Chip packaging method and packaging semi-finished product

Abstract

The invention discloses a chip packaging method and a packaged semi-finished product, and relates to the technical field of storage chip packaging. The packaging method of the chip comprises the following steps: coating a soldering flux on a solder ball of the chip, and mounting the chip on a substrate in an inverted manner; the chip and the substrate are welded in a reflow soldering machine under the assistance of the soldering flux, and soldering flux residues are generated at the bottom of the welded chip; filling a filling adhesive between the welded chip and the substrate, reacting the filling adhesive with the soldering flux residue at the bottom of the chip in the pressure oven to form a gaseous reactant, and discharging the generated gaseous reactant from the bottom of the chip through the pressure oven; in a pressure oven, baking the substrate and the chip to cure the filling glue to obtain a baked packaging semi-finished product; according to the packaging method of the chip, the soldering flux residues existing between the chip and the substrate can be removed through the step of removing the soldering flux residues through the filling glue, and the production yield of chip packaging is improved.

Description

Technical Field

[0001] The present application relates to the technical field of memory chip packaging, and in particular to a chip packaging method and a packaging semi-finished product. Background Art

[0002] Since chips are precision equipment, with the miniaturization of chips, the requirements for chip welding in the production process are getting higher and higher. The traditional chip packaging process includes applying flux, flip-chip mounting, reflow soldering, cleaning flux, applying filler and curing filler. After the steps of the packaging process, the chip is fixed on the substrate to form a semi-finished package to facilitate the next step of the production process.

[0003] In the packaging process, sometimes in order to ensure the stability of welding, sufficient flux will be filled to maintain the stability after welding. However, this will cause a lot of residual flux on the chip. In the process of cleaning the flux, it is necessary to use sufficient water to rinse it, and it is still very easy to have an unclean cleaning situation, resulting in the flux not being cleaned up and remaining. When the subsequent steps of applying the filling glue and baking and curing are carried out, the residual flux will be vaporized after being heated, which will cause pores in the filling glue, resulting in unstable connection of the chip and poor connection of the chip pins.

[0004] Therefore, there is an urgent need to optimize and improve the traditional chip packaging process to ensure the production yield. Summary of the invention

[0005] The purpose of the present application is to provide a chip packaging method and a packaging semi-finished product. By removing the flux residue by filling glue, the flux residue between the chip and the substrate can be removed, thereby improving the production yield of chip packaging.

[0006] The present application discloses a chip packaging method, comprising the steps of:

[0007] Flux application step: Apply flux on the solder balls of the chip and flip the chip onto the substrate;

[0008] Welding steps: The chip and substrate are welded in a reflow machine with the aid of flux, and flux residue is generated at the bottom of the chip after welding;

[0009] Steps of removing flux residues by using filler: filler is filled between the soldered chip and the substrate, and in the pressure oven, the filler reacts with the flux residue at the bottom of the chip to form a gaseous reactant, and the generated gaseous reactant is discharged from the bottom of the chip through the pressure oven, so that the flux residue at the bottom of the chip is removed;

[0010] Curing step: In a pressure oven, the substrate and the chip are baked to cure the filling glue to obtain a baked package semi-finished product.

[0011] Optionally, after the welding step, the welded chip and substrate are not subjected to water washing treatment, but the step of directly removing the flux residue by filling glue is performed.

[0012] Optionally, the step of removing flux residues by the filling glue includes:

[0013] Place the soldered chip and substrate into a pressure oven;

[0014] Filling a filling glue between the chip and the substrate, and at least one side of the chip is not filled with the filling glue;

[0015] Pressurization step: Gas is filled into the cavity of the pressure oven to form a high-pressure environment. The filler gradually moves from the periphery of the chip toward the center of the chip and reacts with the flux residue in the process;

[0016] Decompression step: The cavity of the pressure oven is evacuated to form a negative pressure environment, and the gaseous reactants generated by the reaction between the filler and the flux residue are discharged in the process;

[0017] Wherein, in the step of removing the solder flux residue by the filling glue, the pressurization step and the depressurization step are repeated to realize the high-low pressure molecular oscillation treatment, so that the filling glue reacts with the solder flux residue at the bottom of the chip to form a gaseous reactant, and the generated gaseous reactant is discharged from the bottom of the chip during the high-low pressure molecular oscillation treatment, so that the solder flux residue at the bottom of the chip is removed;

[0018] Wherein, all products formed by the reaction between the filling glue and the flux residue are the gaseous reactants.

