Optical module

Abstract

The utility model discloses a light module has element mounting area on the surface of non-airtight circuit board for installing components and parts without air seal, and has chip mounting area on the top of air-tight circuit board for installing bare chip needing air seal, and the air-tight circuit board and tube shell form air-tight space for air seal bare chip and bonding wire. Therefore, the light module reduces the volume of air-tight circuit board, improves the reliability of air-tight circuit board, and solves the technical problems of large volume and low reliability of air-tight circuit board in the prior art.

Description

Technical Field

[0001] This utility model relates to the field of communication technology, and in particular to an optical module. Background Technology

[0002] Optical modules are core components of optical communication networks. Their application environments are diverse and complex. If the optoelectronic chips and gold bonding wires inside the optical module are not sealed, they will face a variety of serious hazards such as moisture corrosion, ion contamination, and oxidation, leading to performance degradation or even functional failure.

[0003] To cope with harsh external environments, a requirement was put forward for hermetic packaging of the core optoelectronic chip and gold wire bonding wire of the optical module.

[0004] Currently, most hermetically sealed optical modules are completely sealed, placing all units in a ceramic sealing structure. Different wiring configurations of ceramic-packaged optical modules need to be developed according to different requirements, and the ceramic substrate is relatively large, which leads to a decrease in the mechanical reliability of the ceramic. Summary of the Invention

[0005] This invention proposes an optical module that solves the technical problems of large size and low reliability of airtight circuit boards in the prior art.

[0006] To achieve the above objectives, the present invention adopts the following technical solution: This utility model provides an optical module, including: Non-hermetic circuit board with component mounting areas on its surface; An airtight circuit board has a chip mounting area and a pad area on its top, the pad area including multiple pads arranged around the chip mounting area; its bottom is electrically connected to the non-airtight circuit board. The housing is mounted on the hermetic circuit board, forming a hermetic space with the hermetic circuit board; the chip mounting area and the pad area are located within the hermetic space. A bare die is mounted in the chip mounting area and located within the hermetic space; the bare die is electrically connected to the pads of the hermetic circuit board via bonding wires.

[0007] In some embodiments of this application, the top of the airtight circuit board has a differential signal wiring area and a normal signal wiring area; The differential signal wiring area includes multiple pairs of differential signal lines, and the ordinary signal wiring area includes multiple ordinary signal lines.

[0008] In some embodiments of this application, the chip mounting area is a square area; The pad area includes a first pad partition, a second pad partition, and a third pad partition; each of the first pad partition, the second pad partition, and the third pad partition includes multiple pads. The ordinary signal cabling area includes a first cabling section and a third cabling section; both the first cabling section and the third cabling section include multiple ordinary signal lines; The first pad partition and the first routing partition are located on the first side of the chip mounting area; the first pad partition is closer to the first side of the chip mounting area than the first routing partition; the pads of the first pad partition are connected to the ordinary signal lines of the first routing partition. The third pad partition and the third wiring partition are located on the third side of the chip mounting area; the third pad partition is closer to the third side of the chip mounting area than the third wiring partition; the pads of the third pad partition are connected to the ordinary signal lines of the third wiring partition. The second pad partition and the differential signal routing area are located on the second side of the chip mounting area; the second pad partition is closer to the second side of the chip mounting area than the differential signal routing area; the pads of the second pad partition are connected to the differential signal lines of the differential signal routing area. The first and third sides of the chip mounting area are opposite sides, and the second side of the chip mounting area is adjacent to the first and third sides respectively.

[0009] In some embodiments of this application, the bottom of the hermetic circuit board has BGA solder balls, and the top of the non-hermetic circuit board has BGA pads, with the BGA solder balls of the hermetic circuit board soldered together with the BGA pads of the non-hermetic circuit board.

[0010] In some embodiments of this application, the chip mounting area is provided with a plurality of vias, and the vias are filled with thermally conductive metal.

[0011] In some embodiments of this application, the airtight circuit board is a ceramic circuit board; the non-airtight circuit board is a resin circuit board.

[0012] In some embodiments of this application, the casing is a metal casing that is welded together with the airtight circuit board.

[0013] In some embodiments of this application, the bare chip includes an electrical chip and an optical chip; The optical chip is electrically connected to the electrical chip via bonding wires; The electrical chip is electrically connected to the pads of the hermetic circuit board via bonding wires.

