EMBEDDED WAFER LEVEL BALL GRID ARRAY:

Modern Education  |     |  

INTRODUCTION:

  • The Embedded WLBGA is a sort of packaging technology for IC’s.
  • Package interconnects are placed on wafers made of silicon chips and  a special casting compound.
  • This technology allows the creation of chips with a huge number of interconnects(ball grid array).
  • Eac and single process for the interconnects(generation of package) is performed on the wafer.
  • Hence a front end processed wafer is sliced and the singulated chips are placed on a carrier.The consecutive distance between each individual chip can be freely selected but usually it is larger than that of the silicon wafer.
  • Now for the next step the extra edges and spaces around the central chip is filled with a compound (casting) in order to form a wafer.
  • Next step involves the curing of the artificial mould frame. This in turn creates the dies for carrying extra package interconnects.
  • Finally after this reconstructed artificial wafer layer is created the connections between chip pads and corresponding interconnects are made using thin film technology.

PURPOSE:

  • The main advantage of this design is that multiple interconnects can be created on the package within an arbitrary(fan out) distance.
  • This sensitive design can be employed in space applications where insufficient chip space is available for the interconnects to be realized.

Eg:- STATS, ChipPac,Infineon

         

                                                      Fig 2. Fan in design of chip interconnects

STEPS INVOLVED IN THE PROCESS:

  1. Mold press
  2. Chip placement onto the wafer.
  3. The Lamination of foil onto the carrier.
  4. The Debonding of carrier
  5. Turn the reconstructed wafers upside down.
  6. The ball drop reflow and wafers test.

ADVANTAGES

  1. Compact and long.
  2. Good thermal and electrical properties.
  3. Good package standards.
  4. No interconnects restrictions on package.
  5. Very high integration potential for stacked and multi-die packages.

DISADVANTAGES:-

  1. High maintenance cost and visual restricted.
  2. High mechanical stress transmitted between the package and board as compared to other technologies.