Device and method for shaping and bonding of ribbon inverted brazing metal electrodes

Abstract

The application belongs to the technical field of semiconductor packaging, and particularly relates to a device and method for shaping and bonding of a carrier tape flip solder metal electrode; the method comprises the following steps: positioning and sleeving an integrated device of a metal electrode and PI into a lower mold according to a positioning pin; sequentially sleeving springs on all guide pins of the lower mold; placing an upper mold on the lower mold so that guide pin through holes of the upper mold are aligned with the guide pins; vertically applying pressure to a middle position of the upper mold, and alternately tightening the pressure screws; when the gap between the upper mold and the lower mold is 2mm, stop tightening the pressure screws; placing a shaping clamp in the center of a pressure test table, and tightly pressing the upper and lower molds with a pressure of 150N; alternately tightening two fixing screws, and taking the shaping clamp off the test table when the feedback force is within the range of 150N+5N; the application has the characteristics of high efficiency, reliability, simplicity, practicality, good alignment, and effective reduction of welding stress.

Description

Technical Field

[0001] This invention belongs to the field of semiconductor packaging technology, specifically relating to an apparatus and method for shaping and bonding flip-chip bonding metal electrodes. Background Technology

[0002] Traditionally, flip-chip bonding involves micron-level bonding between solder joints on a silicon-based PCB. This invention, however, involves bonding a quartz chip to a flexible metal electrode on a PI (polyimide) substrate. The bonding between the chip and the metal electrode presents two scenarios due to the different window sizes of the chip and the PI substrate. For example… Figure 1 As shown, when the chip size is smaller than the PI window size, direct bonding is possible without shaping; however, when the chip size is larger than the PI window size, as... Figure 2 As shown, the metal electrodes need to be shaped first so that the bonding points are higher than the top surface of the PI layer, thus avoiding interference between the chip and the PI. To ensure that the metal electrodes are higher than the top surface of the PI layer while keeping the bonding points within tolerance, a high-precision shaping method is needed to effectively solve the problems of shaping, alignment, and bonding. Summary of the Invention

[0003] To address the shortcomings of existing technologies, this invention proposes an apparatus and method for shaping and bonding flip-chip bonding metal electrodes. The apparatus includes a shaping fixture and a bonding fixture. The shaping fixture comprises an upper die, a lower die, a spring, and a clamping screw. The lower die has multiple guide pins, multiple positioning pins, and multiple threaded holes on its edge. The upper die has through holes that mate with the guide pins, and also multiple threaded holes, with the threaded holes in the upper die corresponding one-to-one with those in the lower die. The spring is mounted on the guide pins, and the clamping screw is installed in the threaded holes for clamping and fixing the upper die and the lower die.

[0004] The bonding fixture includes a bonding pressure plate, a lower die, and a clamping screw. The bonding pressure plate is provided with threaded holes that correspond one-to-one with the threaded holes of the lower die and through holes that cooperate with the guide pins. The clamping screw is installed in the threaded holes. The bonding pressure plate is also provided with multiple pressure plate openings.

[0005] Preferably, both the upper and lower molds are rectangular molds.

[0006] Furthermore, there are four guide pins, located at the four corners of the lower mold.

[0007] Furthermore, both the upper and lower dies have two threaded holes, located at the upper left and lower right corners of the upper die and the lower left and lower right corners of the lower die, respectively.

[0008] A method for shaping and bonding flip-chip bonding metal electrodes with a carrier tape, characterized by comprising:

[0009] S1: The metal electrode is shaped using a shaping fixture;

[0010] S2: The chip and the shaped metal electrode are bonded using a bonding fixture.

[0011] Furthermore, the process of shaping the metal electrode using a shaping fixture includes:

[0012] S11: Position the integrated device of metal electrode and PI according to the positioning pin and fit it into the lower mold;

[0013] S12: Place the springs sequentially onto all the guide pins of the lower mold;

[0014] S13: Place the upper mold on the lower mold so that the guide pin through hole of the upper mold is aligned with the guide pin;

[0015] S14: Apply vertical downward pressure at the middle position of the upper mold and alternately tighten the clamping screws;

[0016] S15: When the gap between the upper and lower molds reaches 5mm, stop tightening the clamping screws;

[0017] S16: Place the shaping fixture in the center of the pressure testing platform and press the upper and lower molds with a pressure of 150N.

