Transfer unit configured to transfer products during inter-factory transport in a clean environment from a first cleanroom to a second cleanroom

Abstract

Transfer unit configured to transfer products during inter-factory transport in a clean environment from a first cleanroom in a first factory to a second cleanroom in a second factory remote from the first factory, comprising: - a container having a plurality of panels that together enclose a compartment configured to receive the products; - a door opening in one of the side panels; - a passive pressure equalizer that is configured to equalize a pressure inside the compartment based on a pressure differential with an ambient pressure in an environment outside the container, comprising one or more than one equalization channel; and - an air conditioner that is in flow connection with at least one of the one or more than one equalization channel and configured to treat ambient air from the environment outside the container that enters to inside the compartment via the one or more than one equalization channel.

Description

[0001] Title: Transfer unit configured to transfer products during inter-factory transport in a clean environment from a first cleanroom to a second cleanroom

[0002] Description:

[0003] The present invention relates to a transfer unit configured to transfer products during inter-factory transport in a clean environment from a first cleanroom to a second cleanroom. More in particular, the first cleanroom is in a first factory, and the second factory is in a second factory, that is remote from the first factory. The inter-factory transport thus involves transport in an uncontrolled environment.

[0004] When transferring products between two cleanrooms, especially when contamination control is critical, a double packaging method is commonly used to ensure sterility and maintain cleanroom integrity. The double packaging method is widely used in industries such as pharmaceuticals, biotechnology, electronics (especially semiconductor manufacturing), and medical device production, where contamination control between cleanrooms is of paramount importance. This technique provides an additional layer of protection by isolating the products inside two layers of packaging, thereby minimizing the risk of contaminants transferring into the cleanroom environment.

[0005] In such a double packaging method, the products are double-bagged or double-packaged with outer and inner layers. The products are thus sealed within two separate layers of packaging - typically an inner sterile layer and an outer non-sterile layer. Each layer plays a specific role in preventing contamination. The outer layer of packaging is typically removed in a controlled environment (e.g., in a pass-through chamber or airlock) when the product moves into the second cleanroom. This ensures that any contamination that may have accumulated on the outer surface of the outer layer during transfer from the first cleanroom towards the second cleanroom, is not carried into the second cleanroom. The inner layer of packaging, being sterile, remains closed and protects the products until it is ready to be used inside the second cleanroom. The outer layer is designed to protect the products from gross contamination during handling and transport between the first and second cleanroom, i.e. when the products are present in areas with lower cleanlinessstandards. As mentioned above, the outer layer is intended to be removed upon entering the second cleanroom.

[0006] The inner layer is sterile and remains intact until the products are inside the second cleanroom. In this way, the inner layer acts as the ultimate barrier between the products and any contaminants that may exist outside the first and the second cleanroom.

[0007] While the double packaging method is highly effective in contamination control, also being flexible in the sense that the packaging can accommodate products of different sizes, shapes, and sterility requirements, it also comes with certain disadvantages.

[0008] One of the most prominent drawbacks is the generation of additional waste. Double packaging inherently means that twice the amount of packaging material is used compared to single-layer packaging. This leads to a significant increase in the volume of waste generated, particularly in industries such as pharmaceuticals, biotechnology, and electronics, where packaging must be disposed of after each transfer. Moreover, some of the materials used for sterile packaging, such as polyethylene bags, may not be easily recyclable or biodegradable. This can contribute to environmental concerns, especially when the packaging is disposed of in large quantities.

[0009] A further disadvantage of the double packaging method is that it is time-consuming and laborious. After all, it requires extra steps in both packaging and unwrapping. Employees must carefully handle and remove the outer layer in controlled environments, such as pass-through chambers or airlocks. This adds time to the overall process and can slow down production or transfer times. Moreover, it also requires personnel to be trained to ensure proper handling, removal of outer packaging, and avoiding of contamination during the process. Human mistakes in this process can lead to contamination, negating the benefits of double packaging, and even damage the products in a worst case scenario.

[0010] In the field of semiconductor manufacturing, this double-packaging method is particularly relevant. The standard solutions for transporting wafer cassettes within a single, highly controlled factory involve specialized containers such as Front-Opening Unified Pods (FOUPs) or Standard Mechanical Interface pods (SMIFs). These containers are specifically designed for intra-factory transport,meaning the movement of wafers between processing stations, typically within the confines of a single cleanroom. However, when these units must be transported between geographically separate facilities - i.e., inter-factory transport - they must leave this controlled environment. In this scenario, the FOUP or SMIF, containing its sensitive payload, is itself treated as the product to be shipped and is subjected to the conventional double-packaging method. The entire pod is placed within an outer, non-sterile packaging layer for protection during transit through uncontrolled environments. This reliance on double-packaging for the inter-factory transport of FOUPs and SMIFs carries with it all the aforementioned drawbacks, including significant waste and laborious handling procedures.

[0011] Even for their intended intra-factory use, the prior art for these FOUPs and SMIFs reveals different, and often conflicting, design philosophies for managing the container's internal environment.

[0012] One approach, exemplified by EP 1 388 165 B1, focuses on creating a self-contained, ultra-pure micro-environment inside a FOUP. This is achieved through a complex, closed-loop internal air conditioning system that uses a fan to continuously circulate the air already sealed inside the container through internal filters and a dehumidifier. The goal is to make the pod's interior significantly cleaner than the surrounding cleanroom. In this "hermetically sealed box" philosophy, interaction with the external atmosphere is avoided; pressure management is handled at a docking station by actively purging the container with a controlled source of clean, dry gas.

[0013] A second, contradictory approach is disclosed in US 5,740,845 for a SMIF pod. This document acknowledges that maintaining a perfect seal is difficult and that pressure differentials can cause structural damage, especially during air transport. It solves this with a "breather assembly" - a valve that is intentionally opened to the ambient environment to equalize pressure. For shipping, it is described that an object of the invention is to provide a breather assembly that can be maintained in an open position to prevent damage to the container from pressure changes. However, the document itself acknowledges that a container with "only an aperture and filter would not be able to maintain an inert environment isolated from the environment external to the SMIF pod.” Thus, this approach teaches that to prevent structural damage, the integrity of the sealed, clean internal atmospheremust be sacrificed. Notably, this document further suggests that alternative solutions involving actively injecting and removing gas can be expensive and may cause operational issues, such as the container door sticking.

[0014] Other specialized transport systems have been proposed for even more specific, niche problems. For example, WO 2019 / 032252 A1 discloses a portable pod for transferring wafers between vacuum processing systems. Its entire design is focused on preventing pressure equalization by using a passively capable vacuum pump to actively fight against any pressure increase during transport.

[0015] Another example, CN 116081081 B, discloses a transfer box designed to be used inside an air shower. Its key feature is a mechanism that allows the box to separate and expose its contents more effectively to the cleaning jets of the shower. This system is a cleaning aid, not a transport solution for moving products between cleanrooms.

[0016] In summary, the prior art is limited to: 1) small-scale, intra-factory containers (FOUPs I SMIFs) that are themselves double-packaged for inter-factory transport and offer conflicting internal design philosophies; or 2) highly specialized systems for niche problems like maintaining vacuum or enhancing cleaning.

