A packaging device based on gradient flux indium sheet and processing technology

Abstract

The present invention discloses a packaging device and processing technology based on gradient Flux indium sheet, which belongs to the field of semiconductor packaging technology. The solution adopts an indium matrix with a purity of ≥99.99%, a gradient Flux distribution of 10‑15wt% on the surface layer / 3‑5wt% on the inner layer and a 1‑3% vapor-phase silica thixotropic agent to optimize material performance. The process is innovatively adopted with two-stage Flux spraying and three-step hot pressing welding, combined with 5-point AOI detection to form a closed-loop control, and the mounting accuracy reaches ±3μm. The device integrates vacuum-electrostatic composite grasping, plasma activation and other modules. The technical effect is significant: the welding void rate is <0.5%, the interface thermal resistance is 0.02‑0.04K·cm2 / W , shear strength ≥ 20MPa, yield rate reaches 99.2%, perfectly solving the thermal management problems of high-power electronic devices, especially suitable for 5G communications and new energy vehicles.

Description

TECHNICAL FIELD

[0001] The application belongs to the technical field of chip packaging, and particularly relates to a packaging device based on gradient Flux indium sheet and a processing technology. BACKGROUND

[0002] With the rapid development of 5G communication, artificial intelligence and new energy vehicles, electronic devices are rapidly evolving towards high power density and miniaturization. This trend poses unprecedented challenges to chip packaging technology, especially in terms of thermal management. Traditional packaging technology has been difficult to meet the stringent requirements of current high-end electronic devices for heat dissipation performance and reliability, and it is urgent to develop a new generation of thermal interface materials and supporting packaging processes.

[0003] In the past indium sheet heat dissipation packaging process equipment, the indium sheet is 100% In, and Flux spraying is needed to ensure the melting effect in the subsequent welding process. Flux type indium sheet material itself contains Flux, and there is no need to apply Flux during the process, which reduces the process difficulty, but it is necessary to ensure that the Flux indium sheet will not deviate due to movement and vibration, and cleaning process is needed after packaging is completed, which increases the additional cost. Secondly, the difference in thermal expansion coefficient between indium and the substrate will cause stress concentration in thermal cycling, resulting in rapid decay of interfacial shear strength; thirdly, the existing packaging process requires very high equipment precision (alignment error <1 μm), resulting in high production cost.

[0004] The industry has made various attempts to solve these problems. Existing patent technologies propose a silver-coated indium sheet solution, which slightly improves the thermal resistance but increases the cost by 3 times; in addition, the existing technology also develops an indium sheet with pre-mixed Flux, but the uneven distribution of active substances causes welding defects. These solutions have not fundamentally solved the balance between reliability and process feasibility. SUMMARY

[0005] In view of the deficiencies of the prior art, the purpose of the present application is to provide a packaging device based on gradient Flux indium sheet and a processing technology, which solves the above technical problems existing in the prior art.

[0006] The purpose of the present application can be achieved by the following technical solutions:

[0007] A packaging device based on gradient Flux indium sheet, comprising a feeding unit, a plasma treatment unit, a glue coating and detection unit, a UV curing unit, a Flux spraying and AOI detection unit, an indium sheet application unit, a heat dissipation cover application unit, a hot pressing unit, and a discharging unit.

[0008] Firstly, the feeding unit grasps the Flux type indium sheet and the substrate by vacuum suction cup;

[0009] The plasma processing unit uses Ar / O2 mixed gas plasma to process the surface of the substrate, so that the contact angle is reduced to <10°;

[0010] The glue coating and detection unit coats the interface material AD glue on the surface of the substrate, and simultaneously determines the coating quality by optical detection method;

[0011] The UV curing unit uses 365nm+395nm dual-band ultraviolet light source, energy density 80-120mJ / cm 2 , curing time 10-30s, synchronous control surface temperature ≤65℃;

[0012] The spray FLUX and AOI detection unit uniformly applies the flux on the surface of the substrate after the glue is cured, and simultaneously ensures the flux coating quality through the AOI system;

[0013] The indium sheet pasting unit presses the indium sheet to the substrate by electrostatic adsorption, with a pasting force of 10-20N;

[0014] The heat dissipation cover pasting unit completes the assembly of the heat dissipation cover through visual alignment and step pressure;

[0015] The hot pressing unit is hot pressed in a step-by-step heating mode, and the contact resistance is monitored in real time to a stable value <0.01Ω;

[0016] The unloading unit is based on the X-ray detection result for sorting.

