Package
By using the firing surface of the ceramic package as the mounting surface and combining the specific ceramic composition and process, the warping and dusting problems of the ceramic package are solved, and the airtightness of the package and the performance of electronic components are improved. It reduces pixel defects in large solid-state camera components.
Patent Information
- Application Number
- CN201980097998.2
- Authority / Receiving Office
- CN · China
- Patent Type
- Patents(China)
- Current Assignee / Owner
- Filing Date
- 2019-10-11
- Publication Date
- 2024-12-24
- Estimated Expiration
- 2039-10-11
AI Technical Summary
When installing large solid-state camera components, warping problems caused by the difference in firing and shrinkage of the ceramic package lead to low flatness and parallelism of the mounting surface, which in turn affects airtightness, and dust is easily generated on the grinding mounting surface , affects the performance of electronic components.
The firing surface of the ceramic package is used as the mounting surface, and combined with specific ceramic composition and process treatment, the mounting surface has an average particle size of more than 1 μm and less than 3 μm and a low porosity, and avoids dust problems after grinding.
It effectively prevents poor movement of electronic components caused by foreign matter in the chamber, improves the airtightness of the package and the performance of electronic components, especially in large solid-state imaging components, which significantly reduces pixel defects.
Smart Images
Figure CN114072912B_ABST
Abstract
Description
Technical Field
[0001] The present invention relates to a package, and in particular to a package for electronic components. Background Art
[0002] Japanese Patent Publication No. 2006-344838 (Patent Document 1) discloses a solid-state imaging device. The solid-state imaging device has an imaging element mounted in a concave ceramic package. As the size of the package, a size of 10 mm square is exemplified. The imaging element is, for example, a charge coupled device (CCD) type or a complementary metal oxide semiconductor (CMOS) type. Since the size of the package is 10 mm square, the imaging element mounted therein is much smaller than 10 mm even on the long side. The opening of the package is sealed by a light-transmitting window member. The window member mounting surface of the package is polished and flattened in order to improve the tightness of the window member and the resulting airtightness, and to serve as a reference surface when mounting the imaging element.
[0003] Prior art literature
[0004] Patent Literature
[0005] Patent Document 1: Japanese Patent Application Publication No. 2006-344838 Summary of the invention
[0006] Problems to be solved by the invention
[0007] As electronic components mounted on the package, there are also electronic components of a size that includes a rectangle with a long side of more than 10 mm. For example, compared with solid-state imaging elements for small cameras, solid-state imaging elements for high-performance large cameras need to have a larger imaging unit, specifically, most of them are semiconductor chips of about 10 to 50 mm square. Correspondingly, the package for mounting the solid-state imaging element requires a large mounting surface. As a result, the influence of warping caused by the difference in firing shrinkage of the ceramic package becomes larger than the size, so the flatness and mutual parallelism of the frame (sealing surface), the back side (mounting surface facing the substrate), and the bottom of the chamber (imaging element mounting surface) are easily disturbed. In particular, when the flatness of the mounting surface is low, the airtightness between the mounting surface of the package and the cover body becomes low. Moreover, in the case where the electronic component is a solid-state imaging element, since the optical axis must be considered, there is also a concern about the parallelism of the solid-state imaging element and the cover body. Therefore, in the past, the flatness of the mounting surface was improved to, for example, about 30 to 50 μm by grinding.
[0008] However, according to the research of the inventors of the present invention, dust is easily generated from the polished mounting surface into the cavity of the package. This dust sometimes has an adverse effect on the operation of the electronic component. In particular, when the electronic component is a solid-state imaging element, dust sometimes causes pixel defects. In the case of large solid-state imaging elements that require high performance, this problem is particularly serious. The present invention is completed to solve such a problem, and its purpose is to provide a package that can prevent the malfunction of the electronic component caused by dust.
[0009] Means for solving problems
[0010] A package in one embodiment of the present invention has: a mounting surface for mounting electronic components; a cavity located on the mounting surface; and a mounting surface for mounting a cover for sealing the cavity. The package includes: a base, which is made of ceramic and has a cavity; and a wiring portion, which extends from the cavity of the base and penetrates the base. The base includes a bottom and a frame. The bottom has a mounting surface, which has a size that includes a rectangle with a long side of more than 10 mm. The frame is arranged on the outside of the mounting surface on the bottom in a manner surrounding the cavity, and has an as-fired surface of the ceramic as the mounting surface.