[0017] There remains a need for an improved transfer unit that can serve as a reliable and reusable alternative to the wasteful double-packaging method, particularly for the long-distance, inter-factory transport of products through uncontrolled ambient environments, while simultaneously managing pressure differentials and maintaining the cleanliness of the internal compartment.

[0018] An objective of the present invention is to provide an alternative to the double packaging for inter-factory transport of products, that is improved relative to the prior art and wherein at least one of the above stated problems is obviated or alleviated.

[0019] Said objective is achieved with the transfer unit according to claim 1 of the present invention, that is configured to transfer products during inter-factory transport in a clean environment from a first cleanroom in a first factory to a second cleanroom in a second cleanroom remote from the first cleanroom, and that comprises:- a container having a plurality of panels comprising one or more than one side panel, a bottom panel and a top panel, that together enclose a compartment configured to receive the products;

[0020] - a door opening in one of the side panels, that is selectively closeable by a door of the transfer unit, and wherein a seal is configured to seal the door relative to the door opening in a closed state of the door;

[0021] - a passive pressure equalizer that is configured to equalize a pressure inside the compartment based on a pressure differential with an ambient pressure in an environment outside the container, wherein:

[0022] - the pressure equalizer comprises one or more than one equalization channel extending through at least one of the plurality of panels;

[0023] - when the pressure inside the compartment is lower than the ambient pressure, allow an underpressure inside the compartment to draw in ambient air to inside the compartment through the one or more than one equalization channel; and

[0024] - when the pressure inside the compartment is higher than the ambient pressure, allow an overpressure inside the compartment to escape through the one or more than one equalization channel towards the environment outside the container; and

[0025] - an air conditioner that is in flow connection with at least one of the one or more than one equalization channel and configured to treat ambient air from the environment outside the container that enters to inside the compartment via the one or more than one equalization channel .

[0026] By using a transfer unit, there is no need to apply double packaging comprising an inner layer and an outer layer. The transfer unit itself now acts as the packaging, adding additional benefits. First of all, the transfer unit is a rigid container, thereby providing a more reliable and re-usable “packaging”. There is no need anymore to throw away single used packaging of often hard to recycle material. Moreover, the use of a transfer unit reduces the need for highly trained personnel, and human errors, because it allows for a high level of automation. Also, the transfer time may be increased significantly, because the time-consuming and laborious tasks of both packaging and unwrapping are not necessary anymore.Conventional inner and outer layers of packaging used for double packaging methods, are flexible layers or bags. The flexibility of these packaging layers allows the packaging to easily compensate for pressure differences caused by varying weather conditions (such as alternating low and high pressure areas), varying temperature, etc. However, using a transfer unit that comprises a container having a plurality of panels, thereby forming a substantially rigid “packaging”, new challenges present themselves. For example, if the ambient pressure is higher than the pressure inside the container, there will be an underpressure inside the compartment relative to the environment outside the container. The effects of pressure differences is not to be underestimated. For example, a difference of only 0.1 bar in ambient pressure already concerns 10,000 N / m2, which can - dependent on the size of the door - already cause a significant load on seals that seal the door relative to the door opening when the door is closed. During transport, however, the air pressure differences can be much higher, which is certainly the case during air transport.

[0027] According to the invention, the pressure equalizer is configured to allow this underpressure inside the compartment to be equalized by ambient air for the environment outside the container, by allowing said ambient air to enter inside the compartment through the at least one equalization channel.

[0028] According to the invention, the pressure inside the compartment is considered to be equalized with the ambient pressure outside the container, if the pressure difference between these pressures is low enough to prevent the seal from leaking. The pressure at which the seal may start leaking is highly dependent on dimensioning of the container, and in particular the sizing of the door. After all, the Sl-unit for pressure, i.e. Pascal, is expressed in N / m2. Consequently, a larger area results in a higher force. After all, in case of such a limited pressure difference, the loads on the container caused by any pressure difference stay within an acceptable range to guarantee that the clean environment may be safely maintained.

[0029] The present invention provides a solution based on the insight that rather than attempting to maintain a perfect hermetic seal against external pressure changes, or conversely, allowing uncontrolled exchange with the ambient environment, a superior result is achieved by allowing for controlled pressure equalization while simultaneously conditioning any ambient air that enters the unit.To this end, the pressure equalizer is a passive pressure equalizer that comprises one or more than one equalization channel extending through at least one of the plurality of panels, and the air conditioner is in flow connection with at least one or more than one equalization channel that allows ambient air to enter to inside the compartment.

[0030] More specifically, the pressure equalizer is configured to:

[0031] - when the pressure inside the compartment is lower than the ambient pressure, allow an underpressure inside the compartment to draw in ambient air to inside the compartment through the one or more than one equalization channel; and - when the pressure inside the compartment is higher than the ambient pressure, allow an overpressure inside the compartment to escape through the one or more than one equalization channel towards the environment outside the container.

[0032] Crucially, the air conditioner is configured to treat the ambient air that is drawn into the compartment via the equalization channel. This ensures that contaminants from the uncontrolled external environment are not introduced into the clean compartment, allowing the internal clean environment to be maintained even while the unit is equalizing pressure with the outside world. This unique combination provides a robust and reliable solution for inter-factory transport, effectively replacing the wasteful double-packaging method while ensuring product integrity.

[0033] According to a preferred embodiment, one equalization channel is configured to allow air to flow therethrough in two directions to thereby allow air to escape via said equalization channel from the compartment to the environment outside the container, and allow ambient air to be drawn into the compartment. If the equalization channel is configured to allow air to flow therethrough in two directions, it is possible to simplify the design, possibly even to only one equalization channel in total.

[0034] According to a further preferred embodiment, the air conditioner comprises one or more than one of: a particle filter; and an activated carbon filter. The particle filter may be a HEPA filter.

[0035] According to an even further preferred embodiment, the air conditioner comprises a dehumidifier, that preferably comprises silica.According to an even further preferred embodiment, the container comprises:

[0036] - a door actuator for actuating a door lock when the transfer unit is docked to the first cleanroom or the second cleanroom;

[0037] - an interface that is arranged at an outside of the container that allows the door actuator to be actuated from the outside of the container when the transfer unit is docked to the first cleanroom or the second cleanroom. More in particular, the transfer unit is preferably docked to a docking station of the cleanroom.

[0038] According to an even further preferred embodiment, the door, in the closed state thereof, is arranged inside the door opening to form a substantially flush outer side of the container that is defined by the door and the side panel that comprises the door opening.

[0039] According to an even further preferred embodiment, the door defines an inner door, and the transfer unit further comprises an outer door that is oversized relative to the inner door and configured to completely shield off the inner door when the outer door is closed.

[0040] According to an even further preferred embodiment, the one or more than one equalization channel is further configured to be arranged in a flow connection with the first cleanroom or the second cleanroom. More in particular, the transfer unit is preferably in flow connection with the docking station of the cleanroom, to which it is docked.

