FIELD OF THE INVENTION

The invention relates to an E-waste demounting device adapted for processing E-waste objects, such as discarded electronic assemblies, for removing waste and for recovering reusable materials and items.

The invention further relates to a method for demounting an E- waste object.

The invention still further relates to use of a demounting liquid for demounting E-waste for purposes of recovering reusable materials and items present on an E-waste object and for removing waste there from.

BACKGROUND OF THE INVENTION

Electronic assemblies and systems generally consist of a variety of components that are mounted on a printed circuit board (PCB) with solder and/or adhesive interconnections (joints). Recycling of such components generally targets the recovery of precious and valuable metals from these components, with an initial step comprising suitable disconnection of these components from the PCBs.

It will be appreciated that waste from electrical and electronic equipment (typically quoted as WEEE or E-waste), such as TV sets, computers, mobile phones and the like is becoming an increasingly pressing matter due to an ever-increasing use and simultaneous decreasing lifespan of these products.

It is estimated that 20 - 50 million metric tons of electronic wastes per year are currently generated worldwide. Of this volume only a small fraction is collected, treated and recycled, with prevailing unsustainable practices, such as manual demounting and dumping. Conventional known solutions for demounting E-waste objects, such as PCBs, relate to burning or heating of the electronic assemblies on an open fire. This approach is widely used in developing countries. However, this approach has a severe disadvantage of substantial health and environmental hazards.

Another known approach for demounting E-waste relates to manual demounting of soldered electronic components by submerging them in an open solder bath. This step is followed by mechanically knocking out the parts on a table, see Moller T. "Beitrag zur automatisierten selektiven Entstukung von Leiterplatten", Shaker Verlag, Aachen, 1996.

The working principle of this process involves disconnection of the PCB's elements by conductive heating and subsequent mechanical agitation.

This method of waste demounting has a severe disadvantage in that unfavorable working conditions are maintained, in particular related to inhalation of metallic fumes.

A still further known method for E-waste demounting is based on dissolution of the solder by leaching agents, such as nitric acid, hydrochloric acid or aqua regia (which is a mixture of the two former examples). This method is usually referred-to as a chemical de-soldering, see Korzenski M.B.: "Electronic waste: A global problem = a global opportunity"; Advanced technology Materials ATMI (May 18, 2011).

The drawback of the known method is that it is very slow, having typical leaching times of several hours. In addition, it is a disadvantage of the common leaching method, such as known from EP 1 811 821, that the leaching reagents may adversely affect the components leading to their destruction.

German Offenlegungsschift DE4131620 discloses the use of a tin bath as a demounting liquid for demounting E-waste. SUMMARY OF THE INVENTION

It is an object of the invention to provide an efficient and safe E- waste demounting method, wherein the electronic waste is removed from an E- waste object, such as a PCB, while useful components are substantially maintained. It is a further object of the invention to provide an E-waste demounting device which enables efficient and safe processing of E-waste objects, such as PCBs for suitable recovering of reusable materials and items and for removing waste present on the E-waste objects.

It will be appreciated that E-waste in general may refer to any electronic appliance, irrespective of its size or usability. In particular, the invention is directed to removing materials and items from printed circuit boards, for example electronic components joined by solder and/or adhesive bonds may be freed and recovered. However, solder material may be recovered as well.

It will be further appreciated that the printed circuit board comprises a fibre-glass reinforced polymer core and copper plating, which defines conductive circuits. The electronic components that are mounted on the board include transistors, capacitors, integrated circuits and the like. Board components are commonly joined by solder joints and may incidentally be joined by conductive adhesive joints. It will be further appreciated that the suitable demounting liquid is chemically inert with respect to the items which have to be recovered. In particular, the demounting hquid is inert with respect to the electronic components freed from the PCBs. Preferably, the demounting liquid is capable of melting the solder and is capable of decomposing or melting any organic substances or polymers.

To this end the E-waste demounting device according to an aspect of the invention comprises a reservoir adapted to be at least partially filled with a working demounting liquid, wherein a temperature of the demounting hquid is in the range of 170 °C - 300 °C, preferably 220 °C - 250 °C . Then, preferably, a density of the demounting liquid is lower than a density of liquid soldering material, particularly liquid soldering material removed from the E-waste objects (during operation of the device).