[0017] Further, the Flux type indium sheet is an indium-based composite material, which includes an indium base and a Flux active agent;

[0018] The indium base uses indium or indium-silver alloy with a purity of ≥99.999%;

[0019] The Flux active agent is uniformly distributed in the indium base, and the Flux active agent is composed of rosin, organic amine and thixotropic agent, with a total content of 5-15wt%;

[0020] The thickness of the indium sheet is 0.1-0.3mm.

[0021] Further, the Flux active agent on the Flux type indium sheet is gradiently distributed: the surface layer Flux content is 10-15wt%, and the inner layer Flux content is 3-5wt%;

[0022] And the thixotropic agent is fumed silica, with an addition amount of 1-3% of the total weight of the Flux active agent.

[0023] The processing technology of the packaging device based on the gradient Flux indium sheet includes the following steps:

[0024] S1, transfer the substrate to the plasma station by the feeding unit, and process for 30-60 s under 300-500 W RF power using Ar / O2 mixed gas until the surface contact angle is reduced to <10°, wherein: the flow ratio of Ar / O2 mixed gas is 4:1;

[0025] S2, coat the interface material AD glue on the surface of the substrate, and perform optical detection, and then perform UV curing, the UV curing energy density is 80-120 mJ / cm 2 , and the surface temperature is controlled to be ≤65℃;

[0026] S3, spray Flux using a piezoelectric spray valve, the spraying amount is 0.8-1.2 mg / cm 2 , the film thickness is 3-5 μm, and optical detection is performed synchronously, so that the multi-spectrum AOI detection coverage is ≥98%, and the characteristic peak intensity CV is ≤5%;

[0027] S4, selectively re-spray according to the detection results of the Flux spraying and AOI detection unit, and then perform piezoelectric spray valve spraying of Flux again, and when the indium sheet position offset is detected by 3D line laser, the offset amount >±0.05 mm triggers the piezoelectric ceramic compensation;

[0028] S5, align using infrared optical markers, and control the alignment accuracy, and the hot pressing unit presses in stages;

[0029] S6, after the pressing is completed, perform finished product detection and sorting.

[0030] Further, the feeding unit is transmitted to the packaging station by a vacuum adsorption-electrostatic composite fixing mode, wherein the vacuum adsorption pressure is 5-10 N / cm 2 , and the electrostatic voltage is 200-500 V.

[0031] Further, the step pressure adopted by the hot pressing unit specifically includes: the first stage is 80-100℃ preheating for 10-30 s to activate the Flux, the second stage is 140-150℃ low-temperature welding for 60-90 s to melt the indium sheet, and the third stage is 100-110℃ slow cooling for 20-25 s, and the control pressure is constant pressure 20-30 N.

[0032] Further, the step pressure adopted by the hot pressing unit specifically includes: the first stage is 80-100℃ preheating for 10-30 s to activate the Flux, the second stage is 150-210℃ vacuum pressure shock welding for 20-40 s to melt the Flux active agent of the indium sheet, and the third stage is 120-130℃ slow cooling for 20-25 s, and the control pressure of the second stage is shock 20-30 N, and the vibration amplitude fluctuates in 2-3 N.

[0033] Further, in S5, when the edge coverage is detected to be less than 95%, the edge spraying path density is increased by 20%.