[0019] Optionally, in the step of removing flux residues by filling the filling glue, the ambient temperature when filling the filling glue is lower than 40 degrees Celsius and higher than 18 degrees Celsius.

[0020] Optionally, in the decompression step, the pressure oven is evacuated to make the pressure in the cavity of the pressure oven less than 2 Kgf / cm 2 , the gaseous reactants generated by the reaction between the filling glue and the flux residue are discharged from the bottom of the chip.

[0021] Optionally, in the step of removing flux residues with the filling glue, the pressurization step and the depressurization step are repeated more than once.

[0022] Optionally, in the pressurizing step, the gas filled into the pressure oven is pure gas, and the pure gas is nitrogen.

[0023] Optionally, in the decompression step, the ambient temperature inside the pressure oven is 40±2 degrees Celsius and the duration is 50±5 minutes;

[0024] During the pressurization step, the ambient temperature inside the pressure oven is 40±2 degrees Celsius and the duration is 5±5 minutes.

[0025] Optionally, in the curing step, the ambient temperature of the pressure oven is between 80 and 160 degrees Celsius, the internal air pressure of the pressure oven is between 6 and 8 kg, and the baking time is between 220 and 240 minutes.

[0026] Optionally, the chip packaging method further comprises the steps of:

[0027] Inspection step: inspect the semi-finished packaged product obtained after baking;

[0028] The semi-finished packaged product is subjected to ultrasonic scanning to detect whether there are bubbles between the substrate and the chip.

[0029] Optionally, the filler may be one of Henkel's 9100AA filler or Hokuriku Paint Co., Ltd.'s U8410-302 filler;

[0030] The soldering flux may be one of TACFLUX-026S soldering flux produced by Indium Corporation of China or NCX-402 soldering flux produced by Alpha.

[0031] The present application also discloses a packaged semi-finished product, which is packaged by the chip packaging method as described above. After the packaged semi-finished product is packaged, the flux residue between the chip and the substrate is removed.

[0032] The chip packaging method of the present application, in the process of filling the filling glue into the gap between the bottom of the chip and the substrate in the pressure oven, makes the filling glue react with the flux residue at the bottom of the chip to form a gaseous reactant, and discharges it from the bottom of the chip through the pressure oven. Therefore, even if a special water washing step is not set, the flux residue at the bottom of the chip can be removed by the filling glue, and the residual flux will not be heated and vaporized to cause pores inside the filling glue, resulting in unstable chip connection and causing yield problems. Compared with the existing flip-chip process flow, the step of cleaning the flux is reduced, thereby avoiding the use of water washing in the chip packaging process, saving water resources and reducing production costs, while avoiding the problem of incomplete washing of the flux residue by water washing, and improving the production yield of chip packaging. BRIEF DESCRIPTION OF THE DRAWINGS

[0033] The included drawings are used to provide a further understanding of the embodiments of the present application, which constitute a part of the specification, are used to illustrate the implementation methods of the present application, and together with the text description, explain the principles of the present application. Obviously, the drawings described below are only some embodiments of the present application. For ordinary technicians in this field, other drawings can be obtained based on these drawings without creative work. In the drawings:

[0034] Figure 1 is a flowchart of the steps of a chip packaging method according to the first embodiment of the present application;

[0035] Figure 2 is a flow chart of the steps of removing flux residues by filling glue in the first embodiment of the present application;

[0036] Figure 3 is a flowchart of a chip packaging method according to the second embodiment of the present application;

[0037] Figure 4 is a structural schematic diagram of a semi-finished packaging product according to the third embodiment of the present application;

[0038] Figure 5 It is a record chart of specific parameters used in experimental verification;

[0039] Figure 6 is Figure 5 Ultrasonic testing diagram of the product produced under the experimental parameters shown.

[0040] Among them, 100, chip; 200, substrate; 300, filling glue; 400, packaging semi-finished product. DETAILED DESCRIPTION

[0041] It should be understood that the terms used herein, the specific structures and functional details disclosed are only for describing specific embodiments and are representative, but the present application can be implemented in many alternative forms and should not be construed as being limited to only the embodiments described herein.

[0042] In the description of this application, the terms "first" and "second" are used for descriptive purposes only and should not be understood as indicating relative importance or implicitly indicating the number of technical features indicated. Therefore, unless otherwise specified, features defined as "first" and "second" may explicitly or implicitly include one or more of the features; "plurality" means two or more. The term "including" and any variation thereof means non-exclusive inclusion, and one or more other features, integers, steps, operations, units, components and / or combinations thereof may exist or be added.