[0011] Effects of the Invention
[0012] According to a package of one embodiment of the present invention, the mounting surface for mounting the cover body is a fired surface of ceramics. Thus, dust generation from the mounting surface is suppressed compared to a case where the mounting surface is a polished surface. Therefore, malfunction of the electronic component caused by foreign matter in the chamber can be prevented.
[0013] The objects, features, aspects and advantages of the present invention will become more apparent from the following detailed description and accompanying drawings. BRIEF DESCRIPTION OF THE DRAWINGS
[0014] Figure 1 It is a cross-sectional view schematically showing the structure of an electronic device in one embodiment of the present invention.
[0015] Figure 2 It roughly indicates Figure 1 A cross-sectional view of the structure of a package body.
[0016] Figure 3 This is an electron microscope photograph of a mounting surface of a package of a comparative example.
[0017] Figure 4 This is an electron microscope photograph of the mounting surface of the package of the example.
[0018] Figure 5 This is an electron microscope image of a fracture surface of the package of the example.
[0019] Figure 6 Yes Figure 5 FIG. 5 is a diagram of an image after binarization processing is performed on an image.
[0020] Figure 7 This is a diagram for explaining an example of a cutting method which is a method of calculating an average grain size from an electron micrograph of a mounting surface of a package of an example. DETAILED DESCRIPTION
[0021] Hereinafter, embodiments of the present invention will be described based on the drawings.
[0022] Figure 1 and Figure 2 These are cross-sectional views schematically showing the structure of the electronic device 900 in this embodiment and the structure of the package 800 used for manufacturing the electronic device 900 .
[0023] Package 800( Figure 2 ) has: a mounting surface SM for mounting electronic components 902 ( Figure 1 The package body 800 has a base 810 and a wiring portion 820.
[0024] The base 810 is made of ceramic. The ceramic is substantially made of an insulator so that the base 810 can function as an insulating member. As long as this function can be ensured, the ceramic does not necessarily have to be made entirely of an insulator. For example, a small amount of non-insulating particles may be dispersed among the insulating particles that account for the majority of the volume.
[0025] The base 810 has a cavity CV. The base 810 includes a bottom portion 811 and a frame portion 812 .
[0026] The bottom 811 has a mounting surface SM. The mounting surface SM has a size that includes a rectangle with a long side of 10 mm or more. For example, the mounting surface SM is a rectangle with a long side of 10 mm or more. The mounting surface SM may also have a size that includes a square with a side of 10 mm or more. In addition, a rectangle is a type of square in terms of geometric definition.
[0027] The frame 812 is provided on the outside of the mounting surface SM on the bottom 811 so as to surround the cavity CV. The frame 812 has a ceramic fired surface as the mounting surface SF. Here, the term "as-fired" means a state in which the surface is not processed while maintaining the state after sintering. Therefore, the "fired surface" is a surface in the "as-fired" state. In other words, the "fired surface" means the outer surface of the aceramic product after sintering. Therefore, the surface to be ground is not the fired surface.
[0028] The ceramic used as the material of the base 810 preferably has an average grain size of 1 μm or more and 3 μm or less, more preferably 1.5 μm or less, on the mounting surface SF. The average grain size can be calculated using a cutting method based on an electron microscope image of the mounting surface SF. Specifically, a line segment of a known length that completely crosses 10 to 50 grains can be drawn on a microscope image or photograph, and the average grain size can be calculated by dividing the known length by the number of these grains.
