COB packaging system for double-sided silicon micro-strip detector

Abstract

The utility model provides a COB packaging system for a double-sided silicon micro-strip detector. The COB packaging system comprises a PCB and a bonding tool. The bonding pads of the double-sided silicon micro-strip detector are respectively positioned on the edges of two adjacent sides, are distributed on the front side and the back side of the double-sided silicon micro-strip detector, and are respectively a front bonding pad of the double-sided silicon micro-strip detector and a back bonding pad of the double-sided silicon micro-strip detector; the PCB comprises a middle hollow structure, and steps are arranged on three surfaces of the PCB and are used for providing corresponding physical support and positioning; the PCB front bonding pad is arranged at the position, close to one of the three steps, of the front surface of the PCB and used for being bonded with the front bonding pad of the double-sided silicon micro-strip detector; the PCB back bonding pad is arranged at the position, close to the position without the step, of the back of the PCB and used for being bonded with the back bonding pad of the double-sided silicon micro-strip detector; the bonding tool comprises a front bonding tool and a back bonding tool. According to the utility model, a better packaging effect is realized.

Description

TECHNICAL FIELD

[0001] The utility model belongs to the field of detector packaging, and particularly relates to a double-sided silicon micro-strip detector COB (Chip on Board, chip on board) packaging system. BACKGROUND

[0002] The silicon micro-strip detector is a kind of particle detector, and its structure is that a plurality of metal micro-strips are covered on the outside of a PN junction silicon sheet type semiconductor detector to accurately determine the position of particles. The detector is widely applied in the field of high-energy astronomical detection and is mainly used for measuring the distribution of space particles and rays.

[0003] The conventional single-sided silicon micro-strip detector is only provided with a solder pad on the junction surface (p-side), so that when bonding, only the ohmic surface (n-side) needs to be pasted to a printed circuit soft board. However, the double-sided silicon micro-strip detector is provided with solder pads on both sides, so that both sides need to be bonded, and the conventional soft board cannot meet the demand of double-sided bonding. In addition, since a chip bonding machine usually adopts a vacuum adsorption mode to fix the bonded object, the existence of the double-sided bonding wire makes it difficult to directly perform vacuum adsorption. Therefore, in order to ensure that the bonding is successfully completed on the chip bonding machine and effectively protect the safety of the bonding wire, it is urgent to design a printed circuit board (PCB) and packaging system for the double-sided silicon micro-strip detector. UTILITY MODEL CONTENT

[0004] To solve the above technical problems, the utility model provides a double-sided silicon micro-strip detector COB packaging system.

[0005] To achieve the above purpose, the utility model adopts the following technical scheme:

[0006] The application discloses a COB packaging system of a double-sided silicon micro-strip detector, which comprises a PCB and a bonding tool; the bonding pads of the double-sided silicon micro-strip detector are located at the edges of two adjacent sides and are distributed on the front and back sides of the double-sided silicon micro-strip detector, and are respectively front bonding pads of the double-sided silicon micro-strip detector and back bonding pads of the double-sided silicon micro-strip detector; the PCB comprises a hollow structure in the middle, the hollow structure is square, three sides of the square are provided with steps for providing corresponding physical support and positioning; the PCB front bonding pads are arranged on the front side of the PCB and are close to one of the three steps for being bonded with the front bonding pads of the double-sided silicon micro-strip detector; the PCB back bonding pads are arranged on the back side of the PCB and are close to the position without the step for being bonded with the back bonding pads of the double-sided silicon micro-strip detector; the connector pads for reading out the front detection data of the double-sided silicon micro-strip detector are arranged on the front side of the PCB and are close to the edge of the PCB and are in the same direction with the PCB front bonding pads, and are responsible for transmitting the data generated by the front detector to an external circuit; the connector pads for reading out the back detection data of the double-sided silicon micro-strip detector are also arranged on the front side of the PCB and are close to the edge of the PCB and are in the same direction with the PCB back bonding pads, and are responsible for transmitting the data generated by the back detector to the external circuit; the bonding tool comprises a front bonding tool responsible for bonding the PCB front bonding pads with the front bonding pads of the double-sided silicon micro-strip detector and a back bonding tool responsible for bonding the PCB back bonding pads with the back bonding pads of the double-sided silicon micro-strip detector.