[0014] In some embodiments of this application, the optical module further includes a first adapter board; the first adapter board is installed in the chip mounting area; The top of the first adapter board has several pads; The pads of the electrical chip are electrically connected to the pads of the first adapter board via bonding wires, and the pads of the first adapter board are electrically connected to the pads of the hermetic circuit board via bonding wires.

[0015] In some embodiments of this application, two electrical chips are provided, wherein a second adapter board is provided on the top of the first electrical chip, and the top of the second adapter board has a plurality of pads. Several pads of the second electrical chip are electrically connected to several pads of the second adapter board via bonding wires, and several pads of the second adapter board are electrically connected to several pads of the hermetic circuit board via bonding wires.

[0016] The technical solution of this utility model has the following advantages over the prior art: The optical module of this utility model features a component mounting area on the surface of a non-hermetic circuit board for mounting components that do not require hermetic sealing; and a chip mounting area on the top of a hermetic circuit board for mounting bare chips that require hermetic sealing. The hermetic circuit board and the housing form a hermetic space for hermetic sealing of the bare chips and bonding wires. Therefore, the optical module of this utility model, by mounting the bare chips and bonding wires that require hermetic sealing on the hermetic circuit board and other components that do not require hermetic sealing on the non-hermetic circuit board, reduces the size of the hermetic circuit board, improves its reliability, and solves the technical problems of large size and low reliability of hermetic circuit boards in the prior art. Attached Figure Description

[0017] To more clearly illustrate the technical solutions of the embodiments of this utility model, the drawings used in the description of the embodiments will be briefly introduced below. Obviously, the drawings described below are only some embodiments of this utility model. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0018] Figure 1 This is a schematic diagram of the structure of one embodiment of the optical module of this utility model; Figure 2 This is a schematic diagram of the structure of one embodiment of the airtight circuit board and the non-airtight circuit board of the optical module of this utility model; Figure 3 This is a diagram of the pads and traces of an embodiment of the airtight circuit board of the optical module of this utility model. Figure 4 This is a chip layout diagram of one embodiment of the airtight circuit board of the optical module of this utility model; Figure 5 This is a chip layout diagram of another embodiment of the airtight circuit board of the optical module of this utility model; Figure 6 This is a chip layout diagram of another embodiment of the airtight circuit board of the optical module of this utility model; Figure 7 This is a chip layout diagram of another embodiment of the airtight circuit board of the optical module of this utility model; Figure 8 This is a chip layout diagram of another embodiment of the airtight circuit board of the optical module of this utility model.

[0019] Figure label: 100. Non-hermetic circuit board; 101. BGA pads; 102. Components; 200. Airtight circuit board; 210. Chip mounting area; 211. Via; 212. Surface mount marker; 221, pad; 222, pad; 223, pad; 224, pad; 225, pad; 231. Differential signal line; 232. Ordinary signal line; 233. Ordinary signal line; 234. Ground line; 241. Electrical chip; 242. Optical chip; 243. Electrical chip; 244. Electrical chip; 245. Electrical chip; 246. Electrical chip; 247. Electrical chip; 248. Optical chip; 249. Optical chip; 291. Optical chip; 292. Optical chip; 250, First adapter board; 251, Solder pads; 260. Second adapter board; 261. Solder pads; 271. Bond wire; 280, BGA solder balls; 300. Tube shell. Detailed Implementation

[0020] The technical solutions of the present utility model will be clearly and completely described below with reference to the accompanying drawings of the embodiments. Obviously, the described embodiments are only some embodiments of the present utility model, and not all embodiments. Based on the embodiments of the present utility model, all other embodiments obtained by those of ordinary skill in the art without creative effort are within the scope of protection of this application.

[0021] In the description of this application, it should be understood that the terms "center", "upper", "lower", "front", "rear", "top", "bottom", "inner", "outer", etc., indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings, and are only for the convenience of describing this application and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation, and therefore should not be construed as a limitation of this application.

[0022] In the description of this application, it should be understood that the terms "first" and "second" are used for descriptive purposes only and should not be construed as indicating or implying relative importance or implicitly specifying the number of indicated technical features. Therefore, a feature defined as "first" or "second" may explicitly or implicitly include one or more of that feature. In the description of this application, unless otherwise stated, "multiple" means two or more.

[0023] In the description of this application, it should be noted that, unless otherwise expressly specified and limited, the terms "installation," "connection," and "linking" should be interpreted broadly. For example, they can refer to a fixed connection, a detachable connection, or an integral connection; they can refer to a mechanical connection or an electrical connection; they can refer to a direct connection or an indirect connection through an intermediate medium; and they can refer to the internal connection between two components. Those skilled in the art can understand the specific meaning of the above terms in this application based on the specific circumstances.