[0043] In addition, terms indicating orientation or positional relationships, such as “center,” “lateral,” “up,” “down,” “left,” “right,” “vertical,” “horizontal,” “top,” “bottom,” “inside,” and “outside,” are described based on the orientation or relative positional relationships shown in the accompanying drawings and are merely simplified descriptions for the convenience of describing the present application. They do not indicate that the devices or elements referred to must have a specific orientation, be constructed and operated in a specific orientation, and therefore should not be understood as limitations on the present application.

[0044] In addition, unless otherwise clearly specified and limited, the terms "installed", "connected", and "connected" should be understood in a broad sense, for example, it can be a fixed connection, a detachable connection, or an integral connection; it can be a mechanical connection or an electrical connection; it can be a direct connection, or it can be indirectly connected through an intermediate medium, or it can be internally connected between two components. For ordinary technicians in this field, the specific meanings of the above terms in this application can be understood according to specific circumstances.

[0045] The present application is described in detail below with reference to the accompanying drawings and optional embodiments. It should be noted that, under the premise of no conflict, the embodiments or technical features described below can be arbitrarily combined to form new embodiments.

[0046] In the original flip chip process, water washing is required in the step of cleaning the solder flux. According to the statistics of water consumption, it usually takes about 6 minutes to clean a product, and only 60 to 80 products are cleaned per hour, but the water consumption of the cleaning machine is about 1 ton. Therefore, from a commercial perspective, the chip packaging method of the present application improves the production yield of chip packaging, and makes a huge commercial contribution to saving water resources and reducing costs, which is beneficial to environmental protection and sustainable development. The chip packaging method of the present application will be described in detail below:

[0047] like Figure 1 As shown, as the first embodiment of the present application, a chip packaging method is disclosed, and the chip packaging method includes the steps of:

[0048] Flux application step: Apply flux on the solder balls of the chip and flip the chip onto the substrate;

[0049] Specifically, the chip can be a memory chip, and a proper amount of flux is applied to the solder ball of the chip. Then the device uses visual recognition alignment or other alignment means to ensure the precise positioning between the chip and the substrate, so as to ensure that the chip can be accurately installed on the substrate. It should be noted that the above-mentioned visual recognition positioning can be achieved by setting a camera module for visual alignment, or other visual recognition technologies, which are not limited in this embodiment. In addition, a proper amount of flux is applied to the solder ball, and the flux is applied only on the top of the solder ball to avoid using too much flux, which may result in poor effect of subsequent removal of flux residues. It should be noted that the above-mentioned device can be a flip-chip machine.

[0050] Welding steps: The chip and substrate are welded in a reflow machine with the aid of flux, and flux residue is generated at the bottom of the chip after welding;

[0051] Specifically, the chip and substrate are positioned and bonded in the device, and with the assistance of flux, they enter the reflow machine for heating to melt the solder balls between the chip and the substrate, thereby achieving electrical connection and physical fixation between the chip and the substrate. After reflow, flux residue is generated at the bottom of the chip.

[0052] Steps of removing flux residues by using filler: filler is filled between the soldered chip and the substrate, and in the pressure oven, the filler reacts with the flux residue at the bottom of the chip to form a gaseous reactant, and the generated gaseous reactant is discharged from the bottom of the chip through the pressure oven, so that the flux residue at the bottom of the chip is removed;

[0053] Specifically, a proper amount of filler is filled between the chip and the substrate. The amount of filler is calculated based on the size of the chip, including the overall size of the chip and the size of the solder ball, and the size of the gap between the chip and the substrate is calculated to obtain the amount of filler to be filled. The filler will flow between the chip and the substrate, and the chip and the substrate are sent into the pressure oven.

[0054] The temperature is raised inside the controlled pressure oven and high and low pressure molecular oscillation treatment is performed. The filler reacts with the flux residue to form gaseous reactants. The generated gaseous reactants are discharged from the bottom of the chip, that is, from between the chip and the substrate, so as to completely remove the flux residue at the bottom of the chip.

[0055] Curing step: In a pressure oven, the substrate and the chip are baked to cure the filling glue to obtain a baked package semi-finished product.

[0056] Specifically, the chip and the substrate are baked in a pressure oven to solidify the filling glue between the chip and the substrate, so as to facilitate the next production process.

[0057] Wherein, after the welding step, the welded chip and substrate are not subjected to water washing treatment, but the step of directly removing the flux residue by filling glue is performed.

