JP2009028920A - Joining method, joined body, liquid droplet ejecting head and liquid droplet ejector - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a joining method in which two bonding bodies can be joined each other firmly with a high dimensional accuracy and efficiently at a low temperature, to provide a joined body of the two bonding bodies firmly joined each other with a high dimensional accuracy, a highly reliable liquid droplet ejecting head equipped with the joined body, and a liquid droplet ejector equipped with the liquid droplet ejecting head. <P>SOLUTION: The joining method has the process (first process) of obtaining a first bonding body 41 and a second bonding body 42 by forming plasma polymerization films 3 on two base materials 2, respectively; the process (second process) of obtaining a temporary joined body 5 by superposing the two bonding bodies 41 and 42 to make the plasma polymerization films 3 adhere to each other; and the process (third process) of obtaining the joined body 1 by applying an energy to each plasma polymerization film 3 in the temporary joined body 5 thereby joining the plasma polymerization films 3 each other. The plasma polymerization films 3 are preferably composed of polyorganosiloxane as a main material. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

  The present invention relates to a bonding method, a bonded body, a droplet discharge head, and a droplet discharge device.

When joining (adhering) two members (base materials), conventionally, a method of using an adhesive such as an epoxy adhesive, a urethane adhesive, or a silicone adhesive is often used.
The adhesive can exhibit adhesiveness regardless of the material of the member. For this reason, members composed of various materials can be bonded in various combinations.
For example, a droplet discharge head (inkjet recording head) provided in an inkjet printer is assembled by bonding parts made of different materials such as a resin material, a metal material, and a silicon material using an adhesive. ing.
When the members are bonded together using the adhesive as described above, a liquid or paste adhesive is applied to the bonding surface, and the members are bonded together via the applied adhesive. Thereafter, the adhesive is cured by the action of heat or light to bond the members together.

However, such an adhesive has the following problems.
・ Low bonding strength ・ Low dimensional accuracy ・ Long curing time, so it takes a long time to bond In addition, in many cases, it is necessary to use a primer to increase the bonding strength. Cost and complexity.

On the other hand, there is a solid bonding method as a bonding method that does not use an adhesive.
Solid bonding is a method of directly bonding members without an intermediate layer such as an adhesive (see, for example, Patent Document 1).
According to such solid bonding, since an intermediate layer such as an adhesive is not used, a bonded body with high dimensional accuracy can be obtained.

However, solid bonding has the following problems.
-There are restrictions on the material of the members to be joined-In the joining process, heat treatment is performed at a high temperature (for example, about 700 to 800 ° C)-The atmosphere in the joining process is limited to a reduced pressure atmosphere. There is a need for a method of joining members firmly with high dimensional accuracy and efficiently at low temperatures regardless of the material of the provided members.

JP-A-5-82404

  An object of the present invention is a bonding method capable of bonding two adherends firmly with high dimensional accuracy and efficiently at low temperature, and joining formed by firmly bonding two adherends with high dimensional accuracy. It is an object of the present invention to provide a highly reliable liquid droplet ejection head including such a bonded body, and a liquid droplet ejection apparatus including such a liquid droplet ejection head.

Such an object is achieved by the present invention described below.
The bonding method of the present invention includes a first step of preparing a first adherend and a second adherend provided with a plasma polymerized film on a substrate,
A second step of superimposing the first adherend and the second adherend so as to bring the plasma polymer films into close contact with each other to obtain a temporary joined body;
And a third step of joining the plasma polymerized films to obtain a joined body by applying energy to the plasma polymerized film.
Thereby, adhesiveness expresses between plasma polymerization films, and two adherends can be joined firmly with high dimensional accuracy and efficiently at low temperature. Further, since the plasma polymerized films are not joined in the temporarily joined state, the first adherend and the second adherend are shifted so that their relative positions can be easily fined. Can be adjusted.

In the bonding method of the present invention, it is preferable that each of the plasma polymerized films is composed mainly of polyorganosiloxane.
Thereby, the water repellency and hydrophilicity of the plasma polymerized film can be easily controlled, and as a result, the adhesion can be easily controlled. In addition, since polyorganosiloxane is relatively flexible, it is possible to relieve the stress associated with the difference in thermal expansion coefficient generated between the substrates. As a result, peeling of the joined body can be reliably prevented. Furthermore, a bonded body having excellent durability can be obtained.

In the bonding method of the present invention, it is preferable that the polyorganosiloxane is mainly composed of a polymer of octamethyltrisiloxane.
Thereby, a plasma polymerization film having particularly excellent adhesiveness can be obtained. In addition, the raw material mainly composed of octamethyltrisiloxane is advantageous in that it is easy to handle because it is liquid at room temperature and has an appropriate viscosity.

