Shielding particles coated with an electrically insulating material

Abstract

Methods include coating shielding particles (114) with an electrically insulating coating, dispersing the coated shielding particles in a matrix material (116) to form a mold structure, and positioning the mold structure proximate a die (102) of an integrated circuit package to shield the die from radiation. Apparatus includes a die and a mold structure (112) proximate the die, the mold structure including a matrix material and shielding particles (114) including an electrically insulating coating, wherein the shielding particles are dispersed in the matrix material (116).

Description

[0001] Priority Statement

[0002] This application claims priority to U.S. Provisional Patent Application No. 63 / 563,243, filed March 8, 2024, the contents of which are incorporated herein by reference in their entirety. Technical Field

[0003] This disclosure relates to a die package for radiation shielding, and in particular to a die package comprising a shielding compound having shielding particles coated with an electrically insulating coating and dispersed in a matrix material. Background Technology

[0004] The demand for radiation-resistant (RT) semiconductors is growing for applications such as avionics and low Earth orbit (LEO) satellites. Typically, these types of products are manufactured using specific, expensive processes or housed in costly ceramic packages.

[0005] There is a need for RT semiconductors that can reduce costs. Summary of the Invention

[0006] Most semiconductors are coated with compounds containing epoxy matrix materials and more than 80% silicon dioxide (SiO2) filler particles to achieve structural stability. One approach is to replace these SiO2 filler particles at least partially with radiation-blocking materials coated with SiO2 (such as tin-silver alloys) to achieve a certain level of radiation blocking without using ceramic packages or changing the manufacturing process.

[0007] Various methods are provided, including: coating shielding particles with an electrically insulating coating; dispersing the coated shielding particles in a substrate material to form a mold structure; and positioning the mold structure close to the die of an integrated circuit package to shield the die from radiation.

[0008] A method is provided according to one aspect described in the preceding paragraph, wherein the shielding particles comprise at least one of the following: boron nitride (BN), bismuth (Bi), bismuth oxide (Bi2O3), tantalum nitride (TaN), tungsten nitride (W3N2), tin oxide (SnO2), copper (I) oxide (Cu2O), or copper (II) oxide (CuO).

[0009] According to one aspect described in the preceding two paragraphs, a method is provided in which the shielding particles comprise a material from at least one of the cobalt oxide, nickel oxide, neodymium oxide, and iron oxide groups.

[0010] A method is provided according to one aspect described in the preceding three paragraphs, wherein the electrically insulating coating comprises silicon dioxide (SiO2).

[0011] A method is provided according to one aspect described in the preceding four paragraphs, wherein the matrix material includes polymers, silicone resins, polyurethanes, chloroprene, butyl rubber, polybutadiene, chloroprene rubber, natural rubber, isoprene, resins, or epoxy resins.

[0012] According to one aspect described in the preceding five paragraphs, a method is provided comprising dispersing a plurality of silica (SiO2) filler particles in a matrix material to form a mold structure.

[0013] A method is provided according to one aspect described in the preceding six paragraphs, wherein the dispersed particles comprise 50% to 95% shielding particles and 50% to 5% silica filler particles.

[0014] According to one aspect, an apparatus is provided comprising: a die; and a mold structure adjacent to the die, the mold structure comprising: a matrix material; and shielding particles including an electrically insulating coating, wherein the shielding is dispersed in the matrix material.

[0015] A method is provided according to one aspect described in the preceding paragraph, wherein the shielding particles comprise at least one of the following: boron nitride (BN), bismuth (Bi), bismuth oxide (Bi2O3), tantalum nitride (TaN), tungsten nitride (W3N2), tin oxide (SnO2), copper (I) oxide (Cu2O), or copper (II) oxide (CuO).

[0016] According to one aspect described in the preceding two paragraphs, a method is provided in which the shielding particles comprise a material from at least one of the cobalt oxide, nickel oxide, neodymium oxide, and iron oxide groups.

