JP7395175B2 - Bonding method of transparent resin using water plasma - Google Patents

Description

The present invention relates to microchannel chips (also called μTAS or Lab-on-Chip) and DNA nanopore devices (hereinafter collectively referred to as microchannel devices) used to analyze minute amounts of biological samples. ), etc., mainly relates to a method of manufacturing a transparent plate-like device.

Microfluidic devices manufactured using MEMS (Micro Electro Mechanical Systems) technology, which is an application of semiconductor manufacturing technology, are widely used when analyzing minute amounts of samples. Furthermore, since channels of various shapes can be formed, it is possible to support analyzes involving complex processing.

Microchannel devices are generally made by bonding at least two transparent flat plates: a flat plate with a channel formed on one side (channel plate) and a flat plate that closes that side (channel) (closure plate). will be produced. PolydiMethylSiloxane (PDMS) is widely used as such a material because it has excellent optical properties and is easy to mold. However, PDMS has high air permeability and also releases low-molecular-weight siloxane from the material itself, so when the sample is flowed through the channel, these enter the sample and interfere with observation and analysis. It has also become clear that when pre-stained cells are passed through a PDMS channel, they can diffuse into the PDMS and cause problems.

Patent Document 1 solves these problems by coating PDMS with parylene (Poly-para-Xylylene, "Parylene" is a registered trademark of Japan Parylene LLC), which has high barrier properties. I'm trying.

Japanese Patent Application Publication No. 2013-188677 Japanese Patent Application Publication No. 2018-013473 Special Publication No. 2011-520216

Coating parylene onto the surface of another material is accomplished by vapor depositing parylene monomer onto the surface of the material. For this reason, the surface of parylene after coating becomes quite rough because the molecular weight of the parylene monomer is large. Therefore, conventionally, the surfaces of members coated with parylene have been joined together by thermocompression bonding (Patent Document 2) or adhesive (Patent Document 3).

However, when thermocompression bonding Parylene, the processing temperature needs to be close to 450°C. In the case of PDMS coated with parylene, thermocompression bonding cannot be used because the PDMS undergoes metamorphosis at that temperature.

In addition, when manufacturing microchannel devices, when bonding with adhesive, if there is too much adhesive, the adhesive may overflow into the channel, the adhesive may elute and contaminate the sample flowing through the channel, or conversely, the adhesive may If there is too little, there is a risk that a gap will be formed between the joint surfaces.

The present invention was made to solve these problems, and its purpose is to make it possible to join the surfaces of members whose surfaces are coated with parylene by a method other than thermocompression bonding or adhesives. The goal is to provide a way to do so.

The present invention has been made to solve the above problems,
Producing a first member having a parylene layer having a smooth plane portion on the surface of the base material,
Producing a second member having a smooth plane part,
treating both the flat part of the first member and the flat part of the second member with water plasma (H ₂ O plasma),
This is a method of joining the first member and the second member by bringing the flat part of the first member and the flat part of the second member together under a pressure of 0.5 MPa or less.

In the above method, "smooth" means that the arithmetic mean roughness Ra is 5 nm or less.

In the water plasma treatment, the water plasma may include oxygen plasma (O plasma). In other words, use a raw material gas for plasma in which the ratio of water vapor (H ₂ 0) to oxygen (O ₂ ) is between H ₂ 0:O ₂ =100:0 and H ₂ 0:O ₂ =20:80. I can do it. Note that the water plasma may contain nitrogen, helium, or argon.

In the water plasma treatment, it is desirable that both the flat part of the first member and the flat part of the second member to be treated be kept at a temperature of 40 to 100°C, and preferably at room temperature (25°C). More desirable.
Furthermore, it is desirable that the pressure of the water plasma be between 0.1 and 400 Pa.

In the water plasma treatment, the high frequency power supplied to the electrode for plasma generation is desirably set to a value within the range of 0.3 to 3000 mW/cm ² with respect to the area to be treated.

The water plasma treatment time is preferably within a range of 1 to 8000 seconds, more preferably 10 to 120 seconds.

As the base material of the first member, PDMS or other silicone can be used.