[0058] The chip packaging method of the present application selects a filling glue and a flux that can react as completely as possible to generate a gaseous reactant, so that the flux residue can react as completely as possible to generate a gaseous reactant in the step of removing the flux residue from the filling glue, so that the chip packaging method of the present application can make the filling glue react with the flux residue at the bottom of the chip to form a gaseous reactant during the process of filling the filling glue between the bottom of the chip and the substrate in the pressure oven, and discharge it from the bottom of the chip through the pressure oven. Therefore, even if a special water washing treatment step is not set, the flux residue at the bottom of the chip can be removed by the filling glue, and the residual flux will not be heated and vaporized, resulting in pores inside the filling glue, causing the chip connection to be unstable and causing yield problems. Compared with the existing flip-chip process, the step of cleaning the flux is reduced, thereby avoiding the use of water washing in the chip packaging process, saving water resources and reducing production costs, while avoiding the problem that the water washing of the flux residue may not be rinsed clean, thereby improving the production yield of chip packaging. Moreover, different from the existing chip packaging method, the present application is a new advanced packaging method with broad application prospects. Based on the current experimental results, the quality of the produced packaging semi-finished products can be improved by about 2% compared with the conventional general-purpose ones, and based on the water consumption of the traditional process, more than 8,000 tons of water can be saved each year, which is beneficial to environmental protection and sustainable development.

[0059] It should be noted that, in this embodiment, the filling glue can be one of Henkel's 9100AA filling glue or Hokuriku Paint Co., Ltd.'s U8410-302 filling glue; the flux can be one of Indium Technology Co., Ltd.'s TACFLUX-026S flux or Alpha's NCX-402 flux; the corresponding filling glue and flux are selected for use in combination so that the filling glue reacts with the flux residue to form a gaseous reactant, which is then discharged from the bottom of the chip to remove the flux residue at the bottom of the chip; wherein, when the filling glue is Henkel's 9100AA filling glue, the flux is preferably Alpha's NCX-402 flux; when the filling glue is Hokuriku Paint Co., Ltd.'s U8410-302 filling glue, the flux is preferably Indium Technology Co., Ltd.'s TACFLUX-026S flux. Of course, the types of filler and flux are not limited to the above materials, as long as the filler and flux can react as completely as possible to generate gaseous reactants.

[0060] Further, such as Figure 2As shown, the step of removing flux residues by the filling glue includes:

[0061] Place the soldered chip and substrate into a pressure oven;

[0062] Filling a filling glue between the chip and the substrate, and at least one side of the chip is not filled with the filling glue;

[0063] Specifically, a filling glue is filled between the chip and the substrate. The filling glue is filled from the outside of the chip and gradually flows into the space between the chip and the substrate, while at least one side of the chip is not filled with the filling glue, so that in the subsequent pressurization step and decompression step, the filling glue will move toward the side of the chip that is not filled with the filling glue, so that the filling glue can completely fill the space between the chip and the substrate; it should be noted that, with respect to the current chip shape, it is a better solution to fill the filling glue on three sides of the chip and reserve one side without filling the filling glue; and in this step, the filling glue will not react with the flux residue, and it is necessary to control the internal temperature of the pressure oven to increase in the pressurization step and the decompression step, so that the reaction will only occur after the temperature in the cavity of the pressure oven reaches the reaction temperature.

[0064] Pressurization step: Fill gas into the cavity of the pressure oven to form a high-pressure environment (the cavity of the pressure oven is sealed, and gas pressure is continuously injected to form an environment higher than normal pressure). Control the filling glue to gradually move from the outer periphery of the chip to the center of the chip due to the effect of gas pressure, and react with the flux residue in the process.

[0065] Decompression step: The cavity of the pressure oven is evacuated to form a negative pressure environment (the cavity of the pressure oven is sealed, and the air pressure is continuously evacuated to form an environment below normal pressure). The gaseous reactants generated by the reaction between the filler and the flux residue are discharged in the process.

[0066] Specifically, the pressure in the high pressure environment in the above pressurization step is 1-3 kgf / cm 2 In this embodiment, the pressure value of the high pressure environment can be 2Kgf / cm 2 .