[0007] Further, the hollow structure of the PCB is used for bonding the double-sided silicon micro-strip detector, reducing the shielding of high-density substances and improving the effect and sensitivity of the detector.

[0008] Further, the three steps of the PCB are used for positioning and bonding the double-sided silicon micro-strip detector on the PCB, and the side without the step is convenient for the wire of the back bonding.

[0009] Further, the PCB is provided with a plurality of through holes with a diameter of φ3.5 for being installed and fixed with the bonding tool.

[0010] Further, the bonding tool provides a stable fixing interface between the PCB and a vacuum table of a chip bonding machine.

[0011] Further, the bonding tool avoids the components, that is, the bonding tool avoids the layout and arrangement of the components on the PCB at the position in contact with the PCB, so as to ensure that the bonding tool does not interfere with or damage any component.

[0012] Further, the bonding tool is provided with a protective cover covering the double-sided silicon micro-strip detector and the bonding wire.

[0013] Further, the front bonding tool and the back bonding tool are both equipped with 11 M3 threaded through holes.

[0014] Further, the bonding tool includes a slotted structure of the front bonding tool, which is not completely dug through the bonding tool to form a protective cover for protecting the double-sided silicon microstrip detector and the bonding wire, the protective cover adopts a plate structure and is made of aluminum alloy material, has a thickness of 5 mm and a slotted depth of 4 mm.

[0015] Further, the other side of the bonding tool is designed as a planar structure of the front bonding tool, so that the bonding tool can be stably fixed on a vacuum table of a chip bonder by means of vacuum adsorption.

[0016] Beneficial effects:

[0017] 1. Enhanced protection capability: the bonding wire is provided with a physical barrier by means of reasonable structure design, so that damage to the bonding wire due to improper operation, physical collision and the like in subsequent processes can be effectively prevented.

[0018] 2. Improved operation safety: the stability of the tool and the design facilitating operation are improved, so that the failure probability of an operator during double-sided bonding is reduced, thereby reducing the failure rate and improving the safety of overall operation.

[0019] 3. Clean environment: the tool can effectively reduce pollution of the environment to the completed bonding wire, ensure the cleanliness of the bonding wire in the entire process flow, and improve the success rate of subsequent bonding processes.

[0020] 4. High repeatability: consistent operation conditions are ensured, so that the result of each bonding is more controllable, and inconsistency of results due to operation changes is reduced.

[0021] 5. Reduced cost: the tool reduces the occurrence rate of damage, reduces rework and material loss, thereby saving production cost and improving economic benefit.

[0022] 6. Improved product quality: the tool ensures protection while also assisting in efficient operation processes, which is helpful to improve the reliability and performance of the double-sided silicon microstrip detector and is conducive to scientific output. BRIEF DESCRIPTION OF DRAWINGS

[0023] Figure 1 is a schematic view of a double-sided silicon microstrip (transparent display).

[0024] Figure 2 is a structural design drawing of a PCB (printed circuit board), the left side is a front view, and the right side is a back view.

[0025] Figure 3It is a schematic diagram of front bonding wires.

[0026] Figure 4 It is a schematic diagram of back bonding wires.

[0027] Figure 5 It is an exploded schematic diagram after the double-sided silicon microstrip detector and the PCB are bonded.

[0028] Figure 6 It is a sectional view after the double-sided silicon microstrip detector and the PCB are bonded.

[0029] Figure 7 It is a schematic diagram of a bonding tool.

[0030] Figure 8 It is an exploded schematic diagram when the front bonding tool is used.

[0031] Figure 9 It is an exploded schematic diagram when the back bonding tool is used.

[0032] Figure 10 It is a sectional view when the front bonding tool is used.