As the second member, similarly to the first member, a base material whose surface is coated with parylene can be used. In addition, glass and cycloolefin polymer (Cycloolefin Polymer (COP), including its copolymers such as cycloolefin copolymer (COC) and cycloblock copolymer (CBC)) can also be used. In addition, the base materials include polyamide, polyester, polyurethane, polysiloxane, phenolic resin, polysulfide, polyacetal, polyacrylonitrile, polyvinyl chloride, polystyrene, polymethyl methacrylate, polyvinyl acetate, polytetrafluoroethylene, polyisoprene, polycarbonate, and polyether. , polyimides, polybenzimidazoles, polybenzoxazoles, polybenzothiazoles, polyoxadiazoles, polytriazoles, polyquinoxalines, polyimidazopyrrolones, epoxy resins, as well as aromatic components and vinyl or cyclobutane groups. It may be organic, such as a polymer, or it may be inorganic, such as sapphire, zinc oxide, or indium tin oxide (ITO).

As a method for producing the first member having a parylene layer having a smooth flat surface on the surface of the base material, for example, parylene monomer is deposited on the surface of a mold having a smooth flat surface. It can be produced by forming a layer, placing a base material on the parylene layer in a state with high adhesion to the parylene layer, and taking out the base material with the parylene layer bonded to the surface from the mold.

In this case, as a method of placing the base material on the parylene layer with high adhesion, the surface of the parylene layer (the side that is not the mold surface) is treated with water plasma or other plasma, and then the One method is to pour a fluid base material (e.g. PDMS) into a mold (on the plasma-treated surface of parylene) and allow it to harden. If the surface of the parylene layer is not plasma-treated and then a fluidized base material is poured into the mold and cured, the parylene layer will remain in the mold when the base material is taken out of the mold. , it is not possible to produce a first member including a parylene layer having a smooth flat surface on the surface of the base material (JP 2016-163549A).

Examples of plasma other than water plasma include oxygen plasma (O plasma), argon plasma (Ar plasma), or a mixed plasma thereof.

As a method for producing the second member having a parylene layer on the surface of the base material, for example, a parylene layer is formed by vapor-depositing a parylene monomer on the surface of a mold having a smooth flat surface, and the parylene layer is formed on the surface of a mold having a smooth flat surface. A base material (for example, a plate made of PDMS, glass, or COP) is further placed on the layer in a state with high adhesion to the parylene layer, and the base material with the parylene layer bonded to the surface is taken out from the mold. It is preferable to do so.

In this case, as a method of placing the base material on the parylene layer with high adhesion, the surface of the parylene layer (the side that is not the mold surface) is treated with water plasma or other plasma, and then the A preferred method is to place the substrate in the mold (on the plasma-treated surface side of the parylene).

Since the parylene layer of the first member and the parylene layer of the second member obtained in this way have smooth plane parts, when the parylene layers are joined together, the first member and the second member are bonded with high strength. However, in order to bond the first member and the second member with even higher strength, it is possible to bond the parylene layers together after treating the parylene layer of the first member and the parylene layer of the second member with water plasma. It is preferable to do so. In the microchannel chip manufactured in this way, the first member and the second member do not separate even if liquid is fed into the channel at high pressure.

According to the bonding method of the present invention, the surface of a member whose surface is coated with parylene can be bonded to another transparent material by a method other than thermocompression bonding or adhesive.

1 is a schematic configuration diagram of an example of a microchannel device produced using the bonding method according to the present invention, in which (a) is a plan view of a channel plate, (b) is a plan view of a closing member, and (c) is a plan view of both. A side view of the combination. 1 is a schematic configuration diagram of a plasma processing apparatus used in an embodiment of a bonding method according to the present invention. Flowchart of the embodiment. FIG. 3 is a cross-sectional view showing the procedure for manufacturing a test piece performed in the embodiment. Plan view (a) and side view (b) of the test piece for the joint strength evaluation test. A photograph showing the results of a joint strength evaluation test. FIG. 2 is an explanatory diagram showing a method of a tensile test performed in a joint strength evaluation test.

An embodiment of a method for manufacturing a microchannel device using the bonding method according to the present invention will be described. FIG. 1 shows an example of a microchannel device manufactured in this embodiment. This microchannel device 10 includes a channel member 11 that is a transparent plate with a channel 13 formed on one surface, and a channel forming side surface of the channel member 11 that is closed (that is, the channel is closed). The closure member 12 is a transparent planar plate for forming the device. Sample inlets/outlets 14 for introducing the sample into the channel 13 and leading it out from the channel 13 are provided at positions corresponding to both ends of the channel 13 of the closing member 12, respectively.