For example, a density of the demounting liquid can be lower than 7.5 kg/dm ³ , and particularly lower than a density of molten soldering material that is to be removed.

According to a further embodiment, the density of the demounting liquid is lower than 7 kg/dm ³ , for example lower than 5 kg/dm ³ . Also, for example, the density of the demounting liquid can be higher than 2 kg/dm ³ . Particularly, the density of the demounting liquid can be higher than 3 kg/dm ³ , for example 4 kg/dm ³ or higher. In a preferred embodiment, the demounting liquid as such does not include tin.

For example, according to an embodiment, a density of the demounting liquid can be between 2 kg/dm ³ and 7.5 kg/dm ³ , preferably, in the range of 4 - 5 kg/ dm ³ .

Preferably, the demounting liquid is selected from the group consisting of: a molten salt, a molten metal, oil or grease. It will be appreciated that when anywhere in the description a reference is made to one of these materials, other materials from this group are contemplated as well.

The invention is based on the insight that the properly prepared demounting liquid may be efficiently and safely used for recovering useful materials, such as lead-free soldering.

It is found that by selecting the density of the demounting liquid between the respective densities of the solder (which is approximately 7.5 kg/dm ³ ) and the components (which is approximately 2 - 3 kg/dm ³ ) an efficient and selective demounting may be achieved. The temperature range of 170 °C - 300 °C, preferably 220 °C - 250 °C is selected to ensure that the solder materials and/or metals contained in conductive adhesives, for example, are demounted whereas the useful components are not destroyed by heat.

Preferably, the device according to an aspect of the invention comprises a receptacle for accommodating the object, the receptacle being suitable for receiving solid useful components freed from the object by the action of the demounting liquid.

It is further observed that when the solder material is removed, it sinks to the bottom of the reservoir, and is present there in a liquid form, while any useful solid components may be floating on the surface or may be collected elsewhere. Preferably, for collecting the melted solder a bottom surface of the reservoir may be inclined having a lowest portion for effectuating

sedimentation in the lowest portion. More details on this embodiment are given in Figure 2. The floating components may be easily collected from the surface.

In a further embodiment of the device according the invention, it further comprises a circulation enhancing unit for causing the liquid inside the reservoir to at least partially circulate or displace.

It is found that the demounting efficiency may be increased when there is a respective movement between the object and the demounting hquid accommodated in the reservoir.

In a further embodiment of the device, the circulation enhancing unit comprises a displaceable holder for holding the object and for displacing the object inside the hquid.

It is found that by suitably affixing the object to the holder and by allowing the holder to move inside the reservoir a substantial relative movement of the hquid and the object may be achieved. In a preferred embodiment, the circulation enhancing unit comprises a rotating carousel adapting for holding a plurality of objects. This embodiment has an advantage that a suitable plurality of the objects may be subjected to a simultaneous demounting.

In a still further embodiment of the device, the circulation enhancing unit comprises an ultrasonic source adapted to generate hquid vibration inside the reservoir. It is found that vibrations of the liquid with respect to the object are sufficient for providing a net movement between the object and the

demounting liquid. Preferably, a suitably tuned electronic transducer is used. The electronic transducer may be arranged around the outer wall of the reservoir, or, alternatively, the ultrasonic transducer may be arranged at a bottom surface of the reservoir.

In a still further embodiment of the device, the circulation enhancing unit comprises a mechanic unit adapted to cause the reservoir to vibrate.

It is also found that mechanical vibrations may be used as well. For example, the mechanical vibrator may be adapted to shake the reservoir as such thereby inducing a net displacement of the demounting liquid with respect to the objects.

In a still further embodiment of the device, the circulation enhancing unit is adapted to generate flow of the demounting hquid inside the reservoir.

For example, the circulation enhancing unit may be adapted with a suitable number of nozzles injecting the demounting liquid inside the reservoir. The reservoir may be further provided with an outlet port or ports where from the demounting hquid may be actively pumped. It will be appreciated that the discharged liquid may re-exit the reservoir from the nozzles when the device is operable using a closed circulation loop.

In a still further embodiment of the device according to an aspect of the invention, it further comprises a heater adapted to maintain the said temperature.

