I.C.T is a manufacturer of SMT machines. It mainly provides customers with SMT production lines including SMT Stencil Printers,  Pick and place machines, Reflow Oven, AOI Machine, Wave Soldering Machine and PCB Handling Machine etc. I.C.T has more than 25 researches on SMT and DIP technology,  for the world Customers provide SMT total solutions. There are successful cases of SMT technICal team in Asia, Europe, AmerICa, AfrICa, and Australia.

I.C.T provide SMT solutions at various stages according to the different needs of customers. I.C.T is not only a provider of SMT equipment and technology, but also is the customer's escort in the field of SMT and DIP.

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Because maximum temperature on the PCB remains the same, the process window shrinks to as little as 5° to 15°C. This narrower process window requires the oven to perform with greater levels of repeatability and accuracy as well as very tight on-board ∆Ts. For example, if the process window is 10°C and the ∆T on the PCB is 10°C, the process would be running with a zero margin of error. In addition to higher temperatures, most lead-free solder pastes require an extended period of time at liquidus — usually 60 to 90 seconds — rather than the traditional 40 to 60 seconds. As a result, the profile for lead-free reflow tends to differ from the typical tin/lead profile.

 Instead of rising to a relatively sharp peak and then dropping off, the heat rises to a higher level and remains at that plateau for a longer period of time. Reflow Ovens Taking into account material and process differences, the data point to forced-convection reflow oven use for these lead-free assemblies to maintain control at higher process temperatures. Nitrogen, which has the effect of widening the process window, is also recommended (but not required) by many lead-free paste suppliers. Process benefits of nitrogen include the use of lower melting point paste formulations (195°C) and improved solder flow and wetting angles. Nitrogen also may reduce discoloration caused by the higher temperatures and longer reflow times for lead-free pastes. Additionally, because lead-free joints tend to be duller than tin/lead joints, nitrogen can improve their appearance. However, in some markets, the cost of nitrogen generation steers manufacturers away from these formulations. 

While newer forced-convection ovens have been (and may continue to be) used for lead-free reflow development, the latest advances in oven design can enhance lead-free assembly implementation. These oven innovations include increased reflow zones, a change in zone configuration, a reduction in overall oven length and new center board-support options. Other developments in reflow technology, such as flux separation and collection systems, are responding to environmental requirements to minimize the oven’s effluent discharge. In an oven designed for lead-free processing, the number of reflow zones has increased, while the size of each individual zone has decreased .

The new configuration provides greater process control while maintaining higher temperatures more consistently at the same throughput rate. This configuration, including warm-up, reflow and cool-down sections, can be contained within a 150" oven length, providing throughput similar to a conventional 183" reflow oven. Redesigning the center board supports responds to the impact higher processing temperatures have on PCB materials. When temperatures rise above 150°C, the PCB enters a glass-transition phase that causes it to sag in the center. The higher the temperature, the greater the sag and the greater the possibility that the board may not recover its flat, rigid form. This is critically important for the first pass of a double-sided board, because second-pass screen printing on a warped board is regarded as a prescription for disaster. The newest design concept in center board support involves using the mechanism only in those areas of the oven where it is required — reflow and cooling. Typically, the supports that run the length of an oven require large, bulky rails that can block air flow to the PCB and increase the board’s ∆T. Additionally, the support mechanism can lower the overall board temperature, requiring different profiles for boards with or without the center support. 

Because boards do not sag appreciably when they are below the glass-transition temperature (150°C), reducing the length of the center support and eliminating it from the preheat section of the oven provides support only where the board needs it. The resulting shorter support rail also can be thinner than traditional rails, making it transparent to the PCB. Testing has shown that the ∆T across a PCB remains unchanged, and the overall board temperatures repeat to within 0.5°C, with or without the center board support installed.  

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