In the bonding method of the present invention, the average thickness of each plasma polymerized film is preferably 1 to 1000 nm.
Thereby, the two adherends can be more firmly bonded to each other while preventing the dimensional accuracy of the bonded body from significantly decreasing. This also ensures a certain degree of shape following in the plasma polymerized film, so that the unevenness present on the bonding surface of the base material can be absorbed to reduce the height of the irregularities generated on the surface of the plasma polymerized film. it can. As a result, the joint strength of the joined body can be further improved.

In the bonding method of the present invention, the application of the energy in the third step is performed by at least one of a method of heating the temporary bonded body and a method of applying a compressive force to the temporary bonded body. Are preferred.
Thereby, energy can be imparted to the plasma polymerization film relatively easily and efficiently.

In the bonding method of the present invention, the heating temperature is preferably 25 to 100 ° C.
Thereby, the plasma polymerized film can be reliably activated and adhesiveness can be expressed in the plasma polymerized film while reliably preventing the base material from being altered or deteriorated by heat.
In the joining method of the present invention, the compressive force is preferably 0.2 to 10 MPa.
Thus, the plasma polymerized film can be reliably activated and the plasma polymerized film can exhibit adhesiveness by simply compressing the temporary joined body without causing damage to the substrate.

In the bonding method of the present invention, at least one of the base material provided in the first adherend and the base material provided in the second adherend has energy ray permeability,
The application of the energy in the third step is preferably performed by a method of irradiating the energy beam from the side of the base material having the permeability of the temporary joined body.
Thereby, a plasma polymerization film | membrane can be activated efficiently. In addition, large energy can be applied in a short time. Accordingly, since the molecular structure in the plasma polymerized film is not cut more than necessary, it can be avoided that the characteristics of the plasma polymerized film deteriorate.

In the bonding method of the present invention, at least one of the base material provided in the first adherend and the base material provided in the second adherend has translucency,
The application of the energy in the third step is preferably performed by a method of irradiating ultraviolet rays from the translucent substrate side of the temporary joined body.
Thereby, it is possible to activate a wide range of the plasma polymerized film without unevenness in a shorter time using simple equipment.

In the bonding method of the present invention, the wavelength of the ultraviolet light is preferably 150 to 300 nm.
Thereby, it is possible to activate the plasma polymerized film while preventing the characteristics of the plasma polymerized film from significantly deteriorating.
In the bonding method of the present invention, it is preferable that the third step is performed in an air atmosphere.
Thereby, it is not necessary to spend time and cost to control the atmosphere, and energy can be applied more easily.

The bonding method of the present invention preferably includes a step of heating the bonded body after the third step.
Thereby, the dehydration condensation of the hydroxyl group further proceeds at the interface of each plasma polymerization film. As a result, the bonding strength in the bonded body can be further increased.
In the bonding method of the present invention, the heating temperature is preferably 25 to 100 ° C.
Accordingly, it is possible to reliably increase the bonding strength of the bonded body while reliably preventing the bonded body from being deteriorated and deteriorated by heat.

In the joining method of this invention, it is preferable to have the process of pressurizing the said joined body after the said 3rd process.
As a result, the surfaces of the respective plasma polymerized films are closer to each other, and dehydration condensation and recombination of binding active hands are promoted. As a result, the integration of the two plasma polymerized films further proceeds, and the bonding strength in the bonded body can be further increased.
In the bonding method of the present invention, it is preferable that the pressure applied to the bonded body is 0.2 to 10 MPa.
Thereby, the joining strength of the joined body can be reliably increased without causing damage to the substrate.

In the bonding method of the present invention, the first adherend or the second adherend is subjected to a surface treatment for improving the adhesion with the plasma polymerized film on the substrate in advance, and then the surface It is preferable that the plasma polymerized film is formed in the treated region.
Thereby, the joint surface of the base material is cleaned and activated, and the plasma polymerized film easily acts chemically on the joint surface. As a result, when a plasma polymerization film is formed on the bonding surface, the bonding strength between the bonding surface and the plasma polymerization film can be increased.

In the bonding method of the present invention, the surface treatment is preferably a plasma treatment.
Thereby, the joint surface of a base material can be cleaned and activated more. As a result, the bonding strength between the bonding surface and the plasma polymerization film can be particularly increased.
In the bonding method of the present invention, it is preferable that the base material provided in the first adherend and the base material provided in the second adherend have different rigidity.
Thereby, two adherends can be joined more firmly.