[0024] The optical module in this embodiment includes a non-hermetic circuit board 100, a hermetic circuit board 200, a housing 300, a bare chip, etc. (See attached image) Figures 1 to 7 As shown.

[0025] The non-hermetic circuit board 100 has a component mounting area on its surface for mounting components 102 that do not require hermetic sealing.

[0026] The hermetic circuit board 200 has a chip mounting area 210 and a pad area on its top. The pad area includes multiple pads arranged around the chip mounting area 210. The bottom of the hermetic circuit board 200 is electrically connected to the non-hermetic circuit board 100.

[0027] The housing 300 is mounted on the hermetic circuit board 200, forming a hermetic space with the hermetic circuit board 200. The chip mounting area 210 and the pad area are located within the hermetic space.

[0028] A bare die is mounted in the die mounting area 210 and located within a hermetically sealed space. The bare die is electrically connected to the pads of the hermetically sealed circuit board 200 via bonding wires. The bare die, bonding wires, etc., are located within the hermetically sealed space.

[0029] The optical module of this embodiment features a component mounting area 210 on the surface of the non-hermetic circuit board 100 for mounting components 102 that do not require hermetic sealing; and a chip mounting area 210 on the top of the hermetic circuit board 200 for mounting bare chips that require hermetic sealing. The hermetic circuit board 200 and the housing 300 form a hermetic space for hermetic sealing the bare chips and bonding wires. Therefore, the optical module of this embodiment, by mounting the bare chips and bonding wires that require hermetic sealing on the hermetic circuit board 200 and mounting other components 102 that do not require hermetic sealing on the non-hermetic circuit board 100, reduces the size of the hermetic circuit board 200, improves its reliability, and solves the technical problems of large size and low reliability of hermetic circuit boards in the prior art.

[0030] In some embodiments of this application, the bonding wire is a gold wire bonding wire, which has high reliability and strong stability.

[0031] In some embodiments of this application, the top of the airtight circuit board 200 has a differential signal wiring area and a general signal wiring area. The differential signal wiring area includes multiple pairs of differential signal lines, and the general signal wiring area includes multiple general signal lines.

[0032] Differential signal lines and general signal lines are connected to the corresponding pads on the hermetic circuit board 200. For example, differential signal line 231 is connected to pad 225, general signal line 232 is connected to pad 221, and general signal line 233 is connected to pad 222.

[0033] By designing multiple pairs of differential signal lines and multiple ordinary signal lines on the top of the hermetic circuit board 200, bare chips that meet the needs of different applications can be made hermetic circuit board 200 universal.

[0034] Ordinary signal lines can be used to transmit ordinary signals, as well as as power lines and ground lines.

[0035] Differential signal lines can be used not only to transmit differential signals, but also to transmit ordinary signals, and can also be used as power lines and ground lines.

[0036] In some embodiments of this application, the chip mounting area 210 is a square area.

[0037] The pad area includes a first pad partition, a second pad partition, and a third pad partition; each of the first, second, and third pad partitions includes multiple pads.

[0038] The general signal cabling area includes the first cabling section and the third cabling section; both the first cabling section and the third cabling section include multiple general signal lines.

[0039] The first pad partition and the first wiring partition are located on the first side of the chip mounting area 210; the first pad partition is closer to the first side of the chip mounting area 210 than the first wiring partition; the pads 221 of the first pad partition are connected to the ordinary signal lines 232 of the first wiring partition.

[0040] The third pad partition and the third wiring partition are located on the third side of the chip mounting area 210; the third pad partition is closer to the third side of the chip mounting area 210 than the third wiring partition; the pads 222 of the third pad partition are connected to the ordinary signal lines 233 of the third wiring partition.

[0041] The second pad partition and the differential signal routing area are located on the second side of the chip mounting area 210; the second pad partition is closer to the second side of the chip mounting area 210 than the differential signal routing area; the pads 225 of the second pad partition are connected to the differential signal lines 231 of the differential signal routing area.

[0042] The first side (as shown on the left) and the third side (as shown on the right) of the chip mounting area 210 are opposite sides. The second side of the chip mounting area 210 is adjacent to the first side and the third side, respectively. See [reference needed]. Figure 3 As shown.

