Page 92 Continued from page 84
tem is hermetically sealed by means of a bulkhead after the workpiece carrier has been moved into place. A specific quantity of Galden®, which
www.us-
tech.com
has been matched to the PCBs, is then injected. After vaporization and heat
transfer to/into the PCBs, the Galden process medium is exhausted from
the chamber and reused. Vacuum can be generated in the process chamber during any desired process step. The PCBs are then cooled down outside of the process chamber. Pressure in the chamber can be
influenced by pre-vacuum and main vacuum. With the help of pre-vacu- um, outgassing which has already been released during the heat-up phase can be removed from the process chamber, making it possible to avoid contamination of the surfaces. Main vacu- um is generated when the solder is in the molten state in order to reduce voids. Time above liquidus
is increased by roughly 20 to 30 seconds. With the Condenso system, the vacuum option is avail- able for the entire dura- tion of the soldering process, making it possi- ble to fulfill highly specif- ic process requirements for soldering. For example, more
February, 2020 The Benefits of Vapor Phase Soldering with Vacuum
300 W/m2K, which is typical for the vapor phase soldering process. All modern vacuum soldering
processes provide the option of reduc- ing the void ratio in the solder joints through flexible vacuum manage- ment. Available thermal processes differ greatly despite their common goal of reducing void numbers and void size. In order to identify a suitable combination of a soldering process and
Figure 1: X-ray images of high-brightness LED solder joints with (top) and without vacuum (bottom).
uniform distribution of the gas (vapor) can be achieved by injecting the Galden into the pre-vacuum, so that a more homogeneous tempera- ture distribution can be ensured over the entire height of a product. PCBs with large thermal masses
can be uniformly heated up to solder- ing temperature, due to the very high heat transfer coefficient of up to 150 to
a vacuum application, the individual goals must be analyzed carefully. Contact: Rehm Thermal
Systems, LLC, 3080 Northfield Place, Suite 109, Roswell, GA 30076 % 770-442-8913 fax: 770-442-8914 E-mail:
c.kramer@
rehm-group.com Web:
www.rehm-group.com r
See at IPC APEX, Booth 707
Piezo Jet Valve Dispensing: Precise Dots at 1,500 Times Per Second
Continued from page 90
DL Technology has been the leader in micro dispensing technology for over 15 years. For more
www.dltechnology.com 216 River Street, Haverhill, MA 01832 • P: 978.374.6451 • F: 978.372.4889 •
sales@dltechnology.com
cutting-edge technology of a piezo jet valve represents a larger upfront investment than that of contact dis- pensing systems. However, it can be surprisingly comparable in cost to the older pneumatic jet valve. Further, helping significantly defray the lifecycle cost is the fact that the most expensive part of the system, the piezo assembly, is highly robust
and rated at around one billion cycles. Nevertheless, if a process will
not benefit from the highest speed dispensing available anywhere as well as super-high precision, the investment may not be worth it. But, if a quantum leap in throughput with super accuracy would be valuable, significantly boosting profitability, then a piezo jet valve is a highly desirable investment. Contact: Techcon, 10800 Valley
View Street, Cypress, CA 90630 % 714-230-2398 Web:
www.techcon.com r
See at IPC APEX, Booth 2247, and ATX/MD&M West, Booth 3063
Run with us.
There is no better way to reach the Electronic High Tech and Manufacturing
See at IPC APEX, Booth 2946
Community than advertising in U.S. Tech.
www.us-tech.com.
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