One point relating to all PCB manufacturing processes, including selective soldering, is becoming increasingly clear: the use of manual production methods in any phase of production is rapidly declining. Industry developments, new technologies and economic forces create pressures on both products and manufacturers.
And these pressures – which include high density assemblies, narrow profit margins, increased international competition, and growing consumer demand for devices with greater functionality in smaller product footprints – are driving the need for complete PCB automation.
Laser soldering is a soldering method that has been used for many years, but mostly associated with big investments and bulky equipment. Not anymore, the recent development of laser systems has simplified and improved the possibilities for successful implementations in production processes.
Cencorp changes the traditional behaviour with the combination of Odd Form Assembly and Laser Soldering in one very compact cell.
Until now, assembly and soldering has always been two separate machines but with this new solution combines them in just one very compact unit.
While surface mount technology and reflow soldering has taken over most of the components and soldering on a PCB there are still in many cases odd components that needs to be handled and soldered separately at end of the production flow. These components can now be inserted and soldered simultaneously and fully automatically with the Cencorp1000LS and there is no need for turning the board upside down as the laser soldering process works from underneath.
Simplified process
Many PCB manufacturers still use a wave-soldering machine for these odd components and when the design not allows that process they are more or less forced to solder manually. Mini wave soldering is available but that’s quite a service demanding process and robot soldering with solder iron is also a possible method but must be done from above so the PCB must be turned upside down after insertion of the component.
Companies that have used a wave soldering process for many years still use it for those odd components and have to accept that it is quite a service demanding process for just a very few components nowadays.
For a double-sided populated PCBs that needs some sort of odd components mounted and soldered after all the other processes this new assembly and laser-soldering machine is perfect as it takes care of assembly as well as soldering of the odd components.
Cencorp developed that combined inline OF-assembly and Laser Soldering system that enables soldering from underneath while assembly components from above. With that solution there is no need for turning the PCB upside down. This is a benefit as turning unsoldered PCBs upside down always is a risk. Furthermore we have built this laser soldering process into our standard odd form assembly cell. The result is two processes in one machine with a length of just one meter. As we do not need to turn the PCB upside down we could replace our clincher with this new laser solder head.
This machine is very well suited in cases where odd components need to be inserted and soldered lately in the process flow.
The laser solder head can be tilted and rotated to enable optimisation of soldering parameters but also facilitate soldering of joints that are difficult or impossible to solder with other methods. A camera is built into the solder head to enable supervision of the laser soldering process.
Furthermore the laser beam diameter can be changed in size to suit different joints and a pyrometer is implemented for supervision of the process. A laser height sensor is built into the laser head for measurements of the distance between optics and PCB and based on that distance the laser head adjusts it
height and thereby enable correct position for laser and wire feed.
Lead-free soldering
The system is ready for the use of lead free solder. Laser soldering is a contact-less method and able to give very high quality joints. Thanks to the non-contact method it's a very clean process. The soldering parameters are easy to adjust and optimise for each different joint through the user interface.
To enable supervision of the two processes there is installed a LCD monitor in the machine door. It is then possible to choose between different cameras so either the solder process or odd form process can be supervised.
An opposition to using automated odd form placement and soldering is the idea that it is expensive to buy and that the return on such an investment makes it difficult to justify. Not true! The investment for the selective soldering equipment, including odd form placement, is minimal compared to the costs of due the slow production, uncertain quality, and growing labour rates – all expenses related to manual processes. The combined Cencorp odd form placement and laser soldering unit offers high profitability, fast production cycle and high output quality. u
Gunnar Mållaberg is a senior specialist with Cencorp Corporation, Virkkala, Finland. www.cencorp.com
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