[0041] According to an even further preferred embodiment, the bottom panel comprises a guide that is configured to receive a product carrier and reinforce the bottom panel. Because the guide reinforces the bottom panel, the bottom panel itself may be lightweight, while still being able to fulfill a load bearing functionality thanks to the guide. The guide and the product carrier provide a rigid support for carrying the products, and consequently the functionality of the container is merely to provide a compartment. However, this compartment does not have to provide constructional rigidity for carrying the products.

[0042] According to an even further preferred embodiment, the panels are made of a material comprising a density in the range of 910 - 970 kg / m3, and are preferably made of a plastic.According to an even further preferred embodiment, the panels are double walled. Vent holes allow an pressure inside the double walled panels to equalize with the ambient pressure.

[0043] According to an even further preferred embodiment, the panels are made via rotational molding. Rotational molding allows the panels to be formed as thin walled parts, thereby reducing the overall weight of the transfer unit, which is advantageous for logistics of said transfer unit. After all, the container itself has only very limited constructional functionality, because the products that are to be received inside the compartment of the container may be placed on a product carrier that defines a rigid support. Moreover, such thin walled parts may be made in mass production, such as via a rotational molding process.

[0044] According to an even further preferred embodiment, the footprint of the transfer unit has a maximum length of 1200 mm and a maximum width of 1200 mm. In this way, the transfer unit will fit in conventional transport means that is designed for the most common types of standardized EUR pallets. Consequently, the transfer unit may be securely handled with conventional products that are capable of handling and transporting standardized.

[0045] According to an even further preferred embodiment, the transfer unit comprises a pallet type carrier having dimensions of 800 x 1200 mm, or having dimensions of 1000 x 1200 mm. In this way, the transfer unit comprises a universal transport interface, and may be securely handled with conventional products that are capable of handling EUR-pallets of types EUR 1 or EUR 3, such as pallet trucks, forklifts, and many commercially available Automated Guided Vehicles (AGV) that are designed for pallet transport. After all, the dimensions of 800 - 1200 mm correspond to the “EUR 1 type” pallet as described in the standard UIC Code 435-2, titled “Standard of quality for EUR flat pallets made of wood measuring 800 mm x 1200 mm (EUR-1)”. The alternative dimensions of 1000 x 1200 mm correspond to the “EUR 3 type” pallet, as described in the standard UIC Code 435-5.

[0046] Preferred embodiments are the subject of the dependent claims.

[0047] The various aspects and features described and shown in the specification can be applied, individually, wherever possible. These individual aspects, and in particular the aspects and features described in the attacheddependent claims, may be an invention in its own right that is related to a different problem relative to the prior art.

[0048] In the following description preferred embodiments of the present invention are further elucidated with reference to the drawing, in which:

[0049] Figure 1 is a schematic view of an embodiment of a system according to an aspect of the present invention;

[0050] Figure 2 is a schematic view of an embodiment of a method according to another aspect of the present invention;

[0051] Figure 3 - 11 are schematic views of respective sub steps of the method of Figure 2;

[0052] Figure 12 - 32 are perspective views of elements of an embodiment of the system according an aspect of the present invention, wherein the system is shown in different states during respective sub steps of the method of Figure 2;

[0053] Figure 33 is a detailed perspective view of a transfer unit according to the invention;

[0054] Figure 34 is a further perspective view of the transfer unit of Figure 33, with a top cover removed;

[0055] Figure 35 is a cross sectional side view of the transfer unit of Figures 33 and 34;

[0056] Figure 36 is a detailed cross sectional side view of a top section of the transfer unit of Figures 35;

[0057] Figure 37 is a perspective exploded view of the transfer unit of Figures 33-36;

[0058] Figure 38 is a cross sectional view of Figure 37; and

[0059] Figure 39 is a detailed perspective view of the locking mechanism.

[0060] The system 1 shown in the schematic view of Figure 1 is configured to transfer products 10 in a clean environment during inter-factory transport from a first cleanroom 50 to a second cleanroom 70. The first cleanroom 50 is in a first factory, and the second cleanroom 70 may be in a second factory, remote from the first factory. As a result the transfer of products 10, such as multiple SMIFs and / or FOUPs, comprises inter-factory transport, through an uncontrolled environment. The first cleanroom 50 comprises a docking station 51 , an outer door 53, an inner door55 of the first cleanroom 50, an inner door 59 of the first docking station 51 , and a conveyor 57. The second cleanroom 70 is similar to the first cleanroom 50, and consequently the second cleanroom 70 comprises a docking station 71, an outer door 73, an inner door 75 of the second cleanroom 70, an inner door 79 of the second docking station 71, and a conveyor 77. The system 1 furthermore comprises at least one transfer unit 3 configured to be releasably connectable to either one of the docking station 51 of the first cleanroom 50 or the docking station 71 of the second cleanroom 70. The transfer unit 3 comprises an outer door 5 and an inner door 7, and is configured to transport the products 10, that is preferably arranged on a product carrier 11.

[0061] The plural form “products” is used throughout this application, because the method is particularly suitable to transfer multiple products 10 at once. The invention may however also be used to transfer a single product 10 at a time, especially if it concerns a large product. The transfer unit 3 is however used over and over again, in the end transferring a plurality of products 10, ether at the same time or subsequently.

[0062] The system 1 is configured to perform the steps of a transfer method TM, for transferring the products 10 in a clean environment from the first cleanroom 50 to the second cleanroom 70, as shown schematically in Figure 2. More in particular, it is verified that the transfer unit 3 is ready to safely transfer said products 10 in a clean environment, ensuring sterility and maintaining cleanroom integrity.

[0063] In a most preferred embodiment, that is now elucidated with reference to the Figures, the transfer method TM comprises the subsequent steps of:

[0064] A) verifying that the transfer unit 3 is ready to receive and transfer products 10 in a clean environment;

[0065] B) docking the transfer unit 3 to the docking station 51 of the first cleanroom 50 in the first factory;

[0066] C) transferring the products 10 from the first cleanroom 50 to the inside 9 of the transfer unit 3, and more in particular to inside the compartment 8 of the transfer unit 3;

[0067] D) undocking the transfer unit 3 from the docking station 51 of the first cleanroom 50; E) transporting the transfer unit 3 from the first cleanroom 50 in the first factory to the second cleanroom 70 in the second factory, wherein the transporting stepcomprises equalizing a pressure inside the compartment 8 of the transfer unit 3 based on a pressure differential with an ambient pressure in an environment outside the transfer unit 3 while treating ambient air that enters the compartment 8 with an air conditioner 15 to maintain the clean environment inside the compartment 8 of the transfer unit;

[0068] F) docking the transfer unit 3 to the docking station 71 of the second cleanroom 70; G) transferring the products 10 from the transfer unit 3 to inside the second cleanroom 70 in the second factory; and

[0069] H) undocking the unloaded transfer unit 3 from the second cleanroom 70.

[0070] The step B) of docking the transfer unit 3 to the docking station 51 of the first cleanroom 50 is finalized with the step of opening the transfer unit 3.

[0071] According to a preferred embodiment, this opening of the transfer unit 3 comprises opening of an inner door 7 thereof, said opening of the inner door 7 being executed after step B7) as described below.