[0033] Wherein, the reference signs are: 1-1 is a front pad of a double-sided silicon microstrip detector; 1-2 is a back pad of the double-sided silicon microstrip detector; 2-1 is a step; 2-2 is a PCB front pad; 2-3 is a PCB back pad; 2-4 is a front connector pad; 2-5 is a back connector pad; 5-1 is a PCB board; 5-2 is a double-sided silicon microstrip detector; 5-3 is a front bonding wire; 5-4 is a back bonding wire; 7-1 is a front bonding tool; 7-2 is a back bonding tool; 8-2 is a PCB assembly after the double-sided silicon microstrip detector is bonded; 8-3 is a M3 screw; 10-1 is a planar structure of the front bonding tool; 10-2 is a slotted structure of the front bonding tool. DETAILED DESCRIPTION

[0034] In order to make the purpose, technical scheme and advantages of the utility model more clearly, the following will be further described in detail by combining with the drawings and examples. It should be understood that the specific examples described here are only used to explain the utility model, and are not used to limit the utility model. In addition, the technical features involved in each embodiment of the utility model described below can be combined with each other as long as they do not conflict with each other.

[0035] The double-sided silicon microstrip detector COB packaging system of the utility model embodiment comprises a PCB board and a bonding tool.

[0036] As Figure 1As shown, the pads of the double-sided silicon microstrip detector are located at the edges of the adjacent two edges of the silicon wafer, distributed on the front and back of the silicon wafer, which are the front pads 1-1 of the double-sided silicon microstrip detector and the back pads 1-2 of the double-sided silicon microstrip detector. Correspondingly, the pads are also arranged on the front and back of the PCB board, and the pads of the double-sided silicon microstrip detector correspond to the pads of the PCB board one by one, so as to facilitate the precise bonding operation by using the bonder.

[0037] In order to realize the efficient bonding of the two pads and the PCB board, as shown in the drawings, Figure 2 As shown, the middle area of the PCB board adopts a hollow structure design. This innovative design not only facilitates bonding from the back, solving the problem of double-sided bonding of the double-sided silicon microstrip detector, but also effectively reduces the "dead" material on the detection path. The so-called "dead" material refers to high-density material that has a shielding effect on particles or rays. By reducing the existence of "dead" material, the background noise of the detector can be maximally reduced, so that the detection result is more accurate. This innovation significantly improves the detection effect and sensitivity.

[0038] As shown in the drawings, Figure 2 The PCB board includes a hollow structure in the middle, the hollow structure is a square, three sides of the square are provided with steps 2-1 for providing corresponding physical support and positioning; the PCB front pad 2-2 is arranged beside one of the three steps 2-1 and located on the front of the PCB board, used for bonding with the front pad 1-1 of the double-sided silicon microstrip detector; the PCB back pad 2-3 is arranged on the side of the square without the step 2-1 and located on the back of the PCB board, used for bonding with the back pad 1-2 of the double-sided silicon microstrip detector; the front connector pad 2-4 for reading out the front detection data of the double-sided silicon microstrip detector is arranged on the same side of the PCB board as the PCB front pad 2-2, responsible for transmitting the data generated by the front detector to the external circuit; the back connector pad 2-5 for reading out the back detection data of the double-sided silicon microstrip detector is also arranged on the same side of the PCB board as the PCB front pad 2-2, responsible for transmitting the data generated by the back detector to the external circuit.

[0039] Because three sides of the hollow structure have steps, it is convenient to stably bond the silicon wafer, and the structural stability and reliability between the double-sided silicon microstrip detector and the PCB board are ensured. The side without the step reserves the necessary space for the bonding wire, ensuring that it is not restricted during the bonding process and avoiding potential interference and damage.

[0040] In addition, several through holes with a diameter of φ3.5 are designed on the PCB board for installation and fixation with the bonding tool. These through holes not only make the installation process smoother, but also provide additional support during the bonding wire welding process, making the area around the pads more stable. Such design ensures the accuracy and reliability of the bonding process, significantly improving the stability and consistency of the bonding wire. Through these meticulous designs, the performance and reliability of the entire system are effectively improved. This series of meticulous designs aims to optimize the bonding process of the double-sided silicon microstrip detector, improve its detection performance and assembly efficiency, and provide more accurate and reliable technical support for high-energy physics and particle detection.