The joined body of the present invention is characterized in that two substrates are joined by the joining method of the present invention.
Thereby, the joined body formed by joining two adherends firmly with high dimensional accuracy is obtained.
In the joined body of the present invention, the joining strength between the two base materials is preferably 5 MPa or more.
Thereby, the joined body which can fully prevent peeling is obtained.
The droplet discharge head of the present invention is characterized by having the joined body of the present invention.
Thereby, a highly reliable droplet discharge head can be obtained.
The liquid droplet ejection apparatus of the present invention includes the liquid droplet ejection head of the present invention.
Thereby, a highly reliable droplet discharge device can be obtained.

Hereinafter, a bonding method, a bonded body, a droplet discharge head, and a droplet discharge device according to the present invention will be described in detail based on preferred embodiments shown in the accompanying drawings.
<Join method>
The joining method of the present invention is a method for joining the first adherend 41 and the second adherend 42. Each of these two adherends 41 and 42 has a base material 2 and a plasma polymerized film 3 provided on the base material 2.
According to the joining method of the present invention, the first adherend 41 and the second adherend 42 can be joined firmly with high dimensional accuracy and efficiently at a low temperature.

Here, prior to explaining the bonding method of the present invention, first, a plasma polymerization apparatus used for producing the above-mentioned plasma polymerization film 3 will be described.
FIG. 1 is a longitudinal sectional view schematically showing a plasma polymerization apparatus used in the bonding method of the present invention. In the following description, the upper side in FIG. 1 is referred to as “upper” and the lower side is referred to as “lower”.
The plasma polymerization apparatus 100 shown in FIG. 1 includes a chamber 101, a first electrode 130 that supports the substrate 2, a second electrode 140, and a power supply circuit 180 that applies a high-frequency voltage between the electrodes 130 and 140. A gas supply unit 190 that supplies gas into the chamber 101 and an exhaust pump 170 that exhausts the gas in the chamber 101 are provided. Among these parts, the first electrode 130 and the second electrode 140 are provided in the chamber 101. Hereinafter, each part will be described in detail.
The chamber 101 is a container that can keep the inside airtight, and is used with the inside being in a reduced pressure (vacuum) state. Therefore, the chamber 101 has pressure resistance that can withstand a pressure difference between the inside and the outside.

A chamber 101 shown in FIG. 1 has a substantially cylindrical chamber body whose axis is arranged in the horizontal direction, a circular side wall that seals the left-side opening of the chamber body, and a circle that seals the right-side opening. And side walls.
A supply port 103 is provided above the chamber 101, and an exhaust port 104 is provided below the chamber 101. A gas supply unit 190 is connected to the supply port 103, and an exhaust pump 170 is connected to the exhaust port 104.

In this embodiment, the chamber 101 is made of a highly conductive metal material and is electrically grounded via the ground wire 102.
The first electrode 130 has a plate shape and supports the substrate 2.
The first electrode 130 is provided on the inner wall surface of the side wall of the chamber 101 along the vertical direction, whereby the first electrode 130 is electrically grounded via the chamber 101. The first electrode 130 is provided concentrically with the chamber body as shown in FIG.

An electrostatic chuck (suction mechanism) 139 is provided on the surface of the first electrode 130 that supports the substrate 2.
As shown in FIG. 1, the electrostatic chuck 139 can support the substrate 2 along the vertical direction. Moreover, even if the base material 2 has some warpage, the base material 2 can be subjected to plasma treatment in a state in which the warpage is corrected by being attracted to the electrostatic chuck 139.

The second electrode 140 is provided to face the first electrode 130 with the base material 2 interposed therebetween. Note that the second electrode 140 is provided in a state of being separated (insulated) from the inner wall surface of the side wall of the chamber 101.
A high frequency power source 182 is connected to the second electrode 140 via a wiring 184. A matching box (matching unit) 183 is provided in the middle of the wiring 184. The wiring 184, the high-frequency power source 182 and the matching box 183 constitute a power circuit 180.
According to such a power supply circuit 180, since the first electrode 130 is grounded, a high frequency voltage is applied between the first electrode 130 and the second electrode 140. As a result, an electric field whose direction is reversed at a high frequency is induced in the gap between the first electrode 130 and the second electrode 140.

The gas supply unit 190 supplies a predetermined gas into the chamber 101.
A gas supply unit 190 shown in FIG. 1 stores a liquid storage unit 191 that stores a liquid film material (raw material liquid), a vaporizer 192 that vaporizes the liquid film material to change it into a gaseous state, and stores a carrier gas. And a gas cylinder 193. Each of these parts and the supply port 103 of the chamber 101 are connected by a pipe 194, and a mixed gas of a gaseous film material (raw material gas) and a carrier gas is supplied from the supply port 103 into the chamber 101. It is configured to supply.

The liquid film material stored in the liquid storage unit 191 is a raw material that is polymerized by the plasma polymerization apparatus 100 to form a polymer film on the surface of the substrate 2.
Such a liquid film material is vaporized by the vaporizer 192 and is supplied into the chamber 101 as a gaseous film material (raw material gas). The source gas will be described in detail later.

