pair, but the other three differential pairs of BGA pads have the same configuration. Furthermore, only one of the other BGA pads 61 is typically labeled. Also, the pad widths for each type of pad are only partially labeled. (The same applies to Figures 7 through 9.)

[0030] In Figure 6, the clamping widths 62b and 62c of the ground electrode BGA pads G67a and 67b, which are diagonally adjacent to the signal electrode BGA pads S64a and 64b, are the same size as the clamping width 62a of the other BGA pad 61. However, the clamping width of these ground electrode BGA pads G67a and 67b may be made smaller, similar to the ground electrode BGA pads 65a to 65d. However, as will be described later, reducing the clamping width of a pad reduces the strength of the pad, so it is desirable to reduce the number of pads with reduced clamping widths as much as possible. Therefore, in this embodiment 1, only the ground electrode BGA pads G65a to 65d, which are the ground electrode BGA pads closest to the signal electrode BGA pads S64a and 64b and are adjacent in the x and y directions, have reduced clamping widths. The ground electrode BGA pads G67a and 67b, which are diagonally adjacent to the signal electrode BGA pads S64a and 64b, may be pads other than ground electrode pads.

[0031] In optical transceivers for coherent optical communication, differential transmission typically uses a total of eight signal terminals: four for transmission and four for reception. As mentioned above, these signal terminals are formed close together on one side of the component. In Figure 6, one differential signal pair consists of two adjacent BGA pads S64a,64b for signal electrodes and six BGA pads G65a~65d,67a,67b for ground electrodes adjacent to the signal electrode BGA pads S. Figure 6 shows that a total of four BGA pads for the transmission paths of differential signal pairs are formed on one end of the component.

[0032] In the electronic component package of this embodiment, as in the conventional design, the BGA pads are arranged at a predetermined pitch in the xy direction within the xy plane. In the BGA of Figure 1, each BGA pad had the same diameter, but in this embodiment, the BGA pads S64a and S64b for signal electrodes, the BGA pads G65c and S65d for ground electrodes adjacent to the BGA pads S for signal electrodes in the x direction, and the BGA pads G65a and S65b for ground electrodes adjacent to the BGA pads S for signal electrodes in the y direction have a pad diameter B smaller than the pad diameter B of the other BGA pads 61 and the BGA pads G67a and S67b for ground electrodes. Furthermore, the diameter A of the pad opening 64 of the BGA pads S64a and S64b for signal electrodes, the BGA pads G65a to S65d, G67a and S67b for ground electrodes, and the other BGA pads 61 are all set to be the same.

[0033] As described above, when transmitting high-frequency signals from BGA pads using internal layer wiring such as vias located inside the substrate that constitutes one side of an electronic component package made of resin or ceramic, it is necessary to adjust and match the characteristic impedance of the transmission path composed of the internal layer wiring. The characteristic impedance of the transmission path can be adjusted by adjusting the distance between the signal electrode through which the high-frequency signal propagates and the ground electrode for carrying the return current. As described above, in order to ensure solder connection strength, BGA pads must have a pad opening that defines the area of ​​the solder bump on the BGA pad, which must be of a certain size or larger, and therefore BGA pads must be of a certain size or larger. Consequently, even when reducing the pitch of BGA pads to miniaturize electronic components, it is undesirable to make the size of the BGA pads smaller than the predetermined size. Due to these constraints, when miniaturizing a BGA while having the same number of BGA pads, the gap between the BGA pads becomes narrower, resulting in a problem where the characteristic impedance becomes lower than the ideal value.

[0034] In this embodiment 1, the clamping width of the BGA pad S for the signal electrode, which requires adjustment of characteristic impedance, and the adjacent BGA pad G for the ground electrode are made smaller than the clamping width of the other BGA pads. This makes it possible to reduce the size of the pads while maintaining the same opening pad diameter. As a result, while keeping the pitch C and opening pad diameter A of all BGA pads the same, the gap D between the BGA pad S for the signal electrode and the adjacent BGA pad for the ground electrode is made larger than the others, preventing a decrease in characteristic impedance.

