Authored By:
Jonas Sjoberg
Flextronics Mobile & Consumer
Shah Alam, Malaysia
Andreas Morr
Flextronics Mobile & Consumer
Hong Kong, China
Summary
Miniaturization and the integration of a growing number of functions in portable electronic devices require a high packaging density for electronic components. One way to increase the packaging density is to reduce the size of the packages and at the same time increase the density of the I/Os. This means that the size and pitch of solder balls or pads in electronic component packages will continue to shrink.
The use of fine pitch components, equal and below 0,5mm pitch, poses a number of challenges for design, SMT assembly process and reliability.
First, a feasible assembly process must be achieved. The assembly process ranges all the way from screen-printing too in many cases underfill of CSP's and LGA's. Many factors influence the quality of the assembly process. The basic processes to control are screen-printing, pick & place, reflow soldering and underfill.
Second, the right materials (such as PCB material, PCB surface finish, solder paste and underfill) and PCB design need to be selected to ensure a cost effective and reliable interconnect. Of coarse the mechanics of the products makes a big difference as well but it is very product dependent and many of today's products leave little room for designing the mechanics in the most reliable way due to total cost and overall looks of the product.
This paper will discuss different assembly and material alternatives to make a handheld product as producer friendly, cost effective and reliable as possible.
Conclusions
There are many ways to achieve miniaturization and the key is to have a "tool box of technologies" to be able to fulfill the needs. Depending on the product several options can be considered and the selection should be based on data on assumptions.
In addition to the technologies mentioned in this paper, there are other technologies such as hot-bar soldering, integrated active and passive parts and COB with wire bonding that could be interesting for a miniaturization and cost point of view.
Initially Published in the SMTA Proceedings
|