[0072] It is remarked that the docking station 51 of the first cleanroom 50 belongs to the first cleanroom 50, and that the docking station 71 of the second cleanroom 70 belongs to the second cleanroom 70. Thus, e.g. the step C) of transferring the products 10 from the first cleanroom 50 to inside the transfer unit 3 also encompasses transferring said products 10 from the docking station 51 of the first cleanroom 50 to inside the transfer unit 3. Likewise, the step G) also encompasses transferring the products 10 from the transfer unit 3 to inside the docking station 71 of the second cleanroom 70. After all, said docking station 70 is part of the second cleanroom 70.

[0073] The step D) of undocking the transfer unit 3 from the docking station 51 of the first cleanroom 50 starts with a closing of the transfer unit 3, thereby confining the products 10 in the clean environment inside the transfer unit 3.

[0074] Like step B), also step F) of docking the transfer unit 3 to the docking station 71 of the second cleanroom 70 is finalized with the step of opening the transfer unit 3. According to a preferred embodiment, this opening of the transfer unit 3 comprises step F8) of opening of an inner door 7 of said transfer unit 3, said opening of the inner door 7 being executed after step F7) as described below.

[0075] Different states of elements of the system 1 are shown in more detail and in perspective views in Figures 12 - 32, corresponding to the steps A) - D) ofthe transfer method TM as described above. In Figures 17 - 28, the perspective views are shown in cross-section. Figures 12-32 are shown in relation to the first cleanroom 50. It is however remarked that the procedure for the second cleanroom 70 is identical for the procedure for the first cleanroom 50. The Figures are therefore applicable in a same manner to the second cleanroom 70. Furthermore, the Figures are applicable, in reverse order, to the steps F) - H) of the transfer method TM for the first cleanroom 50 and the second cleanroom 70.

[0076] By using a transfer unit 3, there is no need to apply double packaging comprising an inner layer and an outer layer. The transfer unit 3 itself now acts as the packaging, adding additional benefits. First of all, the transfer unit 3 is a rigid container, thereby providing a more reliable and re-usable “packaging”. There is no need anymore to throw away single used packaging of - often - hard to recycle material. Moreover, the use of a transfer unit 3 reduces the need for highly trained personnel, and human errors, because it allows for a high level of automation. Also, the transfer time may be increased significantly, because the time-consuming and laborious tasks of both packaging and unwrapping are not necessary anymore.

[0077] Moreover, the transfer unit 3 itself may be recyclable

[0078] It is remarked that especially step A) of verifying that the transfer unit 3 is ready to receive and transfer products 10 in a clean environment, and step H) of undocking the unloaded transfer unit 3 from the second cleanroom 70 are optional, but preferred, steps. In the following, the most preferred embodiment is described, consequently also describing some steps that may be optional.

[0079] The transfer method is only executed further if the verification step A) indicates that the transfer unit 3 is indeed ready to receive and transfer products in a clean environment. If this is not the case, the transfer method is aborted, and the transfer unit 3 is rejected for transferring of the products. Another transfer unit 3 may be provided, and step A) of verifying is repeated for this other transfer unit 3.

[0080] The step A) of verifying that the transfer unit 3 is ready to receive and transfer products 10 in a clean environment, as shown schematically in more detail in Figure 3 and Figures 12 - 14, furthermore comprises the subsequent sub steps of: A1 ) opening an outer door 5 of the transfer unit 3 and thereby exposing an inner door 7 of the transfer unit 3, wherein Figure 13 shows the transfer unit 3 with theouter door 5 open (and positioned in parallel to a side panel 6s of said transfer unit 3);

[0081] A2) inspecting an outside of the transfer unit 3 for contamination or damages, and rejecting the transfer unit 3 when contamination or damages exceed a predetermined level; and

[0082] A3) cleaning at least an outer side of the inner door 7 of the transfer unit 3 with a cleaning agent, wherein Figure 14 shows the transfer unit 3 in the inspecting and cleaning position.

[0083] The step of inspecting the outside of the transfer unit 3 for contamination is performed by an inspecting procedure well known to, and commonly applied by, skilled persons in this type of field. As an example, reference is made to the NEN-EN-ISO 14644-9:2022, IDT, standard of the International Organization for Standardisation (ISO), that is titled “Cleanrooms and associated controlled environments - Part 9: Assessment of surface cleanliness for particle concentration”. Annex D of this norm is directed to “Measurement methods for determining surface cleanliness by particle concentration”, and discusses criteria for the measurement, requirements for the measurement, as well as measurement methods. Exemplary measurement methods mentioned are, amongst others, visual inspection, using light microscopes (with image processing), and oblique-, glancing-, side-light systems (with image processing).

[0084] The transfer unit 3 comprises an inner door 7 and an outer door 5, wherein the outer door 5 is configured to completely shield off the inner door 7 from the environment when said outer door 5 is closed. In step A1), the outer door 5 is opened when the transfer unit 3 is near the first cleanroom 50, ready to be connected to the docking station 51 of the first cleanroom 50 shortly thereafter if it is assessed to be safe to do so.

[0085] The step A2 of inspecting the outside of the transfer unit 3 for contamination or damages particular comprises inspecting an area near the inner door 7 of said transfer unit 3 for contamination and potential damages.

[0086] The step B) of docking the transfer unit 3 to the docking station 51 of the first cleanroom 51, as shown schematically in more detail in Figure 4 and Figures 15 - 18, additionally comprises the subsequent sub steps of:B1 ) opening an outer door 53 of the docking station 51 of the first cleanroom 50, wherein Figures 16 and 17 shows the docking station 51 with the outer door 53 open;

[0087] B2) moving the transfer unit 3 to the docking station 51 of the first cleanroom 50; B3) aligning the transfer unit 3 relative to the docking station 51 of the first cleanroom 50;

[0088] B4) connecting the transfer unit 3 to the docking station 51 of the first cleanroom 50; B5) flushing a grey area between the inner door 7 of the transfer unit 3 and an inner door 59 of the docking station 51 of the first cleanroom 50;

[0089] B6) levelling a pressure inside the transfer unit 3 with a pressure inside the docking station 51 of the first cleanroom 50; and

[0090] B7) opening an inner door 59 of the docking station 51 of the first cleanroom 50 wherein Figure 18 shows the docking station 51 with the inner door 55 of the first cleanroom 50 and the inner door 59 of the first docking station 51 open;

[0091] It is remarked that especially step B3) of aligning the transfer unit 3 relative to the docking station 51 of the first cleanroom 50, and step B5) of flushing a grey area between the inner door 7 of the transfer unit 3 and an inner door 59 of the docking station 51 of the first cleanroom 50 are optional, but preferred, steps.

[0092] The step B2) of moving the transfer unit 3 to the docking station 51 of the first cleanroom 50 optionally comprises the step B2.1) of conveying the transfer unit 3 to a docking station 51 of the first cleanroom 50 with a conveyor 57 that is associated with the docking station 51 of the first cleanroom 50. The conveyor 57 allows the transfer unit 3 to be moved towards the docking station 51 in a controlled and repeatable manner, that does not require any manual interference.