The carrier gas stored in the gas cylinder 193 is a gas that is discharged due to the action of an electric field and introduced to maintain this discharge. Examples of such a carrier gas include Ar gas and He gas.
A diffusion plate 195 is provided near the supply port 103 in the chamber 101.
The diffusion plate 195 has a function of promoting the diffusion of the mixed gas supplied into the chamber 101. Thereby, the mixed gas can be dispersed in the chamber 101 with a substantially uniform concentration.

The exhaust pump 170 exhausts the inside of the chamber 101, and includes, for example, an oil rotary pump, a turbo molecular pump, or the like. Thus, by exhausting the chamber 101 and reducing the pressure, the gas can be easily converted into plasma. In addition, contamination and oxidation of the base material 2 due to contact with the air atmosphere can be prevented, and reaction products resulting from the plasma treatment can be effectively removed from the chamber 101.
The exhaust port 104 is provided with a pressure control mechanism 171 that adjusts the pressure in the chamber 101. Thereby, the pressure in the chamber 101 is appropriately set according to the operation state of the gas supply unit 190.

Next, an embodiment of the bonding method of the present invention will be described by taking the case of using the plasma polymerization apparatus 100 as an example.
2 and 3 are views (longitudinal sectional views) for explaining the joining method of the present invention. In the following description, the upper side in FIGS. 2 and 3 is referred to as “upper” and the lower side is referred to as “lower”.
In the bonding method according to the present embodiment, the plasma polymerized film 3 is formed on the bonding surfaces 21 of the two base materials 2 to obtain a first adherend 41 and a second adherend 42 ( A first step), a step of obtaining a temporary joined body by superimposing two adherends 41 and 42 so that the respective plasma polymer films 3 are brought into close contact with each other (second step), and in the temporary joined body The step (3rd process) which joins each plasma polymerization film 3 by giving energy with respect to each plasma polymerization film 3, and obtains a conjugate | zygote. Hereinafter, each process will be described sequentially.

[1] First, two base materials 2 are prepared. In FIGS. 2A to 2C, one of the two base materials 2 is omitted.
The constituent material of the base material 2 is not particularly limited, but polyolefins such as polyethylene, polypropylene, ethylene-propylene copolymer, ethylene-vinyl acetate copolymer (EVA), cyclic polyolefin, modified polyolefin, polyvinyl chloride. , Polyvinylidene chloride, polystyrene, polyamide, polyimide, polyamideimide, polycarbonate, poly- (4-methylpentene-1), ionomer, acrylic resin, polymethyl methacrylate, acrylonitrile-butadiene-styrene copolymer (ABS resin), Acrylonitrile-styrene copolymer (AS resin), butadiene-styrene copolymer, polyoxymethylene, polyvinyl alcohol (PVA), ethylene-vinyl alcohol copolymer (EVOH), polyethylene terf Polyester such as rate (PET), polyethylene naphthalate, polybutylene terephthalate (PBT), polycyclohexane terephthalate (PCT), polyether, polyetherketone (PEK), polyetheretherketone (PEEK), polyetherimide, polyacetal ( POM), polyphenylene oxide, modified polyphenylene oxide, polysulfone, polyethersulfone, polyphenylene sulfide, polyarylate, aromatic polyester (liquid crystal polymer), polytetrafluoroethylene, polyvinylidene fluoride, other fluororesins, styrene, polyolefin , Polyvinyl chloride, polyurethane, polyester, polyamide, polybutadiene, trans polyisoprene, fluoro rubber Various thermoplastic elastomers such as chlorinated polyethylene, epoxy resins, phenol resins, urea resins, melamine resins, aramid resins, unsaturated polyesters, silicone resins, polyurethanes, etc., or copolymers and blends mainly composed of these, Resin-based materials such as polymer alloys, Fe, Ni, Co, Cr, Mn, Zn, Pt, Au, Ag, Cu, Pd, Al, W, Ti, Ta, V, Mo, Nb, Zr, Pr, Nd, Metals such as Sm, or alloys containing these metals, such as carbon steel, stainless steel, indium tin oxide (ITO), fluorine doped tin oxide (FTO), gallium arsenide (GaAs), gallium phosphide (GaP) Materials, silicon materials such as single crystal silicon, polycrystalline silicon, amorphous silicon, silicate glass (quartz glass) Glass materials such as alkali silicate glass, soda lime glass, potash lime glass, lead (alkali) glass, barium glass, borosilicate glass, alumina, zirconia, ferrite, silicon nitride, aluminum nitride, boron nitride, titanium nitride , Ceramic materials such as silicon carbide, boron carbide, titanium carbide, tungsten carbide, carbon materials such as graphite, or composite materials combining one or more of these materials.