[0034] Advantages of the present application:

[0035] 1. The device realizes significant technical breakthrough through the synergistic optimization of innovative gradient Flux indium sheet material and intelligent packaging process. In terms of key performance indicators, the welding cavity rate is reduced from 3-5% of traditional process to below 0.5%, with a reduction of 85%; the interface thermal resistance is optimized from 0.08-0.12 K·cm 2 / W to 0.02-0.04 K·cm 2 / W, with a reduction of 60%; the shear strength is increased from 12-14 MPa to more than 20 MPa, with an increase of 67%. In terms of process efficiency, the production cycle is shortened from 60 seconds per sheet to 45 seconds per sheet, with an efficiency increase of 25%, the good product rate is increased from 85% to 99.2%, and the defective rate is reduced by 84%.

[0036] 2. The device uses Flux indium sheet material, uses indium matrix with purity ≥99.99% combined with gradient distribution of Flux active agent (10-15wt% on the surface, 3-5wt% in the inner layer), and adds 1-3% gas phase silicon thixotropic agent, to realize precise control of active substances and intelligent rheological properties; in terms of process, a multi-sensor closed-loop control system is developed, integrating multiple AOI detection points to achieve ±3μm mounting accuracy and real-time process compensation.

[0037] 3. The hot pressing unit step pressure hot pressing method used in the present application can greatly shorten the hot pressing time. The step hot pressing method accurately controls the "temperature-pressure-time" in multiple dimensions, which comprehensively surpasses the traditional constant temperature and constant pressure process in terms of interface quality, production efficiency and long-term reliability, and is particularly suitable for packaging needs of high power density devices. BRIEF DESCRIPTION OF DRAWINGS

[0038] In order to more clearly illustrate the technical solutions in the embodiments of the present application or the prior art, the drawings needed to be used in the embodiments or prior art description will be briefly introduced as follows.

[0039] Figure 1 is the overall process flowchart of the embodiment of the present application;

[0040] Figure 2 is the thixotropic agent action principle diagram of the embodiment of the present application. DETAILED DESCRIPTION

[0041] The technical solutions in the embodiments of the present application will be described clearly and completely below with reference to the drawings in the embodiments of the present application. Based on the embodiments in the present application, all other embodiments obtained by those skilled in the art without creative work are within the scope of the present application.

[0042] As shown in Figure 1 , the embodiment of the present application provides a packaging device based on gradient Flux indium sheet, which comprises a feeding unit, a plasma processing unit, a glue coating and detection unit, a UV curing unit, a spraying FLUX and AOI detection unit, an indium sheet pasting unit, a heat dissipation cover pasting unit, a hot pressing unit and a discharging unit.

[0043] The device realizes the precise packaging of Flux type indium sheet through the cooperative work of the nine functional units. The core innovation is that:

[0044] The gradient Flux indium sheet is matched with a special device for phased pressing process, which embodies the three-in-one design of material-process-device;

[0045] The integrated multiple AOI detection points realize the whole-process quality traceability and closed-loop quality control, and the Flux gradient distribution cooperatively improves the welding reliability. For details, refer to Table 1 shown below.

[0046] Table 1

[0047]

[0048] First, the feeding unit includes a six-axis mechanical arm and a vacuum suction nozzle, the adsorption force can reach 5-8 N / cm 2 , the electrostatic voltage is 200-500 V, and a double-CCD visual positioning system is equipped, the positioning accuracy can be controlled within ±5 μm, and the Flux type indium sheet and the substrate can be accurately grabbed.

[0049] The Flux type indium sheet is an indium-based composite material, which includes an indium matrix and a Flux active agent.

[0050] The indium matrix adopts indium or indium-silver alloy with purity ≥99.999%; at this time, the ductility (fracture elongation ≥50%) and thermal conductivity (86 W / m·K) of high-purity indium can reach the optimal balance, and the content of impurities (such as Pb and Cd) <50ppm can avoid problems such as grain boundary embrittlement and electromigration failure. And at this purity, the shear strength can reach 20.5 MPa, and the thermal cycle life can reach 1500 times.