[0029] The base 810 has a side surface SS extending from the outer edge of the mounting surface SF. The side surface SS may have a non-fracture surface SSa and a fracture surface SSb. In a general manufacturing method for a ceramic package product, a green laminated body provided with a plurality of products is subjected to a half-cutting (groove processing) process using a knife. After firing, each product is singulated by a fracture process utilizing the portion subjected to the above-mentioned groove processing process. In this case, the non-fracture surface SSa becomes an as-fired surface obtained by firing after the groove processing, and has substantially 0% porosity. The fracture surface SSb becomes a surface that is fractured by fracture after firing, and preferably has a porosity of 3% or less. In other words, the side surface SS has a non-fracture surface SSa that has substantially no pores and a fracture surface SSb that has pores, and the latter preferably has a porosity of 3% or less, and more preferably a porosity of 1.5% or less. The porosity can be calculated by binarizing an image of an electron microscope photograph of the surface to be evaluated. In addition, as Figure 2 As shown, the fracture surface SSb may be located on the side surface of the bottom portion 811 , or as a modified example, may be located on the side surface of the frame portion 812 , or on the side surface spanning the bottom portion 811 and the frame portion 812 .
[0030] The above-mentioned ceramic preferably contains Al2O3, SiO2 and MnO as essential components, and contains at least one of molybdenum (Mo) atoms and Cr2O3 as an optional component. The content of Al2O3 is greater than 82.0 mass% and less than 95.0 mass%. The content of SiO2 is greater than 3.0 mass% and less than 8.0 mass%. The content of MnO is greater than 2.0 mass% and less than 6.0 mass%. The total content of Mo atoms converted to MoO3 and the content of Cr2O3 is less than 4.0 mass%. At least a part of the Mo atoms can be contained as oxidized Mo. In addition, at least a part of the Mo atoms can also be contained as metallic Mo. The content of the remainder other than the above-mentioned components in the composition of the ceramic is less than 0.1 mass%, and more preferably less than 0.05 mass%.
[0031] The wiring portion 820 extends from the cavity CV and passes through the base 810. Specifically, the wiring portion 820 has: an external electrode terminal 821, which is arranged outside the cavity CV; an internal wiring 822, which passes through the base 810; and an internal electrode terminal 823, which faces the cavity CV. The internal wiring 822 can be composed of at least any one of an internal electrode layer and a through-hole wiring. The material of the wiring portion 820 is substantially composed of a conductor so that the wiring portion 820 can function as a wiring member. As long as the function can be ensured, the material does not necessarily have to be completely composed of a conductor as a whole. For example, a small amount of non-insulating area can be dispersed in the conductor area that occupies the vast majority of the volume.
[0032] Electronic component 902( Figure 1 ) is bonded to the internal electrode terminal 823 via the bonding layer 901. Thus, the electronic component 902 is mounted on the mounting surface SM via the bonding layer 901 and the internal electrode terminal 823. The electronic component 902 may have a size that includes a rectangle having a long side of more than 10 mm, for example, a size that includes a square having a side of more than 10 mm. The electronic component 902 may be a solid-state imaging element. A solid-state imaging element is, for example, a CMOS image sensor. Generally, CMOS image sensors are particularly excellent as solid-state imaging elements having a large imaging portion required for single-lens reflex cameras, some surveillance cameras, and industrial cameras. The planar shape of the solid-state imaging element may be a rectangle having a long side of more than 10 mm, or may be a roughly square having a side of more than 10 mm.
[0033] The cover 907 is mounted on the mounting surface SF of the frame 812 via the adhesive layer 906. Thus, the cavity CV of the package 800 is sealed. The adhesive layer 906 is composed of, for example, a resin adhesive. The adhesive layer 906 can be in direct contact with the mounting surface SF and the cover 907, respectively. In the case where the electronic component 902 is a solid-state imaging element, at least a portion of the cover 907 is substantially transparent to the light being imaged, and typically, the entire cover 907 is substantially transparent to the light being imaged.
[0034] In this embodiment, the wiring portion 820 passes through the bottom portion 811, but as a modification, a wiring portion passing through the bottom portion 811 and the frame portion 812 or a wiring portion passing through the frame portion 812 may be provided. In addition, as a modification, a wiring portion connected to the electronic component 902 by a bonding wire may be provided.
[0035] According to the package 800 ( Figure 2 ), for installing the cover 907 ( Figure 1 ) is a ceramic fired surface. Thus, dust generation from the mounting surface is suppressed compared to a case where the mounting surface is a polished surface. Therefore, malfunction of the electronic component 902 caused by foreign matter in the chamber CV can be prevented.
