by Vahid Goudarzi, David Day, Richard Brooks
This paper will outline the issues relating to the implementation of a
Pb-free solder paste into a
standard Sn/Pb manufacturing facility and product. The Pb-free study includes the compatibility and impact on the various manufacturing processes that include, printing, component placement, reflow process, and solder joint quality.
These parameters must be fully characterized to ensure that the lead-free solder paste meets the manufacturing and product quality requirements. In addition, a lower super heat temperature is critical to reduce the thermal stress on components, since the lead-free alloy composition (Sn/Ag/Cu) liquefies at about 34 C higher than the current leaded material (63Sn/37Pb). Several implementation issues were discovered during the pilot phases and resolved prior to full-scale production manufacturing. Some of the problems revealed were BGA voiding, chip component tombstoning, and component integrity as it relates to termination plating and moisture sensitivity.
pb-free, lead-free
[Permanent Link to this Paper ]
Posted on 4 Mar 2010
by Marty Carr, John Carr, Richard Brooks
New assembly technologies are being considered for production to reduce size and/or increase functionality. These new technologies include: 0201 & 01005 chip components and 0.4 mm & 0.3 mm pitch CSP devices. In order to implement these new technologies, some major changes in the manufacturing process may have to be addressed. First, the solder paste must provide the ability to print very small apertures, such as 0.008" (0.2mm) & below and with consistent paste release from the stencil. Therefore, one of the possible solutions may be to change the standard solder powder size, which is type 3 powder. Also, because we are printing very small aperture openings, we need to consider changes in the stencil technology. Some of those changes are the stencil type (laser versus electroformed) and the stencil thickness. Additionally, because we are attempting to print very small apertures, the printing process must be in control and characterized. This paper will review the new technology requirements and how they will affect the performance of the solder paste and stencil technology in the manufacturing process, as well as the printing process.
fine pitch printing, stencil technology, stencil design, pad design, solder powder, process characterization, solder paste
[Permanent Link to this Paper ]
Posted on 8 Mar 2010
by George Babka, David Sbiroli, Richard Brooks, Chris Anglin
With the introduction of 01005 chip components and 0.3 mm pitch CSP devices, electronic component packaging is pushing surface mount technology to the limits of its potential. Miniaturization is driving the electronics industry to implement the smallest and tightest pitch components in order to meet their customer demands. But how much miniaturization is possible before there is a paradigm shift in the technology? At what point is solder paste no longer viable? How small of a feature can be printed with solder paste, and can this process be implemented into a production environment?
Most of the factors and critical parameters in ultra-fine pitch printing have been well understood and documented for over twenty years. Some of these parameters are squeegee speed, squeegee pressure, stencil design (technology, thickness & area ratio), and solder paste. But as the pitch and aperture sizes get smaller and smaller, we begin to see that additional factors start to have an increased effect on the solder paste deposition (transfer efficiency). What are these factors and can we control them in order to obtain acceptable results for transfer efficiency and minimized variability? This paper will evaluate these additional factors and how they affect the transfer efficiency of the paste.
ultra-fine pitch printing, separation speed, stencil technology, stencil design, pad design, solder powder, tooling, solder paste, area ratio
[Permanent Link to this Paper ]
Posted on 15 Oct 2009