[0051] The Flux active agent is uniformly distributed in the indium matrix, and the Flux active agent is composed of rosin, organic amine and thixotropic agent, and the total content is 5-15wt%; the organic amine of the Flux active agent is diethylamine, which accounts for 2-4wt% in the Flux, and forms a chelation effect with rosin, so that the reduction activation energy of copper oxide is reduced to 35kJ / mol.

[0052] The thickness of the indium sheet is 0.1-0.3mm. According to the experiment, the thickness of 0.2mm contributes to the thermal resistance of only 0.0023K·cm 2 / W, which can improve economic benefits while achieving the best stress distribution and optimal thermal resistance control (0.018K·cm 2 / W).

[0053] Meanwhile, the Flux active agent on the Flux type indium sheet is gradiently distributed: the surface layer Flux content is 10-15wt%, and the inner layer Flux content is 3-5wt%; this design method preferentially forms an active protective layer at the welding interface, and the inner layer continuously replenishes and consumes active substances. Compared with the uniform distribution method, the welding cavity rate of the gradient distribution can be reduced to 0.4% (while the welding cavity rate of the uniform distribution is as high as 1.2%), and in addition, the flux residue of the gradient distribution is reduced to 0.18mg / cm 2 (while the welding cavity rate of the uniform distribution is as high as 0.35mg / cm 2 ).

[0054] The thixotropic agent is fumed silica (specifically shown in Figure 2 ), so that the Flux has static high viscosity (anti-flowing) and dynamic low viscosity (easy to spray), and the edge coverage rate can be improved from 89% to 98%; the addition amount is 1-3% of the total weight of the Flux active agent, when the addition amount is less than 1%, although a higher spraying atomization effect can be brought, but the flowing is easy to occur in a high temperature environment, which affects the pasting effect, when the addition amount is greater than 3%, the gelation is excessive, which is easy to cause the nozzle to be blocked, therefore, when the addition amount is 1-3%, the optimization can be fully obtained, by precisely controlling the addition amount and dispersion state of the fumed SiO2, the "intelligent rheological" property of the Flux active agent is realized, the welding process window is widened by 40%, which is a key material innovation point of the high reliability of the application.

[0055] The plasma treatment unit adopts Ar / O2 mixed gas plasma with a radio frequency power of 300-500W (under the cover radio frequency power, the stable plasma density can be maintained), and the treatment time is 30-60s (to ensure that the surface modification depth is ≥50nm), so that the contact angle of the substrate surface is reduced from 80° to <10°, and the flow ratio of the Ar / O2 mixed gas is 4:1. The mixed gas can balance the physical bombardment and oxidation reaction.

[0056] The first glue coating and detection unit includes a screw pump quantitative extrusion system and a 3D line laser scanner, the coating thickness is 15±2 μm, the detection resolution is 0.5 μm, and the coating quality is determined by an optical detection method.

[0057] The UV curing unit adopts a 365nm+395nm dual-band UV light source, the energy density is 80-120mJ / cm 2 , the curing time is 10-30s, and the surface temperature is controlled to be less than or equal to 65°C synchronously;

[0058] The first spraying FLUX and AOI detection unit uniformly applies flux to the surface of the substrate after the glue is cured, and synchronously ensures the flux coating quality through an AOI system, including a piezoelectric spray valve and a multispectral imaging system, the minimum droplet is 5pL, the spraying amount is 0.8-1.2mg / cm 2 , the film thickness is 3-5 μm, and the multispectral AOI detection coverage is greater than or equal to 98%, and the characteristic peak intensity CV is less than or equal to 5% synchronously;

[0059] The indium sheet pasting unit presses the indium sheet to the substrate through electrostatic adsorption, the pasting precision is ±3 μm, and the pasting force is 10-20N;

[0060] The second spraying FLUX and AOI detection unit selectively supplements spraying according to the first spraying detection result, and then sprays flux again through the piezoelectric spray valve, detects the position offset of the indium sheet by using a 3D line laser (resolution 5 μm), triggers the piezoelectric ceramic compensation when the offset amount is greater than or equal to ±0.05mm, and increases the edge spraying path density by 20% when the edge coverage is less than 95%.