[0036] Figure 3 This is an electron microscope photograph of a polished surface of a mounting surface of a package as a comparative example. Figure 4 This is an electron microscope photograph of the fired surface of the mounting surface SF possessed by the package of the embodiment. Compared with the embodiment, in the comparative example, the surface state is more uneven, and granulation is likely to occur. In addition, in the comparative example, the internal pores are surfaced as defects (holes) by grinding, and foreign matter (ceramics or abrasive particles, etc.) generated during processing and various foreign matter in the process are likely to enter the defects. Therefore, dust may be generated due to the detachment of the foreign matter. In addition, grinding is mechanical processing, and thus, it is easy to produce ceramic particles with low sintering bonding force to the surrounding ceramic particles, and ceramic particles that are only attached to the surrounding ceramic particles. Therefore, granulation of ceramic particles may easily occur.
[0037] The ceramic of the base 810 preferably has a porosity of 3% or less, especially 1% or less, on the fracture surface SSb, and an average grain size of 1 μm or more and 3 μm or less, especially 1.5 μm or less, on the mounting surface SF. Unlike the non-fracture surface SSa and the mounting surface SF, the fracture surface SSb is not an as-fired surface, so it is usually difficult to make its porosity 0%. However, the porosity can be suppressed to less than 3%, especially less than 1%, thereby suppressing the situation where foreign matter enters the pores during the cleaning process of manufacturing. Therefore, the possibility of dust from the pores is reduced. In addition, since the average grain size on the mounting surface SF is 1 μm or more and 3 μm or less, especially 1.5 μm or less, the density can be ensured. As a result, the sintering bond is improved, thereby suppressing the granulation of ceramic particles from the mounting surface SF. Therefore, the possibility of dust caused by granulation is reduced. As a result, dust from the entire base 810 can be more reliably suppressed.
[0038] Figure 5 is an electron microscope image of the ceramic surface at the fracture surface SSb of the package of the example, Figure 6 Yes Figure 5 The image is binarized for the purpose of calculating the average particle size. Figure 5 As shown, pores are observed as areas that are significantly denser than their surroundings. Figure 6 As shown, it is easy to perform binarization processing with a concentration threshold value that basically extracts only the above-mentioned relatively high concentration area. In this example, by calculating the ratio of the area extracted in this way, the porosity is 0.98%.
[0039] Figure 7 This is a diagram illustrating an example of a method for calculating the average grain size from an electron microscope photograph of the mounting surface SF of the package of the embodiment, i.e., a cutting method. In this example, the length of the line segment is divided by the number of grains that each line segment crosses. Then, the value thus obtained is averaged with respect to the three line segments. Thus, an average grain size of 1.22 μm is obtained.
[0040] The electronic component 902 may be a solid-state imaging element having a size that includes a rectangle having a long side of 10 mm or more. This can ensure a sufficient size of the imaging unit of the solid-state imaging element.
[0041] The ceramic of the base 810 preferably contains Al2O3, SiO2 and MnO as essential components, and contains at least one of Mo atoms and Cr2O3 as an optional component. The content of Al2O3 is 82.0 mass % or more and 95.0 mass % or less. The content of SiO2 is 3.0 mass % or more and 8.0 mass % or less. The content of MnO is 2.0 mass % or more and 6.0 mass % or less. The total content of Mo atoms converted to MoO3 and the content of Cr2O3 is 4.0 mass % or less. The content of the remainder is less than 0.1 mass %, more preferably less than 0.05 mass %. By making the ceramic have such a composition, it is easy to obtain the dimensional accuracy of the base 810 composed of ceramics. Therefore, it is easy to ensure the flatness of the mounting surface SF without grinding. In addition, it is easy to ensure the parallelism of the mounting surface SF.
[0042] Specifically, since the content of the above-mentioned surplus is suppressed to less than 0.1 mass %, each component is uniformly sintered in a dispersed state without segregation. Thus, the dimensional deviation of the base 810 is suppressed. Therefore, it is easy to ensure the flatness of the mounting surface SF without grinding. In addition, it is easy to ensure the parallelism of the mounting surface SF.
