Flip Chip Packaging

Flip chip derived its name from the method of flipping over the chip to connect with the substrate or leadframe. Unlike conventional interconnection through wire bonding, flip chip uses solder, copper pillar or gold bumps. Therefore, the I/O pads can be distributed all over the surface of the chip and not only on the peripheral region. The chip size can be shrunk and the circuit path, optimized. Another advantage of flip chip is the absence of bonding wire reducing signal inductance.

Benefits of Flip Chip

Shorter assembly cycle time
  • All the bonding for flip chip packages is completed in one process.
Higher signal density & smaller die size
  • Area array pad layout increases I/O density. Also, based on the same number of I/Os, the size of the die can be significantly shrunk.
Good electrical performance
  • Shorter path between die and substrate improves the electrical performance.
Direct thermal dissipation path
  • External heat sink can be directly added to the chip to dissipate heat from the chip.
Lower packaging profile
  • Absence of wire and molding allows flip chip packages to feature lower profiles.

Capabilities

ASE offers several BGA package types using flip chip technology as below:

Package Type I/O Package Size (mm) Substate Ball Pitch (mm)
FCCSP 16 ~ 200 4x4 ~ 14.0x22.0 2/4 Layer Laminate 0.5 ~ 1.00
FCBGA 100 ~ 1521 27x27 ~ 40.0x40.0 2/4 Laminate, 4-8 Layer Build-up 1.0/1.27
HFCBGA 256 ~ 2401 12x12 ~ 52.5x52.5 4-12 Layer Build-up 1.0/1.27

The thickness and the available ball count of flip chip packages are mostly customized. ASE provides several options to enhance the performance of flip chip packages. They are:

Molded Underfill (MUF) for FCCSP and FCBGA

The molding is used to protect the chip, substitute underfill for lower cost and improve the thermal performance and 2nd level reliability.

Heat spreader for HFCBGA)

The heat spreader provides direct heat conduction by adhering to the rear side of the silicon chip. This method provides 6~8W of thermal dissipation under natural convection.

ASE Flip Chip Packaging Offerings

FCCSP (Flip Chip Chip Scale Package) offers chip scale capacity for I/Os around 200 or less. FCCSP provides better protection for chip and better solder joint reliability compared with direct chip attach (DCA) or chip on board (COB). FCCSP features thin and small profile, and lightweight packages.

Application

Consumer
  • Camcorders
  • Digital Camera
  • DVD
Computer
  • Voltage Regulators
  • High-speed Memory
  • Card
  • PC Peripherals
Telecommunication
  • Pagers
  • Cellular Handsets
  • GPS

Features

  • Thinner Profile: “Wafer Thinning” capability (down to 6~8 mils) to support packages thinner than 1.0 mm
  • Substrate: 2-layer BT laminate substrate is used to reduce overall package cost/li>
  • Improved Performance: Thin core (100um) substrate & via-on-pad design can be adopted to achieve better electrical performance
  • Robust Structure: Molded underfill process can enhance throughput, component and board level reliability
  • NSMD with OSP C4 pad: Low cost solutions for electric interconnect between solder bump and substrate

Laminate or build-up organic substrate offers better electrical performance than wire-bond type BGA package especially in high frequency applications.

Application

Consumer
  • Graphics/Chipsets for PC
  • Server
  • Game Console and High-end Application
  • Microprocessor for PC & Server
  • Memory
Telecommunication
  • Network Products (LAN)
  • Switching
  • Transmission
  • Cellular Base Stations

Features

  • Substrate: 4 layer laminate, 4~12 layer & 800/400um. Build-up substrates are available for different application
  • Passive Component: Passive component attaching is available.

HFCBGA (High Performance FCBGA), a thermally enhanced FCBGA, is the composite package of FCBGA with heat spreader made of Cu, Al, or AlSiC. The heat spreader is used to extend the heat conduction area by connecting itself to the rear side of the silicon chip.

This method desensitizes the performance deviation out of the chip size, lowers the thermal resistance of junction-to-case (θjc) and enables the external heat sink or fan to work more effectively. HFCBGA can produce 6~8 watts of power dissipation under natural convection.

Application

Consumer
  • Graphics/Chipsets for PC
  • Server
  • High-end Application
  • Microprocessor for PC & Server
Telecommunication
  • Network Products (LAN)
  • Switching
  • Transmission
  • Cellular Base Stations

Features

  • Substrate: 4 layer laminate, 4~12 layer build-up, ceramic, and PTFE substrates are available
  • Thermal Lids: Heat spreaders made of Cu with Ni plating, Aluminum, Ceramic,AlSiC