[0041] As shown in Figures 3-6 , Figure 3 and Figure 4 are the actual effect pictures after front and back bonding, respectively. The enlarged part of the picture clearly shows the arrangement of the bonding wires, and the spacing of the bonding wires is 498μm. Figure 5 is an exploded schematic diagram of the double-sided silicon microstrip detector 5-2 and the PCB board 5-1 after bonding, the double-sided silicon microstrip detector 5-2 is fixed to the three-sided step 2-1 of the PCB board 5-1 in a glued manner, the front bonding wire 5-3 connects the PCB front pad 2-2 of the PCB board 5-1 and the front pad 1-1 of the double-sided silicon microstrip detector, the back bonding wire 5-4 connects the PCB back pad 2-3 of the PCB board 5-1 and the back pad 1-2 of the double-sided silicon microstrip detector, and the bonding wire serves to realize the electrical connection between the silicon microstrip detector and the PCB. Figure 6 is a cross-sectional view of the double-sided silicon microstrip detector 5-2 and the PCB board 5-1 after bonding, Figure 6 which shows the actual positional relationship between the double-sided silicon microstrip detector 5-2, the PCB board 5-1, and the front bonding wire 5-3 and the back bonding wire 5-4.

[0042] As shown in Figures 7-10 , the main function of the bonding tool is to ensure that the PCB and the double-sided silicon microstrip detector can be successfully bonded. Its design needs to meet the following key requirements:

[0043] 1. Provide a stable mounting interface: Since the PCB that needs to be double-bonded cannot be directly installed and fixed to the vacuum table of the chip bonder, the bonding tool needs to provide a stable fixing interface between the PCB and the vacuum table of the chip bonder. A stable fixing interface can effectively reduce the displacement caused by external force or vibration during the bonding operation, ensuring the accurate positioning of the welding points. This is a key factor in achieving high-quality bonding, especially when dealing with delicate structures and high-density integrated circuits, any slight deviation can lead to performance degradation or failure.

[0044] 2. Avoiding components: In the design position in contact with the PCB, the bonding tool should fully consider the layout and arrangement of components on the PCB to ensure that the tool will not interfere or damage any components. Therefore, the design process of the tool should include a detailed component layout review to identify the size, shape and position of critical components, so as to leave sufficient space in the tool structure. This consideration is crucial, because the components on the PCB may include sensitive electronic components, connectors and other functional modules, and the precise layout design of the bonding tool is essential for the normal operation of the circuit. In summary, the design of the bonding tool not only needs to focus on its own function, but also needs to carefully analyze the characteristics and layout of the components on the PCB, and through careful design to ensure that the tool provides support and alignment functions while effectively maintaining the integrity and function of the PCB to achieve efficient bonding and reliable electrical performance.

[0045] 3. Protecting silicon microstrip detector and bonding wire: The design of the bonding tool should also have the function of effectively protecting the silicon microstrip detector and the bonding wire from potential damage in the external environment and the operation process. In the bonding process, the silicon microstrip detector and the bonding wire are crucial components, and any slight damage may affect the performance and stability of the entire system. Therefore, it is particularly important to ensure their integrity during the operation process. To achieve this goal, the bonding tool should be designed with a protective cover that covers the silicon wafer and the bonding wire to form a physical barrier against external physical impact, dust or dirt. At the same time, the material of the bonding tool should have certain impact resistance and flexibility to absorb potential impact force, thereby reducing the risk of damage.

[0046] By considering the above key factors, the bonding tool for the double-sided silicon microstrip detector is designed in two versions for the bonding process of the front and back pads. The two tools are highly similar in design and mirror image structure, so as to ensure that the double-sided bonding can be effectively and coordinately completed.

[0047] The bonding tool includes a front bonding tool 7-1 responsible for the bonding of the PCB front pad 2-2 and the front pad 1-1 of the double-sided silicon microstrip detector, and a back bonding tool 7-2 responsible for the bonding of the PCB back pad 2-3 and the back pad 1-2 of the double-sided silicon microstrip detector.