[0093] The optional step B3) of aligning guarantees that the transfer unit 3 approaches the docking station 51 in an aligned manner, thereby providing an evenly distributed load on a seal 61 (Figure 17) between the docking station 51 and the transfer unit 3. Although it is conceivable that the transfer unit 3 is aligned prior to the step B2) of moving the transfer unit 3 to the docking station 51 , it is more likely and preferred that the step B3) of aligning of the transfer unit 3 takes place after or simultaneously with the step B2) of moving the transfer unit 3 to the docking station 51. For example, the step B2) of moving may force the transfer unit 3 to move along a (not shown) guide that causes the alignment of said transfer unit 3.Step B5) of flushing a grey area 60 (Figure 17) between the inner door 7 of the transfer unit 3 and an inner door 59 of the docking station 51 of the first cleanroom 50 is an optional step. Preferably, the first cleanroom 50 comprises an inside pressure that is higher than the pressure in the grey area 60 between the inner door 7 of the transfer unit 3 and the inner door 59 of the docking station 51 of the first cleanroom 50. Due to this overpressure, clean air leaving the first cleanroom 50 may be used to flush the grey area 60, thereby reducing the risk of any contaminants entering the first cleanroom 50 when the inner door 59 of the docking station 51 of the first cleanroom 50 is opened after said flushing.

[0094] The step B6) of levelling a pressure inside the transfer unit 3 with a pressure inside the docking station 51 of the first cleanroom 50, so that an equilibrium in pressure is obtained before the step B7) of opening the inner door 59 of the docking station 51 of the first cleanroom 50 is performed.

[0095] The step C) of transferring the products 10 from the first cleanroom 50 to inside the transfer unit 3 in particular comprises the step of C1 ) of transferring the products 10 with a product carrier 11 from the first cleanroom 50 to inside the transfer unit 3. Step C1), as shown schematically in more detail in Figure 5 and Figures 19 - 28, further comprises the subsequent sub steps of:

[0096] C1.1 ) opening the inner door 55 of the first cleanroom 50, thereby providing a passage from the first cleanroom 50 to the docking station 51 of the first cleanroom 50, wherein Figure 19 shows the transfer unit 3 with the inner door 7 open and the inner door 55 of the cleanroom 50 open;

[0097] C1.2) transferring the product carrier 11 from the first cleanroom 50 to the docking station 51, wherein Figure 20 shows the product carrier 11 in the docking station 51; C1.3) closing the inner door 55 of the first cleanroom 50, wherein Figure 21 shows the inner door 55 of the cleanroom 50 closed;

[0098] C1.4) transferring the product carrier 11 from the docking station 51 to inside the transfer unit 3 that is docked to the docking station 51 of the first cleanroom 50, wherein the steps of transferring the product carrier to the transfer unit 3 are shown in Figures 22 - 25;

[0099] C1.5) closing the inner door 7 of the transfer unit 3 and thereby confining the products 10 safely and secure in the clean environment inside the transfer unit 3,wherein Figure 26 shows the transfer unit 3 with the inner door 7 closed and Figure 27 shows the inner door 59 of the docking station 51 closed; and

[0100] C1.6) disconnecting the transfer unit 3 from the docking station 51 of the first cleanroom 50, wherein Figure 28 shows the transfer unit 3 disconnected from the docking station 51.

[0101] It is remarked that especially step C1.3) of closing the inner door 55 of the first cleanroom 50 is an optional, but preferred, step. This optional step C1.3 guarantees that the first cleanroom 50 has no open connection to the docking station 51 while the product carrier 11 is transferred from the docking station 51 to inside the transfer unit 3, and consequently there is a minimum of air escaping from the first cleanroom 50.

[0102] The step D) of undocking the transfer unit 3 from the docking station 51 of the first cleanroom 50, as shown schematically in more detail in Figure 6 and Figures 29 -32, furthermore comprises the subsequent sub steps of:

[0103] D1) moving the transfer unit 3 away from the docking station 51 of the first cleanroom 50;

[0104] D2) closing the outer door 53 of the docking station 51 of the first cleanroom 50, wherein Figure 29 shows the outer door 53 of the docking station 51 closed;

[0105] D3) cleaning an outside of the transfer unit 3 with a cleaning agent, wherein Figure 30 shows the transfer unit 3 in the cleaning position; and

[0106] D4) closing the outer door 5 of the transfer unit 3 to thereby cover and shield the inner door 7 of the transfer unit 3 off from the environment, wherein Figure 31 shows the transfer unit 3 with the outer door 5 closed and Figure 32 shows the transfer unit 3 in the position ready to be transported.

[0107] It is remarked that especially step D3) of cleaning an outside of the transfer unit 3 with a cleaning agent, and step D4) of closing the outer door 5 of the transfer unit 3 to thereby cover and shield the inner door 7 of the transfer unit 3 off from the environment are optional, but preferred, steps. The cleaning agent may be isopropyl alcohol (IPA), or a similar cleaning agent.

[0108] The step D1) of moving the transfer unit 3 away from the docking station 51 of the first cleanroom 50 optionally comprises the step D1.1) of conveying the transfer unit 3 away from the docking station 51 by the conveyor 57 that is associated with the docking station 51 of the first cleanroom 50.The step E) of transporting the transfer unit 3 from the first cleanroom 50 to the second cleanroom 70, as shown schematically in more detail in Figure 7, preferably comprises the sub step E1) of levelling a pressure inside the transfer unit 3 with a pressure in an environment outside the transfer unit 3 while maintaining the clean environment inside the transfer unit 3. This sub step E1) of levelling the pressure inside the transfer unt 3 with the environmental pressure outside the transfer unit 3 allows the transfer unit 3 to transfer the products in varying conditions, such as changes in air pressure due to weather changers, variations in temperature, etc. This allows the products to be transferred over longer distances, especially between buildings that are geographically remote from each other, thereby requiring road transport, or possibly even air transport. Because the transfer unit 3 itself defines a reliable “packaging”, transport of the transfer unit 3 may even be outsourced to a logistics partner, outside the direct control of the manufacturer, supplier or owner of the products.

[0109] The step F) of docking the transfer unit 3 to the docking station 71 of the second cleanroom 70, as shown schematically in more detail in Figure 8, furthermore comprises the subsequent sub steps of:

[0110] F1) verifying if the transfer unit 3 is ready to transfer the products 10 to the second cleanroom 70;

[0111] F2) opening an outer door 73 of the docking station 71 of the second cleanroom 70; F3) moving the transfer unit 3 towards the docking station 71 of the second cleanroom 70;

[0112] F4) connecting the transfer unit 3 to the docking station 71 of the second cleanroom 70;

[0113] F5) flushing a grey area 60 between the inner door 7 of the transfer unit 3 and the inner door 79 of the docking station 71 of the second cleanroom 70;

[0114] F6) levelling a pressure inside the transfer unit 3 with a pressure inside the docking station 71 of the second cleanroom 70;

[0115] F7) opening the inner door 79 of the docking station 71 of the second cleanroom 70; and

[0116] F8) opening the inner door 7 of the transfer unit 3.It is remarked that especially step F5) of flushing a grey area between the inner door 7 of the transfer unit 3 and the inner door 79 of the docking station 71 of the second cleanroom 70 is an optional, but preferred, step.