[0035] When forming an electronic component package using ceramics, the ceramic coating width needs to be, for example, 75 μm to ensure the strength of the BGA pads. In this embodiment, for example, suppose the coating width for the BGA pad for the signal electrode and the adjacent BGA pad for the ground electrode is set to 45 μm. In this case, the gap between the signal electrode and the adjacent ground electrode can be made 30 μm × 2 larger than conventionally without compromising the strength of the other BGA pads.

[0036] As described above, the electronic component package of this embodiment 1 was able to prevent a decrease in the characteristic impedance of the transmission line composed of the signal electrode and the ground electrode, thereby broadening the operating frequency of the electronic component.

[0037] In order to achieve a compact size while providing all the necessary terminals for the operation of electronic components and optical transceivers used in optical communication systems, it is necessary to arrange the BGA pads closely together. The pitch between BGA pads has started to be used at intervals of 0.5 mm, 0.4 mm, 0.3 mm, etc., and the gap between the signal electrode and the adjacent ground electrode is becoming increasingly narrow. In this context, the electronic component package of Example 1 allows for a larger gap between the signal electrode and the ground electrode adjacent to it in the x and y directions than in conventional designs. [Examples]

[0038] Figure 7 shows an electronic component package having BGA pads according to Embodiment 2 of the present invention. Similar to Figure 5, Figure 7 shows the retaining width of the BGA pads in Embodiment 2. The electronic component shown in Figure 7 has circular BGA pads 71 ​​arranged in a grid pattern at a predetermined pitch in the xy direction on an xy plane, which is one surface 70 of the electronic component package made of a resin such as glass epoxy or ceramic. Each BGA pad is made of a metal such as aluminum or copper. It is desirable that the BGA pads be plated with gold, silver, or palladium to enable soldering.

[0039] In Figure 7, the BGA pads S for signal electrodes and BGA pads G for ground electrodes are shown in the same manner as in Figure 6. The differences from the conventional general electronic component package shown in Figure 1 are, firstly, that the clamping width 76a of the BGA pads S74a and S74b for signal electrodes and the clamping width 76b of the BGA pads S75a and S75b for ground electrodes adjacent to the BGA pads S for signal electrodes are smaller than the clamping width 72a of the other BGA pads 71. Secondly, the BGA pads adjacent to the BGA pads S74a and S74b for signal electrodes in the x-direction have been removed, and the BGA pads for ground electrodes in the x-direction of the BGA pads S74a and S74b for signal electrodes have been replaced with BGA pads 77a and S77b adjacent to the removed BGA pads in the same x-direction. As a result, the distance between the BGA pad S for the signal electrode and the BGA pads G77a and G77b for the ground electrode adjacent to the BGA pad S in the x-direction is greater than the distance between other BGA pads 71. In other words, in Embodiment 2, the distance between the BGA pads S74a and G74b for the signal electrode and the BGA pads 76a and G76b for the ground electrode is greater than the distance between the BGA pad S and the adjacent deleted BGA pad, which is the distance between other BGA pads. In Figure 7, the BGA pad terminals for the transmission paths of the four differential signal pairs are formed close to one side of the electronic component.

[0040] In the electronic component package of this embodiment 2, the BGA pads are arranged in a grid pattern in the xy plane at a predetermined pitch in the xy direction, except for the spacing between the signal electrode BGA pads S74a, 74b and the ground electrode BGA pads G76a, 76b adjacent to the signal electrode BGA pad S in the x direction. In the electronic component package of this embodiment 2, the pad diameter B of the signal electrode BGA pads S74a, 74b and the ground electrodes G75a, 75b adjacent to the signal electrode BGA pad S in the y direction is smaller than the pad diameter of the other BGA pads 71, 77a, 77b, 78a, 78b. In this embodiment 2, the ground electrodes G75a, 75b that are closest to the signal electrode BGA pad S are only adjacent in the y direction, and the BGA pads adjacent in the x direction are omitted. In embodiment 2 as well, the diameter A of the pad opening 73 of all BGA pads is set to be the same. In Example 2, similar to Example 1, in order to reduce the number of pads with reduced clamping width, the clamping width 76b is reduced only for the closest adjacent pads 75a and 75b in the y-direction, while the clamping width 72c of the diagonally adjacent ground electrode pads 78a and 78b is made the same as the clamping width 72b of the other BGA pads 71.