[0043] By designing the first pad partition, the second pad partition, and the third pad partition to be arranged on the first, second, and third sides of the chip mounting area 210, and designing the first wiring partition, the differential signal wiring area, and the third wiring partition to be arranged on the first, second, and third sides of the chip mounting area 210, the layout of the entire airtight circuit board is made reasonable, meeting the needs of different bare chips and improving the versatility of the airtight circuit board 200.

[0044] A surface mount identifier 212 is provided on the fourth side of the chip mounting area 210 to indicate the chip mounting area. A bare chip is mounted in the chip mounting area 210. The fourth side and the second side of the chip mounting area 210 are opposite sides.

[0045] The top of the hermetic circuit board 200 also has a ground line 234, pads 223 and 224. Pad 224 is located on the first side of the chip mounting area 210, between the first pad partition and the second pad partition. Pad 223 is located on the third side of the chip mounting area 210, between the third pad partition and the second pad partition. Pads 223 and 224 are respectively connected to the ground line 234, which is laid around the differential signal wiring area.

[0046] In some embodiments of this application, the bottom of the hermetic circuit board 200 has BGA solder balls 280, and the top of the non-hermetic circuit board 100 has BGA pads 101. The BGA solder balls 280 of the hermetic circuit board 200 and the BGA pads 101 of the non-hermetic circuit board 100 are soldered together to achieve electrical connection between the hermetic circuit board 200 and the non-hermetic circuit board 100. See [link to relevant documentation]. Figure 2 As shown.

[0047] By designing BGA solder balls 280 and BGA pads 101, a stable and reliable electrical connection is achieved between the hermetic circuit board 200 and the non-hermetic circuit board 100.

[0048] In some embodiments of this application, the chip mounting area 210 is provided with a plurality of vias 211, which are filled with thermally conductive metal to provide a heat dissipation channel for the bare chip. The heat of the bare chip is dissipated through the thermally conductive metal to ensure the normal operation of the bare chip.

[0049] Via 211 connects to BGA solder ball 280. The heat generated by the bare chip is conducted to the BGA solder ball through the thermally conductive metal, and then directly to the non-hermetic circuit board 100 through the BGA solder ball, which helps with heat dissipation.

[0050] In some embodiments of this application, the thermally conductive metal is tungsten. It offers stable performance and rapid heat dissipation.

[0051] In some embodiments of this application, the airtight circuit board 200 is a ceramic circuit board.

[0052] Ceramics are airtight, which can prevent moisture and contaminants from entering and protect internal components. Ceramics also have other advantages such as excellent thermal conductivity and low coefficient of thermal expansion. Using ceramics as a substrate to make ceramic printed circuit boards (airtight circuit boards), combined with a 300 housing, can meet the requirements of high reliability and airtight packaging.

[0053] In some embodiments of this application, the non-airtight circuit board 100 is a resin circuit board. Using resin to manufacture circuit boards results in low cost.

[0054] In some embodiments of this application, the casing 300 is a metal casing, which is welded together with the airtight circuit board 200, making the connection convenient and forming a stable and reliable airtight space.

[0055] The casing 300 includes a top cover and four side plates connected in sequence. A welding platform is located on top of the airtight circuit board 200 for welding the metal casing. After the metal casing is welded to the top of the airtight circuit board 200, an airtight seal is achieved.

[0056] In some embodiments of this application, the bare chip includes an electrical chip and an optical chip; the optical chip is electrically connected to the electrical chip via bonding wires; the electrical chip is electrically connected to the pads of the hermetic circuit board 200 via bonding wires.

[0057] Electrical and optical chips are the core chips of an optical module. Placing them in an airtight space ensures their safety and reliable operation, thus guaranteeing the stable operation of the optical module.

[0058] If the size of the electrical chip 241 to be mounted is similar to the size of the chip mounting area 210, the electrical chip 241 and the optical chip 242 can be directly mounted on the chip mounting area 210. See [reference needed]. Figure 4 As shown.

[0059] If the size of the electrical chip 243 to be mounted is smaller than the size of the chip mounting area 210, and the difference is large, it will result in excessively long bonding wires. In this case, a first adapter board 250 can be designed on the chip mounting area 210 to transfer the electrical properties of one side of the electrical chip 243 to the pads of the first adapter board 250. Then, the pads of the first adapter board 250 are wire bonded to the pads of the hermetically sealed circuit board 200, which can avoid excessively long bonding wires.

[0060] Therefore, in some embodiments of this application, the optical module further includes a first adapter board 250; the first adapter board 250 is installed in the chip mounting area 210.