[0018] S17: Tighten the two set screws alternately and observe the feedback force within the range of 150N±5N. Then remove the shaping fixture from the test bench.

[0019] S18: Place the shaping mold in a 150℃ heat preservation box and keep it at that temperature for 24 hours to obtain a successfully shaped metal electrode.

[0020] Furthermore, the process of bonding the chip and the shaped metal electrodes using a bonding fixture includes:

[0021] S21: Alternately loosen the clamping screws of the shaping fixture after shaping is completed until they are loose;

[0022] S22: Gently remove the upper mold and remove the spring on the guide pin;

[0023] S23: Fit the bonding plate into the guide pin, and the guide pin passes through the guide pin through hole on the bonding plate;

[0024] S24: Tighten the clamping screw until the bonding plate is clamped, and the plate opens to expose the metal electrode to be bonded;

[0025] S25: Run the flip-chip bonding equipment, retrieve the bonding program, and place the bonding fixture in the specified position on the equipment;

[0026] S26: The flip-chip bonding equipment uses a hot press head to pick up the chip and sequentially bond the chip and metal electrodes according to the program;

[0027] S27: After bonding is completed, remove the bonding fixture to obtain the bonded device.

[0028] The beneficial effects of this invention are as follows: When the chip size is larger than the PI window size, the present invention is used to shape and bond the metal electrode, which has the characteristics of high efficiency, reliability, simplicity and practicality, good alignment, and effective reduction of welding stress. While ensuring that the metal electrode is higher than the upper surface of the PI layer and that the metal electrode bonding point is kept within the tolerance range, the present invention has high shaping accuracy and good bonding effect, and can effectively solve the problems of metal electrode shaping and alignment and bonding between the metal electrode and the chip. Attached Figure Description

[0029] Figure 1 This is a schematic diagram of a non-shaping chip + metal electrode bonding.

[0030] Figure 2 Schematic diagram of chip + metal electrode shaping and bonding;

[0031] Figure 3 This is a schematic diagram of the initial state of the shaping fixture in this invention;

[0032] Figure 4 This is a close-up view of the shape of the upper and lower mold forming parts in this invention;

[0033] Figure 5 This is a schematic diagram of the clamping state of the shaping fixture in this invention;

[0034] Figure 6 This is a schematic diagram of the bonding state of the bonding fixture in this invention. Detailed Implementation

[0035] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0036] This invention proposes an apparatus and method for shaping and bonding flip-chip bonding metal electrodes, the apparatus comprising: a shaping fixture and a bonding fixture, such as... Figure 3 As shown, the shaping fixture includes an upper die, a lower die, a spring, and a clamping screw; the lower die edge is provided with multiple guide pins, multiple positioning pins, and multiple threaded holes; the upper die is provided with through holes that mate with the guide pins, and the upper die is also provided with multiple threaded holes, the threaded holes of the upper die and the threaded holes of the lower die being positioned one-to-one; the spring is mounted on the guide pin, and the clamping screw is mounted in the threaded hole for clamping and fixing the upper die and the lower die;

[0037] The bonding fixture includes a bonding pressure plate, a lower die, and a clamping screw. The bonding pressure plate is provided with threaded holes that correspond one-to-one with the threaded holes of the lower die and through holes that cooperate with the guide pins. The clamping screw is installed in the threaded holes. The bonding pressure plate is also provided with multiple pressure plate openings.

[0038] Preferably, both the upper and lower molds are rectangular molds; there are four guide pins, located at the four corners of the lower mold; and there are two threaded holes on both the upper and lower molds, located at the upper left and lower right corners of the upper mold and the lower left and lower right corners of the lower mold, respectively.

