January 20, 2021
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MCP-the beginning of memory integration
MCP is the abbreviation of Multi Chip Package. It combines two or more memory chips into the same BGA package through horizontal placement or stacking. The MCP is combined into one. Compared with the previous mainstream TSOP package, it is two separate packages. A chip saves 70% of the space, simplifies the structure of the PCB board, and simplifies the system design, which improves the assembly and test yield.
Generally, there are two ways to combine MCP: one is NOR Flash plus Mobile DRAM (SRAM or PSRAM), the other is NAND Flash plus DRAM or Mobile DRAM (SRAM or PSRAM). NAND Flash has high storage density, low power consumption, and small size. The cost is also lower than that of NOR Flash. From the current basic 1Gb configuration, the price of NOR Flash 1Gb is about $6, which is six times that of SLC NAND Flash with the same capacity, making NAND gradually replace NOR.
In general, MCP reduces the cost of system hardware, and the price is even cheaper than its own independent chips. The final value of MCP depends on the price change of NAND Flash, but generally speaking, it can be at least 10% cheaper.
The key to the development of MCP technology is thickness control and actual yield. The more MCP stacked wafers, the thicker the thickness, but the thickness must be maintained at a certain thickness during the design process. The maximum height defined at the beginning is about 1.4 mm (currently generally 1.0mm), there are certain technical limitations. In addition, one of the chips fails, and the other chips cannot work.
MCP technology is usually based on SLC NAND with LPDDR1 or 2, and Mobile DRAM does not exceed 4Gb. It is mainly used in feature phones or low-end smart phones. The mainstream configuration is 4+4 or 4+2. According to DRAMeXchange's current quotation in 2015, the price of a 4+4 MCP is about US$4.5, and the price of 4+2 MCP is about US$3, making its price lower than 3 of the overall bill of materials (BOM) of low-end smartphones. ～6%.
The emergence of MCP was early, and limitations in technological development gradually appeared. Samsung, SK Hynix and other major manufacturers began to turn to eMMC, eMCP and other technology research and development, but Chinese low-end mobile phone manufacturers still have certain demand in the low-capacity MCP market, such as Taiwanese factories such as Jinghao and Ketong are optimistic about this market and are actively rushing into it.
EMMC with unified specifications
After MCP, the MultiMediaCard Association (MMCA) has set the standard specification of embedded memory for mobile phones and tablet PCs ──eMMC (embedded Multi Media Card), which uses MCP to control NAND Flash The chips are integrated in the same BGA package.
NAND Flash is developing rapidly, and products of different NAND suppliers are slightly different. When NAND Flash is packaged with its control chip, mobile phone manufacturers can save the trouble of redesigning specifications due to changes in NAND Flash suppliers or process generations. Further save the cost of R&D and test, shorten the product launch or update cycle.
eMMC is ordered in four sizes: 11.5mm x 13 mm x 1.3mm, 12mm x 16mm x 1.4mm, etc. (see Table 1 for details). The specifications continue to evolve. For example, v4.3 adds a boot function and saves NOR Flash. And other components, it can also be turned on quickly. The capacity and reading speed are also accelerated in the evolution of each generation. It has now developed to eMMC 5.1. In February 2015, almost at the same time as the official specification release, Samsung launched eMMC 5.1 products with capacity Up to 64GB, read speed 250MB/s, write performance increased to 125MB/s.
In the choice of eMMC NAND Flash, MLC used to be the main choice. 3-bit MLC (TLC) is not as good as MLC due to the number of erasing (product life). It is generally used in external plug-in products such as memory card flash drives. The introduction of 3-bit MLC into eMMC has prompted other NAND manufacturers to follow up, and the number of erasures has also increased. 3-bit MLC has a price advantage that is about 20% cheaper than MLC, and the proportion of use in smartphones and tablets has increased year by year. , And most of them are mid-range mobile devices. In the second half of 2014, after the iPhone 6 and iPhone 6 Plus adopted 3-bit MLC eMMC, Apple began to expand from mid-range models to the high-end market.
The use of eMMC on mobile devices requires additional DRAM. High-end mobile phones have gradually switched from LPDDR3 to LPDDR4 in DRAM selection. It is reported that the next generation of iPhone will increase from LPDDR3 1GB to LPDDR4 2GB. Currently, Samsung Galaxy S6 and LG G4 are both equipped 3GB LPDDR 4, according to the research organization DRANeXchange, LPDDR 4 in the second quarter of 2015 is estimated to have a 30-35% premium over LPDDR3.
EMCP compatible with MCP and eMMC
eMCP Embedded Multi Chip Package is eMMC combined with MCP package. Same as MCP configuration, eMCP also packages NAND Flash and Mobile DRAM together. Compared with traditional MCP, it has more NAND Flash control chip to manage Large-capacity flash memory reduces the computational burden of the main chip. It is smaller in size and saves more circuit connection designs, making it easier for smartphone manufacturers to design and produce.
eMCP is mainly developed to shorten the time to market for low-end smartphones, which is convenient for mobile phone manufacturers to test. The competition in the Chinese mobile phone market is becoming increasingly fierce, and the time to market is becoming more and more important. Therefore, eMCP is especially popular with public version customers such as MediaTek. Favor.
The configuration is based on LPDDR3, with 8+8 and 8+16 being the most. But in terms of price, compared with the same specification MCP plus NAND Flash control chip, the price difference can reach 10-20%. It depends on the cost of mobile phone manufacturers. The trade-off with time to market.
eMCP has the same size limitation of 11.5mm x 13mm x 1.Xmm as eMMC in terms of specifications. To assemble eMMC and LPDDR together, it is not easy to increase the capacity, and secondly, the combination of the two can easily cause signal interference, and the quality will not increase. Certainty has become the difficulty for eMCP to develop into the high-end market.
Generally speaking, MCP is mainly used in the very low-end smartphone or feature phone market. eMCP is suitable for mainstream smartphones. Especially for mobile phone manufacturers using processors such as MediaTek, the adoption of eMCP will help advance the time to market , EMCP mainly straddles the low-end and mid-tier markets, and has a tendency to gradually move towards the high-end markets. However, eMMC and separate Mobile DRAM have greater flexibility in configuration, and manufacturers have greater control over the specifications. It also has a good grasp of the cooperation between the processor and the memory, and is suitable for use in the top flagship models that pursue performance.
Samsung launched the eMMC 5.0 specification and 128GB large-capacity affordable storage memory in March 2015 to attack the mid-to-low-end mobile phone market. The distinction between memory integration methods in low-, mid- and high-end mobile phones has become blurred. In terms of choice, not the most advanced integration technology is the best. On the whole, it is appropriate, conforms to the chip platform, can meet the specified specifications, and has stability and cost as expected, which is the best memory integration technology.