[0061] The top of the first adapter board 250 has a plurality of pads 251; the pads of the electrical chip 243 are electrically connected to the pads 251 of the first adapter board 250 via bonding wires, and the pads 251 of the first adapter board 250 are electrically connected to the pads of the hermetic circuit board 200 via bonding wires. (See also...) Figure 5 As shown.

[0062] Therefore, an electrical chip 243, an optical chip 242, and a first adapter board 250 are mounted on the chip mounting area 210. The first adapter board 250 is located on one side (left or right) of the electrical chip 243. The optical chip 242 is electrically connected to the electrical chip 243 via bonding wires; some pads of the electrical chip 243 are directly electrically connected to the pads of the hermetic circuit board 200; and some pads of the electrical chip 243 are electrically connected to the pads of the hermetic circuit board 200 via the first adapter board 250 to avoid excessively long bonding wires.

[0063] The positions of the electrical chip 243 and the first adapter board 250 are interchangeable. The number of pads on the first adapter board 250 is designed according to the required number of wires.

[0064] The first adapter board 250 is a ceramic adapter board, which is attached to the chip mounting area 210.

[0065] In some embodiments of this application, two electrical chips are provided: electrical chip 244 and electrical chip 245; and one optical chip is provided: optical chip 242. Optical chip 242 is electrically connected to electrical chips 244 and 245 via bonding wires; electrical chips 244 and 245 are electrically connected to the pads of the hermetic circuit board 200 via bonding wires. (See [reference]). Figure 6 As shown. By setting two electrical chips and one optical chip 242 in the chip mounting area 210, the layout is both reasonable and meets the requirements of the optical module for the number of signal transmission channels.

[0066] In some embodiments of this application, two electrical chips are provided: electrical chip 244 and electrical chip 245; two optical chips are provided: optical chip 291 and optical chip 292. Optical chip 291 is electrically connected to electrical chip 244 via bonding wires; optical chip 292 is electrically connected to electrical chip 245 via bonding wires; electrical chips 244 and 245 are respectively electrically connected to the pads of the hermetic circuit board 200 via bonding wires. See [reference needed]. Figure 8 As shown, by setting two electrical chips and two optical chips in the chip mounting area 210, the layout is reasonable and meets the requirements of the optical module for the number of signal transmission channels.

[0067] By setting two electrical chips and two optical chips, it can be used for 4-channel transmission and 4-channel reception, or 8-channel transmission and 8-channel reception, or other products with fewer than 8 channels.

[0068] The number of optical modules, electrical chips, and optical chips in this application can be set according to actual needs.

[0069] In some embodiments of this application, two electrical chips are provided: electrical chip 246 and electrical chip 247. The top of the first electrical chip 246 is provided with a second adapter board 260, and the top of the second adapter board 260 has a plurality of pads 261. The pads of the second electrical chip 247 are electrically connected to the pads 261 of the second adapter board 260 via bonding wires. The pads 261 of the second adapter board 260 are electrically connected to the pads of the hermetic circuit board 200 via bonding wires. See [reference needed]. Figure 7 As shown.

[0070] Electrical chips 246 and 247 are arranged on the left and right sides. If bonding wires are required on the left side of the right chip, a second adapter board 260 can be designed above the left chip to transfer the electrical properties of the right chip to the pads of the hermetically sealed circuit board 200, thus avoiding excessively long bonding wires. The number of channels on the second adapter board 260 is designed according to the required number of bonding wires, and the positions of the left and right chips can be interchanged.

[0071] By designing a second adapter board 260, some of the pads of the second electrical chip 247 are electrically connected to the pads of the hermetic circuit board 200 through the second adapter board 260 to avoid excessively long bonding wires.

[0072] The second adapter board 260 is a ceramic adapter board, which is attached to the top of the electrical chip 246.

[0073] Two optical chips can be configured: optical chip 248 and optical chip 249; optical chip 248 is electrically connected to electrical chip 246 via bonding wire 271, and optical chip 249 is electrically connected to electrical chip 247 via bonding wire. (See [reference]) Figure 7As shown. Electrical chip 246 is a 4-channel electrical chip, and electrical chip 247 is an 8-channel electrical chip. Of course, a 12-channel optical chip can also be used, which is electrically connected to electrical chips 246 and 247 respectively.

[0074] Assuming the differential signal wiring area has 13 pairs of differential signal lines, the optical module can achieve 12-channel signal transmission. It can accommodate, but is not limited to, the following types of chips for mounting.