[0039] Four springs are fitted onto the guide pins. Based on the ease of spring selection and in conjunction with this invention, springs made of piano wire can be selected, with a wire stiffness modulus G = 8000, wire diameter d = 1.2 mm, mean diameter Dm = 9 mm, N = 7 (total number of turns); Nc = N - 2 = 5 (effective number of turns).

[0040] Preferably, there are four locating pins, located at the four corners of the lower mold.

[0041] Preferably, the lower mold has a shaping protrusion, and the upper mold has a shaping groove that mates with the shaping protrusion of the lower mold. Specifically, such as... Figure 4 As shown, based on the final required height (140μm) and shape of the metal electrode on the PI, the shapes of the upper and lower molds corresponding to the positions of the metal electrode are designed accordingly.

[0042] This invention also provides a method for shaping and bonding flip-chip carrier metal electrodes. This method uses the aforementioned apparatus (shaping fixture and bonding fixture) for shaping and bonding flip-chip carrier metal electrodes. The process of shaping the metal electrode includes the following steps:

[0043] S11: Position the integrated device of metal electrode and PI according to the positioning pin and fit it into the lower mold;

[0044] S12: Place the springs sequentially onto all the guide pins of the lower mold;

[0045] S13: Place the upper mold on the lower mold so that the guide pin through hole of the upper mold is aligned with the guide pin;

[0046] S14: Apply vertical downward pressure at the middle position of the upper mold and alternately tighten the clamping screws;

[0047] S15: When the gap between the upper and lower molds reaches 5mm, stop tightening the clamping screws;

[0048] S16: Place the shaping fixture in the center of the pressure testing platform and press the upper and lower molds with a pressure of 150N.

[0049] This invention aims to shape the metal electrode correctly without damaging it. The spring compression is designed to be 5mm, and the required applied pressure is calculated as follows:

[0050]

[0051]

[0052] F 总 =4F 单 =15.044kgf≈150N

[0053] Where k represents the spring constant and S represents the spring compression. The design value of this invention is 5mm, and the actual measured value is 4.8mm.

[0054] When the spring compression is designed to be 5mm, the final shaped metal electrode best meets expectations.

[0055] S17: Alternately tighten the two set screws; at this point, the shaping fixture should be in the following state: Figure 5 As shown, since the upper and lower molds are designed with corresponding curved surface models at the bonding position, the deformation of the metal electrode will change according to the pre-made model; when the feedback force is within the range of 150N±5N, the shaping fixture is removed from the test table.

[0056] S18: Place the forming mold in a 150℃ heat preservation box and keep it at that temperature for 24 hours to obtain a successfully shaped metal electrode; heat preservation can effectively eliminate most of the stress caused by deformation.

[0057] Taking full account of the springback of the metal electrode, a corresponding annealing process was specially formulated to further limit the springback within the allowable range. In this invention, the annealing process has undergone multiple rounds of exploration and verification. Finally, it was determined that the assembled PI along with the shaping fixture is placed in a temperature chamber, kept at 150°C for 24 hours, and then naturally cooled to room temperature of 20°C to eliminate most of the stress caused by deformation and obtain a successfully shaped metal electrode.

[0058] The process of bonding a chip and a shaped metal electrode using a bonding fixture includes the following steps:

[0059] S21: Alternately loosen the clamping screws of the shaping fixture after shaping is completed until they are loose;

[0060] S22: Gently remove the upper mold and the spring on the guide pin; the removed upper mold and spring are for use in the next shaping process;

[0061] S23: Fit the bonding plate into the guide pin, and the guide pin passes through the guide pin through hole on the bonding plate;

[0062] S24: Tighten the clamping screws until the bonding plate is clamped, and the opening of the plate exposes the metal electrode to be bonded; the positions of the multiple metal electrodes and the integrated PI device fitted into the lower mold correspond one-to-one with the opening of the plate. When the bonding plate is clamped to the lower mold, the opening of the plate will expose the metal electrode to be bonded.