[0041] In Example 2, the ground electrode BGA pads adjacent to the signal electrode BGA pads S74a and 74b in the x-direction are assigned to the BGA pads 77a and 77b adjacent to the deleted BGA pads in the same x-direction. As a result, the spacing between the signal electrode BGA pads S74a and 74b and the ground electrode BGA pads G76a and 76b adjacent to the signal electrode BGA pads S in the x-direction is larger than the spacing between the signal electrode BGA pad S and the deleted BGA pad adjacent to it in the x-direction, i.e., the spacing between other BGA pads. The retaining width 72b of the ground electrode BGA pads 77a and 77b adjacent to the signal electrode pads in the x-direction is the same as the retaining width 72a of the other pads, but it may be made narrower, similar to the ground electrode pads 75a and 75b. Furthermore, the BGA pads S74a and S74b for signal electrodes and the BGA pad G for ground electrodes adjacent in the x-direction may be the third or subsequent adjacent BGA pads in the x-direction. As described above, when transmitting high-frequency signals from BGA pads using internal layer wiring such as vias configured inside a substrate made of resin or ceramic, it is necessary to adjust and match the characteristic impedance of the transmission path composed of the internal layer wiring.

[0042] The characteristic impedance of the transmission path can be adjusted by adjusting the spacing between the signal electrode through which the high-frequency signal propagates and the ground electrode for carrying the return current. As mentioned above, BGA pads require that the pad openings defining the area of ​​the solder bumps be at least a certain size in order to ensure solder connection strength. Therefore, even when reducing the spacing between BGA pads to miniaturize electronic components, it is undesirable to reduce the size of the BGA pads below a predetermined size. Due to these constraints, when miniaturizing a BGA while maintaining the same number of BGA pads, the spacing between the BGA pads becomes narrower, resulting in a problem where the characteristic impedance becomes lower than the ideal value.

[0043] In this embodiment 2, the restraining width of the BGA pad S for the signal electrode, which requires adjustment of its characteristic impedance, and the BGA pad G for the ground electrode adjacent to it in the y-direction, is made smaller than the restraining width of the other BGA pads. This allows for a larger spacing between the BGA pad S for the signal electrode and the BGA pad G for the ground electrode adjacent to it in the y-direction. Furthermore, the BGA pad S for the signal electrode and the BGA pad adjacent to it in the x-direction are removed, and the BGA pad G (76) for the ground electrode adjacent to it in the x-direction is placed on the pad adjacent to the removed pad in the same x-direction. Therefore, a larger spacing can be made between the BGA pad S for the signal electrode and the BGA pad G for the ground electrode adjacent to it in the x-direction. Consequently, a decrease in the characteristic impedance of the transmission path composed of these components is prevented, and the operating frequency of the electronic components is widened.

[0044] In order to reduce the size of a BGA while still providing all the necessary terminals for the operation of electronic components and optical transceivers used in optical communication systems, it is necessary to arrange the BGA pads closely together. The pitch between BGA pads has started to be used at intervals of 0.5 mm, 0.4 mm, 0.3 mm, etc., and the gap between the signal electrode and the adjacent ground electrode is becoming increasingly narrow. The BGA in Example 2 was able to increase the gap between the signal electrode and the ground electrode adjacent in the x direction, and the ground electrode adjacent in the y direction, compared to conventional designs. [Examples]

[0045] Figure 8 shows an electronic component package having BGA pads according to Embodiment 3 of the present invention. In Figure 8, as in Figure 5, the restraining width of the solder resist or ceramic coating on the BGA pads of Embodiment 3 is shown. In Figure 8, as in Figure 6, the BGA pads S for signal electrodes and BGA pads G for ground electrodes are shown in the same manner as in Figure 6. In the BGA pads of Embodiment 3, as in Embodiment 1, the restraining width 87a of the BGA pads S84a, 84b for signal electrodes and the restraining widths 86b, 86c of the BGA pads G85a~d for ground electrodes adjacent to the BGA pads S for signal electrodes in the x direction and the BGA pads G85e, 85f for ground electrodes adjacent in the y direction are smaller than the restraining width 82a of the other BGA pads 81.

