A soldering method that utilizes adjustment of the temperature and amount of gas molecules in the chamber

Abstract

To provide a soldering method that can achieve a high coverage rate and a low void rate of a soldering medium and obtain excellent heat dissipation performance.SOLUTION: A soldering method according to an embodiment may include the steps of placing a first component and a second component to be soldered, which are temporarily joined with a soldering medium, in a chamber, and adjusting the temperature and the amount of gas molecules in the chamber to achieve periodic changes in the heat and the amount of the gas molecules in the chamber, thereby solidifying the soldering medium and completing the soldering of the first component and the second component. The temperature in the chamber changes continuously between rising and falling due to the heat changes, and the pressure in the chamber changes between positive and negative pressures at regular intervals due to the periodic changes.SELECTED DRAWING: Figure 1

Description

[Technical Field]

[0001] This application relates to the industrial manufacturing field, and more particularly to a soldering method and packaged chips that utilizes adjustment of the temperature and amount of gas molecules in a chamber. [Background technology]

[0002] In recent years, with the increasing integration density of chips, chip power consumption and power density have also increased, resulting in heat generation issues that have become a major factor limiting chip performance and lifespan. To ensure good heat dissipation, conventional techniques often involve applying a thermal interface material to the chip surface and then attaching a heat sink cover. This process is sometimes called soldering. Currently, flux is commonly added during soldering, but the evaporation of solvents contained in the flux can lead to the formation of numerous voids at the solder joint interface, ultimately affecting heat dissipation efficiency.

[0003] Therefore, a new soldering method is urgently needed to solve the problem of voids in the soldering process. Summary of the Invention [Problem to be solved by the invention]

[0004] To solve the above technical problems, the present application provides a soldering method using adjustment of the temperature and amount of gas molecules in a chamber, and a packaged chip manufactured by the method, which can achieve a high coverage rate of the soldering medium and a low void rate, resulting in excellent heat dissipation performance. [Means for solving the problem]

[0005] One aspect of the present application provides a soldering method that utilizes adjustment of the temperature and amount of gas molecules in a chamber, which may include the steps of: placing a first component and a second component to be soldered, which are temporarily joined with a soldering medium, in a chamber; and adjusting the temperature and amount of gas molecules in the chamber to achieve periodic changes in heat and the amount of gas molecules in the chamber, thereby solidifying the soldering medium and completing the soldering of the first component and the second component, wherein the temperature in the chamber continuously changes between rising and falling due to the heat changes, and the pressure in the chamber changes between positive and negative pressures at regular intervals due to the periodic changes.

[0006] In some possible embodiments, the temperature within the chamber is varied continuously between increasing and decreasing over time, including first increasing and then decreasing, and the temperature increase includes a constant temperature step.

[0007] In some possible embodiments, the pressure in the chamber varies between positive and negative pressures at regular intervals, including varying between positive and negative pressures over time.

[0008] In some possible embodiments, when the pressure in the chamber becomes negative, the degree of vacuum in the chamber changes continuously in multiple stages.

[0009] In some possible embodiments, the multi-step continuous change causes the vacuum level to continuously increase and then decrease, and the continuous change to increase the vacuum level includes decreasing from an initial vacuum level to an intermediate vacuum level and then increasing to a target vacuum level.

[0010] In some possible embodiments, when the pressure in the chamber is at the end of the constant interval change, the predetermined positive pressure is maintained until the soldering is completed.

[0011] In some possible embodiments, the temperature is continuously decreased until the soldering is completed when the pressure in the chamber is maintained at a predetermined positive pressure until the soldering is completed.

[0012] In some possible embodiments, when the pressure in the chamber is positive, the positive pressure is 2 atm or more.

[0013] In some possible embodiments, the first component includes a chip, the second component includes a heat sink cover, and the soldering medium includes a flux and a thermal interface material.

