A multi-chip package method based on MCU
By combining conductive sheets and high-temperature thermally conductive silicone, the problem of messy wiring in traditional multi-chip packaging is solved, achieving stable chip connection and heat dissipation, simplifying the package appearance, and improving the performance and lifespan of the MCU.
Patent Information
- Authority / Receiving Office
- CN · China
- Patent Type
- Patents(China)
- Current Assignee / Owner
- 江苏盐芯微电子有限公司
- Filing Date
- 2023-02-07
- Publication Date
- 2026-05-22
AI Technical Summary
In traditional multi-chip packaging methods, a large number of wires are required to ensure a stable electrical connection between the chip and the circuit board, resulting in a messy appearance, poor simplicity, and hindering the stable packaging of multi-chip chips.
The chips are connected by conductive sheets (copper foil), and high-temperature resistant thermally conductive silicone is applied between the chips. The conductive sheets are folded to form conductive areas, and epoxy thermally conductive UV adhesive is used for encapsulation. Thermal holes and thermal pillars are set inside the encapsulation to achieve stable connection and heat dissipation of the chips.
It achieves stable electrical connections between chips, simplifies the appearance, reduces the package size, improves the neatness and stability of chip placement, and enhances the heat dissipation and mechanical strength of the MCU.
Smart Images
Figure CN116259551B_ABST
Abstract
Description
Technical Field
[0001] This invention relates to the field of chip packaging technology, specifically to a multi-chip packaging method based on an MCU. Background Technology
[0002] MCU stands for Microcontroller Unit, also known as a single-chip microcomputer or microcontroller. It is a chip-level computer that integrates a central processing unit (CPU) with a reduced frequency and specifications, and peripheral interfaces such as memory, counters, USB, A / D converter, UART, PLC, DMA, and even LCD driver circuitry onto a single chip. It can perform different combinations of control for different applications. There are multiple chips with different functions in an MCU. The traditional method of chip spacing makes the MCU large and unsuitable for small devices. With the continuous improvement of technology, in order to reduce the size of the MCU, different chips are stacked and packaged, which reduces the size of the MCU.
[0003] For example, the authorized patent with announcement number CN101179033A (a chip packaging method) encapsulates at least two stacked chips using a cap and a printed circuit board, including the following steps: first, the chips are stacked vertically on the printed circuit board, and electrical connections between the chips and between the chips and the printed circuit board are achieved by wire bonding; then, the cap is put on according to the direction, and cured to complete the encapsulation.
[0004] While the aforementioned existing technologies simplify the packaging process and improve the reliability of multi-chip packaging, they achieve electrical connections between chip pins and corresponding circuits on the circuit board through wire bonding. Different chips cannot be stably connected, and a large number of wires are required to ensure a stable electrical connection between the chips and the circuit board, resulting in a messy and unsimplistic appearance, which is not conducive to stable multi-chip packaging. Therefore, the market urgently needs to develop a multi-chip packaging method based on MCU to help people solve the existing problems. Summary of the Invention
[0005] The purpose of this invention is to provide a multi-chip packaging method based on MCU, so as to solve the problem mentioned in the background art that in order to achieve a stable electrical connection between the chip and the circuit board, a large number of wires are required in the traditional multi-chip packaging process, resulting in a messy appearance, poor simplicity, and being detrimental to the stable packaging of multi-chips.
[0006] To achieve the above objectives, the present invention provides the following technical solution: a multi-chip packaging method based on an MCU, the method being implemented based on a chip packaging body, the chip packaging body including a carrier board, a cover and chips, solder balls being disposed below the carrier board, the carrier board being configured as a printed circuit board, a surrounding plate being disposed inside the cover, the chips being configured as bare chips, and multiple chips being disposed, the multiple chips being stacked on the carrier board, conductive sheets being disposed at both ends of the chips, the conductive sheets being configured as copper foil, and conductive plates being disposed on both sides below the bottommost chip;
[0007] The MCU-based multi-chip packaging method includes the following steps:
[0008] Step 1: Surface Mounting. Attach conductive sheets to different chips with the front side facing up. Apply glue to one end of each of the two conductive sheets and symmetrically attach the glued ends of the two conductive sheets to the two sides above the chip.
[0009] Step 2: Apply adhesive to the soldering board, then solder conductive plates to both ends of the carrier board corresponding to the chip mounting positions and apply conductive adhesive to the two conductive plates. Then apply high-temperature resistant thermally conductive silicone between the two conductive plates.