[0075] To achieve 12-channel transmission or 12-channel reception, the optical module can be equipped with either a 12-channel electrical chip 241 or a 12-channel optical chip 242. The size of the electrical chip 241 is similar to the size of the chip mounting area 210, see [reference needed]. Figure 4 As shown.

[0076] To achieve 12-channel transmission or 12-channel reception, the optical module can be equipped with either a 12-channel electrical chip 243 or a 12-channel optical chip 242. Since the size of the electrical chip 243 differs significantly from the size of the chip mounting area 210, a first adapter board 250 needs to be designed on the chip mounting area 210. (See [reference needed]). Figure 5 As shown.

[0077] To achieve 4-channel transmit and 4-channel receive, the optical module can be equipped with either a 4-channel electrical chip 244, a 4-channel electrical chip 245, or a 12-channel optical chip 242 (which only occupies 8 channels). See [link / reference]. Figure 6 As shown. The optoelectronic chip can be a combination of two 4-channel chips, or any other combination that satisfies the requirement of 4-channel transmission and 4-channel reception.

[0078] To achieve 4-channel transmit and 4-channel receive, or 8-channel transmit and 8-channel receive, the optical module can be equipped with either a 4-channel electrical chip 244, a 4-channel electrical chip 245, a 4-channel optical chip 291, or a 4-channel optical chip 292. (See [link to relevant documentation]). Figure 8 As shown.

[0079] To achieve 8-channel transmit and 4-channel receive, or 4-channel transmit and 8-channel receive, the optical module can be configured with a 4-channel electrical chip 246, an 8-channel electrical chip 247, a 4-channel optical chip 248, or an 8-channel optical chip 249. In this case, a second adapter board 260 needs to be designed on the electrical chip 246. (See [reference needed]). Figure 7 As shown. The optoelectronic chip can also be any other combination that satisfies either 8-channel transmission and 4-channel reception or 4-channel transmission and 8-channel reception.

[0080] The unwired pads are empty pads. Depending on the chip size and the number of channels used, different wires can be defined for flexible wire bonding.

[0081] The optical module of this application includes: a non-hermetic circuit board 100 (resin circuit board), a hermetic circuit board 200 (ceramic circuit board with BGA solder balls), a metal casing, a bare chip, bonding wires, and other components 102 that do not require sealing (such as molded chips and resistor-capacitor units, etc.).

[0082] The optical module of this application is designed with a non-hermetic circuit board 100 (resin circuit board) to carry components 102 that do not require sealing, such as plastic-encapsulated chips and resistor-capacitor units. BGA pads 101 are designed on the top of the non-hermetic circuit board 100 and are soldered to BGA solder balls 280 of the hermetic circuit board 200 (ceramic circuit board).

[0083] The hermetic circuit board 200 is a ceramic circuit board, which uses ceramic as a substrate and fabricates conductive lines on its surface. The ceramic circuit board is made by sintering multiple layers of ceramic substrate. The bottom of the hermetic circuit board 200 has BGA solder balls 280 for soldering to the non-hermetic circuit board 100. The BGA solder balls 280 are high-lead solder balls; during SMT reflow soldering, high-lead BGA solder balls will not melt, thus avoiding the significant solder ball collapse phenomenon seen with lead-free solder balls. The top of the hermetic circuit board 200 has a soldering platform for soldering metal housings to achieve a hermetic seal. The surface traces (differential signal lines, general signal lines, and ground lines) on the top of the hermetic circuit board 200 accommodate various chip mounting configurations, and surface mount markings are designed for different mounting scenarios.

[0084] The vias 211 in the chip mounting area 210 are connected to the bottom BGA solder balls 280. The vias are filled with tungsten metal to provide a heat dissipation channel for the chip. Each pad is independently designed to accommodate more chip mounting methods. After the bare chip is mounted, the chip pads are electrically connected to the pads of the hermetically sealed circuit board 200 via bonding wires. The pads are routed through the surface layer and then through vias to the inner layer, finally connecting to the bottom BGA solder balls 280 via the inner layer traces. The first and third pad zones are designed with as many pads as possible, within the limits of physical size, for backup. Differential signal lines can meet high-speed signal transmission requirements. From right to left, every two traces form a differential pair, for a total of 13 pairs. This differential trace design meets the requirements for high-speed signal transmission and can also be used as power, general signal, or ground traces, but the reverse is not true. The differential design has an impedance of 100Ω, and impedance matching is achieved by adjusting the trace width, trace spacing, and the thickness of the ceramic substrate of the trace reference layer.