[0067] When the pressurization step is performed, the ambient temperature in the pressure oven can be 40 degrees Celsius, and the cavity of the pressure oven is gradually pressurized from the normal air pressure value. During the pressurization process, due to the inconsistency between the pressure on the outer surface of the filling glue at the periphery of the chip and the pressure on the inner surface at the bottom side of the chip, the filling glue will gradually move slowly from the periphery of the chip toward the center of the chip, and react with the flux residue to form a gaseous reactant. By controlling the size of the pressure, the speed at which the filling glue moves from the periphery of the chip toward the center of the chip can be controlled. Among them, the gaseous reactant formed is formed by the filling glue reacting with the flux residue on the solder ball that it contacts during the gradual movement. The gaseous reactant formed in this aspect will be discharged directly from the bottom of the chip and remain in the cavity of the pressure oven due to the high pressure environment in the cavity of the pressure oven, and will be discharged from the pressure oven when the pressure is reduced. On the other hand, the gaseous reactant formed is formed by reacting with the flux residue on the solder ball covered by the filling glue, and will remain in the filling glue when it is formed. Since the cavity of the pressure oven is a high-pressure environment, the gaseous reactants formed by the reaction of the filling glue and the flux residue will be squeezed out from the inside of the filling glue by the air pressure, that is, discharged from the inside of the filling glue to remain in the cavity of the pressure oven and wait to be discharged from the pressure oven at the decompression step. That is, when the cavity of the pressure oven is adjusted to a high-pressure environment, the gaseous reactants formed by the reaction of the filling glue and the flux residue will be squeezed out from the inside of the filling glue by the air pressure to enter the cavity of the pressure oven.

[0068] Specifically, the negative pressure environment in the above-mentioned decompression step can also be a vacuum environment (it can be close to vacuum by the vacuum pumping step), so that the gaseous reactants generated by the reaction between the filling glue and the flux residue can be discharged from the cavity of the pressure oven as much as possible. During the decompression step, the filling glue will also move slowly (the filling glue may move toward the center of the chip or to other directions outside the chip), but the movement distance is not obvious compared to the pressurization step. The specific movement of the filling glue is related to the air pressure value in the negative pressure environment. Designers can adjust the air pressure value according to actual needs to control the movement of the filling glue.

[0069] Among them, in the step of removing the flux residue from the filler, the above-mentioned pressurization step and decompression step can be repeated multiple times to achieve high-low pressure molecular oscillation treatment, so that the filler and the flux residue can fully react. And through multiple pressurization steps and decompression steps, the speed of the filler moving to the bottom of the chip can be more accurately controlled, and the inertia of movement caused by pressure can be removed, so that the moving position of the filler can be more accurately controlled; therefore, the filler can react with the flux residue at the current position to completely generate gaseous reactants, and only move to the next position when there is no flux residue left, so as to minimize the situation where the flux is not completely reacted and is wrapped inside the filler because the filling speed is too fast, resulting in the residual flux residue. Moreover, even if some of the flux residue is wrapped in the filler, in the subsequent pressurization step, the high pressure will force the gaseous reactants generated by the reaction between the filler and the flux residue out of the filler, so that in the decompression step, the gaseous reactants are drawn out of the pressure oven. In addition, since the movement speed of the filling glue can be controlled to be slow during the pressurization step and the decompression step, the flux is mostly wrapped at the edge of the chip periphery, where the thickness of the filling glue is relatively thin. Therefore, when the pressurization step and the decompression step are performed, the gaseous reactants generated by the reaction between the filling glue and the flux residue are more likely to escape from the filling glue and be discharged outside the filling glue, and then be extracted from the pressure oven.

[0070] In general, the filling glue reacts with the flux residue at the bottom of the chip to form a gaseous reactant. The generated gaseous reactant will be discharged from the bottom of the chip during the high and low pressure molecular oscillation treatment (formed by the pressurization step and the decompression step) to remove the flux residue at the bottom of the chip. It should be noted that all products formed by the reaction of the filling glue and the flux residue are gaseous reactants, and the gaseous reactants are macromolecular particle gaseous reactants. The components in the macromolecular particle gaseous reactants can be new substances generated by chemical reactions between the flux residue and the filling glue, or gaseous reactants formed by physical reactions between the flux residues, that is, the components of the macromolecular particle gaseous reactants are not limited, and only need to be able to form the gaseous reactants. For ease of understanding, the morphology of the macromolecular particle gaseous reactants is similar to that of PM2.5 particles.

[0071] When filling the filling glue, this step can be performed under normal temperature environment. However, the inventor of the present application considers that under normal temperature environment, the reaction efficiency of the filling glue and the flux residue will be slightly lower, and the fluidity of the filling glue is not good. Therefore, in the step of removing the flux residue by the filling glue, the ambient temperature when filling the filling glue is lower than the ambient temperature when baking the substrate, which is lower than 40 degrees Celsius in this embodiment, and higher than the normal temperature of the production environment, which can be higher than 18 degrees Celsius, so that when filling the filling glue, the filling glue will not be solidified or cured due to the excessively high ambient temperature during filling, so that it cannot be completely filled between the chip and the substrate, resulting in a gap between the chip and the substrate and the inability to proceed to the next step; the filling glue is filled at an ambient temperature higher than the normal temperature environment, which can ensure the fluidity of the filling glue while improving the reaction efficiency of the filling glue and the flux residue, speeding up the time of removing the flux residue, and improving the production efficiency and production yield to a certain extent; it should be noted that the normal temperature of the above-mentioned production environment has a temperature value of 23±5 degrees Celsius.