[0017] A method is provided according to one aspect described in the preceding three paragraphs, wherein the electrically insulating coating comprises silicon dioxide (SiO2).

[0018] A method is provided according to one aspect described in the preceding four paragraphs, wherein the matrix material comprises a material selected from the group consisting of polymers, silicone resins, polyurethanes, chloroprene, butyl rubber, polybutadiene, chloroprene rubber, natural rubber, isoprene, resins, and epoxy resins.

[0019] According to one aspect described in the preceding five paragraphs, a method is provided in which the mold structure includes silica (SiO2) filler particles.

[0020] According to one aspect described in the preceding six paragraphs, a method is provided in which the particles in the mold structure comprise 50% to 95% shielding particles and 50% to 5% silica (SiO2) filler particles.

[0021] According to one aspect described in the preceding seven paragraphs, a method is provided in which a mold structure includes a first shielding layer and a second shielding layer, wherein the first shielding layer and the second shielding layer include shielding particles of different concentrations. Attached Figure Description

[0022] The accompanying drawings illustrate an example of a semiconductor that is encapsulated in epoxy resin and a radiation-blocking material coated with SiO2 (such as an Ag-Sn alloy) to achieve a certain level of radiation blocking without using ceramic packages or changing the manufacturing process.

[0023] Figure 1 This is a cross-sectional side view of an example integrated circuit package, showing a die mounted on a die carrier and a mold structure (e.g., a mold encapsulation) that at least partially encapsulates the mounted die.

[0024] Figure 2 A cross-sectional side view of an example integrated circuit package is shown, which has a die on a die carrier and an encapsulation for encapsulating the die, as well as a mold structure that covers the encapsulation to shield the die from radiation.

[0025] Figure 3 A cross-sectional side view of an example integrated circuit package is shown, which has a die on a die carrier and a mold structure for encapsulating the die, wherein the mold structure includes layers.

[0026] Figure 4 These are SEM images of shielding compounds containing shielding particles coated with an electrical insulator (such as SiO2), where the shielding particles are spherical and colloidal particles of various sizes.

[0027] Figure 5 This shows the phase diagram of alloys such as Ag-Sn.

[0028] Figure 6 This is a cross-sectional side view of an integrated circuit package, which includes a die mounted on a die carrier and a mold structure that at least partially encapsulates the mounted die, wherein the mold structure has a shielding compound having shielding particles coated with an electrical insulator and filler particles dispersed in a matrix material.

[0029] Figure 7 This is a flowchart of a method for manufacturing a die package with a shielded mold structure.

[0030] Reference numerals for any illustrated element appearing in multiple different figures have the same meaning in all figures, and any reference or discussion of any illustrated element in the context of any particular figure also applies to every other figure (if any) in which the same illustrated element is shown. Detailed Implementation

[0031] According to one aspect, a shielding compound is provided for encapsulating a die in a package. The shielding compound comprises shielding particles coated to render them non-conductive. The coated shielding particles are dispersed in a matrix material, such as a polymer, like epoxy resin.

[0032] Figure 1 This is a cross-sectional side view of an example integrated circuit package 100, showing a die 102 mounted on a die carrier 104 and a mold structure 106 (e.g., a mold encapsulator) that at least partially encapsulates the mounted die 102. The mold structure 106 may be close to the die 102.

[0033] Die 102 may include any type of die, chip (e.g., a silicon substrate on which integrated circuits are formed) or other integrated circuit device (e.g., including analog devices, digital devices, or a mixture of analog and digital devices) that generates or outputs heat. For example, die 102 may include a microprocessor (e.g., a central processing unit (CPU) chip), a microcontroller (MCU), an application-specific integrated circuit (ASIC), a graphics processing unit (GPU), a digital signal processor (DSP), an A / D converter or a D / A converter, or a memory (e.g., flash memory, random access memory (RAM), read-only memory (ROM) (e.g., electrically erasable programmable read-only memory (EEPROM) or other memory), or a system-on-a-chip (SoC) device.

