Method and apparatus for supporting a computer chip on a printed circuit board assembly

摘要

A printed circuit board assembly and method of assembly in which underfill is placed between a chip and substrate to support the chip. A trench is formed in the upper layer of the printed circuit board to limit the flow of the underfill and in particular to limit the underfill from contact with adjacent components so that the underfill does not interfere with adjacent components on the printed circuit board assembly.

主权项

1. A method comprising:
providing a printed circuit board, the printed circuit board defining a trench, wherein the trench separates a first portion of the printed circuit board from a second portion of the printed circuit board; positioning a first chip on the first portion of the printed circuit board such that no part of the first chip is on the second portion of the circuit board, wherein the first chip has a plurality of solder bumps outside of a central region where no solder bumps are present; securing the first chip on the printed circuit board by solder joints; dispensing an underfill to the first portion of the printed circuit board in proximity to the first chip, the trench limiting the flow of the underfill to a component secured to the second portion of the printed circuit board, wherein the underfill is drawn under the first chip by capillary effect; and positioning a second underfill on the printed circuit board in the central region, the second underfill having a lower viscosity than the underfill drawn under the first chip by capillary effect.