Why BGA welding preferred lead-free solder paste?

Why BGA welding preferred lead-free solder paste?

The trend of the development of semiconductor packaging is more and more high frequency,

multi chip module MCM system integrated SiP package and stacked package PiP, PoP

development. The integration between the semiconductor assembly and the traditional board

assembly, such as the flip chip FlipChip, is assembled directly in the terminal product..

Characteristics of semiconductor assembly equipment

At the same time, it has higher accuracy and the function of the flux is applied, began to appear

on the multi-functional fine pitch placement machine. It can be said that the component stacking

technology is already developed in the technology of the flip chip assembly technology

Emerged in 2004, showing the mobile phone of logic operations since 2003 components before

stacking technology most is only used in the flash memory and a number of mobile memory card.

Including mobile phone for stacking technology application will account for 17% of the whole

market, element and a storage unit between the stacked package. The average financial year the

entire stack technology market growth rate reached 60%. To predict 2009 growth rate of 21%.3G

mobile phone and MPEG4 will also be a lot of use of this technology.

Mobile communication products, the key is to solve the problem of "bandwidth". Popular is the

high-speed signal processing ability. This requires a new type of digital signal processor.

To solve the scheme one is logic controller placed a gold memory is typically a dynamic memory)

to achieve the

And function have been strengthened. And mature of flip chip technology contributed to the this

technology can be a large number of applications possible. Basically I can use existing SMT

equipment and downstream resources and existing logistics supply chain into the technology,

miniaturization, mass production.

Structure of stacked components

STMICRO claims so far thickness to 40 micron chip can be from two stacked to eight SRA m, a stack

of chip components in most of the gold wire bonding way WireBond stacked layers can be from

2 to 8 layers. DRA, M flash, 40 micron thin chip stacked 8 total thickness of 1.6mm stacked two

thickness of 0.8mm.

The same stack golden thread through the substrate bonding between two stacked, encapsulated

within a chip through the wire bond synthetic stacked onto the substrate. Then the whole package

into a component is the device built-in device (PIP, PackaginPackag.)

The end user has no freedom to choose. PIP package shape at low altitudes, standard SMT circuit

board assembly process can be used, the assembly of a single device on interest lower. But because

in the package before a single chip can not be tested individually, so total cost will higher

encapsulation yield) and prior to determine the structure of memory device by the design

service company decide in advance.

Typically 24 layers, component stacking package PoP, PackagonPackag bottom components and then

placed components - logic + storage. Storage PoP can reach 8 levels. Overall height is slightly high,

but the assembly before each device can be individually tested, to ensure a higher yield rate, the

total package of interest can be is reduced to the minimum, combination of devices can be selected

by the terminal users' freedom, for 3G mobile phone and digital like machines, which is optimal

selection method of assembly.