[0014] Another aspect of the present application also provides a packaged chip that can be manufactured by the above soldering method. [Effects of the Invention]

[0015] The implementation of this application has the following advantageous effects: The soldering method provided in the present application, which utilizes adjustment of the temperature and amount of gas molecules in the chamber, can achieve controlled changes in heat and pressure in the chamber by adjusting the temperature and amount of gas molecules in the chamber, and can effectively remove voids generated from the soldering medium during the soldering process, thereby achieving high component coverage and low void rate, improving heat dissipation effect, and improving product yield. [Brief explanation of the drawings]

[0016] This application will be further described in the form of examples, which are illustrated in detail with the accompanying drawings, in which the examples are not limiting, and in which like numerals refer to like structures. [Figure 1] 1 is an exemplary flowchart of a soldering method utilizing adjustment of the amount of gas molecules in a chamber according to some embodiments of the present application. [Figure 2] 1 is an exemplary waveform diagram of temperature and pressure changes according to some embodiments of the present application. [Figure 3] 1 is a scanned image of a solder joint interface according to some embodiments of the present application. [Figure 4] 1 is another scanned image of a solder joint interface according to some embodiments of the present application. [Figure 5] 1 is a scanned image of a solder joint interface obtained using conventional technology. [Figure 6] 1 is another scanned image of a solder joint interface obtained using the prior art; DETAILED DESCRIPTION OF THE INVENTION

[0017] In order to make the above-mentioned objects, features, and advantages of the present application clearer and easier to understand, the following detailed description of specific implementations of the present application will be given with reference to the accompanying drawings. In the following description, numerous specific details are set forth to fully understand the present application. However, the present application can be implemented in many other ways different from those described herein, and those skilled in the art can make similar improvements without departing from the spirit of the present application. Therefore, the present application is not limited by the specific embodiments disclosed below.

[0018] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by those skilled in the art of this application. The terms used herein are for the purpose of describing specific examples and are not intended to be limiting of the application. As used herein, the term "and / or" includes any and all combinations of one or more of the associated listed items.

[0019] In conventional technology, vacuum reflow soldering equipment is commonly used to solder components. Vacuum reflow soldering equipment can have multiple chambers. Each chamber has a preset temperature, also known as a temperature zone. Vacuum reflow soldering equipment differs in the number of temperature zones, which are roughly divided into 7 to 13 (including a vacuum temperature zone and a cooling temperature zone located after the vacuum temperature zone). Products required for soldering are placed on a chain conveyor and sequentially enter each temperature zone. The conveyor speed is controlled to indirectly control the product's residence time in each temperature zone. After the product enters the vacuum temperature zone, the vacuum temperature zone's chamber door is closed, creating an enclosed space and achieving the purpose of evacuation. After the vacuum stage is completed, the chamber door is opened, and the product flows to the next temperature zone. After solidifying in the cooling temperature zone, the product flows out of the device's outlet, completing the soldering process.

[0020] Currently, the void rate of products manufactured using vacuum reflow soldering equipment is 6% or more, which means that the heat dissipation function of the products is not fully utilized.

[0021] One aspect of the present application provides a soldering method that utilizes adjustment of the amount of gas molecules in a chamber, which can achieve high coverage and low void rate of a soldered product. Referring to Figure 1, as shown in Figure 1, the soldering method can include the following steps:

[0022] Step 110: A first component and a second component to be soldered are placed in the chamber.

[0023] In some possible embodiments, the chamber is sealable, and the temperature and pressure within the chamber can be adjusted. For example, the chamber may have an openable / closable door plate. Opening and closing the door plate allows the chamber to communicate with the outside or to be sealed. The chamber may include a heating / cooling assembly and / or a gas flow path, and / or these may be attached to the outside. The temperature within the chamber can be adjusted via the heating / cooling assembly, and the pressure within the chamber can be adjusted via the gas flow path. Alternatively, the gas flow path may include a cooling device such as a condenser and a circulation pipe equipped with a power device such as a fan or pump. The gas within the chamber circulates through the circulation pipe under the action of the power device, and the cooling device simultaneously lowers the temperature of the circulating gas.

[0024] In some possible embodiments, the first and second components can be temporarily joined using a soldering medium. For example, the first component can include a chip, and the second component can include a heat sink cover. The heat sink cover can be made of a metal or alloy with excellent thermal conductivity, such as copper, aluminum, iron, zinc, nickel, or titanium; a ceramic material, such as aluminum oxide or zirconium oxide; a polymer material, such as polyimide or polyamic acid ester; or a carbon material, such as graphite or carbon fiber. Soldering the heat sink cover onto the chip allows rapid heat conduction to the chip, reducing its temperature. The soldering medium can include a thermal interface material, such as a silicone-based thermally conductive material, such as thermally conductive silicone grease, or a metal heat sink, such as an indium sheet. These thermal interface materials can bond the first and second components together in certain situations and also serve as a thermal bridge between the two components.