[0043] In addition, as described above, each component is uniformly sintered in a dispersed state without segregation, so that the timing of melting the glass component of the base 810 is substantially the same on the side facing the firing setter and the opposite side. As a result, the base 810 is prevented from warping in the thickness direction due to the deviation of the timing. Therefore, it is easy to ensure the flatness and parallelism of the mounting surface SF without grinding.
[0044] The content of the surplus is more preferably less than 0.05% by mass. This can further suppress dimensional variation. The content of the surplus is particularly preferably 0% by mass. This can further suppress dimensional variation.
[0045] The ceramic of the base 810 includes a crystalline phase and a glass phase. In the case where the ceramic contains Mo atoms as a colorant, the crystalline phase contains a Mo crystalline phase as a sub-crystalline phase in addition to the Al2O3 crystalline phase as the main crystalline phase. The crystalline phase may also contain a crystalline phase other than the Al2O3 crystalline phase and the Mo crystalline phase (hereinafter referred to as the "remaining crystalline phase"). Here, in the case of measuring the X-ray diffraction pattern of the sample obtained by crushing the base 810, the main peak intensity of the remaining crystalline phase is preferably less than 0.5% relative to the main peak intensity of the Al2O3 crystalline phase. Thus, it is possible to suppress the deformation of the glass phase due to the presence of the remaining crystalline phase. Thus, the bending strength (so-called bending strength) of the ceramic can be improved.
[0046] Table 1 below shows the results of an experiment conducted to examine the relationship between the composition of ceramics represented by composition numbers 1 to 25, the firing temperature suitable for the composition, and the characteristics of the ceramic plates obtained by the composition.
[0047]
Table 1
[0048]
[0049] In order to make a ceramic plate, first, the raw material powders are mixed in the proportions shown in Table 1 to obtain a mixed powder. In the obtained mixed powder, polyvinyl butyral, tertiary amine and phthalate (diisononyl phthalate: DINP) are mixed as organic components, and IPA (isopropyl alcohol) and toluene are further mixed as solvents to prepare a slurry. The prepared slurry is used to prepare raw sheets with a thickness of 50 to 400 μm by a scraper method. The obtained ceramic raw sheets are cut into 50 mm in length and 50 mm in width, and arranged on a Mo-made firing support plate, and fired for 2 hours at the firing temperature (maximum temperature) shown in the above Table 1. Thus, 100 ceramic plates of each composition number are produced.
[0050] The dimensional deviation of the obtained ceramic plate is measured. Specifically, the outer dimensions of the ceramic plate are measured using a dimensional measuring device. The average value and standard deviation thereof are calculated. The value obtained by dividing the standard deviation by the average value is taken as the dimensional deviation. As a result, the dimensional deviation of composition numbers 1 to 17 among composition numbers 1 to 25 is small, and in particular, the dimensional deviation of composition numbers 1 to 8 and 12 to 17 is smaller.
[0051] The number of ceramic plates with surface defects due to adhesion to the firing setter during the firing process was counted. As a result, the number of composition numbers 1 to 17 among composition numbers 1 to 25 was small, and the number of composition numbers 1 to 5 and 12 to 17 was particularly small.
[0052] The average value of the warpage of the ceramic plate was measured using a three-dimensional shape measuring device. As a result, among composition numbers 1 to 25, composition numbers 1 to 17 had small warpage, and composition numbers 1 to 9 and 12 to 17 had small warpage in particular.
[0053] The bending strength of the ceramic plate was measured at room temperature by a three-point bending strength test based on JIS R 1601. In addition, the relative dielectric constant of the ceramic plate was measured at room temperature and a frequency of 10 GHz by a cavity resonance method based on JIS R 1641.
[0054] Composition numbers 1 to 17 suppress dimensional deviation, adhesion to the setter plate, and warping compared to composition numbers 18 to 25. It is believed that this is because the content of the remainder other than Al2O3, SiO2, MnO, and coloring agent (Mo atom or / and Cr2O3) is suppressed to less than 0.1 mass %, so each component is uniformly sintered in a dispersed state without segregation. In addition, the same results can be obtained when additives other than MgO, ZrO2, CaO, and BaO are added, which is confirmed by experiments.