[0046] In Embodiment 3, as shown in Figure 8, a pair of terminals for operating signals is formed by two adjacent BGA pads S84a,84b for differential signal pairs, six BGA pads G85a~85f for ground electrodes adjacent to the signal electrode BGA pads S in the x and y directions, and four BGA pads G88a~88d for ground electrodes diagonally adjacent to the signal electrode BGA pads S84a,84b. In total, four pairs of BGA pads for the transmission path of differential signal pairs are formed. Unlike Embodiment 1, in Embodiment 3, the BGA pads S84a,84b for signal electrodes that input or output electrical signals are located in the second row of BGA pads from the left.

[0047] Furthermore, in the first column of BGA pads from the left, unlike in Example 1, there are pads 88a and 88b whose retaining width 82b is the same as the retaining width 82a of the other pads. In the electronic component package of this embodiment, as in Example 1, the BGA pads S84a and 84b for signal electrodes and the BGA pads G85a to 85f for ground electrodes have smaller pad diameters than the other BGA pads 81. Also, the diameter A of the pad opening 83 of all BGA pads is set to be the same.

[0048] In this embodiment, the solder resist or ceramic coating holding width 86a of the signal electrode BGA pads S84a, 84b and the holding widths 86b, 86c of the ground electrode BGA pads G85a~85f adjacent to them in the xy direction are smaller than the holding width 82a of the other BGA pad 81 and the holding width 82b of the ground electrode BGA pads G88a~88d, thus reducing their strength compared to the other BGA pads. If a BGA pad located at one end of a BGA pad arranged at a predetermined pitch in the xy direction within the xy plane is weaker than other BGA pads, the BGA pad located at one end is more prone to fracture due to stress from thermal shrinkage or pressure applied during the operation of electronic components.

[0049] Therefore, in Example 3, the BGA pads S84a and S84b for signal electrodes are placed in the second row of BGA pads from the left. In addition, in the first and third rows of BGA pads from the left, there are ground electrode BGA pads G85a to G85d adjacent to the signal electrode BGA pads S84a and S84b in the x direction, and ground electrode BGA pads G88a to G88d adjacent to the ground electrode BGA pads G85e and G85f adjacent to the signal electrode BGA pad S in the y direction in the x direction. The solder resist or ceramic coating restraint widths 82b and 82c of these ground electrode BGA pads G88a to G88d are the same normal size as the restraint width 82a of the other BGA pads 81, so the pad strength is not reduced. Note that these ground electrode BGA pads 88a to G88d may be pads other than ground electrode pads.

[0050] Thus, in this embodiment 3, the first row of BGA pads from the left on one end of the electronic component contains BGA pads 88a and 88b, which have not experienced a decrease in strength. These BGA pads 88a and 88b protect the BGA pads S84a and 84b for signal electrodes, which have experienced a decrease in strength, and the BGA pads G85a to 85f for ground electrodes that are adjacent to them in the x and y directions.