Moreover, the base material 2 may be subjected to a plating treatment such as Ni plating, a passivation treatment such as a chromate treatment, or a nitriding treatment on the surface thereof.
Note that the constituent materials of the two base materials 2 may be the same or different.
Moreover, it is preferable that the thermal expansion coefficients of the two base materials 2 are substantially equal. If the thermal expansion coefficient of each base material 2 is substantially equal, when the two base materials 2 are joined together, it becomes difficult to generate stress accompanying thermal expansion at the joint interface. As a result, peeling can be reliably prevented in the finally obtained bonded body 1.

In addition, although it explains in full detail later, even when the thermal expansion coefficient of each base material 2 differs mutually, in the process mentioned later, by optimizing the conditions at the time of joining two base materials 2, two base materials The two can be firmly bonded with high dimensional accuracy.
Moreover, it is preferable that the two base materials 2 have mutually different rigidity. Thereby, two base materials 2 can be joined more firmly.
Moreover, it is preferable that at least one constituent material of the two base materials 2 is a resin material. The resin material can relieve stress (for example, stress accompanying thermal expansion, etc.) generated at the bonding interface when the two base materials 2 are bonded to each other due to its flexibility. For this reason, it becomes difficult to destroy the bonding interface, and as a result, the bonded body 1 having high bonding strength can be obtained.

Moreover, the shape of the base material 2 should just be a shape which has the surface which supports the plasma polymerization film | membrane 3, For example, it is set as plate shape (layer shape), lump shape (block shape), rod shape, etc.
In this embodiment, as shown in FIG. 2A, the base material 2 has a plate shape. Thereby, the base material 2 becomes easy to bend, and when the two base materials 2 are overlapped, they can be sufficiently deformed along the shape. For this reason, the adhesiveness when the two base materials 2 are overlapped is increased, and the bonding strength in the finally obtained bonded body is increased.
Moreover, the base material 2 can be expected to act to alleviate the stress generated at the bonding interface to some extent.
In this case, the average thickness of the substrate 2 is not particularly limited, but is preferably about 0.01 to 10 mm, and more preferably about 0.1 to 3 mm.

  Next, if necessary, a surface treatment for improving the adhesion with the plasma polymerization film 3 is performed on the bonding surface 21 of the substrate 2. Thereby, the bonding surface 21 is cleaned and activated, and the plasma polymerization film 3 easily acts on the bonding surface 21 chemically. As a result, when the plasma polymerization film 3 is formed on the bonding surface 21 in a process described later, the bonding strength between the bonding surface 21 and the plasma polymerization film 3 can be increased.

This surface treatment is not particularly limited, for example, physical treatment such as sputtering treatment, blast treatment, plasma treatment using oxygen plasma, nitrogen plasma, corona discharge treatment, etching treatment, electron beam irradiation treatment, Examples thereof include a chemical surface treatment such as ultraviolet irradiation treatment, ozone exposure treatment, or a combination thereof.
In addition, especially when the base material 2 which performs surface treatment is comprised with the resin material (polymer material), corona discharge treatment, nitrogen plasma treatment, etc. are used suitably.
Further, as the surface treatment, the bonding surface 21 can be further cleaned and activated by performing a plasma treatment in particular. As a result, the bonding strength between the bonding surface 21 and the plasma polymerization film 3 can be particularly increased.

Further, depending on the constituent material of the base material 2, there is a material in which the bonding strength with the plasma polymerization film 3 is sufficiently high without performing the surface treatment as described above. Examples of the constituent material of the base material 2 that can obtain such an effect include those mainly composed of various metal-based materials, various silicon-based materials, various glass-based materials and the like as described above.
The surface of the substrate 2 made of such a material is covered with an oxide film, and a relatively active hydroxyl group is bonded to the surface of the oxide film. Therefore, by using the base material 2 made of such a material, the bonding strength between the bonding surface 21 of the base material 2 and the plasma polymerization film 3 can be increased without performing the surface treatment as described above. it can.
In this case, the entire base material 2 may not be made of the material as described above, and at least the vicinity of the bonding surface 21 may be made of the material as described above.

Further, instead of the surface treatment, an intermediate layer may be formed in advance on the bonding surface 21 of the substrate 2.
This intermediate layer may have any function, and for example, a layer having a function of improving adhesion to the plasma polymerized film 3, a cushioning function (buffer function), a function of reducing stress concentration, and the like are preferable. The base material 2 and the plasma polymerized film 3 are joined via such an intermediate layer, and the highly reliable joined body 1 can be obtained.

