Lead (Pb), is a toxic metal, harmful. And it is very destructive to the natural environment. Due to the requirements of environmental protection, especially the introduction of ISO14000, most countries in the world have banned the use of lead-containing components in welding materials, namely leadfree welding.
In 2004, Japan banned the production or sale of electronic production equipment using leaded materials for welding. In 2006, Europe and the United States banned the production or sale of electronic production equipment using leaded materials for welding. The use of lead-free soldering is the trend of the times, and some large-scale electronic processing enterprises in China will accelerate the development of lead-free soldering in China.
Dr. Iwona Turnik, Director of the Motorola Advanced Technology Center, presented in a market research report published by the IPC-sponsored Works99 conference:
1. 20% of consumers will take the initiative to consider environmental issues when purchasing.
2. 45% of consumers are motivated to purchase because the product is safe for the environment.
3. 50% of consumers change brands because they are found to be harmful to the environment.
4. 76% of consumers will choose environmentally friendly products first when prices and quality are comparable.
For example, all large consumer electronics companies in Japan are producing large quantities of lead-free electronic products, using "green products" as a competitive selling point, especially in the consumer electronics market. In 1998, Panasonic introduced a lead-free micro CD player with a green leaf on the packaging. As an environmental safety sign, the market share increased significantly: from 4.7% to 15%.
The automotive industry will be the main driver of the â€œlead-freeâ€ trend. Automotive â€œlead-freeâ€ is not only good for the environment, but also lead-free soldering improves the temperature resistance of the solder joints. Most automotive electronic components are installed in the engine compartment, so they are subject to higher operating temperatures (up to 150 degrees Celsius) and more severe temperature changes. The pressure of competition and the double concern of being excluded from the international market have led most of the world's major electronics manufacturers to prepare for lead-free products.
Director Gao Zhenjie of the Department of Economic Operations of the Ministry of Information Industry introduced that the "Measures for the Prevention and Control of Pollution Prevention of Electronic Information Products", which has been brewing for two years, is expected to be introduced during the year.
The management approach (first draft) stipulates that the design of electronic information products should consider their impact on the environment and human health, and should choose a program that is non-toxic, harmless, easy to degrade and easy to recycle. Producers should take measures to gradually reduce and electronic information products out of lead, mercury, cadmium, hexavalent chromium, bromo biphenyls polymerization (the PBB), polybrominated biphenyls polymerization ether (PBDE) content and other hazardous substances. The Directive on the Prohibition of the Use of Certain Hazardous Substances in Electrical and Electronic Equipment, promulgated by the European Union, stipulates that the sale of electrical and electronic equipment containing six hazardous substances such as lead, mercury and cadmium in the EU market will be banned from July 1, 2006. [next]
As a measure to deal with this directive, China has introduced this management method, and its lead-free timetable may be synchronized with the EU, which means that China will launch electronic information products in the national key regulatory directory on July 1, 2006. Can not contain the above six hazardous substances.
According to industry insiders, the introduction of this management method will mean that the electronic information industry is facing a technological revolution. Lead-free electronic products include lead-free solders, new fluxes, electronic assembly lead-free equipment, and new process parameters. Enterprises and research institutions need to attach great importance to and deal with them early, otherwise domestic enterprises will fall into a passive situation in the future domestic and international market competition.
In order to adapt to the changes in this series of welding processes and to meet the objective needs of the market, the process requirements of lead-free soldering have also become the work theme of many companies.
Lead-free soldering consists of lead-free solder, lead-free soldering tools, and a lead-free soldering environment. Each of these three components is critical to the success of lead-free soldering.
one. Lead-free solder:
Compared to conventional lead-containing solders, the principle of lead-free solders is to replace the original lead with some alloy mixtures, which is characterized by a melting temperature slightly higher than that of lead-containing solders.
Taking Sn/Ag alloy as an example, the melting temperature is 221 degrees Celsius, which is higher than the melting temperature of lead-containing solder by 183 degrees Celsius, while the melting point of other lead-free solders Sn/Ag/Cu is 218 degrees Celsius, and the melting point of Sn/Ag/Cu/Sb It is 217 degrees Celsius.
two. Lead-free soldering tools:
Lead-free soldering tools will not have much change in production equipment compared to previous lead-based soldering, and will face even greater challenges for rework processes.