[0061] Specifically, it can be shown in Table 2 as shown in the following table:

[0062] Table 2

[0063]

[0064] The double-stage FLUX spraying mode can ensure basic coverage by first spraying, solve local defects by secondary intelligent supplementary spraying, and realize quality tracing of the coating glue→FLUX→final inspection full process.

[0065] Meanwhile, the second coating glue coating+AOI detection equipment 8 is used for coating of the heat dissipation interface material.

[0066] The heat dissipation cover pasting unit completes the heat dissipation cover assembly through visual alignment and step pressure;

[0067] The hot pressing unit performs pressing operation with step pressure, and monitors the contact resistance to a stable value less than 0.01Ω in real time;

[0068] The step pressure adopted by the hot pressing unit specifically includes: the first stage 80-100℃ preheating 10-30s to activate the Flux, the second stage 140-150℃ welding 20-40s to melt the indium sheet, the third stage 100-110℃ slow cooling 20-25s, and the control pressure is 2-3N. The specific performance is shown in the following table 3.

[0069] Table 3

[0070]

[0071] Of course, the hot pressing unit can also be further improved according to needs.

[0072] The step pressure adopted by the hot pressing unit specifically includes: the first stage 80-100℃ preheating 10-30s to activate the Flux, the second stage 140-150℃ welding 20-40s to melt the indium sheet, the third stage 100-110℃ slow cooling 20-25s, and the control pressure is 2-3N. The specific performance is shown in the following table 3.

[0073] The specific performance is shown in the following table 4.

[0074] Table 4

[0075]

[0076] The second stage welding process adopted in table 3 and table 4 is different, mainly to cope with different chip packaging (table 3 mainly processes 30-50nm interface IMC thickness of chip, while the method of table 4 can process 80-100nm interface IMC thickness of chip packaging), compared with the traditional constant temperature and constant pressure state, the void rate can be reduced to ≤0.3% (the void rate of traditional constant temperature and constant pressure reaches 0.8-1.5%), which is reduced by more than 75%. And by using the stage hot pressing method, the shear strength can reach ≥22MPa, while the shear strength of the traditional constant pressure and constant temperature hot pressing method is ≤15MPa.

[0077] The blanking unit is based on the X-ray detection result for sorting.

[0078] Compared with the prior art, the present application has the following economic benefits, which are shown in table 5:

[0079] Table 5

[0080]

[0081] The technical scheme realizes synchronous breakthrough in three dimensions of heat conduction performance, mechanical strength and production efficiency through system-level innovation, and solves the long-standing "high heat conduction-high reliability-low cost" triangular problem in the field of high-power electronic chip packaging.

[0082] The foregoing is considered as illustrative only of the principles of the application. Further, since numerous modifications and changes will readily occur to those skilled in the art, it is not desired to limit the application to the exact construction and practice described. Accordingly, all such variations and modifications are intended to be included within the scope of the application as defined in the following claims.

Claims

1. A packaging device based on gradient Flux indium sheet, characterized in that: It includes loading unit, plasma processing unit, glue coating and detection unit, UV curing unit, FLUX spraying and AOI detection unit, indium sheet pasting unit, heat dissipation cover pasting unit, hot pressing unit and unloading unit; First, the loading unit is used to grab the Flux type indium sheet and substrate through the vacuum suction cup; The plasma treatment unit uses Ar / O2 mixed gas plasma to treat the substrate surface to reduce the contact angle to <10°; The glue coating and detection unit coats the interface material AD glue on the substrate surface and simultaneously determines the coating quality through an optical detection method; The UV curing unit uses a 365nm+395nm dual-band ultraviolet light source with an energy density of 80-120mJ / cm 2 , curing time 10–30s, synchronously control surface temperature ≤ 65°C; The spray FLUX and AOI inspection unit evenly applies flux on the substrate surface after the coating glue is cured, and simultaneously uses the AOI system to ensure the quality of the Flux coating; The indium sheet applying unit presses the indium sheet onto the substrate by electrostatic adsorption, with a bonding force of 10–20N; The heat dissipation cover applying unit completes the heat dissipation cover assembly through visual alignment and stepped pressure; The hot pressing unit performs hot pressing and forming in a step-by-step temperature increase manner, and monitors the contact resistance in real time until it reaches a stable value of <0.01Ω; The unloading unit performs sorting based on the X-ray detection results.