[0117] The step F 1 ) of verifying if the transfer unit 3 is ready to transfer the products 10 to the second cleanroom 70, as shown schematically in more detail in Figure 9, preferably comprises the sub steps of:

[0118] F1.1 ) opening the outer door 5 of the transfer unit 3, thereby exposing the inner door 7 of the transfer unit 3 that is covered and shielded off from the environment when the outer door 5 of the transfer unit 3 is closed;

[0119] F1.2) inspecting the outside of the transfer unit 3, and rejecting the transfer unit 3 when contamination or damages exceed a predetermined level; and

[0120] F1.3) cleaning at least an outer side of the inner door 7 of the transfer unit 3 with a cleaning agent.

[0121] The step G) of transferring the products 10 from the transfer unit 3 to inside the second cleanroom 70 in particular comprises the step of G1) of transferring the products 10 with the product carrier 11 from the transfer unit 3 to inside the second cleanroom 70. As mentioned above, the product carrier 11 allows the products to be securely supported during transport. It also allows the products to be easily moved - possibly even in an automated and controlled manner - from the first cleanroom 50 into the transfer unit 3, and from the transfer unit 3 into the second cleanroom 70.

[0122] Step G1), as shown schematically in more detail in Figure 10, preferably comprises the subsequent sub steps of:

[0123] G1.1 ) opening the inner door 79 of the docking station 71 of the second cleanroom 70;

[0124] G1.2) opening the inner door 7 of the transfer unit 3, thereby providing a passage from the transfer unit 3 to the docking station 71 of the second cleanroom 70;

[0125] G1.3) transferring the product carrier 11 from the transfer unit 3 to inside the docking station 71 of the second cleanroom 70; and

[0126] G1.4) opening the inner door 75 of the second cleanroom 70, thereby providing a passage from the second cleanroom 70 to the docking station 71 thereof, allowing the products 10, or the product carrier 11 with products 10, to be moved from the docking station 71 of the second cleanroom 70 to inside the second cleanroom 70.The step H) of undocking the unloaded transfer unit 3 from the second cleanroom 70, as shown schematically in more detail in Figure 11, furthermore comprises the subsequent sub steps of:

[0127] H1) closing the inner door 75 of the second cleanroom 70 to thereby close off the passage between the second cleanroom 70 and the docking station 71 of the second cleanroom 70;

[0128] H2) closing the inner door 7 of the transfer unit 3;

[0129] H3) undocking the transfer unit 3 from the docking station 71 of the second cleanroom 70;

[0130] H4) moving the transfer unit 3 away from the docking station 71 of the second cleanroom 70, by conveying the transfer unit 3 away from the docking station 71 with a conveyor 77 that is associated with the docking station 71 of the second cleanroom 70;

[0131] H5) closing the outer door 73 of the docking station 71 of the second cleanroom 70; H6) cleaning an outside of the transfer unit 3 with a cleaning agent; and

[0132] H7) closing the outer door 5 of the transfer unit 3 to thereby cover and shield the inner door 7 of the transfer unit 3 off from the environment.

[0133] It is remarked that especially step H6) of cleaning an outside of the transfer unit 3 with a cleaning agent, and step H7) of closing the outer door 5 of the transfer unit 3 to thereby cover and shield the inner door 7 of the transfer unit 3 off from the environment are optional, but preferred, steps.

[0134] In the subsequent steps shown in Figures 19 to 25 a product carrier 11 is moved from the docking station 51 of the first cleanroom 50 to inside the transfer unit 3. In Figure 19, the inner door 7 of the transfer unit 3 is opened, and the compartment 8 of the transfer unit 3 is now in open connection with the docking station 51. An inner door 55 of the first cleanroom 50 is open, and a lift 62 is in a lowered position, ready to receive a product carrier 11. In Figure 20, the product carrier 11 is moved from the first cleanroom 50 onto the lift 62 inside the docking station 51. The inner door 55 of the first cleanroom is subsequently closed (Figure 21), and the lift 62 is raised to a lifted position, that is shown in Figure 22. This lifted position levels the product carrier 11 with the transfer unit 3, and more in particular with a guide 23 inside the compartment 8 of the transfer unit 3. Please note that the guide 23 is only shown in Figures 33, 34, 35, 37 and 38, and not in the simplifiedFigures 19-25. In Figure 23, the product carrier 11 is moved forward into the compartment 8 of the transfer unit 3. In the preferred embodiment shown in the embodiments, the lift 62 may comprise a lift guide 63 that is able to extend forward relative to the lift 62 to thereby move the product carrier 11 into the compartment 8 (or vice versa take a product carrier 11 out of the compartment 8). In Figure 24, the lift guide 63 is retracted again, while the product carrier 11 remains in the compartment 8. The lift 62 may now be lowered (Figure 25), and the inner door 7 of the transfer unit 3 may be closed.

[0135] A preferred embodiment of the transfer unit 3 that is configured to transfer products in a clean environment from the first cleanroom 50 to the second cleanroom 70 is shown in Figures 12-32, and especially in the detailed Figures 33-38. The transfer unit 3 comprises an outer door 5 and an inner door 7, and is configured to transport the products 10, that is preferably arranged on a product carrier 11.

[0136] The transfer unit 3 comprises a container 4 having a plurality of panels 6 comprising one or more than one side panel 6s, a bottom panel 6b and a top panel 6t, that together enclose a compartment 8 configured to receive the products 10. One of the side panels 6 comprises a door opening 12, that is selectively closeable by a door 7. A seal 13 is configured to seal the door 7 relative to the door opening 12 in a closed state of the door 7. The transfer unit 3 further comprises a passive pressure equalizer 14 and an air conditioner 15. The passive pressure equalizer 14 is configured to equalize a pressure inside the compartment 8 based on a pressure differential with an ambient pressure in an environment outside the container 4. The air conditioner 15 is configured to treat ambient air from the environment outside the container 4 that enters to inside the compartment 8 during pressure equalization when the ambient pressure is higher than the pressure inside the compartment 8.

[0137] By using a transfer unit 3, there is no need to apply double packaging comprising an inner layer and an outer layer. The transfer unit 3 itself now acts as the packaging, adding additional benefits. First of all, the transfer unit 3 is a rigid container 4, thereby providing a more reliable and re-usable “packaging”. There is no need anymore to throw away single used packaging of often hard to recycle material. Moreover, the use of a transfer unit 3 reduces the need for highly trained personnel,and human errors, because it allows for a high level of automation. Also, the transfer time may be increased significantly, because the time-consuming and laborious tasks of both packaging and unwrapping are not necessary anymore. Furthermore, the double-packaging method requires a transport box or assy, and this functionality is now fully integrated in the transfer unit 3.

