A three-dimensional stacked shielding structure and its preparation method

Abstract

The present invention discloses a three-dimensional stacked shielding structure and a method for preparing the same. The shielding structure includes a first chip and a second chip, each having two rows of oppositely arranged radio frequency ground pads and signal transmission pads disposed peripherally thereon. The signal transmission pads of the first chip are bonded with signal transmission double-layer gold-based stud bumps. The two rows of oppositely arranged radio frequency ground pads on the first chip are sequentially interconnected by shielding gold wires. The shielding gold wires are bonded with single-layer stud bumps at their bonding points with the radio frequency ground pads. The single-layer stud bumps and the bonding points combine to form grounded double-layer gold-based stud bumps. The second chip is flip-chip mounted on a combination of the first chip, the signal transmission double-layer gold-based stud bumps, and the grounded double-layer gold-based stud bumps to form a three-dimensional stacked structure. The present invention can solve the problem of electromagnetic interference between upper and lower layers caused by insufficient air cavity height in a three-dimensional stacked structure of microwave chips.

Description

Technical Field

[0001] The present invention belongs to the technical field of microelectronic packaging, and in particular relates to a three-dimensional stacked shielding structure and a preparation method thereof. Background Art

[0002] With the development demand for miniaturization and high integration of microwave products, three-dimensional integration technology has been widely used. However, in the microwave chip flip-chip structure, due to the small size and low height of the micro-bumps, it is difficult to form a high air cavity, that is, the isolation is insufficient. This leads to inter-layer crosstalk and self-excitation during the transmission of microwave signals between the upper and lower chips, seriously affecting product performance.

[0003] To address the above issues, Chinese invention patent CN114300446B discloses a chip stack shielding structure and manufacturing method. This structure achieves external electromagnetic shielding by arranging metal shielding wires around the periphery of the three-dimensional stacking structure. However, this method does not address the problem of electromagnetic signal crosstalk between layers within the three-dimensional stacking structure.

[0004] For example, Chinese patent CN110868793A discloses a three-dimensional integrated microwave circuit shielding structure that uses shielding grounding solder balls to form a closed shield. However, this structure is mainly used for board-level flip-chips, and the solder balls are large in size, making it unsuitable for chip-level flip-chips.

[0005] For example, Chinese patent CN114373740B discloses an electromagnetic shielding packaging structure, an electronic device module, and a manufacturing method. Electromagnetic isolation between adjacent devices is achieved by conductively connecting two sections of a lead to a first shielding member and a second shielding member, respectively. However, the process is relatively complex to implement and is only applicable to structures with large air cavities within components. It cannot be applied to chip-level flip-chip micromodules with air cavities on the order of tens of microns.

[0006] That is, the current existing technology is difficult to solve the problem of inter-layer crosstalk and self-excitation in the process of microwave signal transmission between upper and lower chips in the microwave chip flip-chip structure. Summary of the Invention

[0007] The purpose of the present invention is to overcome the defects of the prior art and provide a three-dimensional stacked shielding structure and a preparation method thereof, wherein shielding gold wires are bonded between parallel RF ground pads, and the bonding points of the shielding gold wires are used as lower-layer micro-bumps to combine with the single-layer nail head bumps on the shielding gold wires to form grounded double-layer gold-based nail head bumps, and the signal transmission pads located outside the RF ground pads are bonded to the signal transmission double-layer gold-based nail head bumps, and the first chip and the second chip are flipped to form a three-dimensional stacked structure. The array of shielding gold wires in the air cavity of the structure can well isolate the upper and lower microwave signals, thereby solving the problem of electromagnetic interference between the upper and lower layers caused by insufficient air cavity height in the three-dimensional stacked structure of microwave chips.

[0008] The object of the present invention is achieved through the following technical solutions:

[0009] A three-dimensional stacked shielding structure includes a first chip and a second chip, each of the first chip and the second chip having two rows of oppositely arranged radio frequency ground pads and signal transmission pads arranged around the radio frequency ground pads, the signal transmission pads of the first chip are bonded with signal transmission double-layer gold-based stud bumps, the two oppositely arranged rows of radio frequency ground pads on the first chip are sequentially interconnected by shielding gold wires, the shielding gold wires are bonded with single-layer stud bumps at the bonding points with the radio frequency ground pads, the single-layer stud bumps and the bonding points are combined to form grounded double-layer gold-based stud bumps, the second chip is flip-chip mounted on a combination of the first chip, the signal transmission double-layer gold-based stud bumps and the grounded double-layer gold-based stud bumps to form a three-dimensional stacked structure.