[0072] In the decompression step, the pressure oven is evacuated to make the pressure value in the cavity of the pressure oven less than 2 Kgf / cm 2 During the exhaust process, the gaseous reactants generated by the reaction between the filling glue and the flux residue are discharged from the cavity of the pressure oven; in this embodiment, during the decompression step, the ambient temperature inside the pressure oven is 40 degrees Celsius, and the duration is 50±5 minutes; in the pressurization step, the ambient temperature inside the pressure oven is 40 degrees Celsius, and the duration is 5±5 minutes. In the pressurization step, the ambient temperature inside the pressure oven is increased to 40 degrees Celsius, so that the filling glue can react with the flux residue, and the air pressure value in the pressurization step is 2Kgf / cm 2 The gaseous reactants generated by the reaction will be discharged from between the chip and the substrate into the cavity of the pressure oven under this pressure; it should be noted that the above data are the better data values ​​obtained by the inventor of this application through multiple experiments and testing the yield of the semi-finished packaging products after the experiments.

[0073] That is, in the process of the reaction between the filler and the flux residue, a suitable temperature can be selected to improve the reaction efficiency. The higher the reaction efficiency, the more flux residue is removed and the less the flux residue remains. After many experiments by the applicant, it was found that under the condition of 40 degrees Celsius (±2 degrees error), the filler is Henkel's 9100AA filler and the flux is Alpha's NCX-402 flux. The reaction efficiency of these two types of fillers and flux is significantly higher than the reaction efficiency under other conditions. In addition, the pressurization and decompression steps are carried out at a relatively slow speed (the data value adjusted by the above test). In this process, the filler and flux residue can better contact and more fully react to generate gaseous reactants. Under the pressure and temperature conditions selected by the applicant (40 degrees Celsius during the pressurization step, the pressure value is 2Kgf / cm 2 , the duration is 5 minutes; the decompression step is 40 degrees Celsius, and the pressure value is less than 2Kgf / cm 2 , the duration is 50 minutes, and the conversion time from the air pressure value of the pressurization step to the air pressure value of the decompression step is 5 minutes). The two can almost completely react to generate reactants, so that there is no residual flux residue, or the amount of residual substance will not produce bubbles in the subsequent drying step to cause quality problems; it should be noted that the temperature and air pressure are obtained after many experiments. Any change may cause the flux residue to remain, resulting in a decrease in the production yield.

[0074] Furthermore, in the step of using the filling glue to remove the flux residue, the pressurizing step and the decompression step are repeated for more than one cycle, so that the filling glue can fully react with the flux residue and completely remove the flux residue between the chip and the substrate, thereby improving the production yield of the product; of course, in order to take into account the issues of production efficiency and production cost, the pressurizing step and the decompression step are preferably performed only once; and the pressurizing step and the decompression step are not limited to the above-mentioned number of cycles, and designers can design them according to actual conditions. For example, the pressurizing step is first set to be performed, followed by the decompression step, and then the step cycle of performing the pressurizing step once without performing the decompression step is repeated, and in the repeated pressurizing step and the decompression step, the air pressure value and temperature value used can also be changed according to the actual production situation, and the duration can also be changed according to the actual production situation, which is not limited here.

[0075] Furthermore, in order to ensure that the filling glue only reacts with the flux residue in the pressure oven, and that no pollutants or moisture appear between the chip and the substrate in the produced packaged semi-finished product, in the pressurization step, the gas filled into the pressure oven is a pure gas, and the pure gas is nitrogen; of course, designers can also use other pure gases to fill the pressure oven, which is not limited here.