[0085] All pads on the hermetic circuit board 200 are independently designed, and the definition of each pad is determined by the chip it is bonded to. The mounting size is 6.0mm long x 3.0mm wide; all chips smaller than this mounting size can use the first adapter board. Assuming the differential signal routing area has 13 pairs of high-speed differential signal lines, it can support signal transmission for optical module products with 13 or fewer channels of pure transmit, pure receive, or any combination of transmit and receive. (The number of channels indicates the quantity of high-speed signal transmission; each channel corresponds to a set of differential traces). The optical module of this application can be a die-bonded parallel optical module.

[0086] The optical module of this application employs two printed circuit boards (PCBs) for device placement and routing: a standard resin PCB (non-hermetic) and a ceramic PCB (hermetic). Core optoelectronic chips and bonding wires requiring hermetic sealing are placed on the ceramic PCB. The ceramic PCB, combined with a metal housing, achieves hermetic sealing. Other components not requiring hermetic sealing are placed on the standard resin PCB. This reduces the size of the ceramic PCB and improves its reliability. Inside the ceramic PCB, routing design allows for the mounting of bare dies to meet different application requirements. These dies are connected to surface traces on the ceramic PCB via bonding wires. Through internal routing design, they connect to BGA solder balls at the bottom of the ceramic PCB. The BGA solder balls on the outside of the ceramic PCB are soldered to the resin PCB, ultimately transmitting power to the optical module pins via the resin PCB, achieving internal and external electrical conduction.

[0087] Ordinary resin circuit boards cannot achieve hermetic sealing, requiring the use of ceramic circuit boards and metal casings for this purpose. Placing all circuit chips on a ceramic circuit board increases its size; ceramic is inherently brittle, and a larger volume increases its susceptibility to breakage due to its own weight or external forces, leading to reduced structural strength and reliability. Furthermore, a larger volume increases the likelihood of cracking and deformation during firing, further complicating manufacturing. This application hermetic-seals the photoelectric chips and bonding wires that require hermetic sealing, while placing other non-hermetic components such as molded chips and resistors / capacitors outside the ceramic circuit board, using a resin substrate for electrical connections. This significantly reduces the size of the ceramic circuit board, thereby improving its structural strength and increasing the yield rate during manufacturing.

[0088] This application fulfills the requirement for hermetically sealed packaging of the core optoelectronic chip and bonding wires in optical modules. Units requiring hermetically sealed packaging (core optoelectronic chip and bonding wires) are placed on a ceramic circuit board for separate hermetically sealed packaging, while units not requiring sealing are placed on a resin circuit board. This reduces the size of the ceramic circuit board and improves the overall reliability of the optical module.

[0089] By designing the traces of the ceramic circuit board, different surface mount requirements can be met simultaneously, satisfying diverse product needs. The resin circuit board can be replaced according to different user needs, making the ceramic circuit board universal, improving the universality of ceramic materials, increasing the material utilization rate of the ceramic circuit board, and saving costs.

[0090] The ceramic circuit board is designed with routing to accommodate different chip mounting requirements. Since customers have different combinations of transmit and receive channels for optical modules, there are various chip mounting methods inside the ceramic package cavity. Each chip has different defined attributes, which leads to the need to manufacture multiple ceramic printed circuit boards to match. The routing of the ceramic circuit board designed in this application meets the mounting requirements of different types of chips. To meet different user needs, only the resin substrate needs to be replaced, which reduces the types of materials, improves the universality of ceramic materials, and reduces the cost of new product development.

[0091] The optical module of this application has the following advantages: (1) By using a combination of resin circuit boards and ceramic circuit boards, the core optoelectronic chip and bonding wires are sealed, the volume of the ceramic circuit board is reduced, and the reliability of the product is improved.

[0092] (2) The ceramic circuit board uses BGA solder balls to connect to the resin circuit board. It is small in size and can be designed with more pins to meet the sealing requirements.

[0093] (3) A welding platform is designed on the ceramic circuit board for welding metal tube shells. The designed welding platform can meet the requirements for welding with metal tube shells, and the product can be sealed after welding.

[0094] (4) The ceramic circuit board routing design can meet the mounting requirements of different types of chips and save material costs.

[0095] (5) Ceramic circuit board marking design: design a variety of markings to meet the chip placement requirements under different mounting conditions.

