Differences and connections between MCP, eMMC, eMCP

MCP - The Origin of Memory Integration

MCP is the abbreviation of Multi Chip Package, which is to put two or more memory chips into the same BGA package by horizontal placement or stacking. It saves 70% of the space, simplifies the structure of the PCB board, and simplifies the system design, which improves the assembly and test yield.

There are two general MCP combinations: 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 US$6, which is six times that of SLC NAND Flash of the same capacity, making NAND gradually replacing NOR.

In general, MCP reduces the cost of system hardware, and the price is even cheaper than independent chips. The final price of MCP depends on the price change of NAND Flash, but generally it can be at least 10% cheaper.

The key to the development of MCP technology lies in the control of thickness and the actual yield rate. The more wafers stacked in MCP, the thicker the thickness. However, the design process still has to maintain a certain thickness. The maximum height defined at the beginning is about 1.4 mm (currently generally 1.0mm), there are certain technical limitations, in addition, if one of the chips fails, the other chips cannot work.

MCP technology is usually based on SLC NAND with LPDDR1 or 2. 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 research institutions According to the current quotation of DRAMeXchange in 2015, the price of a 4+4 MCP is about 4.5 US dollars, and the price of a 4+2 MCP is about 3 US dollars, so that the price can be pressed in the overall bill of materials (BOM) of low-end smartphones. ~6%.

MCP appeared earlier, and there are gradually limitations in technology development. Samsung, SK Hynix and other major manufacturers have begun to turn to eMMC, eMCP and other technology research and development. However, Chinese low-end mobile phone manufacturers still have certain needs in the low-capacity MCP market, such as Taiwanese factories such as Jinghao and Ketong are optimistic about this market and actively rush into it.

eMMC with unified specifications

After MCP, the MultiMediaCard Association (MMCA) has set a standard specification for embedded memory, eMMC (embedded Multi Media Card), for products such as mobile phones and tablet computers. The chips are integrated in the same BGA package.

NAND Flash is developing rapidly, and there are slight differences between products of different NAND suppliers. 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 savings in R&D testing costs and shorter time-to-market or update cycles.

eMMC has four sizes of 11.5mm x 13 mm x 1.3mm, 12mm x 16mm x 1.4mm (see Table 1 for details), and the specifications continue to evolve. For example, v4.3 adds a boot function, saving NOR Flash and other components, it can also be turned on quickly, and 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 was released, Samsung launched eMMC 5.1 products. Up to 64GB, the read speed is 250MB/s, and the write performance is improved to 125MB/s.

In the selection of NAND Flash, eMMC was mainly MLC in the past. 3-bit MLC (TLC) is not as good as MLC due to the number of erasures (product life), and is generally used in external plug-in products such as memory cards and 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 of about 20% cheaper than MLC, and the proportion of its use in smartphones and tablets is increasing year by year. In the second half of 2014, after adopting 3-bit MLC eMMC in the iPhone 6 and iPhone 6 Plus, Apple began to expand from the mid-range models to the high-end market.

The use of eMMC on mobile devices requires additional DRAM. In terms of DRAM selection, high-end mobile phones are gradually switching from LPDDR3 to LPDDR4. It is reported that the next-generation iPhone will be upgraded from LPDDR3 1GB to LPDDR4 2GB. Currently, Samsung Galaxy S6 and LG G4 are equipped with 3GB LPDDR 4. According to the data of DRANeXchange, a research institute, LPDDR 4 is estimated to have a 30-35% premium over LPDDR3 in the second quarter of 2015.

eMCP compatible with MCP and eMMC

eMCP embedded Multi Chip Package is an eMMC combined with MCP package. Same as MCP configuration, eMCP also packages NAND Flash and Mobile DRAM together. Compared with traditional MCP, there are more NAND Flash control chips to manage The large-capacity flash memory reduces the computational burden of the main chip, reduces the volume and saves more circuit connection design, and is more convenient for the design and production of smartphone manufacturers.

eMCP is mainly developed to shorten the time-to-market of low-end smartphones and is convenient for mobile phone manufacturers to test the characteristics. The competition in the Chinese mobile phone market is becoming more and more fierce, and the time-to-market is more important. Therefore, eMCP is especially popular among public customers such as MediaTek. favor.

In terms of configuration, it is based on LPDDR3, with 8+8 and 8+16 as the most, but in terms of price, compared with MCP plus NAND Flash control chip of the same specification, the price difference can reach 10-20%, depending on the cost of mobile phone manufacturers. trade-off with time to market.

eMCP has the same size limit 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 is prone to signal interference, which increases the quality. Certainty has become a difficult point for eMCP to develop into the high-end market.

Generally speaking, MCP is mainly used in the very low-end smart phone or feature phone market, eMCP is suitable for mainstream smart phones, especially for mobile phone manufacturers using processors such as MediaTek, the adoption of eMCP helps to promote the time-to-market. , eMCP mainly spans the low-end and mid-range markets, and has a trend of gradually moving towards the high-end market, while eMMC and discrete Mobile DRAM have greater flexibility in configuration, and manufacturers have greater control over specifications. It can also have a good grasp of the cooperation between the processor and the memory, which is suitable for use in the top flagship models that pursue performance.

In March 2015, Samsung launched the eMMC 5.0 specification and 128GB large-capacity affordable storage memory to attack the mid-to-low-end mobile phone market. In terms of selection, not the most advanced integration technology is the best, but it is generally appropriate, conforms to the chip platform, can meet the specified requirements, and the stability and cost are as expected, so it is the best memory integration technology.