A method and apparatus for centering a chip and stacked chips

Abstract

The application provides a chip centering method and device. The chip centering device comprises a bearing, a connecting device and a supporting device. The connecting device is fixedly connected with the inner ring of the bearing and has a bearing part for placing a bearing table; the supporting device is fixedly connected with the outer ring of the bearing and the outer ring of the bearing can be fixed in the supporting device through stainless steel screws. The chip centering method comprises: a plurality of chips in a stacked chip set are stacked in sequence from bottom to top, and the chips are set as a first chip, a second chip to an Nth chip from near to far according to the adjacent bearing table, and the centering of the first chip to the Nth chip is completed in sequence according to the chip centering method. The centering method of the stacked chip set comprises: the centering of each chip is completed in sequence according to the chip centering method from near to far according to the adjacent bearing table; the application does not need to repeatedly disassemble and position, and a plurality of chip centering processes are completed through one positioning, so that the chip centering precision is improved and the chip packaging process cycle is shortened.

Description

Technical Field

[0001] The present invention relates to the technical field of chip packaging, and in particular to a method and device for centering a chip and a stacked chip. Background Art

[0002] Infrared detectors generally consist of three parts: a detector chip, a micro-dewar, and a cooler. The detector chip is the core component of the infrared detector assembly, located on a cold head, and is used to receive photoelectric signals and convert them into photoelectric information. The packaging of different infrared detector chip models varies significantly. In recent years, with the rapid development of infrared detectors, the demand for components to achieve multi-functional and multi-band detection has become increasingly high. The packaging structure design of stacked infrared chips well meets this development trend. Stacked chip packaging refers to the stacking and packaging of multiple chips with different functions inside the dewar to achieve multi-spectral detection of the detector.

[0003] Compared to traditional single-chip or multi-chip planar assembly, stacked chip packaging requires not only a proper layout of electrical leads and a reasonable gap between the bottom chip and the top chip, but also high-precision positioning of the chips in the horizontal projection direction. Due to the relatively complex design of the stacked package structure, the process is difficult to manufacture, and the relative positioning accuracy between the multi-layer chips is difficult to ensure. Therefore, to address this problem, a method and device for centering chips and stacked chips have been developed. This improves packaging accuracy while reducing the cycle time for infrared detector chip packaging and increasing packaging efficiency. Summary of the Invention

[0004] The present invention aims to solve the problem of inaccurate centering during chip and stacked chip packaging in the prior art, that is, to solve how to make the center of each chip and each stacked chip coincide with the axis of the carrier platform that supports the chip, ensuring that the chip is accurately fixed on the carrier platform. The present invention provides a centering method and centering device for chips and stacked chips, including placing a carrier device in the centering device, utilizing the principle that the axis position of the bearing in the centering device remains unchanged during rotation to ensure that the center of the carrier platform remains unchanged during rotation, and using tools to observe the trajectory of the center of the chip during rotation to achieve accurate centering of each chip.

[0005] The present invention provides a chip centering device comprising a bearing, a connecting device, and a supporting device. The connecting device is fixedly connected to the inner ring of the bearing and includes a supporting portion for placing a supporting platform. The supporting device is fixedly connected to the outer ring of the bearing and is used to support the bearing and the connecting device. During chip centering, the chip is placed on the supporting platform. As the bearing drives the supporting platform to rotate, the center of the chip's rotational trajectory is aligned with the center of the supporting platform, achieving chip centering.

[0006] According to some embodiments of the present invention, the bearing and the connecting device are connected by expansion studs.

[0007] According to some embodiments of the present invention, the bearing platform is fixed to the bearing portion by a pressure ring and a locking nut.

[0008] According to some embodiments of the present invention, the chip centering device further includes: a tool microscope, configured to provide a reference line intersection point.

[0009] The present invention provides a chip centering method, which uses a chip centering device to perform chip centering, comprising:

[0010] Fix the bearing platform to the bearing part and make the center of the bearing platform coincide with the axis of the bearing;

[0011] Place the chip on the carrier and rotate the carrier by rotating the bearing;

[0012] Adjust the chip position. When the center of the chip's rotation trajectory coincides with the center of the carrier, fix the chip on the carrier to achieve centering of the chip.

[0013] According to some embodiments of the present invention, a method for determining whether the center of a chip's rotation trajectory coincides with the center of a carrier platform includes: adjusting the intersection of a baseline of a tool microscope to coincide with the center of the carrier platform, observing the center of the trajectory of the chip during rotation through the tool microscope until the center of the trajectory coincides with the intersection of the baseline, and determining that the center of the chip's rotation trajectory coincides with the center of the carrier platform.

