Pulverization of waste printed circuit boards

Abstract

A new pulverization method to reduce the volume of waste printed circuit boards is reported. About 50% of printed circuit boards with integrate circuits (ICs) could be pulverized by our method in one 20-min batch, but boards without ICs could not be pulverized. By repeating the process three times, about 95% of printed circuit boards with ICs could be made into a fine powder with particles less than 106 µm. A weight-drop test was also performed to examine the strength of the printed circuit boards and clarify the mechanism of pulverization. When a weight was dropped on the solder-welding side of the board ruptures occurred more easily than when the weight was dropped on the IC-mounted side. With a heavy weight, the IC was fractured more easily when the potential energy was low. Where the stress was concentrated, two types of rupture location were found on printed circuit boards with ICs. One was where the IC was connected to the printed circuit board. The other was where the surface had undulations. It also became clear that the fracture of printed circuit boards depends on the impacting weight rather than on the potential energy.

Techniques to separate metal from waste printed circuit boards from discarded personal computers

“…As mentioned above, we previously reported that it is possible to perform fi ne pulverization of printed circuit boards with the chip components still attached at exceedingly high effi ciencies. 2 With regard to small chip parts, the concentration of precious metals is high and these parts are further miniaturized every year. In our process, we believe that pulverizing the printed circuit boards with the chip components still attached is a highly effective method for removing the small chip parts in particular.…”

“…2 The impact energy T (Ns), a relative value that indicates the degree of impact on the sample, was calculated using the following equation by setting the number of balls to B (units), the weight of a ball per unit to W (kg), and the ball acceleration rate to A (m/s 2 ):…”

“…2 Also, thermoset resins are used as the main material for printed circuit boards and for the mold resin for the built-in components; these resins do not melt even with the application of extreme heating. Further, brominated fl ame retardants (BFR) are added to the resins, 3 making combustion diffi cult, and when combusting these materials, there are concerns about the generation of toxic gases.…”

Characterization of waste printed circuit boards recycled using a dissolution approach and ultrasonic treatment at low temperatures

“…[1][2][3][4][5][6] Therefore, a number of methods have been developed and applied for treatment of WPCBs; these include mechanical separation, biological recycling, crushing, hydrometallurgical and pyrometallurgical treatment, pulverization, plasma treatment, etc. [7][8][9][10][11][12][13] However, many of these methods have certain restrictions related to energy consumption, process efficiency, recovery yield or recycling rate, economic protability, pollution rate, and a limited focus on metals or non-metals recovery only. [14][15][16][17][18] These problems emerged as a result of the complexity of WPCB structure, which is comprised of berglass reinforced with resin and metal parts having a high hardness and tenacity.…”

Materials Separation from Pulverized Waste Printed Circuit Boards

“…We have developed a method for pelletizing and pulverizing waste PCBs together with the attached ICs to a powder with a grain size of less than 106 µm, which reduces the volume of waste and also allows recovery of the metals (3) . We found the powder contained about 400 ppm Ag, 220 ppm Pd, and 200 ppm Au.…”