[0010] In one embodiment, the signal transmission pads on the second chip are bonded to the signal transmission double-layer gold-based stud bumps, and the radio frequency ground pads on the second chip are bonded to the ground double-layer gold-based stud bumps.

[0011] In one embodiment, it also includes an adapter board arranged between the first chip and the second chip, one side of the adapter board is bonded to the signal transmission double-layer gold-based nail head bumps and the grounding double-layer gold-based nail head bumps, and the other side is bonded to the second chip through the double-layer gold-based nail head bumps. The adapter board is provided with a cavity structure located between two rows of oppositely arranged RF ground pads. Through this embodiment, an adapter board with a cavity structure is arranged between the first chip and the second chip to increase the height of the air cavity between the first chip and the second chip, improve the isolation between the two, and at the same time avoid the situation where the shielding gold wire is too close to the upper chip to cause contact short circuit.

[0012] In one embodiment, the two ends of the shielding gold wire are bonded to the relatively set RF ground pads by ball welding, and the solder balls at the welding points are combined with the single-layer stud bumps bonded to the shielding gold wire to form a grounded double-layer gold-based stud bump. Through this embodiment, the two ends of the shielding gold wire are bonded to the relatively set RF ground pads by ball welding, and the two columns of RF ground pads are sequentially arranged with shielding gold wires along their arrangement direction. The array composed of multiple shielding gold wires isolates the upper and lower microwave signals.

[0013] In one embodiment, the surfaces of the radio frequency ground pad and the signal transmission pad are both gold-plated.

[0014] In one embodiment, the signal transmission double-layer gold-based stud bump is bonded to the signal transmission pad of the first chip by a wire bonding machine.

[0015] In one embodiment, the diameter of the signal transmission double-layer gold-based stud bump is 1 / 4 of the diameter of the signal transmission pad. times, n is greater than 1.

[0016] The present invention also provides a method for preparing a three-dimensional stacked shielding structure, which is used to prepare the above-mentioned three-dimensional stacked shielding structure, comprising the following steps:

[0017] Step S1, bonding signal transmission double-layer gold-based stud bumps to the signal transmission pads of the first chip using a wire bonder;

[0018] Step S2: bonding shielding gold wires sequentially between two rows of oppositely arranged RF ground pads of the first chip through a ball bonding process;

[0019] Step S3, bonding a single layer of gold-based stud bumps on the shielding gold wire at the ball solder joints of the two ends of the shielding gold wire and the radio frequency ground pad;

[0020] Step S4: flip-chip the second chip onto the assembly consisting of the first chip, the signal transmission double-layer gold-based stud bumps, and the grounding double-layer gold-based stud bumps to form a three-dimensional stacked structure.

[0021] In one embodiment, in step S4, the method further includes:

[0022] The assembly is placed on the hot plate surface of the flip-chip bonder, and vacuum is applied to fix the assembly. The flip-chip bonder picks up the second chip and flips it over. The alignment of the first chip and the second chip is completed through the equipment recognition system. The suction nozzle applies pressure and ultrasound to complete the thermal ultrasonic welding of the first chip and the second chip.

[0023] In one embodiment, in step S4, the method further includes:

[0024] Place the adapter plate with a cavity structure on the surface of the hot table of the flip-chip bonder, apply vacuum to fix the adapter plate, the flip-chip bonder sucks the assembly and flips it over, the equipment recognition system completes the alignment recognition of the assembly and the adapter plate, and the suction nozzle applies pressure and ultrasound to complete the thermal ultrasonic welding of the assembly and the adapter plate. Bond a double-layer gold-based nail head bump on the adapter plate, and place it on the surface of the hot table of the flip-chip bonder, apply vacuum to fix it, the flip-chip bonder sucks the second chip and flips it, and the equipment recognition system completes the alignment recognition of the assembly and the adapter plate, and the suction nozzle applies pressure and ultrasound to complete the thermal ultrasonic welding of the adapter plate and the second chip.

