This is the second part of an article describing an innovative hybrid rework system from ERSA. Part one was published in the 16 April 2008 issue of Dataweek.
With the Hybrid Rework System HR100, IR radiation heat transfer is combined and enhanced via a precise amount of hot air. This unique hybrid tool can uniformly, safely and rapidly heat components ranging from 0201s up to SMD sizes larger than 20 x 20 mm. Three exchangeable hybrid adapters focus up to 200 W of heating power from the hybrid heating element, while neighbouring components remain protected from overheating and blowing away.
Homogenous heat radiation in the medium wavelength IR range, paired with gentle but concentrated convection, provides a unique mix for efficient rework soldering. For the small surfaces of modern CSP, QFN and MLF components, this combination of heating technologies provides ideal conditions for efficient heat transfer.
When compared to larger IR systems, the surface area profile of the radiation is quite small. Due to the shortened working distance to the component and the convective portion, however, the efficiency of the hybrid heat transfer is comparable or even superior to semi-automated IR machines (see Figure 4). Efficient and safe rework with the temperature gradients recommended by IPC is now possible with this bench-top unit.
With this innovative technology, ERSA has now bridged the gap between 'tools' and 'machines' with respect to rework. In general, bench-top rework applications are conducted by operators using a variety of handheld tools in order to complete their work quickly and safely. A hot air gun is frequently one of these tools, found on bench-tops around the globe. Such tools offer on the one hand quick and simple heating of SMDs, but on the other hand pose the serious risk of blowing away neighbouring chips. The hybrid tool offers all the advantages of a handheld hot air gun without the disadvantages. Flexibility combined with safety and process control are the value-added benefits of this new technology.
With the help of an integrated laser pointer in the ergonomic handle, the user focuses the hybrid heat energy to the component being worked without damaging the assembly housing. Even demanding repairs or component exchanges, for example, if the board is still inserted in the assembly housing, can be carried out without difficulty and safely with the hybrid tool (see Figures 5 and 6). This results in tremendous time savings for operators as they are no longer required to remove the PCB from its housing in order to perform rework.
Unlike hot air guns which require a myriad of different nozzles, the hybrid tool only needs three adapters and these are included standard with the system (see Figure 7). The visible countdown timer on the HR 100 offers operators the simplest form of process control which can be expanded upon to include closed-loop temperature profiling with an optional thermocouple (see Figure 8).
The HR 100 is a very flexible, low-cost solution for both beginners and advanced operators. When combined with the optional IRHP 100 (see Figure 9), however, this bench-top system can be expanded to offer many of the features seen in larger and more expensive rework machines. The Z-axis, height-adjustable tool holder for the hybrid tool and the X-Y PCB holder offer repeatable, machine-like results.
The powerful and highly reactive 800 W infrared heating plate guarantees safe, bottom side, closed-loop heating of the assembly during rework. This additional power from the bottom combined with the efficient hybrid heating technology allows operators to handle the most difficult, heavy mass rework applications where hot air fails. Figures 10 and 11 depict a heavy mass SMD with a ground plane which has been desoldered from a ceramic plate attached to an aluminium carrier.
Via a mini USB port, it is possible to connect the HR 100 to the tried and trusted ERSA IRSoft rework software platform which is used for all ERSA rework machines. This opens up new possibilities for operating this bench-top system.
The hybrid system now bridges the gap between rework tools and rework machines. In the same way as for the larger rework systems, the HR 100 can run a closed-loop, temperature-controlled process and document this completely via the IRSoft and PC interface (see Figure 12). Individual parameter settings, ramp-guided temperature profiles, 2-channel temperature recording and process documentation are all possible. Finally, password lockout and user administration rights offer a level of process safety not seen with hand-held or bench-top rework units.
Conclusion
Hybrid rework is not simply a fancy marketing slogan but rather the start of a new era for bench-top rework. The patented ERSA Hybrid Rework System HR 100 combines infrared and convection heating in a handheld device for safely soldering and de-soldering densely packed SMDs. Simplicity, flexibility, process control and documentation are the four pillars upon which this new technology is based.
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