[0010] Step 3: First step placement, then place the first chip face down on the carrier plate. The conductive sheets on both sides below the first chip are stably bonded to the two conductive plates. Then heat to cure the high-temperature resistant thermally conductive silicone coated on the carrier plate, and the first chip and the carrier plate are stably connected.
[0011] Step 4: The second step is placement. Then, apply high-temperature resistant thermally conductive silicone to the first chip, and fold the conductive sheets at both ends of the first chip to the two sides above the first chip, and place them above the high-temperature resistant thermally conductive silicone. Apply conductive adhesive to the two conductive sheets, and then place the second chip on the first chip. The conductive sheets on the two chips are stably bonded. Then heat to cure the applied high-temperature resistant thermally conductive silicone. The first chip and the second chip are stably connected. Then, repeat the operation of step 4 to place other chips.
[0012] Step 5: Encapsulation. After the chips are placed, place a baffle plate on the outside of the stacked chips and attach the baffle plate to the carrier plate. Then inject glue into the baffle plate to encapsulate the stacked chips.
[0013] Step Six: Seal. Apply high-temperature resistant thermally conductive silicone to the bottom of the cap and place it on the surrounding plate. Then heat and cure to seal. Place solder balls on the bottom of the carrier board to complete the multi-chip packaging.
[0014] Preferably, in step one, the front side of the chip is an end face with conductive lines, and the adhesive applied to the conductive sheet is conductive adhesive.
[0015] Preferably, in step one, the chip at the top of the stack in multi-chip packaging does not need to be bonded with a conductive sheet.
[0016] Preferably, in step two, the distance between the welding positions of the two conductive plates plus the length of the two conductive plates is the same as the length of the chip.
[0017] Preferably, in step two, the thickness of the high-temperature resistant thermally conductive silicone applied between the two conductive plates is greater than the thickness of the conductive plates.
[0018] Preferably, in step five, the adhesive injected into the enclosure is an epoxy-type thermally conductive UV adhesive, and the height of the adhesive is flush with the top of the enclosure.
[0019] Preferably, in step five, after the adhesive is injected into the inner panel, it needs to be irradiated with ultraviolet light.
[0020] Preferably, the solder balls are made of one or more of the following metals: tin, lead, copper, silver, gold, bismuth, etc.
[0021] Preferably, a heat-conducting sheet is bonded to the top of the inside of the cover, and a plurality of heat-conducting holes are provided inside the cover, and heat-conducting columns are filled inside the heat-conducting holes.
[0022] Compared with the prior art, the beneficial effects of the present invention are:
[0023] This invention utilizes conductive sheets to connect the two ends of different chips during chip stacking. These conductive sheets are made of copper foil and can be folded. By folding the conductive sheets, conductive areas are formed above and below the two ends of the chips, facilitating electrical connections between different chips. The overall appearance is simple and clear, which can reduce the size of multi-chip packages, minimize the interconnection between chips, and reduce the overall size. This effectively realizes 3D chip stacking, making it easier to manufacture MCUs with more complex structures and more powerful performance.
[0024] This invention, by applying high-temperature resistant thermally conductive silicone between two stacked adjacent chips, not only ensures a stable connection between the two adjacent chips, but also prevents discharge between the two adjacent chips due to the insulation properties of the high-temperature resistant thermally conductive silicone, thus improving safety. At the same time, the thermal conductivity of the high-temperature resistant thermally conductive silicone also helps with overall heat dissipation.
[0025] This invention improves the neatness and stability of chip placement by heating and curing one chip at a time before placing the next chip in the stack. This prevents slippage between different chips due to the uncured high-temperature thermally conductive silicone when placing them simultaneously.
[0026] This invention fills the enclosed plate with epoxy thermally conductive UV adhesive and then applies ultraviolet light after the adhesive is applied, which allows the epoxy thermally conductive UV adhesive to cure quickly. The cured epoxy thermally conductive UV adhesive can effectively reduce the temperature expansion between the chip and the carrier board or the impact of external forces, thereby improving the mechanical strength of the chip and extending the performance and lifespan of the MCU.
