Flip chip assembly process for forming an underfill encapsulant

A flip chip assembly process for forming an underfill encapsulant, comprising:

• providing a chip having an active surface and a plurality of conductive bumps arranged in array with a predetermined bump pitch;
• providing a substrate having a surface, having a die-attaching region, having a plurality of pads with previously formed solder paste respectively thereon, arranged in array with the same predetermined pad pitch as the active surface;
• forming an encapsulant in the die-attaching region excluding the pads, using a stencil and screen printing, the stencil having a plurality of openings, allowing the encapsulant to pass when forming the encapsulant, to deposit the encapsulant onto the substrate, a plurality of covers arranged in array with a predetermined cover pitch the same as the predetermined bump pitch, covering the pads when forming the encapsulant, and a plurality of connecting devices, connecting every two neighboring covers, or every cover with other regions of the stencil;
• and
• attaching the chip to the substrate, thereby one-to-one joining the conductive bumps and the pads.