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+ | ====== Why? ====== | ||
+ | According to [Lange, FIXME page number]: | ||
+ | * Better sealed than plastic. | ||
+ | * Easier to combine several components into one package | ||
+ | * Dissipates heat better | ||
+ | * " | ||
+ | * Harder to warp | ||
+ | |||
+ | Well then why is plastic more popular? | ||
+ | |||
+ | These packages were a lot more popular in the 70/ | ||
+ | |||
+ | |||
+ | ====== General notes ====== | ||
+ | |||
+ | Typical non-ceramic parts include glass seals, metal seals, metal conductors, quartz windows, and electronic components, and the die itself. | ||
+ | |||
+ | Ceramic packages can be fabricated in multiple layers. | ||
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+ | {{: | ||
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+ | The DEC chip in the upper left hand corner of the top menagerie is multi-layer but the metalization can is only faintly visible. | ||
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+ | [Lange, 23] say that alumina is by far the widest used material followed by beryilia [Lange, 24]. | ||
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+ | |||
+ | ====== Package types ====== | ||
+ | |||
+ | ===== Alumina (Al2O3) ===== | ||
+ | |||
+ | {{: | ||
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+ | White ceramic packages are usually alumina (Al2O3) with [Lange] mentioning that some are AlN. According to [Lange] alumina packages typically use tungsten or molybdenum conductors and implies that copper conductors aren't used due to firing temperatures. | ||
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+ | {{: | ||
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+ | Dark brown packages are 90% alumina [Lange, 24]. According to the composition data below, it seems the other 10% is typically SiO2 and the brown color comes from a few percent of MnO. Due to EPROMs popularity these are the most common ceramic packages one is likely to encounter. | ||
+ | |||
+ | ==== Example substrate composition ==== | ||
+ | |||
+ | Based off of data from [Materials Declaration of 8L CerDIP]. | ||
+ | |||
+ | ^ Material ^ % ceramic ^ % total (ceramic) ^ % sealing glass ^ % total (sealing glass) ^ % package ^ Appearance ^ | ||
+ | | Al2O3 | 88.48 | 62.11 | 3.09 | 0.92 | 63.03 | White | | ||
+ | | PbO | 0.00 | 0.00 | 44.55 | 13.28 | 13.28 | Red-yellow | | ||
+ | | B2O3 | 0.00 | 0.00 | 27.24 | 8.12 | 8.12 | White | | ||
+ | | SiO2 | 2.88 | 2.02 | 5.23 | 1.56 | 3.58 | Clear | | ||
+ | | SnO2 | 0.00 | 0.00 | 11.67 | 3.48 | 3.48 | White | | ||
+ | | MnO2 | 3.39 | 2.38 | 0.03 | 0.01 | 2.39 | Brown-black | | ||
+ | | TiO2 | 1.82 | 1.28 | 4.29 | 1.28 | 2.56 | White | | ||
+ | | Cr2O3 | 1.44 | 1.01 | 0.10 | 0.03 | 1.04 | Green | | ||
+ | | MgO | 0.53 | 0.37 | 1.54 | 0.46 | 0.83 | White | | ||
+ | | Fe2O3 | 1.17 | 0.82 | 0.10 | 0.03 | 0.85 | Red-brown | | ||
+ | | CaO | 0.04 | 0.03 | 1.54 | 0.46 | 0.49 | White to pale yellow/ | ||
+ | | Co3O4 | 0.26 | 0.18 | 0.00 | 0.00 | 0.18 | Black | | ||
+ | | ZnO | 0.00 | 0.00 | 0.60 | 0.18 | 0.18 | White | | ||
+ | | Na2O | 0.00 | 0.00 | 0.01 | 0.00 | 0.00 | White | | ||
+ | | Total | 100.00 | 70.20 | 100.00 | 29.81 | 100.01 | Light to dark brown? | | ||
+ | |||
+ | |||
+ | ===== Aluminum nitride (AlN) ===== | ||
+ | |||
+ | According to [Rao et al, II-330] these can be found in: thyristors, TO packages, RF packages, heat sinks for car ignition, high power switching modules (ex: IGBT), submounts for laser diodes, MCM PGAs, and QFPs. It may contain 0.5 to 1.5 % Y2O3 by weight as a sintering aid [Lange, 27]. | ||
+ | |||
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+ | ===== Purple ceramic ===== | ||
+ | |||
+ | Usually metal sealed. | ||
+ | |||
+ | AZ's [[decap: | ||
+ | |||
+ | |||
+ | ===== Berylia (BeO) ===== | ||
+ | |||
+ | According to [Rao, II-333] "Power hybrids, bipolar chips, LSI devices, and microwave integrated circuits are often housed in berylia packages." | ||
+ | |||
+ | [Lange, 24] says that it has 8 to 10 times thermal conductivity of alumina. | ||
+ | |||
+ | |||
+ | ===== Silicon carbide (SiC) ===== | ||
+ | |||
+ | [Lange, 27] says this material is uncommon and costs 20-100 times as much as alumina. | ||
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+ | |||
+ | ===== Composite ===== | ||
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+ | {{: | ||
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+ | Its not uncommon for ceramic packages to contain a variety of materials. | ||
+ | |||
+ | ===== Ceramic tie bar ===== | ||
+ | |||
+ | {{: | ||
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+ | Name Actel calls the ceramic leadframe around the package (highlighted in red above, Actel RT54SX). [Microsemi Packaging FAQs] | ||
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+ | ====== Co-fired ceramics ====== | ||
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+ | [Minges] says package ceramics are classified into organic and inorganic parts. | ||
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+ | |||
+ | ===== Low-temperature co-fired ceramic (LTCC) ===== | ||
+ | |||
+ | [[Minges, 461] says typical inorganics are 25% ceramic, 10% borosilicate. | ||
+ | |||
+ | |||
+ | ===== High-temperature co-fired ceramic (HTCC) ===== | ||
+ | |||
+ | [[Minges] says inorganics include 90% alumina, 10% borosilicate. | ||
+ | |||
+ | |||
+ | ===== Die attach ===== | ||
+ | |||
+ | Include: | ||
+ | * Glass (common in EPROM packages) | ||
+ | * Silver solder | ||
+ | * Silver epoxy | ||
+ | * Cynate Esther Paste [Microsemi Packaging FAQs] | ||
+ | |||
+ | |||
+ | ====== References ====== | ||
+ | |||
+ | * Characterizing Integrated Circuit Packaging Materials, Mary Beth Lange: http:// | ||
+ | * Microelectronics Packaging Handbook: Semiconductor packaging By Rao R. Tummala, Eugene J. Rymaszewski, | ||
+ | * Etching processes: http:// | ||
+ | * Electronic Materials Handbook: Packaging, Merrill L. Minges: http:// | ||
+ | * Microsemi Packaging FAQs: http:// | ||
+ | * Materials Declaration of 8L CerDIP: http:// |