[0027] This invention, by setting a heat-conducting sheet at the top inside the cover and a heat-conducting pillar inside the cover, enables the heat generated when multiple chips are working to be quickly dissipated upwards, which is beneficial to the heat dissipation of the MCU. Attached Figure Description
[0028] Figure 1 This is an overall schematic diagram of the chip package of the present invention;
[0029] Figure 2 This is a cross-sectional view of the chip package of the present invention;
[0030] Figure 3 This is an enlarged schematic diagram of part A of the present invention;
[0031] Figure 4 This is a flowchart illustrating a multi-chip packaging method based on an MCU according to the present invention.
[0032] In the diagram: 1. Carrier plate; 2. Cap; 3. Chip; 4. Solder ball; 5. Enclosure plate; 6. Conductive sheet; 7. Thermal sheet; 8. Thermal hole; 9. Conductive plate. Implementation
[0033] The technical solutions of the present invention will be clearly and completely described below with reference to the accompanying drawings of the embodiments of the present invention. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments.
[0034] Please see Figure 1-4 The present invention provides an embodiment of a multi-chip packaging method based on an MCU. The method is based on a chip packaging body, which includes a carrier board 1, a cover 2, and a chip 3. Solder balls 4 are arranged below the carrier board 1. The carrier board 1 is a printed circuit board, which enables the chip 3 to work stably. A surrounding plate 5 is arranged inside the cover 2. The chip 3 is a bare chip, which can reduce the overall packaging thickness. Multiple chips 3 are arranged and stacked on the carrier board 1. Conductive sheets 6 are arranged at both ends of the chip 3. The conductive sheets 6 are copper foil. Conductive plates 9 are arranged on both sides below the bottom chip 3.
[0035] The MCU-based multi-chip packaging method includes the following steps:
[0036] Step 1: Attach conductive sheets 6 to different chips 3. Place the chip 3 face up, apply glue to one end of the two conductive sheets 6, and attach the glued ends of the two conductive sheets 6 symmetrically to the two sides above the chip 3.
[0037] Step 2: Apply adhesive to the soldering board, then solder conductive plates 9 at both ends of the carrier board 1 corresponding to the positions where the chip 3 is installed, and apply conductive adhesive to the two conductive plates 9. Then apply high-temperature resistant thermally conductive silicone between the two conductive plates 9.
[0038] Step 3: First step placement, then place the first chip 3 face down on the carrier plate 1. The conductive sheets 6 on both sides below the first chip 3 are stably bonded to the two conductive plates 9. Then heat to cure the high temperature resistant thermally conductive silicone coated on the carrier plate 1, and the first chip 3 and the carrier plate 1 are stably connected.
[0039] Step 4: The second step is placement. Then, apply high-temperature resistant thermally conductive silicone to the first chip 3, and fold the conductive sheets 6 at both ends of the first chip 3 to the two sides above the first chip 3, and place them above the high-temperature resistant thermally conductive silicone. Apply conductive adhesive to the two conductive sheets 6, and then place the second chip 3 on the first chip 3. The conductive sheets 6 on the two chips 3 are stably bonded. Then heat to cure the applied high-temperature resistant thermally conductive silicone. The first chip 3 and the second chip 3 are stably connected. Then, repeat the operation of step 4 to place other chips 3.
[0040] Step 5: Sealing. After the chip 3 is placed, place the surrounding plate 5 on the outside of the stacked chip 3 and attach the surrounding plate 5 to the carrier plate 1. Then inject glue into the surrounding plate 5 to seal the stacked chip 3.
[0041] Step 6: Seal. Apply high-temperature resistant thermally conductive silicone to the bottom of the cover 2 and place it on the enclosure plate 5. Then heat and cure to seal. Place solder balls 4 on the bottom of the carrier plate 1 to complete the multi-chip packaging.
[0042] Furthermore, by using conductive sheets 6 to connect the two ends of different chips 3 during chip stacking, conductive areas are formed above and below the two ends of each chip 3, facilitating electrical connections between different chips 3. The overall appearance is simple and clear, which reduces the size of multi-chip packages, minimizes the interconnection points between chips 3, and reduces the overall size. This effectively achieves 3D stacking of chips 3, making it easier to manufacture MCUs with more complex structures and higher performance. It solves the problem of numerous wires in stacked chips, resulting in a messy appearance and poor simplicity. At the same time, by heating and curing each chip 3 before placing it, slippage between different chips 3 is prevented due to the uncured high-temperature thermally conductive silicone, improving the neatness and stability of chip 3 placement.
