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ELP (Exposed Leadframe Package)
Samsung's ELP (Exposed Leadframe Package) is a surface-mounted Chip Scale Package (CSP) that uses a copper leadframe. An ELP is typically mounted on a main board through metal lands perimetrically placed on the bottom surface of the package. An ELP thus provides the most efficiently sized solution among leadframe packages. Additionally, an ELP can improve ground line connections to the package to the maximum extent by down bonding on the exposed pad on the bottom surface of the package, and turn out to be an outstanding packaging solution for high frequency devices. Furthermore, the exposed pad serves as an efficient heat dissipation path since it can be used as an area that can be soldered directly to the main board. An ELP thus also offers sufficiently high thermal performance.
Figure 1 illustrates the top and bottom views of an ELP, along with a cross-sectional view of its internals.
The small size, low thermal impedance, and very low profile makes the ELP suitable for deployment in applications across multiple segments, such as analog devices, RF chipsets, gallium arsenide logic devices (which have higher power consumption than their silicon counterparts), microcontrollers, and memory devices (such as DRAM and flash memory). ELPs are capable of operating over both high frequencies (more than 1 GHz) and handling medium powers (from 1 to 2 W). Additionally, they can easily carry a low to medium number of pins (up to 150 pins).
The principal areas where ELPs are deployed are in high density PCBs, in applications such as mobile handsets, personal digital assistants (PDAs), LCD televisions, laptop computers, and personal multimedia players (PMPs), among others.
- Ease of mass production using standard technology and infrastructure, such as existing semiconductor fabrication plants
ignificant improvement in the mounting space efficiency, detailed as under:
- - Reduction in mounting space (standard package size: 3 x 3 mm to 11 x 11 mm)
- - Reduction in mounting height (standard thickness: 0.4~1.0 mm)
- - Reduction in package mass
- Available in low and medium pin counts: 6 to 148 pins
- Good thermal and electrical performance
- High reliability (EIAJ Level 1)
ELPs demonstrate outstanding thermal performance in their small sized packages, since the die paddle can be attached to the application's PCB for better heat dissipation and consequently, a low thermal resistance for the package.
ELPs offer excellent electrical performance due to the extremely short lengths of their interconnection pins, which offer very low impedances for power and ground connections, as well as low inductances (less than 0.5 nH) for high frequency signals. The exposed pad available on ELPs also serves as a common ground (used via down bonding).
The unique design and fabrication processes of an ELP offer superior reliability, resulting in the package withstanding long term storage conditions. The following are some of the reliability characteristics for an ELP :
- Moisture sensitivity characterization :
- EIAJ Level 1 (85°C/85%, 168 hours, IR 240°C, test repeated 3 times)
- Highly Accelerated Stress Test (HAST) :
- 96 hours (130°C, 85% relative humidity)
- Temperature cycling test :
- 500 cycles (-65°C~150°C)
- High temperature storage :
- 500 hours (150°C)