Packaging module and packaging method for packaging wafers in outer space

Abstract

The present application relates to the field of semiconductor manufacturing technology, and provides a packaging module for packaging wafers in outer space and a packaging method thereof, wherein the packaging module comprises: a printed circuit board and a radiation shield; wherein the radiation shield is used to cover the wafer in the printed circuit board, a first plastic sealing layer exists in the inner space between the radiation shield and the wafer, and a second plastic sealing layer exists in the outer space of the radiation shield. In the present application, the wafer in the printed circuit board is covered by the radiation shield, and the space radiation is blocked by the radiation shield, which is conducive to reducing the impact of space radiation on the packaging module.

Description

Technical Field

[0001] The present invention relates to the technical field of semiconductor manufacturing, and in particular to a packaging module for packaging wafers in outer space and a packaging method thereof. Background Art

[0002] There is space radiation in outer space, which can affect the normal operation of electronic equipment. For example, cosmic rays are part of space radiation. Cosmic rays are high-energy particle streams from inside and outside the Milky Way, including high-speed protons, heavy ions and a small amount of electrons. The energy range of cosmic rays is wide, and some can be extremely high, making conventional electronic equipment unable to be used in outer space. Summary of the invention

[0003] In view of the deficiencies in the prior art, the present application provides a packaging module and a packaging method for packaging wafers for outer space, which are helpful in reducing the impact of space radiation on the packaging module.

[0004] To solve the above problems, the present invention provides the following technical solutions:

[0005] In a first aspect, an embodiment of the present application provides a packaging module for packaging wafers in outer space, the packaging module comprising a printed circuit board and a radiation shield; wherein:

[0006] The radiation shield is used to cover the wafer in the printed circuit board. A first plastic sealing layer exists in the inner space between the radiation shield and the wafer, and a second plastic sealing layer exists in the outer space of the radiation shield.

[0007] In some embodiments, the radiation shield is made of lead-titanium alloy.

[0008] In some embodiments, the material of the radiation shield is lead aluminum alloy.

[0009] In some embodiments, the radiation shield is made of lead-titanium alloy.

[0010] In some embodiments, the first molding layer and the second molding layer are molded using epoxy resin or silicone resin.

[0011] In some embodiments, the thickness of the radiation shield is in the range of [0.01 mm, 0.09 mm].

[0012] In some embodiments, the radiation shield is used to shield a central processing unit, at least one double data rate synchronous dynamic random access memory, and at least one flash memory in the printed circuit board.

[0013] In a second aspect, an embodiment of the present application provides a packaging method, the packaging method is used to manufacture a packaging module for a packaging wafer for outer space as in the first aspect, the method comprising:

[0014] Covering the wafer of the printed circuit board with a radiation shield;

[0015] Using a divided hole mold to plastic-seal the inner space between the radiation shield and the wafer through a plurality of injection holes reserved on the radiation shield to discharge the gas in the inner space to form a first plastic-sealing layer;

[0016] Sealing a plurality of injection holes reserved on the radiation shield;

[0017] The outer space of the radiation protection cover is plastic-sealed to form a second plastic-sealed layer.

[0018] In some embodiments, the step of sealing the plurality of injection holes reserved on the radiation shield comprises:

[0019] The multiple injection holes reserved on the radiation shield are welded and sealed.

[0020] In some embodiments, the step of welding and sealing the plurality of injection holes reserved on the radiation shield comprises:

[0021] placing an ultrasonic probe in contact with or close to one of the injection holes;

[0022] Performing ultrasonic testing on the first plastic sealing layer by using the ultrasonic probe to determine whether bubbles or voids remain in the first plastic sealing layer;

[0023] When the detection result shows that no bubbles or voids remain, the multiple injection holes reserved on the radiation shield are welded and sealed.