[0025] The beneficial effects of the present invention are:

[0026] By bonding shielding gold wires between parallel RF ground pads, and using the bonding points of the shielding gold wires as the lower-layer micro-bumps to combine with the single-layer nail head bumps on the shielding gold wires to form grounded double-layer gold-based nail head bumps, the signal transmission pads located outside the RF ground pads are bonded to the signal transmission double-layer gold-based nail head bumps, and the first chip and the second chip are flipped to form a three-dimensional stacked structure. The array of shielding gold wires in the air cavity of this structure can effectively isolate the upper and lower microwave signals, solving the problem of electromagnetic interference between the upper and lower layers caused by insufficient air cavity height in the three-dimensional stacking structure of microwave chips. BRIEF DESCRIPTION OF THE DRAWINGS

[0027] The present invention will be described in more detail below based on embodiments and with reference to the accompanying drawings, wherein:

[0028] Figure 1 A schematic structural diagram of an embodiment of the present invention is shown;

[0029] Figure 2 Shows Figure 1 A schematic top perspective structural diagram of the embodiment shown;

[0030] Figure 3 shows a schematic structural diagram of another embodiment of the present invention;

[0031] Figure 4 A schematic flow chart of steps S1 to S3 in the preparation method of the present invention is shown;

[0032] Figure 5 A schematic flow chart showing an embodiment of step S4 in the preparation method of the present invention

[0033] In the drawings, like reference numerals are used for like parts, but the drawings are not necessarily true to scale.

[0034] Reference numerals:

[0035] 101 - first chip, 102 - second chip, 103 - signal transmission double-layer gold-based stud bump, 104 - grounding double-layer gold-based stud bump, 105 - shielding gold wire, 106 - adapter board, 107 - double-layer gold-based stud bump. DETAILED DESCRIPTION

[0036] The present invention will be further described below with reference to the accompanying drawings.

[0037] The present invention provides a three-dimensional stacked shielding structure, such as Figure 1 and Figure 2As shown, it includes a first chip 101 and a second chip 102. The first chip 101 and the second chip 102 each have two rows of oppositely arranged RF ground pads and signal transmission pads arranged around the RF ground pads. The signal transmission pads of the first chip 101 are bonded with signal transmission double-layer gold-based stud bumps 103. The two rows of oppositely arranged RF ground pads on the first chip 101 are bonded in sequence through shielding gold wires 105. The shielding gold wires 105 are bonded with single-layer stud bumps at the bonding points with the RF ground pads. The single-layer stud bumps and the bonding points are combined to form grounded double-layer gold-based stud bumps 104. The second chip 102 is flip-chip mounted on the assembly consisting of the first chip 101, the signal transmission double-layer gold-based stud bumps 103, and the grounded double-layer gold-based stud bumps 104 to form a three-dimensional stacked structure.

[0038] It should be noted that two rows of oppositely arranged RF ground pads are set in the central area of ​​the first chip 101 and the second chip 102, and a circle of signal transmission pads in a rectangular structure is set around the RF ground pads. By bonding a shielding gold wire 105 between the parallel RF ground pads, and using the bonding point of the shielding gold wire 105 as the lower layer micro-bump, it is combined with the single-layer nail head bump on the shielding gold wire 105 to form a grounded double-layer gold-based nail head bump 104, and the signal transmission double-layer gold-based nail head bump is bonded on the signal transmission pad. At point 103, the first chip 101 and the second chip 102 are flipped to form a three-dimensional stacked structure. In the three-dimensional stacked structure, an array of multiple shielding gold wires 105 can effectively isolate the microwave signals of the upper and lower layers, solving the electromagnetic interference problem between the upper and lower layers caused by insufficient air cavity height in the three-dimensional stacked structure of microwave chips. The first chip 101 and the second chip 102 can be made of silicon, gallium arsenide, gallium nitride, glass, ceramic, etc. The RF ground pad and the signal transmission pad are plated with a material that meets gold bonding requirements.

[0039] Specifically, the signal transmission pad on the second chip 102 is bonded to the signal transmission double-layer gold-based stud bump 103, and the RF ground pad on the second chip 102 is bonded to the ground double-layer gold-based stud bump 104. In this embodiment, the first chip 101 is used as a basis, and the ground double-layer gold-based stud bump 104 and the signal transmission double-layer gold-based stud bump 103 can also be bonded to the second chip 102, and then the first chip 101 is flip-chip mounted thereon;

[0040] In one embodiment, Figure 3 As shown, the adapter board 106 is further provided between the first chip 101 and the second chip 102. One side of the adapter board 106 is bonded to the signal transmission double-layer gold-based stud bumps 103 and the ground double-layer gold-based stud bumps 104, and the other side is bonded to the second chip 102 through the double-layer gold-based stud bumps 107. The adapter board 106 has a cavity structure located between two rows of oppositely arranged RF ground pads.