[0014] The present invention provides a centering method for a stacked chip group. Multiple chips in the stacked chip group are stacked in sequence from bottom to top, and are arranged as the first chip, the second chip to the Nth chip from near to far according to the adjacent supporting platforms. The centering of the first chip to the Nth chip is completed in sequence according to the above-mentioned chip centering method.

[0015] According to some embodiments of the present invention, the second chip to the Nth chip are all placed on the carrier via a bracket.

[0016] According to some embodiments of the present invention, a centering method for a stacked chip set is used for centering a stacked chip set of an infrared detector.

[0017] The chip and stacked chip centering method provided by the present invention has the following advantages:

[0018] 1) Without the need for repeated disassembly and positioning, multiple chips can be centered using one positioning.

[0019] 2) The positioning reference is unified and the positioning accuracy is high, ensuring the coaxiality of the stacked chips after mounting.

[0020] 3) Reduce the stacked chip packaging process cycle, improve the stacked chip packaging accuracy, and reduce the stacked chip packaging difficulty.

[0021] 4) No special centering position is required on the chip surface, which is suitable for centering small-sized chips. BRIEF DESCRIPTION OF THE DRAWINGS

[0022] Figure 1 Schematic diagram of a stacked chip on a carrier according to an embodiment of the present invention;

[0023] Figure 2 2 is a cross-sectional view of a centering device according to an embodiment of the present invention.

[0024] Reference numerals

[0025] Centering device 10,

[0026] Bearing 110, connecting device 120, expansion stud 131, screw 132, pressure ring 133, locking nut 134, supporting device 140,

[0027] Carrying platform 20,

[0028] The stacked chipset 30 comprises a first chip 310 , a second chip 320 , and a third chip 330 .

[0029] Bracket 40. DETAILED DESCRIPTION

[0030] In order to further illustrate the technical means and effects adopted by the present invention to achieve the predetermined purpose, the present invention is described in detail below with reference to the accompanying drawings and preferred embodiments.

[0031] like Figure 1 As shown, the chip centering device of the present invention includes: a bearing 110, a connecting device 120, and a supporting device 140. The connecting device 120 is fixedly connected to the inner ring of the bearing 110 and has a supporting portion for placing the carrier 20. The supporting device 140 is fixedly connected to the outer ring of the bearing 110 and can be fixed to the supporting device 140 via stainless steel screws 132. In the chip centering device of the present invention, the axis of the bearing 110 coincides with the center of the connecting device 120. The bearing 110 can be a P2-grade high-precision bearing 110. The axis position of the high-precision bearing 110 remains unchanged during rotation. The connecting device 120 indirectly connects the carrier 20 and the bearing 110, ensuring that the center of the carrier 20 coincides with the axis of the bearing 110.

[0032] like Figure 1By moving the outer edge of connecting device 120, the inner ring of bearing 110 and carrier 20 rotate. High-precision bearing 110 maintains a fixed axis during rotation, keeping the center of carrier 20 constant. A chip is placed on carrier 20. As bearing 110 drives carrier 20 to rotate, the center of the chip's rotation trajectory is aligned with the center of carrier 20, achieving chip centering.

[0033] According to some embodiments of the present invention, the inner ring of the bearing 110 and the connecting device 120 are connected by expansion screws 131. The connecting device 120 extends into the inner ring of the bearing 110, and the expansion screws 131 secure the inner ring of the bearing 110 to the connecting device 120 by expansion. At this time, the center of the connecting device 120 coincides with the center of the bearing 110.

[0034] According to some embodiments of the present invention, the support platform 20 is fixed to the support portion by a pressure ring 133 and a locking nut 134. Figure 1 As shown, the carrying platform 20 is placed on the carrying portion, and when the carrying platform 20 is fixed to the carrying portion by the pressure ring 133 and the locking nut 134 , the position of the carrying platform 20 is adjusted so that the center of the carrying platform 20 coincides with the center of the connecting device 120 .

[0035] According to some embodiments of the present invention, the chip centering device further includes a tool microscope configured to provide a reference line intersection point. The reference line intersection point of the tool microscope is a crosshair intersection point. During centering, the crosshair intersection point of the tool microscope is adjusted to coincide with the center of the carrier 20.

[0036] The present invention provides a chip centering method, which uses a chip centering device to perform chip centering, comprising:

[0037] Step 1: Secure the platform 20 to the load-bearing portion, aligning the center of the platform 20 with the axis of the bearing 110. In the centering device of the present invention, the axis of the bearing 110 and the center of the connecting device 120 coincide with each other. When the platform 20 is secured to the load-bearing portion using the pressure ring 133 and the lock nut 134, the center of the platform 20 and the center of the connecting device 120 coincide with each other, thereby aligning the center of the platform 20 with the axis of the bearing 110.