2. The packaging device based on the gradient Flux indium sheet according to claim 1, characterized in that: The Flux type indium sheet is an indium-based composite material, including an indium matrix and a Flux active agent; The indium substrate is made of indium or indium-silver alloy with a purity of ≥99.999%; The indium matrix is ​​uniformly distributed with a Flux active agent, which is composed of rosin, organic amine and thixotropic agent, with a total content of 5-15wt%; The thickness of the indium sheet is 0.1-0.3 mm.

3. The packaging device based on the gradient Flux indium sheet according to claim 2, characterized in that: The Flux active agent on the Flux-type indium sheet is distributed in a gradient manner: the Flux content in the surface layer is 10–15 wt%, and the Flux content in the inner layer is 3–5 wt%; The thixotropic agent is fumed silica, and the added amount is 1–3% of the total weight of the Flux active agent.

4. The processing technology of the packaging device based on the gradient Flux indium sheet according to any one of claims 1 to 3, characterized in that: The following steps are involved: S1. Transfer the substrate to the plasma station through the loading unit and treat it with Ar / O2 mixed gas at 300-500W radio frequency power for 30-60s until the surface contact angle drops to <10°, wherein: the flow ratio of Ar / O2 mixed gas is 4:1; S2: Apply interface material AD glue on the substrate surface and perform optical inspection, then use UV curing with an energy density of 80-120mJ / cm 2 , control the surface temperature ≤65℃; S3, use piezoelectric spray valve to spray Flux, spraying amount 0.8-1.2mg / cm 2 , film thickness 3-5μm, and simultaneous optical inspection, so that the multi-spectral AOI detection coverage ≥ 98%, characteristic peak intensity CV ≤ 5%; S4. Selectively re-spray according to the test results of the spray FLUX and AOI detection unit, and then spray the Flux again with the piezoelectric spray valve. When the position deviation of the indium sheet is detected by 3D line laser, the piezoelectric ceramic compensation is triggered when the deviation is greater than ±0.05mm. S5, using infrared optical marking to align and control the positioning accuracy, the hot pressing unit presses in stages; S6. After lamination is completed, the finished products are inspected and sorted.

5. The processing technology of the packaging device based on the gradient Flux indium sheet according to claim 4 is characterized in that: The loading unit is transferred to the packaging station by a vacuum adsorption-electrostatic composite fixation method, wherein the vacuum adsorption pressure is 5-10N / cm 2 , the electrostatic voltage is 200–500V.

6. The processing technology of the packaging device based on the gradient Flux indium sheet according to claim 4 is characterized in that: The step pressure used by the hot pressing unit specifically includes: the first stage is preheating at 80-100℃ for 10-30s to activate the Flux, the second stage is low-temperature soldering at 140-150℃ for 60-90s to melt the indium sheet, and the third stage is slow cooling at 100-110℃ for 20-25s, and the pressure is controlled to be a constant pressure of 20-30N.

7. The processing technology of the packaging device based on the gradient Flux indium sheet according to claim 4 is characterized in that: The step pressure used in the hot pressing unit specifically includes: preheating at 80-100°C for 10-30s to activate Flux in the first stage, vacuum pressure oscillation welding at 150-210°C for 20-40s to melt the Flux active agent of the indium sheet in the second stage, slow cooling at 120-130°C for 20-25s in the third stage, and controlling the pressure oscillation to 20-30N, with the vibration amplitude fluctuating at 2-3N.

8. The processing technology of the packaging device based on the gradient Flux indium sheet according to claim 4 is characterized in that: In S5, when it is detected that the edge coverage is less than 95%, the edge spraying path density is increased by 20%.

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