JP2003247031A - Refining method for removing residual lead and the like from recycled (regenerated) lead-free solder (solder containing tin as main component and no lead) - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a refining method for removing lead from tin with which a lead-free solder can be recycled by disolving such problem that the mixture of the lead into the lead-free solder can not avoided in many case, because ordinarily the lead solder and the lead-free solder are used in the same site in manufacturing and using when the lead-free solder (the tin is the main component) is recycled. <P>SOLUTION: The recycling lead-free solder material made into small blocks is charged into a rotating drum opening small holes, and in the case of slowly rotating the drum while keeping the inner part of the drum to a little lower temperature than the melting point of the recycling lead-free solder material, since the tin is made to brittle, the tin is cracked to form the cracked tin. Then, the lead, etc., can be separated and removed by making flow-down the lead (183°C melting point), etc., forming an eutectic material with the tin from the small holes. <P>COPYRIGHT: (C)2003,JPO

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for removing and refining lead and the like mixed in a lead-free solder reclaimed material due to lead-free solder (without using toxic lead) due to environmental problems.

[0002]

[Prior Art] Most of the conventional solders are lead-containing solders, so it is not necessary to remove lead even after recycling.

[0003]

In the past, solder was a term for solder containing lead, but recently, the toxicity of lead has become a problem, and the use of solder has begun to shift to lead-free solder that does not use lead. I will. Since lead-free solder has tin as a main component, even if you try to recycle and recycle, if a small amount of lead is mixed (generally, the lead content is 0.1% or less), the regenerated lead-free solder contains lead. Not available. The result is that it cannot be recycled as lead-free solder. Since the manufacturing site and the usage site of the solder are the same, it can be said that it is natural that lead solder containing lead is mixed with lead-free solder containing no lead. Common lead-free solders, which are currently mainstream, contain a lot of expensive silver, and tin is also an expensive metal. It is considered necessary to recycle by reusing it because it does not waste resources and is environmentally friendly.

[0004]

[Means for Solving the Problems] In order to solve the above problems, it is necessary to remove the mixed lead from the regenerated regenerated lead-free solder metal. Is used to remove lead, etc. When tin is heated to a temperature close to its melting point, it becomes extremely brittle and cracks with a slight impact. (Cracked tin is called cracked tin) Tin crystals are seen on the cracked surface, and the higher the purity of tin, the larger and coarser the tin crystals. Since lead-free solder is mainly composed of tin, if you keep it at a temperature close to the melting point with a rotating drum etc. and rotate it, the lead-free solder (melting point is generally around 200 degrees) will be finely cracked and broken tin, Etc. make a eutectic with tin (the eutectic of lead and tin has a melting point of 183 ° C), and the eutectic with a melting point lower than that of the lead-free solder and the low-melting substance will be eluted. By removing the eluate and adjusting the composition of the residual metal, it can be reused as the same lead-free solder, and it will also increase the utility value of recycled lead-free solder.

[0005]

BEST MODE FOR CARRYING OUT THE INVENTION If the lead-free solder is made into a small lump, and is put in a rotary drum or the like having small holes and is rotated slowly while maintaining a temperature close to the melting point of the put lead-free solder, the melting point is maintained. Eutectics such as lead below the temperature and substances with low melting points will not elute. It flows out from the small hole.

[0006] At that time, by mounting a blade inside the rotary drum and dropping the metal block from a higher appropriate position, the cracked tin can be efficiently produced. The position where the metal block is dropped can be adjusted by the width of the blade.

For continuous operation, the temperature is kept slightly lower than the melting point of the lead-free solder, the rotary drum is tilted and rotated, and the lead-free solder mass inside is gradually fed backward. Alternatively, while the rotating drum remains horizontal, the blade inside the drum is attached in a screw shape to send the lead-free solder blobs backward. Alternatively, the drum is fixed, the lead-free solder blobs are slowly rotated by the pressure-feeding screw, and the melt is sampled while sending backward, and the residue is automatically charged into the melting pot and melted, and samples are taken for component adjustment, We will cast it into a mold and use it as a base metal.

Analyzing the sample taken, melting the base metal,
Add necessary and deficient components to regenerate the original lead-free solder.

The extracted eluate is added with lead and used for general lead solder, or sent to a mine or the like to separate and recycle the component metals.

Claims (2)

[Claims] 1. A method for producing cracked tin at a temperature close to the melting point of lead-free solder. 2. A method for separating lead, bismuth, etc., which utilizes the difference in melting points between recycled lead-free solder and mixed lead, and a eutectic such as bismuth as a component.