[0048] Both the front bonding tool 7-1 and the back bonding tool 7-2 are equipped with 11 M3 threaded holes, providing convenience for the secure installation of the PCB. During use, the front bonding tool 7-1 is installed on the back of the PCB assembly 8-2 that has completed the bonding of the double-sided silicon microstrip detector, exposing the front pads 1-1 of the double-sided silicon microstrip detector and the front pads 2-2 of the PCB. The PCB board 5-1, the PCB assembly 8-2 that has completed the bonding of the double-sided silicon microstrip detector, and the front bonding tool 7-1 are fixed together through 11 M3 screws 8-3. Conversely, the back bonding tool 7-2 is installed in a similar manner, but on the front side. This design ensures that the PCB board is stably fixed during the bonding process, eliminating any risk of displacement or loosening, thereby significantly improving the accuracy and consistency of the bonding. This is particularly important when dealing with PCB boards with high density and complex wiring, as ensuring stable connection directly affects the performance and reliability of the entire system.

[0049] Overall, the bonding tool presents a "shield" structure design with a central slot, adopting a plate-like structure, manufactured using aluminum alloy material, with a thickness of 5 mm. The slotted structure 10-2 of the front bonding tool is located in the area directly opposite the double-sided silicon microstrip detector after installation, and its slot size is slightly larger than the double-sided silicon microstrip detector, with a slot depth of 4 mm. Because the tool is not completely excavated, this design forms a "shield" that protects the double-sided silicon microstrip detector and the bonding wire. This ingenious slotted design not only helps to reduce the overall weight of the tool, improving operational flexibility, but also effectively protects the silicon microstrip detector and the bonding wire from being squeezed or damaged during operation, ensuring their normal function and service life.

[0050] In addition, the flat structure 10-1 of the front bonding tool is designed as a flat structure, which facilitates its stable fixation on the vacuum table of the chip bonder through vacuum suction. This design not only provides great convenience for the operator, ensuring a quick installation and replacement process, but also ensures accurate alignment and stable operation during the bonding process, further improving production efficiency and accuracy.

[0051] In summary, the bonding tool takes into full consideration various challenges that may be encountered during the bonding process, not only providing strong support for the bonding of the double-sided silicon microstrip, but also playing an important role in improving operational efficiency and product quality. This carefully designed tool will lay a solid foundation for future mass production processes.

[0052] The use process of the utility model is:

[0053] Step 1, Paste double-sided silicon microstrip detector: First, accurately paste the double-sided silicon microstrip detector onto the step 2-1 of the PCB according to the predetermined position, and ensure its stability. Then stand for a period of time until the adhesive is completely cured to ensure good adhesion between the double-sided silicon microstrip detector and the PCB board.

[0054] Step 2, Install front bonding tool 7-1: After the adhesion is completed, install the front bonding tool 7-1 to prepare for the bonding operation of the PCB front pads 2-2 and the front pads 1-1 of the double-sided silicon microstrip detector, and obtain the detector and PCB assembly.

[0055] Step 3, Fix the detector and PCB assembly: Place the pasted detector and PCB assembly on the chip bonder, and firmly fix it by vacuum suction to ensure stability during the welding process.

[0056] Step 4, Bond PCB front pads 2-2 and double-sided silicon microstrip detector front pads 1-1: Start the bonder and perform the bonding operation of the PCB front pads 2-2 and the double-sided silicon microstrip detector front pads 1-1. This process ensures the firm and reliable connection between the pads, laying a good foundation for subsequent operations.

[0057] Step 5, Remove the front bonding tool 7-1: After the front pad bonding is completed, carefully remove the front bonding tool and clean the site to prepare for the installation of subsequent tools.

[0058] Step 6, Install back bonding tool 7-2 to perform the bonding operation of PCB back pads 2-3 and double-sided silicon microstrip detector back pads 1-2, and obtain a new assembly.

[0059] Step 7, Place the new assembly back on the chip bonder and fix it again by vacuum suction to ensure the stability of the entire structure.

[0060] Step 8, Bond PCB back pads 2-3 and double-sided silicon microstrip detector back pads 1-2: Start the bonder and perform the bonding of the back pads. This step also needs to ensure the accuracy of the welding to make the connection effective and reliable.

