Direct application of unpackaged integrated circuit to flexible printed circuit

A flexible printed circuit comprising:

• an adhesiveless flexible printed circuit board having a flexible polyimide substrate and a copper interconnection layer affixed to at least one side of the substrate, the layer having a plurality of contact pads defined thereon, some of the contact pads defined as active contact pads arranged in footprint patterns for electrical connection to a plurality of flip chips;
• and
• a plurality of flip chips electrically connected to the circuit board, each flip chip connected by at least two electrical connections formed between bonding pads on an active side of the flip chip and opposing active contact pads on the circuit board;
• wherein each electrical connection between a flip chip and the circuit board includes a homogeneous solder composition substantially free of undesired crystalline microstructures and deformities, the homogeneous solder composition being formed by reflowing solder paste located on the corresponding active contact pad on the circuit board such that a solder bump located on the corresponding bonding pad on the flip chip is allowed to self-align with the corresponding active contact pad and such that the solder paste mixes with the solder bump, and wherein each electrical connection is formed concurrently by applying heat to the circuit board and flip chips as a whole after the flip chips have been placed on the circuit board in a manner which allows for unobstructed motion of the flip chips during reflow.