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How To Set Profile In I.C.T Lyra Series Reflow Oven 2

Temperature rising rate during preheating stage: In terms of heating stage, low temperature rising rate from room temperature to melting point is expected to reduce most of the defects. In order to get the best profile, temperature rising rate is recommended to be 0.5~1"C/second; for traditional profile, it is better to use a rate of 3~4·C/second.

 

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.

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Reflow soldering: Peak temperature during reflow soldering is usually decided by solder's melting temperature, base-panels' and components' heat-resisting temperatures. Generally, minimum peak temperature lies at around 30*C above solder's melting point (for currently used Sn63-pb solder, its melting point is 183*C, So the lowest peak temperature is about 210*C or so).

Too low peak temperature may lead to cold junction and inufficient wetting easily, and thus cold soldering due to insufficient melting. Generally, the highest temperature is about 235“C. If temperature is too high, epoxy base-panels and plastic parts may be coked and delaminated easily.

Moreover, excess co-boundary metal compounds will form, which may lead to bittle solder joints (soldering strength is affected).

Time length when temperature is over solder's melting point: Affected by such factors as co-boundary metal compound's formation rateand within-solder salt-base metal's decomposition rate, co-boundary metal compound's formation and deposition not only is directly proportional to temperature, but also to the time length when temperature is over solder's melting point. In order to reduce co-boundary metal compound's formation and deposition, time length when temperature is over solder's melting point must be reduced, which is generally set between 45~90 seconds. This time limit needs a high temperature-rise rate so that it can rise from melting point to peak temperature rapidly.

 

Meanwhile, components' resistance to thermal stress should be considered, so rising rate must be set between 2.5~3.5"C/second with the highest change rate of not more than 4·C/second.

Cooling: Low cooling rate when temperature is over solder's melting point will lead to the excessive formation of co-boundary metal compounds and form big grain structure on solder joints easily, thus reducing soldering strength. Generally, this phenomenon occurs at melting point or a temperature a lttle lower than the melting point.

Rapid cooling leads to too high a temperature gradient between components and base-panels, causing mismatched thermal expansions and leading to solder joints' and soldering pads' fissions and base-panels' deformation. In general, the permissible maximum cooling rate is determined by components' tolerance to thermal shock.

 

Considering all the above factors, cooling rate in cooling zone is generally set at about 4·C/second and it is okay when it cools to 75C.

 

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文章From:http://www.smt33.com//te_news_news/2021-09-02/30562.chtml