[0051] In the electronic component package of Example 3, in addition to making the gap between the signal electrode and the ground electrode adjacent to it in the x and y directions larger than in conventional designs, the possibility of the BGA pad S for the signal electrode and the BGA pad G for the ground electrode adjacent to it in the x and y directions breaking due to stress from thermal shrinkage or pressure applied during operation can be reduced. [Examples]

[0052] Figure 9 shows an electronic component package having BGA pads according to Embodiment 4 of the present invention. In Figure 9, as in Figure 5, the clamping width of the BGA pads in Embodiment 4 is shown. In Figure 9, as in Figure 6, the BGA pad S for signal electrodes and the BGA pad G for ground electrodes are shown in the same manner as in Figure 6. In Embodiment 4, as in Embodiment 1, the clamping width 96a of the BGA pads S94a and 94b for signal electrodes and the clamping width 96b of the BGA pads G95a and 95b for ground electrodes adjacent to the BGA pad S for signal electrodes in the y direction are smaller than the clamping width 92a of the other BGA pads 91.

[0053] Furthermore, similar to Example 2, the BGA pads adjacent to the signal electrode BGA pads 94a and 94b in the x-direction are deleted. Then, the ground electrode BGA pads corresponding to the x-direction of the signal electrode BGA pads S94a and 94b are replaced with BGA pads 97a and 97b, which are located in the same x-direction adjacent positions as the deleted BGA pads. As a result, the spacing between the signal electrode BGA pads S94a and 94b and the ground electrode BGA pads S96a and 96b adjacent to the signal electrode BGA pad S in the x-direction is made larger than the spacing between other BGA pads 91.

[0054] In other words, in Example 4, the spacing between the signal electrode BGA pads S94a, 94b and the ground electrode BGA pads G96a, 96b is greater than the spacing between the electrodes of other BGA pads, which is the spacing between the BGA pads S94a, 94b and the adjacent deleted BGA pads. In Example 4, as in Example 3, the signal electrode BGA pads S94a, 94b are located in the second column of BGA pads from the left. Therefore, in Example 4, the BGA pads to be deleted that are adjacent to the signal electrode BGA pads S94a, 94b in the x-direction are located to the left and right of the signal electrode BGA pad S in the x-direction.

[0055] In Example 4, when the BGA pads S94a and 94b for the signal electrodes are positioned in the third row of BGA pads from the left, the ground electrode pad G adjacent to the BGA pad S for the signal electrodes is positioned to the left of the BGA pads S94a and 94b in the x-direction.

[0056] As shown in Figure 9, a pair of differential signal terminals consists of two BGA pads S94a, 94b for signal electrodes, two BGA pads G95a, 95b for ground electrodes adjacent to BGA pad S in the y-direction, two BGA pads G97a, 97b for ground electrodes adjacent to BGA pad S in the x-direction, and BGA pads G98a~98d for ground electrodes adjacent in the x-direction to BGA pads G95a, 95b adjacent to BGA pad S in the y-direction. In this embodiment 4, as shown in Figure 9, a total of four GPA pads for the transmission paths of differential signal pairs are formed.

[0057] In this embodiment 4, as in embodiment 2, the BGA pads S94a, 94b for signal electrodes and the BGA pads G95a, 95b for ground electrodes adjacent to the BGA pads S for signal electrodes in the y-direction have smaller pad diameters than the other BGA pads 91 and the BGA pads G97a, 97b and G98a-98d for ground electrodes. Also, the diameter A of the pad opening 93 of all BGA pads is set to be the same. In this embodiment 4, as in embodiment 2, the BGA pads are arranged at a predetermined pitch in the xy direction within the xy plane, except for the spacing between the BGA pads S94a, 94b for signal electrodes and the BGA pads G97a, 97b for ground electrodes adjacent to the BGA pads S for signal electrodes in the x-direction.

[0058] In this embodiment 4, similar to embodiment 2, the clamping width of the BGA pad S for the signal electrode, which requires adjustment of characteristic impedance, and the BGA pad G for the ground electrode, which is adjacent to the BGA pad S for the signal electrode in the y-direction, is made smaller than the clamping width of the other BGA pads. This makes it possible to create a larger gap between the BGA pad S for the signal electrode and the BGA pad G for the ground electrode, which is adjacent to it in the y-direction.