[0061] Step 9, Remove the back bonding tool 7-2: After the bonding of the PCB back pads 2-3 and the double-sided silicon microstrip detector back pads 1-2 is completed, remove the back bonding tool. At this point, the bonding process of the double-sided silicon microstrip detector is successfully completed. Subsequent detection and verification can be carried out to ensure the normal function of the detector and the firm connection between its pads.

[0062] In addition, the bonding sequence of the front side and the back side can be switched flexibly, which significantly enhances the adaptability and operation flexibility of the tool. In actual production process, according to actual demand, the operator can arbitrarily select front side bonding or back side bonding according to different production process or product characteristics.

Claims

1. A double-sided silicon microstrip detector COB packaging system, characterized in that, The PCB board and the bonding tool; the pads of the double-sided silicon micro-strip detector are respectively located at the edges of the adjacent two edges and are distributed on the front and back of the double-sided silicon micro-strip detector, which are the front pad of the double-sided silicon micro-strip detector and the back pad of the double-sided silicon micro-strip detector; the PCB board comprises a hollow structure in the middle, the hollow structure is square, three sides of the square are provided with steps for providing corresponding physical support and positioning; the PCB front pad is arranged on the front of the PCB and is close to one of the three steps, and is used for bonding with the front pad of the double-sided silicon micro-strip detector; The PCB back pad is arranged on the back of the PCB and is close to the position without the step, and is used for bonding with the back pad of the double-sided silicon micro-strip detector; The connector pad for reading out the front detection data of the double-sided silicon micro-strip detector is arranged on the front of the PCB board, is close to the edge of the PCB, and is in the same direction as the PCB front pad, and is responsible for transmitting the data generated by the front detector to the external circuit; the connector pad for reading out the back detection data of the double-sided silicon micro-strip detector is also arranged on the front of the PCB board, is close to the edge of the PCB, and is in the same direction as the PCB back pad, and is responsible for transmitting the data generated by the back detector to the external circuit; the bonding tool comprises a front bonding tool responsible for bonding the PCB front pad with the front pad of the double-sided silicon micro-strip detector, and a back bonding tool responsible for bonding the PCB back pad with the back pad of the double-sided silicon micro-strip detector.

2. The dual-sided silicon microstrip detector COB packaging system of claim 1, wherein, The three steps of the PCB board hollow structure edge are used for positioning and bonding the double-sided silicon micro-strip detector on the PCB board, and the side without the step facilitates the wire running of the back bonding wire.

3. The dual-sided silicon microstrip detector COB packaging system of claim 1, wherein, The hollow structure of the PCB board reduces the shielding of high-density substances and improves the effect and sensitivity of the detector.

4. The dual-sided silicon microstrip detector COB packaging system of claim 1, wherein, A plurality of through holes with a diameter of φ3.5 are arranged on the PCB board for mounting and fixing the bonding tool.

5. The dual-sided silicon microstrip detector COB packaging system of claim 1, wherein, The bonding tool provides a stable fixing interface between the PCB board and the vacuum table of the chip bonding machine.

6. The dual-sided silicon microstrip detector COB packaging system of claim 1, wherein, The bonding tool avoids components, that is, in the position in contact with the PCB board, the bonding tool avoids the layout and arrangement of components on the PCB board to ensure that the bonding tool does not interfere with or damage any components.

7. The dual-sided silicon microstrip detector COB packaging system of claim 1, wherein, The front bonding tool and the back bonding tool are each equipped with 11 M3 threaded through holes.

8. The dual-sided silicon microstrip detector COB packaging system of claim 1, wherein, The bonding tool comprises a center slot structure which is not completely cut through to form a protective cover for protecting the double-sided silicon micro-strip detector and the bonding wire, the bonding tool adopts a plate structure, is made of aluminum alloy material, has a thickness of 5 mm, and has a slot depth of 4 mm.

9. The dual-sided silicon microstrip detector COB packaging system of claim 1, wherein, The other side of the bonding tool is designed as a flat structure, which facilitates stable fixation of the bonding tool on the vacuum table of the chip bonding machine by vacuum adsorption.

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