[0025] In one possible embodiment, the soldering medium may include a flux. The flux may be contained within the thermal interface material or applied on top of the thermal interface material. For example, if a metal heat sink is used as the thermal interface material, the flux may be applied to the surface of the metal heat sink. One method for achieving a temporary bond between the first and second components using the soldering medium is to first apply flux to the chip surface to form a first flux layer, then apply or mount the thermal interface material on the first flux layer, and then apply flux to the surface of the thermal interface material to form a second flux layer. The temporary bond between the first and second components is completed by attaching a heat sink cover on top of the second flux layer. In this way, the components can be soldered in a subsequent process after the soldering medium has solidified, effectively improving the heat dissipation efficiency of the first component, e.g., the chip.

[0026] Step 120: Adjusting the temperature and amount of gas molecules in the chamber to achieve periodic changes in heat and amount of gas molecules in the chamber, solidifying the soldering medium and completing the soldering of the first component and the second component.

[0027] In some possible embodiments, the temperature in the chamber can be adjusted by adjusting the heating / cooling assembly of the chamber, thereby achieving thermal changes within the chamber. For example, a heating coil or hot water pipe surrounding the chamber can add heat to the chamber through heat conduction, thereby increasing the temperature within the chamber. A cooling assembly, such as a cooling water circulator or gas flow path, can absorb and dissipate heat within the chamber, thereby decreasing the temperature within the chamber. In some possible embodiments, the thermal changes within the chamber can cause the temperature within the chamber to continuously change between increasing and decreasing. For example, throughout the soldering process, the temperature within the chamber may first increase and then decrease over time. As the temperature increases, the soldering medium reaches the appropriate melting point, forming a eutectic interface and creating a tighter bond. As the temperature decreases, the soldering medium cools and begins to solidify, achieving a bond between the components.

[0028] It is understood that the flux solvent evaporates during the heating process, generating gas and forming voids in the soldering medium. The generation of voids affects the final soldering quality and thermal conductivity. Simply put, the more voids there are, the lower the thermal conductivity. In the present application, void elimination can be achieved by adjusting the temperature and amount of gas molecules in the chamber. In some possible embodiments, a periodic change in the amount of gas molecules in the chamber can be achieved by filling and / or removing a predetermined amount of gas molecules from the chamber through a gas flow path. This periodic change can cause the amount of gas molecules in the chamber to increase and decrease at regular intervals. That is, over time, the amount of gas molecules in the chamber may first increase and then decrease, then increase and decrease again, and so on. This is reflected in the pressure in the chamber, which may vary between positive and negative pressures over time. In the positive pressure stage, the chamber pressure is increased to 2 atm or higher, e.g., 2 atm, 3 atm, 5 atm, 8 atm, etc., depending on the amount of gas molecules introduced. As the amount of gas molecules in the chamber increases, on the one hand, it compresses the soldering medium, thereby forcing voids out of the soldering medium. On the other hand, smaller voids are dissolved in the soldering medium by the compression of the large amount of gas molecules, achieving the goal of elimination. As the amount of gas molecules in the chamber decreases, the interference of gas molecules in the environment is reduced, making it easier for the gas molecules that make up the voids to be removed. This achieves the goal of void elimination in two ways.

[0029] Referring to FIG. 2, FIG. 2 is an exemplary waveform diagram of temperature and pressure changes according to some embodiments of the present application. As shown in FIG. 2, Pc represents the pressure curve within the chamber, Tc represents the temperature curve within the chamber, and P0 represents the ambient atmospheric pressure. For example, the temperature within the chamber may increase over time, as time t passes. The temperature increase process may include a stage in which the temperature is maintained stable. Gas molecules within the chamber can be exhausted from the chamber through the gas flow path of the chamber. For example, when the first and second joined components are placed in the chamber, oxygen molecules may enter the chamber. If deoxidation is not performed, these oxygen molecules can adversely affect the soldering process, for example, by oxidizing the solder metal and forming oxides, which affects the soldering quality. Therefore, the oxygen molecules can be effectively removed by a process of exhausting the gas molecules within the chamber and then introducing and exhausting the gas molecules. In some possible embodiments, the gas molecules introduced into the chamber may be protective gas molecules such as nitrogen molecules or argon molecules.

[0030] The soldering medium can be preheated by increasing the temperature. For example, the thermal interface material can be preheated to activate the flux. Activating the flux volatilizes the solvent, which is then expelled from the chamber during the process of adjusting the amount of gas molecules (e.g., by discharging the gas molecules and reducing the pressure in the chamber). For example, the heat in the chamber can be adjusted to first raise the temperature in the chamber to T1, which can be equal to or higher than the activation temperature of the flux to activate it. At the same time, T1 is lower than the melting point of the thermal interface material. In this way, the solvent begins to volatilize as the flux activates, but the thermal interface material remains in a solid state. This prevents voids from entering the heat dissipation medium and allows for easy removal during the process of reducing the amount of gas molecules in the chamber.