A method for manufacturing this microchannel device will be explained using the flowchart of FIG. 3 and the cross-sectional view of the microchannel device of FIG. 4. First, a method for manufacturing the channel member 11 will be explained. A channel mold 21 (FIG. 4(a)), which is a female mold of the channel member 11 as shown in FIG. 1(a), is prepared, and its surface is smoothed (step S1). Here, "smooth" means that the arithmetic mean roughness Ra of the surface is 5 nm or less. Next, parylene is deposited on the inner surface (smooth surface) of this channel mold 21 (step S2, FIG. 4(b)). The surface (evaporation surface) of the parylene layer 22 thus formed is treated with plasma (step S3). The plasmas used here include water plasma (H ₂ O plasma), water-oxygen plasma (H ₂ O-O ₂ plasma), oxygen plasma (O plasma), argon plasma (Ar plasma), etc., which are commonly used for cleaning. Various plasmas used for this purpose can be used. Thereafter, PDMS 23 is injected into the channel mold 21 and thermally cured (step S4, FIG. 4(c)). After the PDMS layer 23 is sufficiently cured, the PDMS layer 23 having the parylene layer 22 on its surface is taken out from the channel mold 21 (step S5). The surface of the parylene layer 22 on the mold side is a smooth surface, whereas the surface on the PDMS layer 23 side is a rough surface with parylene deposited on it. Because of the contact, the PDMS layer 23 adheres well to the parylene layer 22, and the parylene layer 22 does not remain in the channel mold 21, but is taken out from the channel mold 21 together with the PDMS layer 23 (FIG. 4(d)). In this way, the channel member 11 made of the PDMS layer 23 having the smooth parylene layer 22 on the surface is completed (FIG. 4(e) left).

On the other hand, using a similar method, a closing plate type (not shown) provided with convex portions corresponding to the sample inlet/outlet was used to create a closing member 12 made of a PDMS layer 28 having a smooth parylene layer 27 on the surface. (Step S6, FIG. 4(e) right. Both FIGS. 1 and 4 are schematic illustrations, and the width of the channel 13, the size of the sample inlet/outlet 14, etc.) are different in Figures 1 and 4). Note that the closing member 12 may be made of a COP plate or a glass plate having a smooth surface, instead of being a flat plate made of a PDMS layer having such a parylene layer 27.

The parylene layer side surfaces (smooth surfaces) of the flow path member 11 and closing member 12 thus produced are treated with water plasma (step S7). The water plasma treatment can be performed using, for example, a parallel plate type (capacitively coupled) plasma treatment apparatus. A schematic configuration of a plasma processing apparatus 50 (AQ-2000 manufactured by Samco Co., Ltd.), which is an example of such a parallel plate type plasma processing apparatus, will be explained with reference to FIG. Electrodes 52 and 53 are arranged above and below in the processing chamber 51, one of which is grounded and high frequency power is supplied to the other. In the apparatus shown in FIG. 2, high frequency power is supplied from a high frequency power source 54 to the upper electrode 53, the lower electrode 52 is grounded, and the workpiece is placed there (PE mode). This may be reversed, and high frequency power is supplied to the lower electrode 52 on which the member to be processed is placed, and the upper electrode 53 is grounded (RIE mode). The sealed processing chamber 51 can be evacuated by a vacuum evacuation system 55, and water vapor (H ₂ O) is supplied from a water vapor supply system 56 to the processing chamber 51 after evacuation. Each of these parts is controlled by a control section 58 of the plasma processing apparatus 50.

In the processing chamber 51 of this plasma processing apparatus 50, the flow path member 11 and the closing member 12 are installed on the lower electrode 52 so that their smooth surfaces become the processing surface (upper surface) (FIG. 4(e)). , water plasma treatment is performed (step S7). The treatment conditions for the water plasma treatment can be, for example, as follows.
Water vapor ( _H2O ) flow rate 20sccm
BGP 10Pa
Pressure 4Pa
High frequency power 100W (33mW/cm ² )
Test piece temperature 25℃
Processing time 80sec

After water plasma treatment is applied to both smooth surfaces in this manner, both smooth surfaces are brought together and bonded (step S8, FIG. 4(f)). Bonding can be performed using a force of about 0.5 gf due to the weight of the channel member 11 or the closing member 12 (usually about 4 gf when the channel member 11 or the closing member 12 is a flat plate of about 76 mm x 26 mm x 2 mm). A pressure of MPa or less may be applied.
Through the above steps, a microchannel device is completed.

