Analysis Of The Effect Under Different Solder Bump Arrangement On Underfill Flow In Flip-chip Packaging

With the development of the electronic industry, nowadays, the demands of electronicproducts tend towards to smaller size, higher speed, larger capacity, lighter weight andcheaper price. And the trend puts forward more and more severe challenges to integratedcircuit packaging technology. The traditional wire bonding packaging technology cannot meetthe demands of the people, meanwhile, the flip chip packaging technology, with its excellentcharacteristics, gradually becomes one of the most dynamic development direction ofintegrated circuit packaging process.In the flip chip packaging technology, the chip and substrate is mainly connected bysolder bumps and transmits information through them. So the more solder bumps arranged inthe same area shows the higher input and output capacity of the chip. In order to arrange moresolder bumps in chip which is mainly arranged in tandem arrangement, this paper analyses thenumber change of solder bumps when which are arranged in stagger arrangement compared totandem arrangement. Through the analysis, we can find that the chip can contain more solderbumps in the same condition when which arranged in stagger arrangement. And as theincrease of the area, the quantity variance is also gradually widenedIn order to avoid wear failure of the solder bump, usually organic rubber is used in theproduction process of chip to fill the gaps between the chip and substrate. The underfillingintegrity and filling time directly impacts the reliability and efficiency of products. Thisarticle analyzes the filling front characteristics in two kinds of arrangement of solder bumpsboth through the theory and numerical simulation. The research results show that the gap isnot great, although the filling distance is further when the solder bumps arrange in tandemarrangement at the same time. As a result, it is feasible method to improve input/outputcapability by number increase of solder bumps arranged in stagger arrangement theoretically.This paper also analyzes the influence factors impacting filling glue flow which is alsoanalyzed by numerical simulation when solder bumps arranged in different arrangement. Theresults show that properly adjusting the solder bump diameter, gap height and outsideclearance can shorten the filling time. Meanwhile, it also needs to make appropriate adjustments to avoid the appearance of the racing effect phenomenon which will impact thereliability of products when the chip edge clearance is bigger than the outside clearance ofsolder bump.