[0076] Furthermore, in the curing step, the ambient temperature of the pressure oven is between 80 and 160 degrees Celsius, and the internal pressure of the pressure oven is between 6 and 8 Kgf / cm 2 The baking time is between 220 and 240 minutes;

[0077] In this embodiment, the curing step can be divided into four small steps. The first step is the first heating step. At this time, the ambient temperature of the pressure oven is 80 degrees Celsius and the internal pressure of the pressure oven is 7Kgf / cm 2 The baking time of the pressure oven is 15 minutes. The ambient temperature of the pressure oven is first increased for 15 minutes to reach 80 degrees Celsius from the temperature in the decompression step. Then, a temperature maintenance step is performed. The same ambient temperature and pressure value are maintained for 100 minutes to fully bake the filler between the chip and the substrate. Then, a second temperature increase step is performed. At this time, the ambient temperature of the pressure oven is 150 degrees Celsius, and the internal pressure value of the pressure oven is 7Kgf / cm 2 The baking time of the pressure oven is 15 minutes to raise the ambient temperature of the pressure oven from 80 degrees Celsius to 150 degrees Celsius. Then, the temperature maintenance step is performed again at the same ambient temperature and pressure value, that is, the pressure value is maintained at 7Kgf / cm 2 and an ambient temperature of 150 degrees Celsius for 100 minutes; by setting two different ambient temperatures, the filling glue can be fully baked and cured, thereby fixing the chip and the substrate; the filling glue is cured between the chip and the substrate to protect the solder joints between the chip and the substrate from moisture and pollutants in the environment, and to facilitate the next production process.

[0078] Figure 5 It is the specific parameters used in the applicant's experimental verification, including the parameters of the pressurization step, the decompression step and the curing step. The temperature section 1 is the parameter data of the pressurization step, the temperature section 2 is the parameter data of the decompression step, and the temperature sections 3 to 6 are the parameter data of the curing step. Figure 6 This is the ultrasonic test diagram of the product produced by the applicant under the experimental parameters. Figure 6 As can be seen, the pressure step is 40 degrees Celsius and the pressure value is 2Kgf / cm 2, the duration is 5 minutes, the decompression step is 40 degrees Celsius, and the pressure value is less than 2Kgf / cm 2 The pressurization step and the decompression step are performed under the conditions of temperature and pressure for a duration of 50 minutes, which enables the filling glue and the flux residue to react almost completely, and the semi-finished package produced has no bubbles in the subsequent ultrasonic inspection.

[0079] like Figure 3 As shown, as the second embodiment of the present application, which is a further improvement of the first embodiment of the present application, a chip packaging method is disclosed, and the chip packaging method further includes the steps of:

[0080] Inspection step: inspect the semi-finished packaged product obtained after baking;

[0081] The semi-finished packaged product is subjected to ultrasonic scanning to detect whether there are bubbles between the substrate and the chip.

[0082] In this embodiment, after the chip packaging method goes through the flux coating step, welding step, filling glue and removing flux residue step and curing step, a detection step is added. The packaging semi-finished product is subjected to ultrasonic scanning to detect whether there are bubbles between the substrate and the chip, so as to determine the production yield of the packaging semi-finished product. If there are bubbles between the substrate and the chip, it means that the flux residue after welding is still left. The flux residue is vaporized in the curing step to form bubbles in the filling glue. When this happens, the packaging semi-finished product needs to be subsequently reworked or scrapped for recycling.

[0083] like Figure 4 As shown, as the third embodiment of the present application, a packaging semi-finished product is disclosed. The packaging semi-finished product 400 is packaged by the chip packaging method as described in the above embodiment. After the packaging of the packaging semi-finished product 400 is completed, the flux residue between the chip 100 and the substrate 200 is removed, and the filling glue 300 is baked and cured.

[0084] The semi-finished packaged product of this embodiment, during packaging, reacts with the flux residue at the bottom of the chip to form a gaseous reactant during the process of filling the filling glue between the bottom of the chip and the substrate in the pressure oven, and is discharged from the bottom of the chip through the pressure oven. Therefore, even without setting a special water washing step, the flux residue at the bottom of the chip can be removed by the filling glue, and the residual flux will not be heated and vaporized, resulting in pores inside the filling glue, causing the chip connection to be unstable and causing yield problems. Compared with the existing flip-chip process flow, the step of cleaning the flux is reduced, thereby avoiding the use of water washing in the chip packaging process, saving water resources and reducing production costs, while avoiding the problem of incomplete washing of the flux residue by water washing, and improving the production yield of chip packaging.

[0085] It should be noted that the limitations on the various steps involved in this solution, without affecting the implementation of the specific solution, are not deemed to limit the order of the steps. The steps written in front can be executed first, or later, or even simultaneously. As long as this solution can be implemented, it should be deemed to fall within the scope of protection of this application.

[0086] It should be noted that the inventive concept of the present application can form a large number of embodiments, but the length of the application document is limited and it is impossible to list them one by one. Therefore, under the premise of no conflict, the embodiments or technical features described above can be arbitrarily combined to form new embodiments. After the embodiments or technical features are combined, the original technical effects will be enhanced.