[0043] Furthermore, in step one, the front side of chip 3 is the end face with conductive lines, and the adhesive applied to the conductive sheet 6 is conductive adhesive, which improves the stability of mutual conductivity when different chips 3 are stacked. In step one, the chip 3 at the top of the stack in multi-chip packaging does not need to be bonded to the conductive sheet 6.
[0044] Furthermore, in step two, the distance between the welding positions of the two conductive plates 9 plus the length of the two conductive plates 9 is the same as the length of the chip 3, so that the conductive pieces 6 on both sides below the first chip 3 can be stably placed on the two conductive plates 9, improving practicality.
[0045] Furthermore, in step two, the thickness of the high-temperature resistant thermally conductive silicone applied between the two conductive plates 9 is greater than the thickness of the conductive plates 9, so that the first chip 3 and the carrier plate 1 can be stably connected.
[0046] Furthermore, in step five, the adhesive injected into the enclosure 5 is an epoxy thermally conductive UV adhesive, and the adhesive height is flush with the top of the enclosure 5. After the adhesive is injected into the enclosure 5, it needs to be irradiated with ultraviolet light. The enclosure 5 is designed to facilitate stable adhesive injection and sealing. By filling the enclosure 5 with epoxy thermally conductive UV adhesive and then irradiating it with ultraviolet light after the adhesive is injected, the epoxy thermally conductive UV adhesive can be cured quickly. The cured epoxy thermally conductive UV adhesive can effectively reduce the temperature expansion or external impact between the chip and the carrier board, thereby improving the mechanical strength of the chip 3 and extending the performance and lifespan of the MCU.
[0047] Furthermore, the solder ball 4 is made of one or more of the following metals: tin, lead, copper, silver, gold, bismuth, etc.
[0048] Furthermore, a heat-conducting sheet 7 is bonded to the top of the inside of the cover 2, and a number of heat-conducting holes 8 are provided inside the cover 2. The inside of the heat-conducting holes 8 is filled with heat-conducting pillars, which can quickly dissipate the heat generated when multiple chips are working upwards, which is beneficial to the heat dissipation of the MCU.
[0049] Working principle: In use, conductive sheets 6 are attached to different chips 3 with the front side facing up. Adhesive is applied to one end of each of the two conductive sheets 6, and the adhesive-coated ends of the two conductive sheets 6 are symmetrically attached to the two sides above the chip 3. Then, conductive plates 9 are soldered to the two ends of the carrier plate 1 corresponding to the chip 3 mounting positions, and conductive adhesive is applied to the two conductive plates 9. High-temperature thermally conductive silicone is then applied between the two conductive plates 9. The first chip 3 is then placed face down on the carrier plate 1, with the conductive sheets 6 on both sides below the first chip 3 stably bonded to the two conductive plates 9. Heating is then used to cure the high-temperature thermally conductive silicone applied to the carrier plate 1, resulting in a stable connection between the first chip 3 and the carrier plate 1. Finally, high-temperature thermally conductive silicone is applied to the first chip 3, and the conductive sheets at both ends of the first chip 3 are attached to the carrier plate 1. Fold the two conductive sheets 6 to the sides above the first chip 3, and place them above the high-temperature thermally conductive silicone. Apply conductive adhesive to the two conductive sheets 6, and then place the second chip 3 on the first chip 3. The conductive sheets 6 on the two chips 3 are stably bonded. Then heat to cure the applied high-temperature thermally conductive silicone. The first chip 3 and the second chip 3 are stably connected. Then, repeat step four to place other chips 3. After the chips 3 are placed, place the surrounding plate 5 on the outside of the stacked chips 3, and bond the surrounding plate 5 to the carrier plate 1. Then inject glue into the surrounding plate 5 to seal the stacked chips 3. Then apply high-temperature thermally conductive silicone to the bottom of the cover 2 and put it on the surrounding plate 5. Then heat to cure and seal. Place solder balls 4 on the bottom of the carrier plate 1 to complete the multi-chip encapsulation.
[0050] It will be apparent to those skilled in the art that the present invention is not limited to the details of the exemplary embodiments described above, and that the invention can be implemented in other specific forms without departing from its spirit or essential characteristics. Therefore, the embodiments should be considered in all respects as exemplary and non-limiting, and the scope of the invention is defined by the appended claims rather than the foregoing description. Thus, all variations falling within the meaning and scope of equivalents of the claims are intended to be included within the present invention. No reference numerals in the claims should be construed as limiting the scope of the claims.