Examples of the constituent material of the intermediate layer include metal materials such as aluminum and titanium, metal oxides, oxide materials such as silicon oxide, metal nitrides, and nitride materials such as silicon nitride. Carbon materials such as graphite and diamond-like carbon, silane coupling agents, thiol compounds, metal alkoxides, self-assembled film materials such as metal-halogen compounds, resin adhesives, resin films, resin coating materials, Various rubber materials, resin materials such as various elastomers, and the like can be used, and one or more of these can be used in combination.
Further, among the intermediate layers made of these materials, the intermediate layer made of an oxide-based material can particularly increase the bonding strength between the substrate 2 and the plasma polymerized film 3.
The surface treatment and the formation of the intermediate layer as described above may be performed as necessary, and can be omitted when a high bonding strength is not particularly required.

[2] Next, as shown in FIGS. 2A to 2C, the plasma polymerized films 3 are respectively formed on the two base materials 2 (one surface of the base material 2) (first step). ).
The plasma polymerized film 3 can be obtained by polymerizing molecules in the source gas by supplying a mixed gas of the source gas and the carrier gas in a strong electric field.
Specifically, first, the base material 2 is accommodated in the chamber 101 to be in a sealed state, and then the inside of the chamber 101 is depressurized by the operation of the exhaust pump 170.

Next, the gas supply unit 190 is operated to supply a mixed gas of the source gas and the carrier gas into the chamber 101. The supplied mixed gas is filled into the chamber 101 (see FIG. 2A).
The ratio (mixing ratio) of the raw material gas in the mixed gas is slightly different depending on the kind of the raw material gas and the carrier gas, the target film forming speed, and the like. For example, the proportion of the raw material gas in the mixed gas is 20 to 70%. It is preferable to set it to a degree, and it is more preferable to set it to about 30 to 60%. As a result, it is possible to optimize the conditions for formation (film formation) of the polymer film.
Further, the flow rate of the gas to be supplied is appropriately determined depending on the type of gas, the target film formation rate, the film thickness, etc., and is not particularly limited, but usually the flow rates of the source gas and the carrier gas are respectively , Preferably about 1 to 100 ccm, more preferably about 10 to 60 ccm.

  Next, the power supply circuit 180 is activated, and a high frequency voltage is applied between the pair of electrodes 130 and 140. As a result, gas molecules existing between the pair of electrodes 130 and 140 are ionized to generate plasma. Due to the energy of the plasma, molecules in the raw material gas are polymerized, and the polymer is deposited and deposited on the substrate 2 as shown in FIG. Thereby, the plasma polymerization film | membrane 3 is formed on the base material 2 (refer FIG.2 (c)).

  Examples of the source gas include methylsiloxane, octamethyltrisiloxane, decamethyltetrasiloxane, decamethylcyclopentasiloxane, octamethylcyclotetrasiloxane, organosiloxane such as methylphenylsiloxane, trimethylgallium, triethylgallium, trimethylaluminum, Examples thereof include organometallic compounds such as triethylaluminum, triisobutylaluminum, trimethylindium, triethylindium, trimethylzinc, and triethylzinc, various hydrocarbon compounds, and various fluorine compounds.

The plasma polymerized film 3 obtained by using such a raw material gas is obtained by polymerizing these raw materials (polymer), that is, polyorganosiloxane, organometallic polymer, hydrocarbon polymer, fluorine polymer, and the like. Will be composed.
Of these, the plasma polymerized film 3 is preferably composed mainly of polyorganosiloxane. Polyorganosiloxane usually exhibits water repellency (non-adhesiveness), but it can be easily desorbed by passing through the energy application step (third step) described later and changes to hydrophilicity. And adhesiveness is developed.

  That is, even if the plasma polymerized films 3 made of polyorganosiloxane exhibiting water repellency are brought into contact with each other, the adhesion is hindered by the organic group, and it is extremely difficult to adhere. On the other hand, the plasma-polymerized film 3 composed of polyorganosiloxane exhibiting hydrophilicity can be particularly easily adhered when they are brought into contact with each other. That is, the advantage that the water repellency and the hydrophilicity can be easily controlled leads to the advantage that the adhesiveness can be easily controlled.

Therefore, the plasma polymerized film 3 exhibits adhesion relatively easily and uniformly by applying energy, but exhibits non-adhesiveness and prevents unintended adhesion when energy is not applied. It will be a thing.
In addition, since polyorganosiloxane is relatively flexible, for example, even when the constituent materials of the two base materials 2 are different, the stress accompanying the difference in thermal expansion coefficient generated between the base materials 2 can be relieved. Can do. Thereby, peeling can be reliably prevented in the bonded body 1 finally obtained.

  Furthermore, since polyorganosiloxane is excellent in chemical resistance, it can be effectively used for joining members that are exposed to chemicals for a long time. Specifically, for example, when manufacturing a droplet discharge head of an industrial inkjet printer in which an organic ink that easily erodes a resin material is used, by using the plasma polymerized film 3 mainly composed of polyorganosiloxane. , Its durability can be improved.