[0055] In composition numbers 1 to 9 and 12 to 17, in which the content of the remainder is 0.07 mass % or less, warpage is further suppressed. In composition numbers 1 to 8 and 12 to 17, in which the content of the remainder is less than 0.05 mass %, dimensional deviation is further suppressed. In composition numbers 1 to 5 and 12 to 17, in which the content of the remainder is 0 mass %, not only dimensional deviation is further suppressed, but also adhesion to the setter is further suppressed.
[0056] In addition, in composition numbers 1 to 15 in which the ratio of the content of SiO2 to the content of MnO is set to 0.8 or more and 2.1 or less, the bending strength is 700 MPa or more. Therefore, it can be seen that composition numbers 1 to 15 are suitable for ceramic packages requiring strength (for example, packages for sealing oscillators or semiconductor elements).
[0057] In addition, in composition numbers 15 to 17 in which the ratio of the content of SiO2 to the content of MnO is set to 1.9 or more and 3.5 or less, a relative dielectric constant of 8.0 or more and 9.0 or less and a bending strength of 390 MPa or more can be simultaneously achieved. Therefore, it can be seen that composition numbers 15 to 17 are suitable for ceramic packages (such as packages for sealing optical semiconductor elements) that require relatively low relative dielectric constants.
[0058] Although the present invention has been described in detail, the above description is illustrative in all aspects and the present invention is not limited thereto. It should be understood that numerous modifications not illustrated can be conceived without departing from the scope of the present invention.
[0059] Explanation of symbols
[0060] 800 Package
[0061] 810 Base
[0062] 811 bottom
[0063] 812 Frame
[0064] 820 Wiring Department
[0065] 821 External electrode terminal
[0066] 822 Internal Wiring
[0067] 823 Internal electrode terminal
[0068] 900 Electronic Devices
[0069] 901 Bonding layer
[0070] 902 Electronic components
[0071] 906 Adhesive layer
[0072] 907 Cover
[0073] CV Chamber
[0074] SF Mounting surface
[0075] SM installation surface.
Claims
1. A package comprising: a mounting surface for mounting electronic components; a cavity located on the mounting surface; and a mounting surface for mounting a cover for sealing the cavity, wherein: The package body comprises: a base made of ceramic and having the cavity; and a wiring portion extending from the cavity of the base and penetrating the base, The base includes: a bottom portion having the installation surface, the installation surface having a size that includes a rectangle having a long side of 10 mm or more; and a frame portion, which is arranged on the outside of the installation surface in a manner of surrounding the cavity on the bottom portion and has a fired surface of the ceramic as the mounting surface, The base has a side surface extending from an outer edge of the mounting surface, the side surface including a fracture surface, The ceramic has an average grain size of 1 μm or more and 3 μm or less on the mounting surface, and has a porosity of 3% or less on the fracture surface.
2. The package according to claim 1, wherein: The electronic component is a solid-state imaging element having a size that includes a rectangle having a long side of 10 mm or more.
3. The package according to claim 1 or 2, wherein: The ceramic contains Al2O3, SiO2 and MnO as essential components, and contains at least one of molybdenum atoms and Cr2O3 as an optional component, The content of Al2O3 is 82.0 mass % or more and 95.0 mass % or less, The content of SiO2 is 3.0 mass % or more and 8.0 mass % or less, The content of MnO is 2.0 mass % or more and 6.0 mass % or less, The total content of molybdenum atoms calculated as MoO3 and Cr2O3 is 4.0 mass % or less, The remaining content is less than 0.1 mass %.
4. The package according to claim 1 or 2, wherein: The ceramic contains Al2O3, SiO2 and MnO as essential components, and contains at least one of molybdenum atoms and Cr2O3 as an optional component, The content of Al2O3 is 82.0 mass % or more and 95.0 mass % or less, The content of SiO2 is 3.0 mass % or more and 8.0 mass % or less, The content of MnO is 2.0 mass % or more and 6.0 mass % or less, The total content of molybdenum atoms calculated as MoO3 and Cr2O3 is 4.0 mass % or less, The remaining content is less than 0.05 mass %.