It will be appreciated that although it is possible to provide preheated demounting hquid into the reservoir, it may be advantageous to heat the demounting liquid inside the reservoir by the heater, as heat losses will be minimized. Preferably, the heater is arranged circumferentially about the outer surface of the reservoir. In a still further embodiment of the device according to a still further aspect of the invention, the salt is selected from the group consisting of: sodium nitrate (NaNOe), or a mixture of potassium nitrate (KNO3) and sodium nitrate. It will be appreciated that alternatively or additionally any further modifying agents such as sodium chloride (NaCl) and sodium sulphate (Na2SO ₄ ) may be used. Other options for salt compositions are mixtures of sodium hydroxide, potassium hydroxide and water (e.g., 75% NaOH, 19% KOH and 6% H ₂ O). Still another conceivable salt component is sodium nitrite (NaNO2).

The method for demounting E-waste objects, comprises the steps of:

- providing a demounting liquid in a reservoir;

- submerging at least an area comprising the waste in the demounting liquid, wherein a temperature of the demounting liquid is in the range of 170 °C - 300 °C, preferably 220 °C - 250 °C, particularly to melt soldering material of the E-waste objects, and/or wherein a density of the demounting liquid is lower than a density of the molten soldering material, more particularly a density such that soldering material, removed from the E-waste objects, sinks to a bottom of the reservoir.

According to an embodiment, a density of the demounting liquid is between 2 kg/ dm ³ and 7.5 kg/dm ³ , preferably, in the range of 4 - 5 kg/dm ³ .

In accordance with the method of the invention a procedure is provided wherein PCBs and/or other similar objects may be demounted automatically or semi-automatically, flexibly and efficiently, wherein a simultaneous recovery of the solder material and re-usable parts is possible. It will be appreciated that the method according to the invention may use a molten salt, a molten metal, oil or grease which are found to be a suitable demounting liquid which disconnects, separates and shields the useful components from the waste.

Use of the demounting liquid for demounting E-waste from an object in a reservoir according to the invention, is preferable under condition when a density of the demounting liquid is between 2 kg/dm ³ and 7.5 kg/dm ³ , preferably, in the range of 4 - 5 kg/ dm ³ and/or a temperature of the

demounting liquid is in the range of 170 °C - 300 °C, preferably 220 °C - 250 °C.

These and other aspects of the invention will be discussed with reference to drawings wherein hke reference signs correspond to like elements. It will be appreciated that the drawings are presented for illustrative purposes only and may not be used for limiting the scope of the appended claims.

BRIEF DESCRIPTION OF THE DRAWINGS

Figure 1 presents a schematic embodiment of the E-waste demounting device according to an aspect of the invention.

Figure 2 presents in a schematic way a further embodiment of the E- waste demounting device.

Figure 3 presents in a schematic way a still further embodiment of the E-waste demounting device.

DETAILED DESCRIPTION OF THE DRAWINGS

Figure 1 presents a schematic embodiment of the E-waste demounting device according to an aspect of the invention. The device 10 comprises a reservoir 2, such as a bath adapted for accommodating a working liquid 4 for carrying-out demounting from a suitable E-waste object 7. In accordance with an aspect of the invention for the suitable working fluid a molten salt is used. For example, sodium nitrate or a mixture of potassium nitrate and sodium nitrate may be used. In a particular embodiment, a mixture of 50-60% potassium nitrate and 50-40% sodium nitrate has shown superior results. Other embodiments of the suitable demounting liquid set forth in the foregoing may be used as well. Notably, the solder material may be used as a demounting liquid as well. The liquid 4 is preferably supplied by a suitable nozzle 3a and is conducted away by the outlet 3b. Preferably the outlet and the nozzle are in an external fluid communication so that a continuous flow of the liquid 4 inside the reservoir is maintained. The flow, or, in general, any displacement of the liquid 4 with respect to the at least partially submerged object 7 improves efficiency of demounting.

In an alternative embodiment, the displacement of the liquid 4 with respect to the object 7 is reached by inducing vibrations inside the reservoir 2. For example, an ultrasonic transducer 8a, 8b may be used. Preferably, the transducer is provided at a non-actively heated surface of the reservoir, such as a bottom surface 2b.

Still alternatively, the reservoir 2 itself may be subject to displacement in space, for example by coupling it to a mechanical vibrator.