  Such a polyorganosiloxane has a random atomic structure including a siloxane (Si—O) bond. By having such a structure, the polyorganosiloxane becomes a strong film that is hardly deformed. For this reason, the plasma polymerized film 3 exhibits particularly excellent adhesiveness, and the plasma polymerized film 3 itself has high dimensional accuracy. For this reason, finally, the bonded body 1 having excellent bonding strength and high dimensional accuracy is obtained.

  The crystallinity of such a polyorganosiloxane is not particularly limited, but is preferably 45% or less, and more preferably 40% or less. As a result, the polyorganosiloxane contains a sufficiently random atomic structure. For this reason, the characteristic which the polyorganosiloxane mentioned above becomes obvious, and the dimensional accuracy and adhesiveness of the plasma polymerization film 3 become more excellent.

Further, when the plasma polymerized film 3 is composed of polyorganosiloxane, the sum of the Si atom content and the O atom content of all atoms constituting the plasma polymerized film 3 excluding H atoms. However, it is preferable that it is about 10-90 atomic%, and it is more preferable that it is about 20-80 atomic%. If Si atoms and O atoms are included in the above-mentioned range, the plasma polymerized film 3 forms a strong network of Si atoms and O atoms, and the plasma polymerized film 3 itself is strong. Become. Further, the plasma polymerized film 3 exhibits a particularly high bonding strength with respect to each base material 2.
The abundance ratio of Si atoms and O atoms in the plasma polymerized film 3 is preferably about 3: 7 to 7: 3, and more preferably about 4: 6 to 6: 4. By setting the abundance ratio of Si atoms and O atoms to be within the above range, the stability of the plasma polymerized film 3 is increased, and the adherends 41 and 42 can be bonded more firmly. .

  Further, among polyorganosiloxanes, those mainly composed of a polymer of octamethyltrisiloxane are preferred. A plasma polymerized film containing a polymer of octamethyltrisiloxane as a main component is particularly excellent in adhesiveness, and is particularly preferably used in the bonding method of the present invention. Moreover, since the raw material which has octamethyltrisiloxane as a main component is liquid at normal temperature and has an appropriate viscosity, there is an advantage that it is easy to handle.

In the plasma polymerization, the frequency of the high frequency applied between the pair of electrodes 130 and 140 is not particularly limited, but is preferably about 1 kHz to 100 MHz, and more preferably about 10 to 60 MHz.
Further, the power density of the high frequency is not particularly limited, and is preferably about 0.01 to 10 / cm ^2, more preferably about 0.1 to 1 W / cm ^2.
Further, the pressure in the chamber 101 during film formation is preferably about 133.3 × 10 ^{−5 to} 1333 Pa (1 × 10 ^{−5 to} 10 Torr), and 133.3 × 10 ^{−4 to} 133.3 Pa ( More preferably, it is about 1 × 10 ^{−4 to} 1 Torr).

The raw material gas flow rate is preferably about 0.5 to 200 sccm, and more preferably about 1 to 100 sccm. On the other hand, the carrier gas flow rate is preferably about 5 to 750 sccm, and more preferably about 10 to 500 sccm.
The treatment time is preferably about 1 to 10 minutes, more preferably about 4 to 7 minutes.
Moreover, it is preferable that the temperature of the base material 2 is 25 degreeC or more, and it is more preferable that it is about 25-100 degreeC.

By appropriately setting such conditions, the dense plasma polymerized film 3 can be formed without unevenness.
In this embodiment, the procedure for forming the plasma polymerized film 3 on the base material 2 using the plasma polymerization apparatus is described. However, the base material 2 (adhered body) provided with the plasma polymerized film 3 is used. It may be prepared in advance and the adherend may be used.

  Further, the constituent material of the plasma polymerized film 3 provided in the first adherend 41 and the constituent material of the plasma polymerized film 3 provided in the second adherend 42 may be different from each other, but preferably Are considered to be the same kind of material. Thereby, the affinity between each plasma polymerization film | membrane 3 improves. As a result, the plasma polymerization films 3 can be firmly bonded to each other through the steps described later.

Moreover, it is preferable that the average thickness of the plasma polymerization film | membrane 3 is about 1-1000 nm, and it is more preferable that it is about 2-800 nm. By making the average thickness of the plasma polymerized film 3 within the above range, the dimensional accuracy of the joined body obtained by joining the two base materials 2 can be prevented from being significantly lowered, and the two base materials 2 can be made stronger. Can be joined.
That is, when the average thickness of the plasma polymerized film 3 is less than the lower limit value, there is a possibility that sufficient bonding strength cannot be obtained. On the other hand, when the average thickness of the plasma polymerized film 3 exceeds the upper limit, the dimensional accuracy of the joined body may be significantly reduced.