[0038] Step 2: Place the chip on the carrier 20 and rotate the bearing 110 to drive the carrier 20. Before placing the chip on the carrier 20, you can first apply a fluid adhesive to the carrier 20. When the bearing 110 drives the carrier 20 to rotate, it also drives the chip on the carrier 20 to rotate.

[0039] Step 3: Adjust the chip position. When the center of the chip's rotation trajectory coincides with the center of the carrier 20, fix the chip on the carrier 20 to achieve centering of the chip.

[0040] The centering method provided by the present invention ensures the coaxiality of the chip and the carrier 20 , and improves the positioning accuracy of the chip fixed on the carrier 20 .

[0041] According to some embodiments of the present invention, a method for determining whether the center of the chip's rotation trajectory coincides with the center of the carrier platform 20 includes: adjusting the intersection of the baseline of the tool microscope to coincide with the center of the carrier platform 20, observing the center of the trajectory of the chip during rotation through the tool microscope until the center of the trajectory coincides with the intersection of the baseline, and determining that the center of the chip's rotation trajectory coincides with the center of the carrier platform 20.

[0042] The intersection of the baseline of the tool microscope is a crosshair intersection. When using the tool microscope, align the crosshair intersection with the center of the carrier platform. Then, use the crosshairs as a reference to observe the center of the chip's trajectory during rotation. When the center of the trajectory coincides with the crosshairs, it indicates that the center of the chip coincides with the center of the carrier platform 20. This solution ensures high-precision centering of the chip.

[0043] The present invention provides a centering method for a stacked chipset. Multiple chips in the stacked chipset are stacked sequentially from bottom to top, and are positioned, from closest to farthest from a carrier platform, as a first chip, a second chip, to an Nth chip. The first through Nth chips are then centered sequentially using the aforementioned chip centering method. The present invention achieves centering of multiple chips with a single carrier platform positioning, avoiding the need for multiple assembly and disassembly and positioning during the stacked chip centering process. It also ensures centering accuracy for each layer of chips in the stacked chipset. Experiments have shown that the alignment error between the axis of each layer of chips and the axis of the carrier platform can be guaranteed to be within 5 microns.

[0044] According to some embodiments of the present invention, the second chip to the Nth chip are all placed on the carrier 20 via a bracket. For example, when centering the second chip, the second chip fixed on the bracket is placed on the carrier 20, and the bearing 110 is rotated, causing the carrier 20 to rotate accordingly. When the center trajectory of the second chip fixed on the bracket coincides with the axis of the carrier 20, the bracket with the second chip is fixed on the carrier 20. At this time, the axis of the second chip and the axis of the carrier 20 are highly coincident.

[0045] According to some embodiments of the present invention, a centering method for a stacked chip group is used for centering a stacked chip group for an infrared detector. In infrared detectors, multi-spectral detection is often achieved by stacked chips stacked in sequence from bottom to top. The first chip in the conventional stacked chip bonding process is mounted with the outer edge of the cold head as the reference. Limited by the depth of field of the microscope used for high-precision packaging, each subsequent chip is mounted with the previous chip as the reference coordinate. Taking into account the combined effects of the fluidity of the bonding glue and the non-uniformity of the positioning reference, the cumulative concentricity deviation of the stacked chips will become larger and larger, resulting in a low packaging and bonding accuracy of the final infrared detector chip. In addition, the operation is difficult and time-consuming, and the process is mainly completed manually by skilled technicians with many years of work experience. The conventional stacked chip packaging method for infrared detectors results in a lack of chip bonding accuracy for infrared detectors, which affects the performance of the infrared detector.

[0046] In an infrared detector, the stacked chips are placed on a cold head, which serves as a carrier 20 for the infrared detector's stacked chips. Multiple chips in the stacked chips are positioned sequentially, from near to far from the cold head, as the first chip, the second chip, and finally the Nth chip. Each of the second through Nth chips is placed on the carrier 20 via a bracket. Using the centering method for the stacked chipset 30 of the present invention, multiple chips can be centered in a single positioning operation. To ensure the positioning accuracy of the infrared detector's stacked chips and improve their packaging efficiency, high-precision bearings 110 are used in the specific operation. The specific steps are as follows:

[0047] Step 1: Assemble the connecting device 120 and the high-precision bearing 110. Use the expansion screw 131 to tighten the connecting device 120 and the inner ring of the high-precision bearing 110, and ensure that the axis of the connecting device 120 coincides with the axis of the high-precision bearing 110.