Claims
1. A multi-chip packaging method based on an MCU, the method being implemented based on a chip packaging body, the chip packaging body comprising a carrier board (1), a cover (2), and a chip (3), characterized in that: Solder balls (4) are provided below the carrier board (1). The carrier board (1) is a printed circuit board. A surrounding plate (5) is provided inside the cover (2). The chip (3) is a bare chip. Multiple chips (3) are provided. Multiple chips (3) are stacked on the carrier board (1). Conductive sheets (6) are provided at both ends of the chip (3). The conductive sheets (6) are copper foil. Conductive plates (9) are provided on both sides below the bottom chip (3). The MCU-based multi-chip packaging method includes the following steps: Step 1: Attaching conductive sheets (6) to different chips (3) respectively. With the front of the chip (3) facing up, apply glue to one end of the two conductive sheets (6) and attach the glued ends of the two conductive sheets (6) symmetrically to the two sides above the chip (3). Step 2: Apply adhesive to the soldering board, then solder conductive plates (9) to both ends of the carrier board (1) corresponding to the chip (3) mounting positions, apply conductive adhesive to the two conductive plates (9), and then apply high-temperature resistant thermally conductive silicone between the two conductive plates (9). Step 3: First step placement, then place the first chip (3) face down on the carrier plate (1), the conductive sheets (6) on both sides below the first chip (3) are stably bonded to the two conductive plates (9), then heat to cure the high temperature resistant thermal conductive silicone coated on the carrier plate (1), and the first chip (3) and the carrier plate (1) are stably connected. Step 4: Placement. Apply high-temperature thermally conductive silicone to the first chip (3), and fold the conductive sheets (6) at both ends of the first chip (3) to the two sides above the first chip (3) and above the high-temperature thermally conductive silicone. Apply conductive adhesive to the two conductive sheets (6), and then place the second chip (3) on the first chip (3). The conductive sheets (6) on the two chips (3) are stably bonded. Heat the coated high-temperature thermally conductive silicone to cure it. The first chip (3) and the second chip (3) are stably connected. Then repeat step 4 to place other chips (3). Step 5: Sealing. After the chip (3) is placed, place a retaining plate (5) on the outside of the stacked chip (3) and attach the retaining plate (5) to the carrier plate (1). Then inject glue into the retaining plate (5) to seal the stacked chip (3). Step 6: Seal, then apply high temperature resistant thermal conductive silicone to the bottom of the cover (2) and put it on the enclosure plate (5), then heat and cure to seal, and plant solder balls (4) on the bottom of the carrier plate (1) to complete the multi-chip packaging.
2. The multi-chip packaging method based on MCU according to claim 1, characterized in that: In step one, the front side of the chip (3) is an end face with conductive lines, and the adhesive applied to the conductive sheet (6) is conductive adhesive.
3. The multi-chip packaging method based on MCU according to claim 1, characterized in that: In step one, the chip (3) at the top of the stack in the multi-chip package does not need to be bonded with a conductive sheet (6).
4. The multi-chip packaging method based on MCU according to claim 1, characterized in that: In step two, the distance between the welding positions of the two conductive plates (9) plus the length of the two conductive plates (9) is the same as the length of the chip (3).
5. The multi-chip packaging method based on MCU according to claim 1, characterized in that: In step two, the thickness of the high-temperature resistant thermally conductive silicone applied between the two conductive plates (9) is greater than the thickness of the conductive plates (9).
6. The multi-chip packaging method based on MCU according to claim 1, characterized in that: In step five, the glue injected into the enclosure (5) is epoxy thermally conductive UV glue, and the glue height is flush with the top of the enclosure (5).
7. A multi-chip packaging method based on an MCU according to claim 6, characterized in that: In step five, after the glue is injected into the enclosure (5), it needs to be irradiated with ultraviolet light.
8. The multi-chip packaging method based on MCU according to claim 1, characterized in that: The solder ball (4) is made of one or more of the following metals: tin, lead, copper, silver, gold, bismuth, etc.
9. The multi-chip packaging method based on MCU according to claim 1, characterized in that: A heat-conducting sheet (7) is bonded to the top of the inside of the cover (2). A heat-conducting hole (8) is provided inside the cover (2), and there are several heat-conducting holes (8). The inside of the heat-conducting hole (8) is filled with heat-conducting columns.