Next, among the above steps,
(1) Adhesion between parylene layer and PDMS layer depending on whether plasma treatment is performed on the parylene vapor deposition surface (effect of step S3)
(2) Adhesion between the smooth surfaces of the parylene layer and other smooth surfaces after water plasma treatment (effect of step S8)
A test was conducted to evaluate the

First, in order to evaluate (1), the following test was conducted. As shown in FIG. 5, parylene C (one of the hydrogen atoms in the benzene ring is replaced with chlorine) was deposited on a glass substrate 31 to a thickness of 2 μm. Two test pieces 30 consisting of the glass substrate 31 and the parylene layer 32 were prepared, and the surface (evaporated surface, rough surface) of the parylene layer of one of the test pieces 30 was treated with plasma. The plasma treatment here was water plasma treatment under the same conditions as above. The other test piece 30 was not subjected to plasma treatment. Thereafter, approximately square frames of 15 mm x 15 mm were placed on both test pieces 30, and PDMS was injected into each frame to a thickness of 2 mm and cured. The PDMS used here is Sylgard 184 manufactured by Dow Toray Industries, Inc. (Sylgard is a trademark of that company). Curing was performed by holding at 75°C for 90 minutes. After the PDMS layer 33 was cured, the frame was removed to obtain two types of test pieces 30 in which a laminate of a parylene layer 32 and a PDMS layer 33 was formed on a glass substrate 31. As described above, the surface of one of these parylene layers 32 is subjected to plasma treatment, and the other one is not subjected to plasma treatment. As shown in FIG. 5, a dividing line 34 was inserted into the laminate of the parylene layer 32 and the PDMS layer 33 on the glass substrate 31 of both test pieces 30 using a cutter knife so as to divide the laminate into 3×3 pieces. .

For each of the nine divided regions of both test pieces 30 thus formed, the PDMS layer 33 was suctioned and pulled perpendicularly to the glass substrate 31 using vacuum tweezers, and the boundaries at which each layer peeled were examined. The results are shown in FIG. In the test piece 30 that was not subjected to plasma treatment ("No plasma treatment" column in FIG. 6), peeling occurred at the boundary between the parylene layer 32 and the PDMS layer 33 at 9 out of 9 locations (all samples). That is, all of the parylene layer 32 remained on the glass substrate 31, and no parylene layer 32 adhered to the peeled PDMS layer 33. On the other hand, in the plasma-treated test piece 30 ("plasma-treated" column in FIG. 6), peeling occurred at the boundary between the glass substrate 31 and the parylene layer 32 at 9 out of 9 locations (in total). That is, nothing remained on the glass substrate 31 in all regions, and the parylene layer 32 was peeled off together with the PDMS layer 33 in all regions.

This confirmed the effect of improving the adhesion between the parylene layer 32 and the PDMS layer 33 (the effect of step S3) by performing plasma treatment on the parylene vapor-deposited surface.

In addition, for three of the above plasma-treated test pieces, the water contact angle on the surface of the parylene layer 32 immediately after the plasma treatment was measured. Furthermore, the water contact angle on the surface of the parylene layer was similarly measured for three test pieces that were not subjected to plasma treatment. As a result, the water contact angles were 4°, 5°, and 4° for specimen 30 that was subjected to plasma treatment, whereas the water contact angles were 82° and 90° for specimen 30 that was not subjected to plasma treatment. , 88°. From this, it can be seen that the surface of the parylene layer 32 becomes extremely hydrophilic by performing the plasma treatment. It is thought that this strong hydrophilicity contributes to improved adhesion with the PDMS layer 33.

Next, for the evaluation of (2) above, the following bonded test pieces were prepared.
Bonded test piece 1: A 5 mm x 5 mm x [2 μm + 2 mm] plate-like test piece consisting of [Parylene layer + PDMS layer] peeled off from the glass substrate after plasma treatment in the above evaluation test (1) Bonded test piece 2: White glass plate (Matsunami 76 mm x 26 mm x 1 mm) specimen made of S1112 slide glass manufactured by Glass Industry Co., Ltd.