[0096] (6) The BGA solder balls of the ceramic circuit board are high-lead solder balls. Ceramic circuit boards have a certain weight. If lead-free solder balls are used, solder ball collapse will occur during the SMT reflow soldering process, resulting in poor soldering. High-lead BGA solder balls do not melt, therefore, there will be no significant solder ball collapse phenomenon like that of lead-free solder balls.

[0097] In the description of the above embodiments, specific features, structures, materials, or characteristics may be combined in any suitable manner in one or more embodiments or examples. The above are merely specific embodiments of this utility model, but the protection scope of this utility model is not limited thereto. Any variations or substitutions that can be easily conceived by those skilled in the art within the technical scope disclosed in this utility model should be included within the protection scope of this utility model. Therefore, the protection scope of this utility model should be determined by the scope of the claims.

Claims

1. An optical module, characterized in that, include: Non-hermetic circuit board with component mounting areas on its surface; An airtight circuit board has a chip mounting area and a pad area on its top, the pad area including multiple pads arranged around the chip mounting area; its bottom is electrically connected to the non-airtight circuit board. The housing is mounted on the hermetic circuit board, forming a hermetic space with the hermetic circuit board; the chip mounting area and the pad area are located within the hermetic space. A bare die is mounted in the chip mounting area and located within the hermetic space; the bare die is electrically connected to the pads of the hermetic circuit board via bonding wires.

2. The optical module according to claim 1, characterized in that: The top of the airtight circuit board has a differential signal wiring area and a normal signal wiring area; The differential signal wiring area includes multiple pairs of differential signal lines, and the ordinary signal wiring area includes multiple ordinary signal lines.

3. The optical module according to claim 2, characterized in that: The chip mounting area is a square area; The pad area includes a first pad partition, a second pad partition, and a third pad partition; each of the first pad partition, the second pad partition, and the third pad partition includes multiple pads. The ordinary signal cabling area includes a first cabling section and a third cabling section; both the first cabling section and the third cabling section include multiple ordinary signal lines; The first pad partition and the first wiring partition are located on the first side of the chip mounting area; the first pad partition is closer to the first side of the chip mounting area than the first wiring partition. The pads of the first pad partition are connected to the ordinary signal lines of the first wiring partition; The third pad partition and the third wiring partition are located on the third side of the chip mounting area; the third pad partition is closer to the third side of the chip mounting area than the third wiring partition; the pads of the third pad partition are connected to the ordinary signal lines of the third wiring partition. The second pad partition and the differential signal routing area are located on the second side of the chip mounting area; the second pad partition is closer to the second side of the chip mounting area than the differential signal routing area; the pads of the second pad partition are connected to the differential signal lines of the differential signal routing area. The first and third sides of the chip mounting area are opposite sides, and the second side of the chip mounting area is adjacent to the first and third sides respectively.

4. The optical module according to claim 1, characterized in that: The hermetic circuit board has BGA solder balls at the bottom and BGA pads at the top of the non-hermetic circuit board. The BGA solder balls of the hermetic circuit board are soldered together with the BGA pads of the non-hermetic circuit board.

5. The optical module according to claim 1, characterized in that: The chip mounting area is provided with multiple vias, and the vias are filled with thermally conductive metal.

6. The optical module according to claim 1, characterized in that: The airtight circuit board is a ceramic circuit board; the non-airtight circuit board is a resin circuit board.

7. The optical module according to claim 1, characterized in that: The casing is a metal casing, which is welded together with the airtight circuit board.

8. The optical module according to any one of claims 1 to 7, characterized in that: The bare chip includes electrical chips and optical chips; The optical chip is electrically connected to the electrical chip via bonding wires; The electrical chip is electrically connected to the pads of the hermetic circuit board via bonding wires.

9. The optical module according to claim 8, characterized in that: The optical module further includes a first adapter board; the first adapter board is installed in the chip mounting area; The top of the first adapter board has several pads; The pads of the electrical chip are electrically connected to the pads of the first adapter board via bonding wires, and the pads of the first adapter board are electrically connected to the pads of the hermetic circuit board via bonding wires.

10. The optical module according to claim 8, characterized in that: The electrical chip is provided in two parts, wherein the top of the first electrical chip is provided with a second adapter plate, and the top of the second adapter plate has several pads. Several pads of the second electrical chip are electrically connected to several pads of the second adapter board via bonding wires, and several pads of the second adapter board are electrically connected to several pads of the hermetic circuit board via bonding wires.

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