[0031] Referring back to FIG. 2, heat applied to the chamber can continue to increase over time, increasing the temperature within the chamber. For example, the temperature can be increased to T2. T2 can exceed the melting point of the thermal interface material, converting the thermal interface material to a molten state and better bonding the components. For example, an indium sheet can be wetted in the molten state to form a eutectic interface, resulting in a good soldering effect.

[0032] During this process, the amount of gas molecules in the chamber changes at regular intervals, causing the pressure in the chamber to fluctuate between positive and negative pressures, resulting in better void removal. In some possible embodiments, when the chamber is in a negative pressure state due to the amount of gas molecules in the chamber, the degree of vacuum in the chamber may change continuously in multiple steps. This continuous change in multiple steps may involve the degree of vacuum changing between two values, or the degree of vacuum maintaining the same change trend (e.g., decreasing, increasing, and / or maintaining) in each step. In some possible embodiments, the continuous change in multiple steps may involve the degree of vacuum in the chamber continuously increasing and then decreasing. For example, the degree of vacuum may increase in each step except for the final step, and then decrease in the final step. In some possible embodiments, the continuous increase in the degree of vacuum may decrease from an initial vacuum to an intermediate vacuum, and then increase to a target vacuum. The magnitude of the pressure in the chamber is expressed in Torr. Obviously, 760 Torr is the ambient atmospheric pressure. In a certain stage of change, assuming the initial vacuum level is 300 Torr, some gas molecules can be introduced first to reduce the vacuum level to an intermediate level of 350 Torr. This intermediate vacuum level can be maintained or not, and the gas molecules can then be evacuated to the chamber, increasing the vacuum level to 250 Torr to reach the target vacuum level. In this application, the amount of gas molecules required to create a negative pressure in the chamber is adjusted by, on the one hand, continuously evacuating the gas molecules to avoid contamination due to leakage of the thermal interface material, and, on the other hand, by reducing the vacuum level, the function of "filling the thermal interface material" is achieved using the principle of differential pressure, allowing voids to escape from the thermal interface material and then be removed during the process of evacuating the gas molecules.

[0033] In some possible embodiments, the final interval change in pressure within the chamber, caused by adjusting the amount of gas molecules within the chamber, can include achieving and maintaining a positive pressure within the chamber until the end of soldering. Similarly, the temperature within the chamber can be continuously reduced by adjusting the heat within the chamber until the end of soldering. That is, the interior of the chamber maintains a positive pressure while the temperature is reduced to solidify the molten thermal interface material. While maintaining high pressure, if voids still remain in the thermal interface material, these voids are compressed to a very small size and then trapped within the solid structure during the cooling and solidification process. Meanwhile, under the action of high pressure, the voids can also be compressed and move within the molten thermal interface material, breaking away from the boundaries and further eliminating the voids.

[0034] Another aspect of the present application provides a packaged chip that can be manufactured by the above soldering method.

[0035] The soldering method disclosed in this application, which utilizes adjustment of the temperature and amount of gas molecules in a chamber, and the packaged chip for connecting components manufactured by this soldering method, can achieve a high surface coverage of the components, a high thermal conductivity soldering medium with a low void rate, and excellent heat dissipation performance.

[0036] Referring to Figures 3 to 6, Figures 3 and 4 are scanned images of solder joint interfaces according to some embodiments of the present application, and Figures 5 and 6 are scanned images of solder joint interfaces obtained using conventional technology. Figure 3 shows the void ratio at the solder joint interface. The void ratios corresponding to the three examples were 0.01%, 0.65%, and 0.20%, respectively, all of which were less than 1%. This was much smaller than the void ratio of less than 10% at the solder joint interface of the product produced using the vacuum reflow soldering apparatus shown in Figure 5. The coverage ratios of the solder joint interface, 98.2%, 96.71%, and 98.7%, corresponding to the three examples shown in Figure 4, respectively, were much higher than the coverage ratio of less than 90% at the solder joint interface of the product obtained using conventional technology shown in Figure 6.

[0037] As can be seen from this, compared to the prior art, the soldering method provided in the present application can effectively eliminate voids generated from the flux solvent during the soldering process and improve the coverage rate of the heat dissipation medium.