[0087] The above content is a further detailed description of the present application in combination with specific optional implementation methods, and it cannot be determined that the specific implementation of the present application is limited to these descriptions. For ordinary technicians in the technical field to which the present application belongs, several simple deductions or substitutions can be made without departing from the concept of the present application, which should be deemed to fall within the scope of protection of the present application.

Claims

1. A chip packaging method, characterized in that: Includes steps: Flux application step: Apply flux on the solder balls of the chip and flip the chip onto the substrate; Welding steps: The chip and substrate are welded in a reflow machine with the aid of flux, and flux residue is generated at the bottom of the chip after welding; Steps of removing flux residues by using filler: filler is filled between the soldered chip and the substrate, and in the pressure oven, the filler reacts with the flux residue at the bottom of the chip to form a gaseous reactant, and the generated gaseous reactant is discharged from the bottom of the chip through the pressure oven, so that the flux residue at the bottom of the chip is removed; Curing step: In a pressure oven, the substrate and the chip are baked to cure the filling glue to obtain a baked package semi-finished product.

2. The chip packaging method according to claim 1, characterized in that: After the welding step, the chip and substrate after welding are not subjected to water washing treatment, but directly perform the step of removing the flux residue by filling glue.

3. The chip packaging method according to claim 1, characterized in that: The step of removing flux residues by the filling glue comprises: Place the soldered chip and substrate into a pressure oven; Filling a filling glue between the chip and the substrate, and at least one side of the chip is not filled with the filling glue; Pressurization step: Gas is filled into the cavity of the pressure oven to form a high-pressure environment. The filler gradually moves from the periphery of the chip toward the center of the chip and reacts with the flux residue in the process; Decompression step: The cavity of the pressure oven is evacuated to form a negative pressure environment, and the gaseous reactants generated by the reaction between the filler and the flux residue are discharged in the process; Wherein, in the step of removing the solder flux residue by the filling glue, the pressurization step and the depressurization step are repeated to realize the high-low pressure molecular oscillation treatment, so that the filling glue reacts with the solder flux residue at the bottom of the chip to form a gaseous reactant, and the generated gaseous reactant is discharged from the bottom of the chip during the high-low pressure molecular oscillation treatment, so that the solder flux residue at the bottom of the chip is removed; Wherein, all products formed by the reaction between the filling glue and the flux residue are the gaseous reactants.

4. The chip packaging method according to claim 1, characterized in that: In the step of removing flux residues by filling the filling glue, the ambient temperature when filling the filling glue is lower than 40 degrees Celsius and higher than 18 degrees Celsius.

5. The chip packaging method according to claim 3, characterized in that: In the decompression step, the pressure oven is evacuated to make the pressure in the cavity of the pressure oven less than 2 Kgf / cm 2 , the gaseous reactants generated by the reaction between the filling glue and the flux residue are discharged from the bottom of the chip.

6. The chip packaging method according to claim 3, characterized in that: In the step of removing flux residues by using the filling glue, the pressurization step and the depressurization step are repeated for more than one cycle.

7. The chip packaging method according to claim 3, characterized in that: In the pressurizing step, the gas filled into the pressure oven is pure gas, and the pure gas is nitrogen.

8. The chip packaging method according to claim 3, characterized in that: In the decompression step, the ambient temperature inside the pressure oven is 40±2 degrees Celsius and the duration is 50±5 minutes; During the pressurization step, the ambient temperature inside the pressure oven is 40±2 degrees Celsius and the duration is 5±5 minutes.

9. The chip packaging method according to claim 1, characterized in that: In the curing step, the ambient temperature of the pressure oven is between 80 and 160 degrees Celsius, the internal air pressure of the pressure oven is between 6 and 8 kg, and the baking time is between 220 and 240 minutes.

10. The chip packaging method according to claim 1, characterized in that: Also includes the steps: Inspection step: inspect the semi-finished packaged product obtained after baking; The semi-finished packaged product is subjected to ultrasonic scanning to detect whether there are bubbles between the substrate and the chip.

11. The chip packaging method according to claim 1, characterized in that: The filler can be one of Henkel's 9100AA filler or Hokuriku Paint Co., Ltd.'s U8410-302 filler; The soldering flux may be one of TACFLUX-026S soldering flux produced by Indium Corporation of China or NCX-402 soldering flux produced by Alpha.

12. A semi-finished packaging product, characterized in that: The packaged semi-finished product is packaged by using the chip packaging method according to claims 1 to 11. After the packaged semi-finished product is packaged, the flux residue between the chip and the substrate is removed.

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