[0024] The present application provides a packaging module for packaging wafers in outer space and a packaging method thereof, the packaging module comprising: a printed circuit board and a radiation shield; wherein the radiation shield is used to cover the wafer in the printed circuit board, a first plastic sealing layer exists in the inner space between the radiation shield and the wafer, and a second plastic sealing layer exists in the outer space of the radiation shield. In the present application, the wafer in the printed circuit board is covered by the radiation shield, and the space radiation is blocked by the radiation shield, which is conducive to reducing the impact of space radiation on the packaging module. BRIEF DESCRIPTION OF THE DRAWINGS

[0025] Figure 1 It is a schematic diagram of the structure of a packaging module for packaging wafers in outer space provided in an embodiment of the present application.

[0026] Figure 2It is a structural schematic diagram of a printed circuit board provided in an embodiment of the present application.

[0027] Figure 3 It is a flow chart of a packaging method provided in an embodiment of the present application. DETAILED DESCRIPTION

[0028] The following will be combined with the drawings in the embodiments of the present application to clearly and completely describe the technical solutions in the embodiments of the present application. Obviously, the described embodiments are only part of the embodiments of the present application, not all of the embodiments. Based on the embodiments in the present application, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of this application.

[0029] In addition, the terms "first" and "second" are used for descriptive purposes only and should not be understood as indicating or implying relative importance or implicitly indicating the number of the indicated technical features. Therefore, the features defined as "first" and "second" may explicitly or implicitly include one or more of the features. In the description of the present invention, the meaning of "plurality" is two or more, unless otherwise clearly and specifically defined.

[0030] See also Figure 1 and Figure 2 , Figure 1 is a schematic diagram of the structure of a packaging module for packaging wafers in outer space provided in an embodiment of the present application, Figure 2 Schematic diagram of the structure of the printed circuit board provided in the embodiment of the present application. Figure 1 As shown, the packaging module 1 for packaging wafers in outer space includes: a printed circuit board 10 and a radiation shield 20. Figure 2 As shown, wafers 11 , 12 , and 13 are disposed on one side of the printed circuit board 10 , and solder balls 14 are disposed on the other side of the printed circuit board 10 .

[0031] Understandably, Figure 1 and Figure 2 The number and position of the wafers are for illustration only and should not be construed as limiting the present application.

[0032] In some embodiments, the radiation shielding cover 20 is used to cover the wafer in the printed circuit board (PCB) 10 , a first plastic sealing layer is present in the inner space between the radiation shielding cover 20 and the wafer, and a second plastic sealing layer is present in the outer space of the radiation shielding cover 20 .

[0033] If there is only the second plastic sealing layer, the radiation shield 20 is easily displaced when the outer space of the radiation shield 20 is plastic sealed, resulting in packaging failure. However, if the first plastic sealing layer is formed first, the radiation shield 20 can be fixed, and the plastic sealing material can be selected from silicone resin which also has radiation protection effect, thereby further improving the radiation protection effect.

[0034] In some embodiments, after the second plastic packaging layer is formed, a radiation shield 20 may be disposed outside the second plastic packaging layer.

[0035] In some embodiments, the radiation shield 20 is used to cover all wafers in the printed circuit board (PCB) 10 .

[0036] In some embodiments, a ground connection point is reserved on the radiation shield 20 so as to be connected to a ground layer on the PCB to achieve electromagnetic shielding.

[0037] In some embodiments, radiation shield 20 is constructed of a metallic material.

[0038] In some embodiments, the material of the radiation shield is lead alloy.

[0039] In some embodiments, the material of the radiation shield is lead aluminum alloy.

[0040] In some embodiments, the material of the radiation shield is lead titanium alloy.

[0041] Among them, lead is a metal with a low melting point, high density and softness, while titanium is known for its high strength, low density and good corrosion resistance. Lead has a good radiation shielding effect, while titanium is widely used in the aerospace field and has the characteristics of light weight and high strength. The use of lead-titanium alloy can have both good strength and suitable weight while ensuring the radiation shielding effect.

[0042] In some embodiments, in order to ensure the radiation shielding effect, the mass percentage of titanium in the lead-titanium alloy is 5% to 10%, and the rest is lead.

