4-layers DDR Substrate Board

Characteristics of DDR package carrier

High density junction structure

Hole filling electroplating and hole stacking structure

Various surface treatment methods

Sheet and surface flatness requirements

Resin filling

Application process of DDR package carrier

Semi addition method, laser drilling,

Application of DDR package carrier

Smart phones, computers, Internet of things products, message electronic products

The full name of DDR memory is DDR SDRAM (Double Data Rate SDRAM). DDR SDRAM was first proposed by Samsung in 1996. It is a memory specification negotiated by eight companies, including NEC, Mitsubishi, Fujitsu, Toshiba, Hitachi, Texas Instruments, Samsung and Hyundai, and has been awarded with AMD, VIA, and SiS. Support from chipset manufacturers. It is an upgraded version of SDRAM, so it is also called "SDRAM II".

DDR is the mainstream memory specification at the beginning of the 21st century, and all the mainstream products of major chipset manufacturers support it. The full name of DDR is DDR SDRAM (Double Data Rate SDRAM, Double Data Rate SDRAM). The nominal frequency of DDR is the same as that of SDRAM. As of 2017, DDR operating frequencies are mainly 100MHz, 133MHz, and 166MHz. Because DDR memory has the characteristics of double rate data transmission, the method of operating frequency*2 is adopted in the identification of DDR memory, that is, DDR200, DDR266, DDR333 and DDR400, some memory manufacturers have also introduced higher frequency DDR memory in order to cater to the needs of enthusiasts. The most important change is in the interface data transmission. It can perform data processing on the rising and falling edges of the clock signal, so that the data transmission rate can reach twice that of SDR (Single Data Rate) SDRAM. As for the addressing and control signals, they are the same as SDRAM and are only transmitted on the rising edge of the clock.

Compared with the SDRAM module, the DDR SDRAM module adopts a 184-pin (pin), 4-6 layer printed circuit board, and the electrical interface is changed from "LVTTL" to "SSTL2". It is the same as the SDRAM module in other components or packages. The DDR SDRAM module has a total of 184 pins and only one slot is missing, which is not compatible with the SDRAM module. DDR SDRAM is also different from SDRAM in terms of naming principles. SDRAM is named according to the clock frequency, such as PC100 and PC133. And DDR SDRAM is based on the data transfer volume as the naming principle, such as PC1600 and PC2100, the unit is MB/s. So DDR200 in DDR SDRAM is actually the same specification as PC1600, and the data transfer volume is 1600MB/s (64bit*100MHz*2÷8=1600MBytes/s), and DDR266 and PC2100 are the same (64bit*133MHz*2÷ 8=2128MBytes/s).

DDR SDRAM is based on the signal delay time (CL; CAS Latency, CL refers to the number of system clock cycles after receiving the signal before reading. Generally speaking, the shorter the better, but This also depends on the original setting value of the memory particles, otherwise it will cause system instability) is also different. According to the definition of the Joint Electronic Engineering Design and Development Association (JEDEC) (the specification number is JESD79): DDR SDRAM has two CAS delays, divided into 2ns and 2.5ns (ns is one billionth of a second). The faster CL=2 plus PC 2100 specification DDR SDRAM is called DDR 266A, and the slower CL=2.5 plus PC 2100 specification DDR SDRAM is called DDR 266B. In addition, the slower PC1600 DDR SDRAM does not have a special number in this regard.