As bonding test 1, two bonding test pieces 1 were prepared, and their smooth surfaces (the surface of the parylene layer peeled off from the glass substrate) were treated with water plasma treatment, and then both treated surfaces (both smooth surfaces) were immediately brought together. , and pressurized with a hand roller. The conditions for the water plasma treatment at this time are as described above. The environmental temperature during bonding was 25°C, and the pressure applied by hand rollers on both smooth surfaces was 0.1 MPa. The PDMS layer was removed from each of the two bonded test pieces 1 thus bonded. The reason for this is that this bonding test 1 is for evaluating the bonding strength between smooth parylene layers. The flat surfaces of the heads of plastic bolts 43 were aligned with the outer surfaces on both sides of the two joint test pieces 1 (41 and 42 in Figures 7(a) and (b)) thus prepared, and fixed with adhesive (Figure 7(a), (b)). 4(c)). Both bolts 43 were pulled using a tensile tester, and the tensile strength when both bonded test pieces 1 (41, 42) were separated was measured.

As a result, the bonding strength (tensile strength) of the two test pieces 1 was 192.8 N/cm ² , and it was confirmed that a sufficiently strong bond was formed between the smooth parylene layers treated with water plasma.

In addition, for bonding test 2, one bonding test piece 1 and one bonding test piece 2 (white glass plate) were prepared, and bonding test piece 1 (as above, the PDMS layer was removed before the tensile test). After applying water plasma treatment to the smooth surface of the test piece 2 and one surface (of course, the smooth surface) of the bonding test piece 2 under the above conditions, the two treated surfaces (both smooth surfaces) were immediately brought together and bonded by applying pressure with a hand roller. did. The bonding conditions (environmental temperature, pressure) at this time were the same as in bonding test 1. A tensile strength test was conducted in this state (as before, the PDMS layer of bonded test piece 1 was removed before the tensile test), and the bonding strength (tensile strength) between bonded test piece 1 and bonded test piece 2 was 63.2 N. / ^cm2 . This also has sufficient bonding strength for use as a microchannel device.

Furthermore, after bonding test piece 1 and bonding test piece 2 were bonded as described above, they were heated at 50° C. for 10 minutes, and then a tensile strength test was conducted. As a result, the bonding strength between bonded test piece 1 and bonded test piece 2 increased to 103.4 N/cm ² . That is, it has been found that heating after bonding is effective in improving bonding strength.

10... Microchannel device 11... Channel member 12... Closing member 13... Channel 14... Sample inlet/outlet 21... Channel type 22, 27... Parylene layer 23, 28... PDMS layer 30... Test piece 31... Glass substrate 32...Parylene layer 33...PDMS layer 34...Parting lines 41, 42...Joining test piece 43...Plastic bolt 50...Plasma processing device 51...Processing chamber 52...Lower electrode 53...Upper electrode 54...High frequency power source 55...Evacuation System 56...Steam supply system 58...Control unit

Claims (9)

Producing a first member having a parylene layer made of polyparaxylylene and having a smooth flat surface on the surface of a base material,
Producing a second member having a smooth plane part,
treating both the flat part of the first member and the flat part of the second member with water plasma;
A method of joining a first member and a second member by aligning the flat part of the first member and the flat part of the second member. The method for joining a first member and a second member according to claim 1, wherein the base material of the first member is PDMS. 3. The method of joining a first member and a second member according to claim 1, wherein the second member has a parylene layer on the surface of a base material. 3. The method of joining a first member and a second member according to claim 1, wherein the second member is a glass plate or a COP plate. 4. The method of joining a first member and a second member according to claim 3 , wherein the parylene layer of the first member and the parylene layer of the second member are treated with water plasma to join the parylene layers. The first member is
Forming the parylene layer by depositing a polyparaxylylene monomer on the surface of the mold having a smooth flat surface,
Further placing the base material on the parylene layer in a state of high adhesion with the parylene layer,
The method for joining a first member and a second member according to any one of claims 1 to 5, wherein the method is produced by taking out a base material whose surface is joined to the parylene layer from the mold. A method of placing the base material on the parylene layer in a highly adhesive state,
treating the surface of the parylene layer with plasma,
The method for joining the first member and the second member according to claim 6 , wherein the base material in a fluid state is then poured into the mold and cured. 8. The method for joining a first member and a second member according to claim 7 , wherein the plasma treatment performed on the surface of the parylene layer is water plasma treatment. A first member that is a plate with a flow path formed on one surface and a second member that is a plate that closes the one surface are joined by the joining method according to any one of claims 1 to 8. A method of manufacturing a microfluidic chip by .

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