[0048] Step 2: Fix the outer ring of the assembled high-precision bearing 110 to the support seat using stainless steel screws 132.

[0049] Step 3: Place the infrared detector assembly including the cold head in the connecting device 120, and fix the detector assembly in the connecting device 120 with the pressure ring 133 and the locking nut 134 so that the center of the cold head coincides with the axis of the connecting device 120. At this time, the center of the cold head of the infrared detector assembly coincides with the axis of the high-precision bearing 110.

[0050] Step 4: Under a tool microscope, determine the center of the circle at three points on the outer edge of the infrared detector cold head, and adjust the intersection of the crosshairs of the tool microscope (the reference line of the tool microscope) to coincide with the center of the detector cold head.

[0051] Step 5: Apply fluid adhesive on the cold head and place the first chip on the cold head. Using the crosshairs of the tool microscope as a reference, rotate the high-precision bearing 110 by toggling the outer edge of the connecting device 120. During the rotation of the high-precision bearing 110, the axis point is fixed to center the first chip. Adjust the position of the first chip while rotating the bearing 110, and observe the rotation trajectory of the first chip around the intersection of the crosshairs under the tool microscope. When the center of the rotation trajectory coincides with the intersection of the crosshairs, the center of the first chip is guaranteed to be highly coincident with the center of the detector cold head. At this time, fix the first chip on the cold head.

[0052] Step 6: Using the crosshairs of the tool microscope in step 4 as a reference, perform centering of the second chip to the Nth chip in the same manner as in step 5. For example, when centering the second chip, fix the second chip on the bracket and place it on the cold head. Rotate the bearing 110, and the cold head will rotate accordingly. When the center trajectory of the second chip fixed on the bracket coincides with the intersection of the crosshairs, fix the bracket with the second chip on the cold head. At this time, the axis of the second chip and the axis of the cold head are highly coincident.

[0053] This invention is not limited to the packaging of stacked infrared detector chips; it is also applicable to the packaging of stacked chips in other electronic fields, such as mobile phones. The rotary centering principle of this solution can be used to perform centering during chip placement, eliminating repeated assembly and disassembly, while meeting the requirements of multi-step chip packaging processes. The unified benchmark throughout the chip packaging process helps ensure the coaxiality of the stacked chip packaging and achieve high precision.

[0054] The embodiments of the present application are described above in conjunction with the accompanying drawings, but the present application is not limited to the above-mentioned specific implementation methods. The above-mentioned specific implementation methods are merely illustrative and not restrictive. Under the guidance of this application, ordinary technicians in this field can also make many forms without departing from the purpose of this application and the scope of protection of the claims, all of which are protected by this application.

Claims

1. A method for centering a stacked chipset, characterized in that: The multiple chips in the stacked chipset are stacked sequentially from bottom to top and arranged as the first chip, the second chip, to the Nth chip from closest to farthest adjacent carriers. The chip centering device is used to sequentially center the first chip to the Nth chip according to the following chip centering method: The chip centering device includes: a bearing; a connecting device fixedly connected to the inner ring of the bearing, the connecting device having a bearing portion for placing a carrier; a supporting device fixedly connected to the outer ring of the bearing, for supporting the bearing and the connecting device; when centering the chip, the chip is placed on the carrier, and when the bearing drives the carrier to rotate, the center of the chip rotation trajectory is made to coincide with the center of the carrier, thereby achieving chip centering; the bearing and the connecting device are connected by an expansion stud; the carrier is fixed to the bearing portion by a pressure ring and a locking nut; the chip centering device also includes: a tool microscope for providing a reference line intersection point; The chip centering method comprises: Fixing a bearing platform to the bearing portion so that the center of the bearing platform coincides with the axis of the bearing; Placing the chip on the carrier platform, and driving the carrier platform to rotate by rotating the bearing; Adjusting the position of the chip, and when the center of the rotation trajectory of the chip coincides with the center of the carrier, fixing the chip on the carrier to achieve centering of the chip; and The method for determining whether the center of the rotation trajectory of the chip coincides with the center of the carrier platform includes: Adjust the intersection of the baseline of the tool microscope to coincide with the center of the carrier platform, observe the center of the trajectory of the chip during rotation through the tool microscope until the center of the trajectory coincides with the intersection of the baseline, and determine that the center of the chip's rotation trajectory coincides with the center of the carrier platform.

2. The method for centering a stacked chipset according to claim 1, wherein: The second chip to the Nth chip are all placed on the carrier through a bracket.

3. The centering method of a stacked chipset according to claim 1 or 2, wherein: The centering method of the stacked chip set is used for centering the stacked chip set of an infrared detector.

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