[0138] Conventional inner and outer layers of packaging used for double packaging methods, are flexible layers or bags. The flexibility of these packaging layers allows the packaging to easily compensate for pressure differences caused by varying weather conditions (such as alternating low and high pressure areas), varying temperature, etc. However, using a transfer unit 3 that comprises a container 4 having a plurality of panels 6, thereby forming a substantially rigid “packaging”, new challenges present themselves. For example, if the ambient pressure is higher than the pressure inside the container 4, there will be an underpressure inside the compartment 8 relative to the environment outside the container 4. The effects of pressure differences is not to be underestimated. For example, a difference of only 0.1 bar in ambient pressure already concerns 10,000 N / m2, which can - dependent on the size of the door 7 - already cause a significant load on seals 13 that seal the door 7 relative to the door opening 12 when the door 7 is closed. During transport, however, the air pressure differences can be much higher, which is certainly the case during air transport.

[0139] The transfer unit 3 is configured to be releasably connected to either one of the docking station 51 of the first cleanroom 50 or the docking station 71 of the second cleanroom 70.

[0140] As mentioned above, the transfer unit 3 comprises a pressure equalizer 14 and an air conditioner 15. The pressure equalizer 14 is a passive pressure equalizer that comprises one or more than one equalization channel 16 extending through at least one of the plurality of panels 6. The air conditioner 15 is in flow connection with at least one or more than one equalization channel 16 that allows ambient air to enter to inside the compartment 8.

[0141] The pressure equalizer 14 is configured to allow underpressure inside the compartment 8 to be equalized by ambient air for the environment outside the container 4, by allowing said ambient air to enter inside the compartment 8 through the at least one equalization channel 16.The pressure inside the compartment 8 is considered to be equalized with the ambient pressure outside the container 4, if the pressure difference between these pressures is low enough to prevent the seal 13 from leaking. The pressure at which the seal 13 may start leaking is highly dependent on dimensioning of the container 4, and in particular the sizing of the door 7. After all, the Sl-unit for pressure, i.e. Pascal, is expressed in N / m2. Consequently, a larger area results in a higher force. After all, in case of such a limited pressure difference, the loads on the container 4 caused by any pressure difference stay within an acceptable range to guarantee that the clean environment may be safely maintained.

[0142] When the pressure inside the compartment 8 is lower than the ambient pressure, the pressure equalizer 14 allows an underpressure inside the compartment 8 to draw in ambient air to inside the compartment 8 through the one or more than one equalization channel 16; and

[0143] When the pressure inside the compartment 8 is higher than the ambient pressure, the pressure equalizer 14 allows an overpressure inside the compartment 8 to escape through the one or more than one equalization channel 16 towards the environment outside the container 4.

[0144] In the preferred embodiment shown in the Figures, one equalization channel 16 is configured to allow air to flow therethrough in two directions to thereby allow air to escape via said equalization channel 16 from the compartment 8 to the environment outside the container 4, and allow ambient air to be drawn into the compartment 8. If the equalization channel 16 is configured to allow air to flow therethrough in two directions, it is possible to simplify the design, possibly even to only one equalization channel 16 in total.

[0145] As mentioned above, the air conditioner 15 is in flow connection with at least one or more than one equalization channel 16 that allows ambient air to enter to inside the compartment 8. In the preferred embodiment shown in the Figures, the air conditioner 15 comprises one or more than one of: a particle filter 17, such as a HEPA filter, and an activated carbon filter 18. The air conditioner 15 preferably further comprises a dehumidifier 19, that preferably comprises silica.

[0146] As shown in the Figures, the pressure equalizer 14 and / or the air conditioner 15 is arranged in the top panel 6t. Placement in the top panel 6t has a number of advantages. On the one hand, in the top panel 6t, the pressure equalizer14 and air conditioner 15 are easily accessible for maintenance. Moreover, the top panel 6t is a relative safe position, compared to e.g. the bottom panel 6b where the products 10 are carried and where the container 4 will normally be engaged when handled during logistics. Moreover, the pressure equalizer 14 and the air conditioner 15 are relatively light weight components, that are at least lighter than the product carrier 11 and the products 10 that are to be carried. Placing the product carrier 11 and the products 10 lower than the pressure equalizer 14 and / or the air conditioner 15 is therefore advantageous to keep the center-of-gravity (COG) of the transfer unit 3 as low as possible.

[0147] The transfer unit 4 further comprises a door actuator 20 and an interface 22 that is arranged at an outside of the container 4 that allows the door actuator 20 to be actuated from the outside of the container 4 when the transfer unit 3 is docked to (the docking station 51, 71) of the cleanroom 50, 70. This locking mechanism, that is shown in more detail in Figure 39, prevents that the door lock 21 and actuating thereof interferes with the sterility inside the compartment 8, and thus guarantees that the cleanroom integrity can be maintained. The door actuator 20 is configured to actuate a door lock 21 when the transfer unit 3 is docked to the first or second cleanroom 50, 70, and more in particularly to either the first docking station 51 of the first cleanroom 50, or the second docking station 71 of the second cleanroom 70.

[0148] The door 7, in the closed state thereof, is arranged inside the door opening 12 to form a substantially flush outer side of the container 4 that is defined by the door 7 and the side panel 6s that comprises the door opening 12.

[0149] In the preferred embodiments shown in the Figures, the transfer unit 3 comprises an inner door 7 and an outer door 5. The door 7 defines the inner door 7, and the outer door 5 is oversized relative to the inner door 7 and configured to completely shield off the inner door 7 when the outer door 5 is closed. In this way, the inner door 7 is protected and kept clean during logistics, i.e. during transferring the products 10 by the transfer unit 3 from the first cleanroom 50 to the second cleanroom 70.

[0150] The one or more than one equalization channel 16 is further configured to be arranged in a flow connection with the first cleanroom 50 or the second cleanroom 70, and more in particular with a first docking station 51 of said firstcleanroom 50 or with a second docking station 71 of said second cleanroom 70. The pressure inside the cleanroom 50, 70 will be higher than the pressure inside the transfer unit 3. After all, the pressure inside the cleanroom 50, 70 is deliberately kept above the atmospheric pressure outside the cleanroom 50, 70, to thereby prevent that outside air, that possibly contain contaminants, may enter the cleanroom 50, 70 if there would be a small leakage anywhere. The transfer unit 3 is however kept at the same pressure as the ambient, atmospheric, pressure outside the transfer unit 3. The pressure inside the cleanroom 50, 70 will always be higher than the pressure inside the compartment 8 of the transfer unit 3 when the transfer unit 3 is docked to (a docking station 51, 71) of the cleanroom 50, 70. Consequently, when the transfer unit 3 is docked to the docking station 51 , 71 , clean air will flow from the first cleanroom 50 or the second cleanroom 70, via the one or more than one equalization channel 16, into the transfer unit 3, and not vice versa. This flow will continue until a pressure equalization has taken place between the docking station 51, 71 of the cleanroom 50, 70 and the compartment 8 of the transfer unit 3. When a transfer unit 3 is docked to a docking station 51, 71 of a cleanroom 50, 70, the ambient pressure in the environment outside the container 4 is thus defined by the pressure inside the docking station 51, 71 of the cleanroom 50, 70. Thus, in a docked state, the environment outside the container 4 is defined by the cleanroom 50, 70, that will always have an overpressure relative to the transfer unit 3. Therefore, the flow of ambient air comprises a flow of air from the cleanroom 50, 70 to inside the compartment 8 of the transfer unit 3.