[0034] The die carrier 104 may include any structure on which the die 102 can be mounted, such as a printed circuit board (PCB), lead frame, through-hole, heat sink, or another die. The die 102 may be mounted on the die carrier 104 in any suitable manner, such as solder mounting, adhesive bonding (e.g., using epoxy resin), flip chip bonding, or eutectic bonding.

[0035] like Figure 1As shown, in some examples, the mold structure 106 may include a shielding compound 112 comprising shielding particles 114 dispersed in or otherwise incorporated in a matrix material 116, which may be, for example, a polymer, such as epoxy resin or a polymeric resin. In some examples, the shielding compound 112 comprises a mixture of shielding particles 114, filler particles comprising silica (SiO2) particles, and a matrix material 116 comprising epoxy resin. The mold structure 106 may be accessible to the die 102 to shield the die from radiation.

[0036] As used herein, "compound" can refer to a single element or substance, a mixture of elements or substances, or other combinations thereof. As used herein, the term particle refers to particles with a maximum size between 1 nanometer and 1000 micrometers, and can be spherical or colloidal in shape without limitation. The maximum size of particles can be between 1 and 300 micrometers or between 50 and 80 micrometers. Shielding particles and filler particles are described below.

[0037] In some examples, the shielding particles 114 include, but are not limited to, at least one of gold-tin, silver-tin, tungsten, antimony, bismuth, and any heavy metal. Heavy metals include those with high density (e.g., 5 g / cm³). 3 Metals with high atomic weights (e.g., greater than 63.5 gmol⁻¹) or atomic numbers greater than 20, such as, but not limited to, boron nitride (BN), bismuth (Bi), bismuth oxide (Bi₂O₃), tantalum nitride (TaN), tungsten nitride (W₃N₂), tin oxide (SnO₂), copper oxide (I)(Cu₂O) (i.e., cuprous oxide) or copper oxide (II)(CuO) (i.e., copper oxide), antimony (Sb), tin (Sn), and tungsten (W) particles, wherein the heavy metal particles may be coated or encapsulated with a non-conductive material, such as silicon dioxide (SiO₂). Shielding particles 114 are coated or encapsulated with a non-conductive material, such as silicon dioxide (SiO₂) (also known as silica). Shielding particles 114 may be coated with a non-conductive material to reduce the possibility of conductive paths that could short-circuit the pins of an integrated circuit package together.

[0038] In some examples, the shielding particles 114 are dispersed in or otherwise bonded to the matrix material 116. The matrix material 116 may include, for example, elastomers (e.g., silicone, polyurethane, chloroprene, butyl rubber, polybutadiene, chloroprene, natural rubber, or isoprene), thermosetting materials (e.g., thermosetting resins), or other molding compounds that may be supplied in particulate, liquid, or powder form. In some examples, the shielding particles 114 may shield the die 102 from ionizing radiation, magnetic fields, or a combination of ionizing radiation and magnetic fields. Shielding particles 114 shielding against magnetic fields may include materials from the cobalt group, nickel group, neodymium group, and iron group oxides. Shielding particles 114 may include materials from at least one of the cobalt group, nickel group, neodymium group, and iron group oxides. Shielding particles 114 shielding against ionizing radiation may include, for example, highly permeable alloys or hematite (Fe2O3) particles. Therefore, the shielding particles 114 do not need to be uniform and can include a variety of different types of shielding particles.

[0039] The shielding particles 114 can be coated or encapsulated with non-conductive materials, such as silicon dioxide (SiO2), through a sol-gel process or a spin-coating glass process.

[0040] The coated or encapsulated shielding particles 114 may be dispersed in or otherwise combined with the matrix material 116 to produce a shielding compound 112. In some examples, a surfactant 113 may be (optionally) added to enhance or accelerate the dispersion of the shielding particles 114 in the matrix material 116. The shielding particles 114 (with or without surfactant 113) may be mixed or combined with the matrix material 116 in any suitable manner (e.g., using a stirring or ultrasonic vibration process).