[0043] Preferably, the mass percentage of titanium in the lead-titanium alloy is 7%-8%, and the rest is lead.

[0044] Specifically, the melting point of lead is about 327°C, while the melting point of titanium is as high as 1668°C. The huge melting points make it difficult to prepare lead-titanium alloys. However, the inventors found in actual practice that lead-titanium alloys with a titanium mass percentage of 7%-8% have better compatibility and are easier to produce in the actual processing and manufacturing process.

[0045] In some embodiments, the first plastic sealing layer and the second plastic sealing layer are sealed with epoxy resin or silicone resin.

[0046] Because when the package module is used in the outer space environment, it is necessary to consider the performance of the plastic packaging material under the extreme conditions of outer space. Among the four commonly used plastic packaging materials: epoxy resin, silicone resin, polyurethane, and UV curing resin, silicone resin is preferably used for plastic packaging. Silicone resin has the following advantages:

[0047] Wide temperature range: Silicone can withstand extreme changes from very low temperatures to very high temperatures, and can better adapt to the extreme temperature difference environment of outer space.

[0048] Radiation resistance: Silicone resin generally has better radiation resistance than other plastic packaging materials, and can better protect the wafers on the PCB board from cosmic rays and high-energy particles.

[0049] Weather resistance: Silicone has excellent resistance to UV rays and chemical corrosion and can withstand long-term exposure to space environments.

[0050] In some embodiments, the thickness of the radiation shield is in the range of [0.01 mm, 0.09 mm].

[0051] In some embodiments, the thickness of the package module is in the range of [1.8 mm, 2.2 mm]

[0052] Exemplarily, the thickness of the radiation shield is 0.01 mm or 0.02 mm or 0.03 mm or 0.04 mm or 0.05 mm or 0.06 mm or 0.07 mm or 0.08 mm or 0.09 mm.

[0053] In some embodiments, the radiation shield 20 is used to cover a central processing unit, at least one double data rate synchronous dynamic random access memory, and at least one flash memory in the printed circuit board 10 .

[0054] Optionally, the printed circuit board 10 is provided with a central processing unit, two double data rate synchronous dynamic random access memories (DDR SRAMs) and at least one flash memory.

[0055] In some embodiments, the packaging module further includes a communication antenna extending from the first plastic packaging layer to the outside of the second plastic packaging layer to realize the communication function between different packaging modules. In this case, a through hole is reserved on the radiation shield for the communication antenna to pass through.

[0056] Optionally, the through hole is spiral-shaped.

[0057] Please refer to Figure 3 , Figure 31 is a flow chart of a packaging method provided in an embodiment of the present application. The method is used to manufacture the packaging module of the packaging wafer for outer space, and the method 100 includes: steps 110 to 140.

[0058] Step 110: Cover the printed circuit board wafer with a radiation shield.

[0059] In some embodiments, the shape of the radiation shield is approximately a cuboid or a hemisphere, etc., which is not limited in the present application.

[0060] Step 120: Use a multi-hole mold to plastic-seal the inner space between the radiation shield and the wafer through a plurality of injection holes reserved on the radiation shield to discharge the gas in the inner space to form a first plastic-sealing layer.

[0061] Specifically, the split-hole mold, also known as the breathable mold or exhaust mold, is a commonly used mold design in the plastic packaging process, especially when packaging electronic components (such as integrated circuits, sensors, etc.). The purpose of designing this type of mold is to effectively exhaust the air and other volatile substances in the mold cavity during the injection molding process, prevent the formation of bubbles or voids inside the packaging material, and thus ensure the quality and reliability of the packaged product.

[0062] In some embodiments, after the first plastic encapsulation layer is formed, the radiation shield is stabilized, and there is no need to additionally fix the radiation shield when the second plastic encapsulation layer is subsequently formed.

[0063] Step 130: Seal the multiple injection holes reserved on the radiation shield.

