Technology

Chip On Board, ...

Tape Automated Bonding (TAB)

Molding 

Heat sealing

HOT BAR soldering

SMT, uBGA , ...

Flip Chip Bonding

Mechanical parts assembly

Flip Chip Bonding

In the development of packaging of electronics the aim is to lower cost, to increase the packaging density and to improve the performance while still maintaining or even improving the reliability of the circuits. The concept of flip-chip process where the semiconductor chip is assembled face down onto circuit board is ideal for size considerations, because there is no extra area needed for contacting on the sides of the component (true also with TAB). The performance in high frequency applications is superior to other interconnection methods, because the length of the connection path is minimized. Potentially flip chip technology is cheaper than wire bonding (true also with TAB) because bonding of all connections takes place simultaneously whereas with wire bonding one bond is made at a time. In practice, however, this price benefit is not always achieved due to immature processes, e.g. the cost of die bumping with current processes can be significant, especially in low volumes.

There are many different alternative processes used for flip-chip joining. A common feature of the joined structures is that the chip is lying face down to the substrate and the connections between the chip and the substrate are made using bumps of electrically conducting material. 

Examples of the different types of flip chip joints.

Microbonding SA is able to realize your assembly using the techniques a), b) and e).

With the technique b), the solder bumped chips are directly soldered onto the circuit board. With the technique a), the Solder could be deposited also on to the substrate pad areas (e.g. by electroplating, solder ink jet or solid solder deposition). Then, the dices are positioned in the substrate and they are reflowed in an oven. 

After the reflow process cleaning of the flux is preferred. The underfill material is applied by dispensing along one or two sides of the chip, from where the low viscosity epoxy is drawn by capillary forces into the space between the chip and substrate. Finally the underfill is cured by heat. Repairing of the flip chip joint is usually impossible after the underfill process. Therefore testing must be done after reflow and before the underfill application.

Microbonding SA can mount bumped devices on rigid or flexible substrates in flip chip technique.

Examples of realization:

With solder Bump 

                             View with also the returned die (not mounted)

See in the  Heat Sealing section an example of assembly with an anisotropic glue