[0151] As is only shown in Figures 33, 34, 35, 37 and 38 the bottom panel comprises a guide 23 that is configured to receive the product carrier 11 and reinforce the bottom panel 6b. Although it is conceivable that the guide 23 itself already provides sufficient rigidity to the bottom panel 6b, the embodiment shown in the Figures further comprises a frame 26 that strengthens the guide 23, that is rigidly connected to this frame 26. In the shown embodiment, frame 26 is arranged inside the double walled bottom panel 6b. More in particular, the frame 26 may be arranged intermediate the guide 23 and the pallet type carrier 25. Due to the reinforcement provided by the guide 23, the bottom panel 6b may be lightweight, while still being able to fulfill a load bearing functionality. The guide 23 and the product carrier 11 provide a rigid support for carrying the products 10, and consequently thefunctionality of the container 4 is merely to provide a compartment 8 that is able to ensure sterility and maintain cleanroom integrity. However, this compartment 8 does not have to provide constructional rigidity for carrying the products 10. For this reason, the panels may be made of a material comprising a density in the range of 910 - 970 kg / m3, and are preferably made of a plastic.

[0152] As can be best seen in the cross sectional views of Figures 35-38, the panels 6, 6b, 6s, 6t of the shown preferred embodiment of the transfer unit 3 are double walled. Vent holes 24 allow a pressure inside the double walled panels 6 to equalize with the ambient pressure.

[0153] The double walled panels 6, 6b, 6s, 6t are preferably made via rotational molding. Rotational molding allows the panels 6, 6b, 6s, 6t to be formed as thin walled parts, thereby reducing the overall weight of the transfer unit 3, which is advantageous for logistics of said transfer unit 3. After all, the container 4 itself has only very limited constructional functionality, because the products 10 that are to be received inside the compartment 8 of the container 4 may be placed on a product carrier 11 that defines a rigid support. Moreover, such thin walled parts may be made in mass production, such as via a rotational molding process.

[0154] In the shown preferred embodiment, the footprint of the transfer unit 3 has a maximum length of 1200 mm and a maximum width of 1200 mm. In this way, the transfer unit 3 will fit in conventional transport means that is designed for the most common types of standardized EUR pallets. Consequently, the transfer unit 3 may be securely handled with conventional products that are capable of handling and transporting standardized EUR pallets.

[0155] As shown in Figures 35, 37 and 37, the transfer unit 3 comprises a pallet type carrier 25 having dimensions of 800 x 1200 mm, or having dimensions of 1000 x 1200 mm. The pallet type carrier 25 having such dimensions provides a universal transport interface to the transfer unit 3. The dimensions of 800 - 1200 mm correspond to the “EUR 1 type” pallet as described in the standard UIC Code 435-2, titled “Standard of quality for EUR flat pallets made of wood measuring 800 mm x 1200 mm (EUR-1)”. The alternative dimensions of 1000 x 1200 mm correspond to the “EUR 3 type” pallet, as described in the standard UIC Code 435-5. A pallet type carrier 25 with such dimensions thus guarantees that the transfer unit 3 may be securely handled with conventional products that are capable of handling EUR-pallets of types EUR 1 or EUR 3, such as pallet trucks, forklifts, and many commercially available Automated Guided Vehicles (AGV) that are designed for pallet transport.

[0156] The above described embodiments are intended only to illustrate the invention and not to limit in any way the scope of the invention. Accordingly, it should be understood that where features mentioned in the appended claims are followed by reference signs, such signs are included solely for the purpose of enhancing the intelligibility of the claims and are in no way limiting on the scope of the claims. The scope of protection is defined solely by the following claims.

Claims

CLAIMS1. Transfer unit configured to transfer products during inter-factory transport in a clean environment from a first cleanroom in a first factory to a second cleanroom in a second factory remote from the first factory, comprising:- a container having a plurality of panels comprising one or more than one side panel, a bottom panel and a top panel, that together enclose a compartment configured to receive the products;- a door opening in one of the side panels, that is selectively closeable by a door of the transfer unit, and wherein a seal is configured to seal the door relative to the door opening in a closed state of the door;- a passive pressure equalizer that is configured to equalize a pressure inside the compartment based on a pressure differential with an ambient pressure in an environment outside the container, wherein:- the pressure equalizer comprises one or more than one equalization channel extending through at least one of the plurality of panels;- when the pressure inside the compartment is lower than the ambient pressure, allow an underpressure inside the compartment to draw in ambient air to inside the compartment through the one or more than one equalization channel; and- when the pressure inside the compartment is higher than the ambient pressure, allow an overpressure inside the compartment to escape through the one or more than one equalization channel towards the environment outside the container; and- an air conditioner that is in flow connection with at least one of the one or more than one equalization channel and configured to treat ambient air from the environment outside the container that enters to inside the compartment via the one or more than one equalization channel.

2. Transfer unit according to claim 1, wherein one equalization channel is configured to allow air to flow therethrough in two directions to thereby allow air to escape via said equalization channel from the compartment to the environment outside the container, and allow ambient air to be drawn into the compartment.

3. Transfer unit according to any of the foregoing claims, wherein the air conditioner comprises one or more than one of:- a particle filter; and- an activated carbon filter.

4. Transfer unit according to any of the foregoing claims, wherein the air conditioner comprises a dehumidifier, that preferably comprises silica.

5. Transfer unit according to any of the foregoing claims, wherein the container comprises:- a door actuator for actuating a door lock when the transfer unit is docked to the first cleanroom or the second cleanroom;- an interface that is arranged at an outside of the container that allows the door actuator to be actuated from the outside of the container when the transfer unit is docked to the first cleanroom or the second cleanroom.

6. Transfer unit according to any of the foregoing claims, wherein the door, in the closed state thereof, is arranged inside the door opening to form a substantially flush outer side of the container that is defined by the door and the side panel that comprises the door opening.

7. Transfer unit according to any of the foregoing claims, wherein: - the door defines an inner door; and- the transfer unit further comprises an outer door that is oversized relative to the inner door and configured to completely shield off the inner door when the outer door is closed.

8. Transfer unit according to any of the foregoing claims, wherein the one or more than one equalization channel is further configured to be arranged in a flow connection with the first cleanroom or the second cleanroom.

9. Transfer unit according to any of the foregoing claims, wherein the bottom panel comprises a guide that is configured to receive a product carrier and reinforce the bottom panel.

10. Transfer unit according to any of the foregoing claims, wherein the panels are made of a material comprising a density in the range of 910 - 970 kg / m3, and are preferably made of a plastic.

11. Transfer unit according to any of the foregoing claims, wherein the panels are double walled.

12. Transfer unit according to claim 10 or 11, wherein the panels are made via rotational molding.

13. Transfer unit according to any of the foregoing claims, wherein the footprint of the transfer unit has a maximum length of 1200 mm and a maximum width of 1200 mm.

14. Transfer unit according to any of the foregoing claims, wherein the transfer unit comprises a pallet type carrier having dimensions of 800 x 1200 mm, or having dimensions of 1000 x 1200 mm.

Images