[0041] It should be noted that the three-dimensional stacked structure provided in this embodiment further includes an adapter plate 106 having a cavity structure disposed between the first chip 101 and the second chip 102 to increase the height of the air cavity between the first chip 101 and the second chip 102, thereby improving the isolation between the two and preventing the shielding gold wire 105 from being too close to the upper chip and causing a contact short circuit.

[0042] Specifically, the two ends of the shielding gold wire 105 are bonded to the oppositely arranged RF ground pads by ball welding. The solder balls at the welding points are combined with the single-layer stud bumps bonded to the shielding gold wire 105 to form a grounded double-layer gold-based stud bump 104. The surfaces of the RF ground pads and the signal transmission pads are gold-plated. The signal transmission double-layer gold-based stud bump 103 is bonded to the signal transmission pads of the first chip 101 by a wire bonding machine. That is, the two ends of the shielding gold wire 105 are bonded to the oppositely arranged RF ground pads by ball welding. The two columns of RF ground pads are sequentially provided with shielding gold wires 105 along their arrangement direction. The array composed of multiple shielding gold wires 105 isolates the upper and lower microwave signals.

[0043] In one embodiment, the diameter of the signal transmission double-layer gold-based stud bump 103 is 1 / 4 of the diameter of the signal transmission pad. times, n is greater than 1, such as the diameter of the signal transmission double-layer gold-based stud bump 103 is the diameter of the signal transmission pad or wait;

[0044] In one embodiment, Figure 1 As shown, the first chip 101 is a gallium arsenide chip with an outer size of 1.5mm×2.0mm. The signal transmission pad and the radio frequency ground pad on it are gold-plated, and the pad size is 100um×100um. The second chip 102 is a silicon chip with the same outer size as the first chip 101, and the pads on it are also the same as the pads on the first chip 101. The signal transmission double-layer gold-based stud bump 103 is bonded to the signal transmission pad of the first chip 101 by a wire bonding machine. The bump diameter is 80um and the bump thickness is 60um. The shielding gold wire 105 has a diameter of 25 μm and is bonded to two opposite RF ground pads on the first chip 101. Multiple shielding gold wires 105 are sequentially bonded to the two rows of RF ground pads. The prepared shielding gold wire 105 has a span of 0.6 mm and a height of 28 μm between the welding point and the RF ground pad. The grounded double-layer gold-based stud bump 104 consists of a welding point and a single-layer stud bump on the shielding gold wire 105. The bump diameter is 80 μm and the total bump thickness is 60 μm. The second chip 102 is flip-chip mounted on the first chip 101 using a flip-chip bonder.

[0045] In one embodiment, Figure 3 As shown, the first chip 101 is a radio frequency chip, made of glass, with an outer size of 3.0mm×3.0mm, and the signal transmission pad and radio frequency ground pad thereon are gold-plated, and the pad size is 100um×100um. The second chip 102 is a radio frequency chip, made of glass, with the same appearance as the first chip 101, and the pad thereon is also the same as the pad of the first chip 101. The adapter board 106 provides signal transmission for the first chip 101 and the second chip 102, and is made of glass, with an outer size of 3.0mm×3.0mm, and a 1.0mm×1.0mm cavity structure in the middle, and the surface pad is gold-plated. The signal transmission double-layer gold-based nail head bump 103 is bonded to the signal transmission pad of the first chip 101 by a wire bonding machine, and the bump diameter is 75um. , the bump thickness is 45um, the shielding gold wire 105 has a diameter of 25um, which is bonded to two opposite RF ground pads on the first chip 101, and multiple shielding gold wires 105 are bonded in sequence on the two rows of RF ground pads. The prepared shielding gold wire 105 has a span of 1.2mm, and the height of the welding point with the RF ground pad is 22um. The grounded double-layer gold-based stud bump 104 consists of a welding point and a single-layer stud bump on the shielding gold wire 105. The bump diameter is 75um, and the total bump thickness is 45um. The adapter plate 106 is thermally ultrasonically flip-chipped on the first chip 101 by a flip-chip bonder, and then a double-layer gold-based stud bump 107 is prepared on the upper layer of the adapter plate 106. After the preparation is completed, the second chip 102 is bonded to the double-layer gold-based stud bump 107 on the adapter plate 106 by a flip-chip bonder;

[0046] The present invention also provides a method for preparing a three-dimensional stacked shielding structure, which is used to prepare the three-dimensional stacked shielding structure provided in the above embodiment, comprising the following steps:

[0047] Step S1, bonding signal transmission double-layer gold-based stud bumps to the signal transmission pads of the first chip using a wire bonder;

[0048] Step S2: bonding shielding gold wires sequentially between two rows of oppositely arranged RF ground pads of the first chip through a ball bonding process;

[0049] Step S3, bonding a single layer of gold-based stud bumps on the shielding gold wire at the ball solder joints of the two ends of the shielding gold wire and the radio frequency ground pad;

[0050] Step S4: flip-chipping the second chip onto the assembly consisting of the first chip, the signal transmission double-layer gold-based stud bumps, and the grounding double-layer gold-based stud bumps to form a three-dimensional stacked structure;

[0051] It should be noted that in step S2, after using the spark rod to discharge a molten ball on the tip of the shielding gold wire, a gold bump is first bonded to the RF ground pad on the right of the two opposite RF ground pads, and the splitter moves to above the RF ground pad on the left, and the spark rod discharges a molten ball on the tip of the shielding gold wire to complete the bonding of the shielding gold wire to form a first solder joint, and the splitter rises to a safe height, and bends the heat-affected area of ​​the shielding gold wire through a first segment of retreat movement, and the bent shielding gold wire is pressed against the first solder joint, and pressure and ultrasound are applied to bond the heat-affected area of ​​the shielding gold wire to the first solder joint, and then the splitter moves through a normal arc trajectory to the gold bump surface of the RF ground pad on the right, completing the bonding of the shielding gold wire and the gold bump to form a second solder joint, and the first solder joint and the second solder joint serve as micro-bumps, and together with the single-layer gold-based nail head bump bonded in step S3, form a grounded double-layer gold-based nail head bump;

[0052] In one embodiment, Figure 1 and Figure 4 As shown, step S4 also includes:

[0053] The assembly is placed on the hot plate surface of the flip chip bonder, and vacuum is applied to fix the assembly. The flip chip bonder picks up the second chip 102 and flips it over. The first chip 101 and the second chip 102 are aligned and identified by the device identification system. The nozzle applies pressure and ultrasound to complete the thermal ultrasonic welding of the first chip 101 and the second chip 102, thus forming a Figure 1 The three-dimensional stacked shielding structure shown;

[0054] In one embodiment, Figure 4 and Figure 5 As shown, step S4 also includes:

[0055] The adapter plate with a cavity structure is placed on the hot table surface of the flip-chip bonder, and vacuum is applied to fix the adapter plate. The flip-chip bonder absorbs the assembly and flips it over. The equipment identification system completes the alignment identification of the assembly and the adapter plate 106. The suction nozzle applies pressure and ultrasound to complete the thermo-ultrasonic welding of the assembly and the adapter plate 106. A double-layer gold-based stud bump 107 is bonded on the adapter plate 106, and the adapter plate is placed on the hot table surface of the flip-chip bonder, and vacuum is applied to fix it. The flip-chip bonder absorbs the second chip 102 and flips it over. The equipment identification system completes the alignment identification of the assembly and the adapter plate 102. The suction nozzle applies pressure and ultrasound to complete the thermo-ultrasonic welding of the adapter plate 107 and the second chip 102, thus forming the following. Figure 5 The three-dimensional stacked shielding structure shown increases the height of the air cavity between the first chip 101 and the second chip 102, thereby improving the isolation between the two and preventing the shielding gold wire 105 from being too close to the upper chip and causing a short circuit.

[0056] In the description of the present invention, it should be understood that the terms "upper", "lower", "bottom", "top", "front", "back", "inside", "outside", "left", "right", etc., indicating directions or positional relationships, are based on the directions or positional relationships shown in the accompanying drawings, and are only for the convenience of describing the present invention and simplifying the description, rather than indicating or implying that the device or element referred to must have a specific direction, be constructed and operated in a specific direction, and therefore cannot be understood as limiting the present invention.

[0057] Although the present invention is described herein with reference to specific embodiments, it should be understood that these embodiments are merely illustrative of the principles and applications of the invention. It should be understood that many modifications may be made to the illustrative embodiments, and that other arrangements may be devised, without departing from the spirit and scope of the invention as defined by the appended claims. It should be understood that features described herein may be combined in ways other than those described in the original claims. It should also be understood that features described in conjunction with individual embodiments may be used in other embodiments.