[0041] Figure 2 A cross-sectional side view of an encapsulation 200 having a die 202 on a die carrier 204 is shown. The encapsulation 208 encapsulates the die 202 and includes a material that may not shield the die 202 from radiation. A mold structure 206 including a shielding compound 212 covers the encapsulation 208 to shield the die 202 from radiation. The illustrated example shows a shielding compound 212 formed above the encapsulation 208. The shielding compound 212 is similar in all respects to the shielding compound 112 described above. The mold structure 206 can be close to the die 202 to shield the die 202 from radiation.

[0042] Figure 3A cross-sectional side view of a package 300 is shown, the package having a die 302 on a die carrier 304 having a mold structure 306 including three shielding layers 330. Other examples not shown include a single shielding layer, two shielding layers, or three or more shielding layers. Each shielding layer may include shielding particles dispersed in or otherwise combined with a matrix material. For example, each shielding layer may include shielding particles to shield the die 302 from ionizing radiation, magnetic fields, or a combination of ionizing radiation and magnetic fields, for example, as referenced above. Figure 1 Regarding the discussion of shielding compound 112, mold structure 306 can be accessed to the die 302 to shield the die 302.

[0043] In an example with multiple shielding layers, the different shielding layers 330 may include different types or concentrations of shielding particles. For example, see reference... Figure 3 As illustrated, shielding layer 332 may include magnetically shielding particles (e.g., for shielding die 302 from magnetic fields), and shielding layer 334 may include shielding particles (e.g., for shielding die 302 from ionizing radiation). As another example, shielding layers 332, 334, and 336 may include the same type of particles (e.g., magnetically shielding particles or shielding particles), but with correspondingly different particle concentrations, thereby defining a shielding gradient along directions toward or away from die 302. For example, shielding layers 332, 334, and 336 may provide a greater degree of shielding in the direction toward die 302 (e.g., where shielding layer 332, which may be referred to as inner shielding layer 332, can provide a greater degree of shielding than shielding layer 336, which may be referred to as outer shielding layer 336). Although Figure 3 The diagram shows three shielding layers 330, but is not limited to these. Any number of shielding layers can be used, and each layer can have any ratio of shielding particles to filler particles without limitation. The shielding particles of each shielding layer in shielding layer 330 can be coated or encapsulated with a non-conductive material, such as silicon dioxide (SiO2).

[0044] Figure 4 This is a scanning electron microscope (SEM) image of a shielding compound 412 having shielding particles 414 dispersed in a matrix material 416. The shielding particles 414 are shown in cross-section to show that they are coated with an electrical insulator 415 (such as silicon dioxide (SiO2)), wherein the shielding particles 414 are spherical and colloidal particles of various sizes. Filler particles 418 may also be dispersed in the shielding compound 412. The filler particles 418 may thicken or otherwise enhance the structural integrity of the matrix material 416.

[0045] Figure 5This is a phase diagram illustrating alloys such as Ag-Sn that allow for the introduction of radiation-blocking capabilities while withstanding the processing temperatures and workload distributions of the final device. Sn has more effective radiation-blocking properties than Ag. However, Sn has a relatively low melting point and may not be able to withstand the processing temperatures on its own. By increasing the percentage of Ag in the Ag-Sn alloy, the melting point also increases. In some respects, a higher percentage of Sn compared to Ag can be used, so the alloy will effectively block radiation without melting during package processing.