[0038] The technical features described in the above embodiments can be arbitrarily combined. For the sake of brevity, not all possible combinations of the technical features in the above embodiments are described. However, as long as there is no contradiction in the combination of these technical features, any combination should be considered to fall within the scope described in this specification.

[0039] The above-described examples illustrate some embodiments of the present application, and although the descriptions are specific and detailed, they should not be construed as limiting the scope of the claims. It should be noted that a person skilled in the art can make numerous modifications and improvements without departing from the concept of the present application, all of which are within the scope of protection of the present application. Therefore, the scope of protection of the patent of the present application should be determined by the scope of the attached claims.

[0040] The basic concepts have been described herein. Obviously, for those skilled in the art, the above detailed disclosure is merely illustrative and does not limit the present invention. Although not expressly described herein, those skilled in the art may make various changes, improvements, and modifications to the present invention. Such changes, improvements, and modifications are proposed herein and therefore are intended to be within the spirit and scope of the exemplary embodiments herein.

[0041] It should be noted that in the description of the embodiments of this specification, multiple features may be grouped together in one embodiment, drawing, or description to simplify the disclosure and facilitate understanding of one or more application embodiments. However, this disclosure method does not imply that the subject matter of this specification requires more features than those recited in the claims. In fact, the embodiments may include fewer features than all of the features included in the disclosure of each individual embodiment described above.

[0042] In some examples, numerical values ​​are used to express the quantities of components or attributes. It should be understood that in some examples, the numerical values ​​described in these examples are modified by terms such as "about," "approximately," or "substantially." Unless otherwise specified, "about," "approximately," or "substantially" indicate that the numerical value in question may vary by ±20%. Thus, in some examples, all numerical parameters used in the specification and claims are approximations, and these approximations may vary depending on the desired properties of a particular example. In some examples, the numerical parameters should be calculated using the specified significant digits and conventional methods for preserving digits. Although the numerical ranges and parameters used to specify the breadth of ranges in some examples herein are approximations, in specific examples, these numerical values ​​are set as precisely as practicable.

[0043] Finally, it should be understood that the embodiments described herein are intended to illustrate the principles of the embodiments herein. Other variations may be within the scope of the present disclosure. Thus, by way of example and not limitation, alternative configurations of the embodiments herein are considered consistent with the teachings herein. Accordingly, the embodiments herein are not intended to be limited to the embodiments expressly disclosed and described herein.

Claims

1. A soldering method utilizing adjustment of the temperature and amount of gas molecules in a chamber, a step of placing a first component and a second component to be soldered, which are temporarily joined with a soldering medium, in a chamber; and adjusting the temperature and the amount of gas molecules in the chamber to achieve a periodic change in the heat and the amount of gas molecules in the chamber, thereby solidifying the soldering medium and completing the soldering of the first component and the second component; The thermal change causes the temperature in the chamber to change continuously between rising and falling, and the periodic change causes the pressure in the chamber to change between positive and negative pressure at regular intervals. A soldering method characterized by:

2. 2. The soldering method according to claim 1, wherein the temperature in the chamber continuously changes between rising and falling over time, including first rising and then falling, and the temperature rising process includes a constant temperature stage.

3. 2. The method of claim 1, wherein the pressure in the chamber varies between positive and negative pressures at regular intervals, including varying between positive and negative pressures over time.

4. 4. The soldering method according to claim 3, wherein when the pressure in the chamber becomes negative, the degree of vacuum in the chamber changes continuously in multiple stages.

5. The multi-step continuous change causes the degree of vacuum to increase and then decrease continuously, and the continuous change that increases the degree of vacuum is This includes decreasing the initial vacuum to an intermediate vacuum and then increasing the vacuum to the target vacuum.

5. The soldering method according to claim 4, wherein:

6. 4. The soldering method according to claim 3, further comprising maintaining a predetermined positive pressure until soldering is completed when the pressure in said chamber is at the final stage of the constant interval change.

7. 7. The soldering method according to claim 6, further comprising the step of: when the pressure in the chamber is maintained at a predetermined positive pressure until the completion of soldering, the temperature is continuously decreased until the completion of soldering.

8. 2. The soldering method according to claim 1, wherein when the pressure in the chamber is positive, the positive pressure is 2 atm or more.

9. 9. The soldering method according to claim 1, wherein the first component comprises a chip, the second component comprises a heat sink cover, and the soldering medium comprises a flux and a thermal interface material.

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