[0064] In some embodiments, the reserved injection hole is sealed after filling the molding material, and the following methods can be used:

[0065] Use sealant: Use fast-curing sealant or epoxy resin, drip or apply it to the injection hole manually or with automated equipment. The selected sealant should be compatible with the plastic material, not produce chemical reactions, and provide good sealing performance and environmental resistance. After curing, the excess colloid can be scraped or polished to keep the surface flat.

[0066] Hot melt sealing: For thermoplastic molding materials, you can use a hot air gun or infrared heater to locally heat the material around the injection hole to soften it and then apply pressure to close the hole using the material's own viscosity. This method is suitable for molding materials that can reflow by heating.

[0067] Plugs: For larger injection holes, small plugs of matching size can be pre-made (commonly used materials include epoxy ferrules, plastics or metals) and quickly inserted into the hole before the molding compound cures. The material will then cure and fix it in place to form a seal.

[0068] Welding seal: If the edge of the injection hole is made of metal and the plastic sealing material allows high temperature processing, welding can be used to seal the hole. Use low melting point solder or laser welding technology to form a sealing ring around the hole.

[0069] Automatic sealant: On some high-end production lines, special automatic sealing equipment is used, which can apply the sealant and cure it at the injection point immediately after filling the plastic sealing material, so as to achieve efficient and consistent sealing effect.

[0070] In some embodiments, the radiation shield is made of metal material, so step 130 includes the following steps: welding and sealing a plurality of injection holes reserved on the radiation shield, thereby forming sealing rings around the injection holes.

[0071] In some embodiments, if bubbles exist in the space inside the radiation shield after plastic sealing, subsequent use may cause expansion, deformation, or even explosion, which may damage the equipment. Therefore, the exhaust condition needs to be detected after plastic sealing. At this time, step 130 includes the following steps.

[0072] (1) The ultrasonic probe is brought into contact with or close to one of the plurality of injection holes.

[0073] (2) Performing ultrasonic detection on the first plastic sealing layer by using the ultrasonic probe to determine whether bubbles or voids remain in the first plastic sealing layer.

[0074] (3) When the test result shows that no bubbles or voids remain, the multiple injection holes reserved on the radiation shield are sealed.

[0075] In some embodiments, since the radiation shield has a radiation protection function, the X-ray detection effect is poor, so the present application adopts ultrasonic detection to improve the detection accuracy.

[0076] In some embodiments, because the detection range of an injection hole is limited, each injection hole is used for ultrasonic detection. At this time, the step of bringing the ultrasonic probe into contact with or close to one of the multiple injection holes includes: bringing the ultrasonic probe into contact with or close to the multiple injection holes in turn, so as to detect the next injection hole after detecting the current injection hole.

[0077] In some embodiments, the radiation shield is made of metal material, which will affect the penetration of ultrasound and signal interpretation. In this application, the injection hole reserved on the preset shield is used as a window for ultrasonic detection. The design is ingenious, cost-saving and can ensure the safety of the product after leaving the factory.

[0078] In some embodiments, it is necessary to adjust the parameters of the ultrasonic detector such as frequency, power and pulse width according to the thickness of the radiation shield, the density and thickness of the first plastic sealing layer. Due to the existence of the first plastic sealing layer, it is best to use low-frequency ultrasound to better penetrate the plastic sealing layer.

[0079] In some embodiments, if the ultrasonic probe does not touch the injection hole but is close to the injection hole for detection, a coupling agent (such as water or a special gel) may be used to improve the propagation of ultrasonic waves.

[0080] Specifically, the propagation efficiency of ultrasound in the air is much lower than that in solids or liquids. The air gap will absorb and scatter a large amount of ultrasonic energy, resulting in severe signal attenuation. The coupling agent fills the tiny gap between the ultrasonic probe and the injection hole, eliminating the air layer, reducing energy loss and improving detection accuracy.

[0081] In the above ultrasonic detection method, bubbles or other internal defects will cause abnormal ultrasonic reflection. Since the acoustic impedance difference between bubbles and plastic packaging materials is large, a strong reflection signal will be generated, thus realizing the detection of bubbles.