[0046] Figure 6 This is a cross-sectional side view of an example integrated circuit package 600, showing a die 602 mounted on a die carrier 604 and a mold structure 606 (e.g., a mold encapsulator) that at least partially encapsulates the mounted die 602. Figure 6 As shown, mold structure 606 includes a shielding compound 612 comprising shielding particles 614 dispersed in a matrix material 616 (e.g., a polymer such as epoxy resin). The shielding compound 612 also includes filler particles 618 (e.g., in the form of fumed silica (SiO2) or colloidal silica (SiO2)) to thicken or otherwise enhance the structural integrity of the matrix material 616 (e.g., epoxy resin). Therefore, the shielding compound 612 may comprise shielding particles 614 and filler particles 618 dispersed in or otherwise combined with the matrix material 616. In one example, in the shielding compound 612, the particles may comprise 90% to 95% shielding particles 614 and 10% to 5% filler particles. In another example, in the shielding compound 612, the particles may comprise 50% to 95% shielding particles 614 and 50% to 5% filler particles 618.

[0047] Figure 7 A flowchart of the method is shown. Shielding particles 702 are coated with an electrically insulating coating. The coated shielding particles 704 are dispersed 704 in a substrate material to form a mold structure. The mold structure 706 is positioned close to the die of the integrated circuit package to shield the die from ionizing radiation.

[0048] Although examples have been described above, other variations and examples may be made in accordance with this disclosure without departing from the substance and scope of these disclosed examples.

Claims

1. A method, the method comprising: The shielding particles are coated with an electrically insulating coating. The coated shielding particles are dispersed in the matrix material to form a mold structure; as well as The mold structure is positioned close to the die of the integrated circuit package to shield the die.

2. The method according to claim 1, wherein the shielding particles comprise at least one of the following: boron nitride (BN), bismuth (Bi), bismuth oxide (Bi2O3), tantalum nitride (TaN), tungsten nitride (W3N2), tin oxide (SnO2), copper (I) oxide (Cu2O) or copper (II) oxide (CuO).

3. The method of claim 1, wherein the shielding particles comprise materials from at least one of the cobalt group, nickel group, neodymium group, and iron group.

4. The method according to claim 1, wherein the electrically insulating coating comprises silicon dioxide (SiO2).

5. The method according to claim 1, wherein the matrix material comprises a polymer, silicone resin, polyurethane, chloroprene, butyl rubber, polybutadiene, chloroprene rubber, natural rubber, isoprene, resin or epoxy resin.

6. The method according to claim 1, comprising dispersing a plurality of silica (SiO2) filler particles in the matrix material to form the mold structure.

7. The method of claim 6, wherein the dispersed particles comprise 50% to 95% shielding particles and 50% to 5% silica filler particles.

8. An apparatus, said apparatus comprising: Core; and A mold structure adjacent to the die, the mold structure comprising: Matrix material; and The shielding particles include an electrically insulating coating, wherein the shielding particles are dispersed in the matrix material.

9. The device according to claim 8, wherein the shielding particles comprise at least one of the following: boron nitride (BN), bismuth (Bi), bismuth oxide (Bi2O3), tantalum nitride (TaN), tungsten nitride (W3N2), tin oxide (SnO2), copper (I) oxide (Cu2O) or copper (II) oxide (CuO).

10. The device of claim 8, wherein the shielding particles comprise a material from at least one of the cobalt group, nickel group, neodymium group, and iron group.

11. The device of claim 8, wherein the electrically insulating coating comprises silicon dioxide (SiO2).

12. The device according to claim 8, wherein the matrix material comprises a material selected from the group consisting of polymers, silicone resins, polyurethanes, chloroprene, butyl rubber, polybutadiene, chloroprene rubber, natural rubber, isoprene, resins, and epoxy resins.

13. The device according to claim 8, wherein the mold structure comprises silica (SiO2) filler particles.

14. The device according to claim 13, wherein the particles in the mold structure comprise 50% to 95% shielding particles and 50% to 5% silica (SiO2) filler particles.

15. The device according to claim 8, wherein the mold structure includes a first shielding layer and a second shielding layer, wherein the first shielding layer and the second shielding layer include shielding particles of different concentrations.

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