Claims

1. A three-dimensional stacked shielding structure, characterized in that: The invention comprises a first chip and a second chip, wherein the first chip and the second chip each have two rows of oppositely arranged radio frequency ground pads and signal transmission pads arranged around the radio frequency ground pads, the signal transmission pads of the first chip are bonded with signal transmission double-layer gold-based nail bumps, the two rows of oppositely arranged radio frequency ground pads on the first chip are bonded to each other in sequence through shielding gold wires, the shielding gold wires are bonded with single-layer nail bumps at the bonding points between the shielding gold wires and the radio frequency ground pads, the single-layer nail bumps and the bonding points are combined to form grounded double-layer gold-based nail bumps, and the second chip is flip-chip mounted on a combination of the first chip, the signal transmission double-layer gold-based nail bumps and the grounded double-layer gold-based nail bumps to form a three-dimensional stacked structure.

2. The three-dimensional stacked shielding structure according to claim 1, characterized in that: The signal transmission pads on the second chip are bonded to the signal transmission double-layer gold-based stud bumps, and the radio frequency ground pads on the second chip are bonded to the grounding double-layer gold-based stud bumps.

3. The three-dimensional stacked shielding structure according to claim 1, characterized in that: It also includes an adapter board arranged between the first chip and the second chip, one side of the adapter board is bonded and interconnected with the signal transmission double-layer gold-based stud bumps and the grounding double-layer gold-based stud bumps, and the other side is bonded and interconnected with the second chip through the double-layer gold-based stud bumps. A cavity structure is provided on the adapter board between two rows of oppositely arranged RF ground pads.

4. The three-dimensional stacked shielding structure according to claim 1, characterized in that: The two ends of the shielding gold wire are bonded to the oppositely arranged radio frequency ground pads through ball welding, and the solder balls at the welding points are combined with the single-layer stud bumps bonded on the shielding gold wire to form grounded double-layer gold-based stud bumps.

5. The three-dimensional stacked shielding structure according to claim 1, characterized in that: The surfaces of the radio frequency ground pad and the signal transmission pad are both gold-plated.

6. The three-dimensional stacked shielding structure according to claim 1, characterized in that: The signal transmission double-layer gold-based stud bumps are bonded to the signal transmission pads of the first chip through a wire bonding machine.

7. The three-dimensional stacked shielding structure according to claim 1, characterized in that: The diameter of the signal transmission double-layer gold-based stud bump is the diameter of the signal transmission pad. times, n is greater than 1.

8. A method for preparing a three-dimensional stacked shielding structure, for preparing the three-dimensional stacked shielding structure according to any one of claims 1 to 7, characterized in that: The steps include: Step S1, bonding signal transmission double-layer gold-based stud bumps to the signal transmission pads of the first chip using a wire bonder; Step S2: bonding shielding gold wires sequentially between two rows of oppositely arranged RF ground pads of the first chip through a ball bonding process; Step S3, bonding a single layer of gold-based stud bumps on the shielding gold wire at the ball solder joints of the two ends of the shielding gold wire and the radio frequency ground pad; Step S4: flip-chip the second chip onto the assembly consisting of the first chip, the signal transmission double-layer gold-based stud bumps, and the grounding double-layer gold-based stud bumps to form a three-dimensional stacked structure.

9. The method for preparing a three-dimensional stacked shielding structure according to claim 8, wherein: In step S4, it also includes: The assembly is placed on the hot plate surface of the flip-chip bonder, and vacuum is applied to fix the assembly. The flip-chip bonder picks up the second chip and flips it over. The alignment of the first chip and the second chip is completed through the equipment recognition system. The suction nozzle applies pressure and ultrasound to complete the thermal ultrasonic welding of the first chip and the second chip.

10. The method for preparing a three-dimensional stacked shielding structure according to claim 8, wherein: In step S4, it also includes: Place the adapter plate with a cavity structure on the surface of the hot table of the flip-chip bonder, apply vacuum to fix the adapter plate, the flip-chip bonder sucks the assembly and flips it over, the equipment recognition system completes the alignment recognition of the assembly and the adapter plate, and the suction nozzle applies pressure and ultrasound to complete the thermal ultrasonic welding of the assembly and the adapter plate. Bond a double-layer gold-based nail head bump on the adapter plate, and place it on the surface of the hot table of the flip-chip bonder, apply vacuum to fix it, the flip-chip bonder sucks the second chip and flips it, and the equipment recognition system completes the alignment recognition of the assembly and the adapter plate, and the suction nozzle applies pressure and ultrasound to complete the thermal ultrasonic welding of the adapter plate and the second chip.

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