[0082] In some embodiments, when considering the penetration ability of ultrasound, the acoustic impedance of the material (the product of sound velocity and density) is a key factor. In theory, the acoustic impedance is proportional to the ultrasonic propagation speed and density of the medium. The closer the acoustic impedance is to that of human tissue (approximately 1.5 MRayls), the smaller the reflection of ultrasound and the better the penetration. From the perspective of acoustic performance, among plastic encapsulation materials, the acoustic impedance of silicone resin is closer to the acoustic impedance of human tissue, and therefore it usually has better acoustic transparency. Therefore, the first plastic encapsulation layer can be encapsulated with silicone resin.

[0083] Step 140: Plastic-sealing the outer space of the radiation protection cover to form a second plastic-sealing layer.

[0084] Through the above method, the packaging module of the packaging wafer used in outer space can be packaged, and the packaged module obtained by packaging has good radiation protection effect and can reduce space radiation by at least 50%.

[0085] In summary, the present application provides a packaging module for packaging wafers in outer space and a packaging method thereof, the packaging module comprising: a printed circuit board and a radiation shield; wherein the radiation shield is used to cover the wafer in the printed circuit board, a first plastic sealing layer exists in the inner space between the radiation shield and the wafer, and a second plastic sealing layer exists in the outer space of the radiation shield. In the present application, the wafer in the printed circuit board is covered by the radiation shield, and the space radiation is blocked by the radiation shield, which is conducive to reducing the impact of space radiation on the packaging module.

[0086] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present application, rather than to limit it. Although the present application has been described in detail with reference to the aforementioned embodiments, those skilled in the art should understand that they can still modify the technical solutions described in the aforementioned embodiments, or make equivalent replacements for some of the technical features therein. However, these modifications or replacements do not cause the essence of the corresponding technical solutions to deviate from the spirit and scope of the technical solutions of the embodiments of the present application.

Claims

1. A packaging method, characterized in that: The packaging method is used to manufacture a packaging module for packaging wafers in outer space, wherein the packaging module comprises a printed circuit board and a radiation shield; wherein the radiation shield is used to cover the wafer in the printed circuit board, a first plastic sealing layer is present in the inner space between the radiation shield and the wafer, and a second plastic sealing layer is present in the outer space of the radiation shield; the packaging method comprises: Covering the wafer of the printed circuit board with a radiation shield; Using a divided hole mold to plastic-seal the inner space between the radiation shield and the wafer through a plurality of injection holes reserved on the radiation shield to discharge the gas in the inner space to form a first plastic-sealing layer; Sealing a plurality of injection holes reserved on the radiation shield; Plastic-sealing the outer space of the radiation protection cover to form a second plastic-sealing layer; The step of sealing a plurality of injection holes reserved on the radiation shield comprises: placing an ultrasonic probe in contact with or close to one of the injection holes; Performing ultrasonic testing on the first plastic sealing layer by using the ultrasonic probe to determine whether bubbles or voids remain in the first plastic sealing layer; When the detection result shows that no bubbles or voids remain, the multiple injection holes reserved on the radiation shield are sealed.

2. The packaging method according to claim 1, characterized in that: The material of the radiation shield is lead alloy.

3. The packaging method according to claim 2, characterized in that: The material of the radiation shield is lead-aluminum alloy.

4. The packaging method according to claim 2, characterized in that: The material of the radiation protection shield is lead-titanium alloy.

5. The packaging method according to claim 1, characterized in that: The first plastic sealing layer and the second plastic sealing layer are sealed with epoxy resin or silicone resin.

6. The packaging method according to claim 1, characterized in that: The thickness of the radiation shield is in the range of [0.01 mm, 0.09 mm].

7. The packaging method according to claim 1, characterized in that: The radiation shield is used for shielding a central processing unit, at least one double rate synchronous dynamic random access memory and at least one flash memory in the printed circuit board.

8. The packaging method according to claim 1, characterized in that: The step of sealing a plurality of injection holes reserved on the radiation shield comprises: The multiple injection holes reserved on the radiation shield are welded and sealed.

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