It will be appreciated that the composition of the salt may be tunable on demand, depending on the constitution of the electronic waste which has to be demounted.

In an embodiment of the device, a temperature of the demounting liquid is in the range of 170 °C - 300 °C, preferably 220 °C - 250 °C, and/or a density of the demounting liquid is between 2 kg/dm ³ and 7.5 kg/dm ³ , preferably, in the range of 4 - 5 kg/ dm ³ . It is found that the given temperature range is particularly suitable for demounting lead-free soldering, such as SAC305 (alloy of SnAg3Cu0.5).

In order to preserve the working temperature inside the reservoir 2 the device 10 may comprise a heater 5a, 5b. Preferably, the heater is an elongated member which is cooperating with an outer surface 2a of the reservoir 10.

When a suitable E-waste object, such as a PCB 7 is introduced into the reservoir, the working hquid 2 demounts the electronic assembly with the constituting fractions gathering according to their relative density. Accordingly, the solder material shall be accumulated at a bottom of the reservoir 10 as a conglomerate 9.

Preferably, the bottom surface 2b has an inclination, so that the solder 9 is accommodated at the lowest collection point. For this purpose a suitable valve 3 may be envisaged.

Re-usable parts, such as electronic components 6 may be

advantageously floating on the surface of the liquid. It will be appreciated that when the density of the liquid 4 is larger than the density of the components, the components will have a positive buoyancy and shall drift on the surface. The components may be then collected from the surface and made ready for a suitable re-use.

Figure 2 presents in a schematic way a further embodiment of the E- waste demounting device. In this particular embodiment a different type of inclination of the bottom surface 2b is schematically presented. In this embodiment, the bottom surface 12 of the reservoir 2 has a uni-directional inclination, so that the material 13 accumulated at the bottom of the reservoir shall move in direction of the arrow 13a towards a collection point 15, wherein a conglomerate 14 may be formed.

This embodiment may have an advantage, because in this case the waste collection point is located close to a side wall 2a of the reservoir 2, leaving the remaining portion of the bottom surface 12 free for cooperating with a suitable mechanical vibrator 11.

It will be further appreciated that the demounting liquid 4 may have different levels of respective constituents. For the sake of clarity, an

imaginative line separating the constituents of the demounting liquid is indicated by 36. Region 36a may correspond to the demounting liquid

substantially formed of a molten salt, oil, metal or grease. Region 36b may then correspond to the deposition of the recoverable material from the E- waste, such as liquid solder material. In this case the object 7 is being substantially treated by the region 36a. However, it is also possible that the reservoir 2 is substantially filled with a hquid solder, which may be

accumulated during preceding demounting operations, such as SAC 305. It is noted that even in the case when the demounting liquid takes a very small volume of the reservoir with respect to a volume taken by the hquid solder, the object 7 may be adequately released from the E-waste as well.

Figure 3 presents in a schematic way a still further embodiment of the E-waste demounting device. In the present embodiment the E-waste demounting device 30 comprises a reservoir 32, which is arranged in fluid cooperation with a depositor 40. The depositor 40 is arranged for

accommodating heavier liquids 39 which shall be collected at the lowest level. Notably, hquid solder material or metals originally present in the object 7 shall be collected in the depositor 40. The depositor 40 is provided with a valve 33 for collecting the heavier liquids.

Preferably, the reservoir 32 is arranged to collect re-circulated demounting liquid which is transported through the piping 32b cooperating with the walls 32a of the reservoir 32. The conduit 32b may be provided with a pump (not shown) for effectuating transport of the demounting hquid from the bottom part of the reservoir 32 to an upper part of the reservoir 32.

In order to easily recover solid components freed from the object 7, the reservoir 32 may comprise a receptacle 37a for accommodating the object and for retaining the freed useful components. The receptacle may be preferably displaceable in the demounting hquid.

Molten plastic and/or organic materials due to their low density will be floating on the surface of the demounting liquid. They may be conveniently removed from the surface by skimming, for example.

While specific embodiments have been described above, it will be appreciated that the invention may be practiced otherwise than as described. The descriptions above are intended to be illustrative, not hmiting. Thus, it will be apparent to one skilled in the art that modifications may be made to the invention as described in the foregoing without departing from the scope of the claims set out below.