[0059] In Example 4, the BGA pads adjacent to the signal electrode BGA pads S94a and 94b in the x-direction are further removed. The BGA pads 97a and 97b adjacent to the removed BGA pads in the same x-direction are then used as ground electrode BGA pads G adjacent to the signal electrode BGA pad S in the x-direction. As a result, the spacing between the signal electrode BGA pad S and the ground electrode BGA pad G adjacent to it in the x-direction is larger than the spacing between other BGA pads. Consequently, a decrease in the characteristic impedance of the transmission path formed by these pads is prevented, and the operating frequency of the electronic components is broadened.

[0060] Furthermore, in this embodiment 4, the BGA pads S94a and 94b for signal electrodes are located in the second column of BGA pads from the left. The BGA pads adjacent to the signal electrode BGA pads S94a and 94b in the first column of BGA pads from the left have been removed. In the first column of BGA terminals from the left, there are ground electrode BGA pads 98a and 98b adjacent in the x direction to the ground electrode BGA pads G95a and 95b adjacent in the y direction to the signal electrode BGA pads S94a and 94b. Note that BGA pads 98a to 98d may be pads other than ground electrode pads.

[0061] Since the clamping width 92c of these BGA pads 98a to 98d is the same normal size as the clamping width 92a of the other BGA pads 91, the strength of the BGA pads is not reduced. Therefore, in Example 4, similar to Example 3, the possibility of the BGA pads S94a, 94b for the signal electrodes and the BGA pads 95a, 95b for the ground electrodes adjacent to them in the y-direction being fractured due to stress from thermal shrinkage or pressure applied during operation can also be reduced.

[0062] (Effects of the invention) As described above, the present invention provides an electronic component such as an IC or optical transceiver having BGA pads, in which the gap between the BGA pads for signal electrodes, which require adjustment of characteristic impedance, can be made larger than the gap between BGA pads arranged at a predetermined pitch. This allows the characteristic impedance of the BGA connection portion to be maintained at an appropriate value without decreasing. By realizing an impedance-matched IC or optical transceiver with the present invention, it is possible to provide a compact, high-capacity, and high-performance optical communication system. [Industrial applicability]

[0063] The present invention can be used in optical communication systems in general. In particular, it relates to an electronic component package, such as an optical transceiver having a BGA pad, used in optical communication systems.

Claims

1. An electronic component package in which pads are arranged in a grid pattern at a predetermined pitch in the x-y plane in the x direction and in the y direction perpendicular to the x direction, The solder resist or ceramic coating restraint width and pad size for the signal electrode pads that input or output high-frequency signals, located on one of the outermost edges, and the ground electrode pads adjacent to the signal electrode pads in the x and y directions, The solder resist of other pads, or the retaining width and size of the ceramic coating, are smaller than the pad size. An electronic component package characterized by the following features.

2. An electronic component package in which pads are arranged in a grid pattern at a predetermined pitch in the x-y plane in the x direction and in the y direction perpendicular to the x direction, The solder resist or ceramic coating restraint width and pad size of the signal electrode pads for inputting or outputting high-frequency signals, located in the second row on the outermost edge of one side, and the ground electrode pads adjacent to the signal electrode pads in the x and y directions, are as follows: The solder resist of other pads, or the retaining width and size of the ceramic coating, are smaller than the pad size. An electronic component package characterized by the following features.

3. The electronic component package according to claim 1 or 2, characterized in that the solder resist or ceramic coating restraint width and pad size of the pad adjacent in the x direction to the ground electrode pad adjacent in the y direction to the signal electrode pad are the same as those of the other BGA pads.

4. An electronic component package in which pads are arranged in a grid pattern at a predetermined pitch in the x-direction of the x-y plane and in the y-direction perpendicular to the x-direction, An electronic component comprises a pad for a signal electrode that inputs or outputs a high-frequency signal, arranged on one side of the outer circumference of the electronic component, and a ground electrode pad adjacent to the signal electrode pad in the x-direction, wherein the pad adjacent to the signal electrode pad in the x-direction has been removed, and the spacing between the signal electrode pad and the ground electrode pad adjacent to the signal electrode pad in the x-direction is greater than the spacing between other pads. An electronic component package characterized by the following features.

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