As in the lead-free solders of the previous section, the principle of lead-free solders has been mentioned to replace the original lead by some alloy mixtures, and the composition of these alloy materials is the most used in Cu. Cu is readily oxidizable, CuO2 and oxides Cu lower than hardness, like iron oxide (rust). Once the Cu in the lead-free solder is soldered for too long during the soldering process, it is easily oxidized and eventually becomes a defect in product quality.
From this it can be concluded that the shorter the welding process, the more reliable the welding quality! [next]
There are a number of soldering irons on the market for lead-free soldering, and an experiment has been made (see table below):
The time required for the head to reach the temperature required for all welding loads
330 Â° C
330 Â° C
330 Â° C
330 Â° C
The following are two test conditions and results:
1. The temperature of the four soldering iron tips is set at 329Co, and each soldering iron head completes 10 solder joints in succession. When the temperature of each solder joint reaches the same temperature of 232Co, the next solder joint is completed.
When all 10 solder joints are completed, the total time required to record each soldering iron is as follows:
METCAL - 150 seconds PACE - 204 seconds WELLER - 245 seconds HAKKO - 316 seconds This test shows that the METCAL soldering iron takes the shortest time, indicating that its power output efficiency is high, more than double the speed of HAKKO.
2. If the four soldering irons are kept at the same welding speed, even if each soldering iron is used for 150 seconds, the other soldering irons must raise the temperature of the soldering iron, while the METCAL soldering iron still maintains the temperature of 329Co:
METCAL - 150 seconds - 329 Co PACE - 150 seconds - 349 Co
WELLER - 150 seconds - 380 Co HAKKO - 150 seconds - 409 Co
We can conclude that the Metcal SP200 is at least 25% faster than the others, and more than double the Hakko926ESD. [next]
Although lead-free soldering has put forward higher requirements for soldering tools, we have found that some lead-free soldering irons can meet the requirements of existing lead-free solders. The use of Metcal soldering iron can effectively prevent oxidation during soldering. Ensure the reliability of lead-free soldering.
three. Lead-free soldering environment:
Lead-free soldering environment refers to some surrounding environment that is decisive for the success of lead-free soldering during lead-free soldering. A more typical example is nitrogen protection during lead-free reflow, lead-free wave soldering, and lead-free chip-level rework.
The oxidation of metal objects mentioned in the section of the lead-free soldering tool in the previous section is due to the presence of oxygen during the soldering process, and nitrogen protection can avoid this phenomenon, thus ensuring the soldering of lead-free solder. The reliability of the welding quality during the process.
At present, the technology of lead-free reflow soldering and lead-free wave soldering is relatively mature, and the competition between brands has shifted from technology to price and service. The reason is that many lead-free reflow soldering and lead-free wave soldering manufacturers Consistent recognition of nitrogen protection technology.
In the lead-free chip-level rework, the BGA chip has been gradually popularized in the near future. Due to the particularity of its packaging characteristics, the BGA rework technology has been divided into two types: hot air and infrared.
The hot-air BGA rework station features reliable quality and controllable welding process. The infrared BGA rework station features fast speed.
In the hot air BGA rework station, some products provide nitrogen protection, which meets the basic requirements of lead-free soldering environment. The infrared BGA rework station accelerates chip oxidation due to the absence of nitrogen protection during lead-free soldering.
In the development of a new generation of computer CPUs, INTEL also adopted a lead-free soldering process and promoted a hot air rework system. The hot air rework equipment provided by OK International Group of the United States and INTEL jointly developed a new generation of computer CPUs. (pictured) [next]
The world today is increasingly concerned about the environmental and health hazards of lead. Although the use of lead in the electronics industry is only a tiny fraction of the world's total lead, our concern is that most of the e-waste is buried underground, polluting the planet and water.
Many companies today, especially some consumer electronics manufacturers in Japan, are producing lead-free products in large quantities and have achieved remarkable results. In addition, a large number of lead-free experiments on production, strength and service life have been carried out in different laboratories and production lines around the world. Perhaps these tests will unexpectedly prove that lead-free solder joints are stronger and have longer-term reliability than normal lead-containing solder joints under proper process operation.
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