[0063] S25: Run the flip-chip bonding equipment, retrieve the bonding program, and place the bonding fixture in the specified position on the equipment;

[0064] S26: The flip-chip bonding equipment uses a hot press head to pick up the chip and sequentially bonds the chip to the metal electrodes according to the program; a schematic diagram of the bonding is shown below. Figure 6 As shown;

[0065] S27: After bonding is completed, remove the bonding fixture to obtain the bonded device (PI + metal electrode + chip), ready for use in the next process.

[0066] The above-described embodiments further illustrate the purpose, technical solution, and advantages of the present invention. It should be understood that the above-described embodiments are merely preferred embodiments of the present invention and are not intended to limit the present invention. Any modifications, equivalent substitutions, improvements, etc., made to the present invention within the spirit and principles of the present invention should be included within the protection scope of the present invention.

Claims

1. An apparatus for shaping and bonding flip-chip metal electrodes, characterized in that, include: A shaping fixture and a bonding fixture, wherein the shaping fixture includes an upper die, a lower die, a spring, and a clamping screw; The lower mold edge is provided with multiple guide pins, multiple positioning pins and multiple threaded holes; the upper mold is provided with through holes that mate with the guide pins, and the upper mold is also provided with multiple threaded holes, the threaded holes of the upper mold and the threaded holes of the lower mold are positioned one by one; the spring is installed on the guide pin, and the clamping screw is installed in the threaded hole to clamp and fix the upper mold and the lower mold. The bonding fixture includes a bonding pressure plate, a lower die, and a clamping screw. The bonding pressure plate is provided with threaded holes that correspond one-to-one with the threaded holes of the lower die and through holes that cooperate with the guide pins. The clamping screw is installed in the threaded holes. The bonding pressure plate is also provided with multiple pressure plate openings.

2. The apparatus for shaping and bonding flip-chip bonding metal electrodes according to claim 1, characterized in that, Both the upper and lower molds are rectangular molds.

3. The apparatus for shaping and bonding flip-chip bonding metal electrodes according to claim 2, characterized in that, There are four guide pins, located at the four corners of the lower mold.

4. The apparatus for shaping and bonding flip-chip bonding metal electrodes according to claim 2, characterized in that, The upper and lower dies each have two threaded holes, located at the upper left and lower right corners of the upper die and the lower left and lower right corners of the lower die, respectively.

5. A method for shaping and bonding flip-chip bonding metal electrodes, characterized in that, include: S1: The metal electrode is shaped using a shaping fixture; The process of shaping a metal electrode using a shaping fixture includes: S11: Position the integrated device of metal electrode and PI according to the positioning pin and fit it into the lower mold; S12: Place the springs sequentially onto all the guide pins of the lower mold; S13: Place the upper mold on the lower mold so that the guide pin through hole of the upper mold is aligned with the guide pin; S14: Apply vertical downward pressure at the middle position of the upper mold and alternately tighten the clamping screws; S15: When the gap between the upper and lower molds reaches 5mm, stop tightening the clamping screws; S16: Place the shaping fixture in the center of the pressure testing platform and press the upper and lower molds with a pressure of 150N. S17: Tighten the two set screws alternately and observe the feedback force within the range of 150N±5N. Then remove the shaping fixture from the test bench. S18: Place the shaping mold in a 150℃ heat preservation box and keep it at that temperature for 24 hours to obtain a successfully shaped metal electrode. S2: The chip and the shaped metal electrodes are bonded using a bonding fixture; the process of bonding the chip and the shaped metal electrodes using a bonding fixture includes: S21: Alternately loosen the clamping screws of the shaping fixture after shaping is completed until they are loose; S22: Gently remove the upper mold and remove the spring on the guide pin; S23: Fit the bonding plate into the guide pin, and the guide pin passes through the guide pin through hole on the bonding plate; S24: Tighten the clamping screw until the bonding plate is clamped, and the plate opens to expose the metal electrode to be bonded; S25: Run the flip-chip bonding equipment, retrieve the bonding program, and place the bonding fixture in the specified position on the equipment; S26: The flip-chip bonding equipment uses a hot press head to pick up the chip and sequentially bond the chip and metal electrodes according to the program; S27: After bonding is completed, remove the bonding fixture to obtain the bonded device.

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