Furthermore, if the average thickness of the plasma polymerized film 3 is within the above range, a certain degree of shape followability is ensured for the plasma polymerized film 3. For this reason, for example, even when unevenness is present on the bonding surface 21 (surface adjacent to the plasma polymerized film 3) of the base material 2, depending on the height of the unevenness, it follows the shape of the unevenness. A plasma polymerized film 3 can be deposited. As a result, the plasma polymerized film 3 can absorb the unevenness and reduce the height of the unevenness generated on the surface. Thereby, the adhesiveness of the plasma polymerization film | membrane 3 and the base material 2 can be improved more, and the further improvement of the joining strength of the joined body finally obtained can be aimed at.
In addition, the degree of the shape followability as described above becomes more prominent as the thickness of the plasma polymerization film 3 increases. Therefore, in order to ensure sufficient shape followability, the thickness of the plasma polymerization film 3 should be as thick as possible.

[3] Next, the two adherends 41 and 42 are overlapped so that the surfaces 31 of the respective plasma polymerization films 3 are in close contact with each other (see FIG. 2D). Thereby, the temporary joined body 5 shown in FIG.3 (e) is obtained (2nd process).
In addition, in the state of this temporary joining body 5, between each plasma polymerization film | membrane 3 is not joined. For this reason, the 1st to-be-adhered body 41 and the 2nd to-be-adhered body 42 can be shifted, and these relative positions can be adjusted. In this way, after the two adherends 41 and 42 are superposed, their positions can be easily fine-adjusted, so that the workability of the position adjustment is improved and the finally obtained joining The dimensional accuracy in the surface direction of the body 1 can be increased.
In particular, when the plasma polymerized film 3 is composed of polyorganosiloxane as a main material, the surface 31 of the plasma polymerized film 3 exhibits sufficient non-adhesiveness as described above. , 42 can freely adjust their positions. For this reason, the positions of the two adherends 41 and 42 can be finely adjusted particularly easily.

  In FIG. 2D, when obtaining the temporary joined body 5, two adherends 41 and 42 are overlapped so that the entire surface 31 of each plasma polymerization film 3 is covered with each other. The relative positions may be shifted from each other. That is, the first adherend 41 and the second adherend 42 may be overlapped so that the surface 31 of each plasma polymerization film 3 is exposed.

[4] Next, energy is applied to the obtained temporary joined body 5. Thereby, in the temporary joined body 5, a part of molecular bond of each plasma polymerization film | membrane 3 is cut | disconnected and activated (3rd process).
The “activation” means a state in which molecular bonds in the vicinity of and inside the surface 31 of the plasma polymerization film 3 are cut, and unterminated bonds (unbonded or dangling bonds) are generated, It means a state in which a hydroxyl group is bonded to the cleaved bond or a state in which these states are mixed.

When energy is applied to the temporary bonded body, the molecular bonds in the vicinity of and inside the surface 31 of the plasma polymerized film 3 are broken, and atomic groups (leaving groups) are desorbed from the plasma polymerized film 3. As a result, the bond to which the leaving group is bonded becomes an unterminated bond (unbonded bond).
Further, when moisture is contained in the surrounding atmosphere, the moisture acts on the dangling bonds, so that the dangling hands are terminated with a hydroxyl group.

  Here, the leaving group is, for example, selected from the group consisting of an H atom, a B atom, a C atom, an N atom, an O atom, a P atom, an S atom and a halogen atom, or an atomic group containing each of these atoms. Those composed of at least one selected from the above are preferably used. Such a leaving group is relatively excellent in bond / elimination selectivity by energy application. For this reason, such a leaving group can highly control the adhesiveness developed in the plasma polymerized film 3.

Specific examples of leaving groups include, for example, alkyl groups such as methyl and ethyl groups, alkenyl groups such as vinyl and allyl groups, aldehyde groups, ketone groups, carboxyl groups, amino groups, amide groups, nitro groups, and the like. Group, halogenated alkyl group, mercapto group, sulfonic acid group, cyano group, isocyanate group and the like.
Among these groups, the leaving group is particularly preferably an alkyl group. Since the alkyl group has high chemical stability, the plasma polymerized film 3 containing the alkyl group has excellent weather resistance and chemical resistance.

For example, when the plasma polymerized film 3 is composed of polyorganosiloxane as a main material, an alkyl group such as a methyl group mainly acts as a leaving group.
Based on the phenomenon as described above, the plasma polymerized film 3 is activated, and adhesiveness develops in each plasma polymerized film 3. And by this adhesiveness, each plasma polymerization film | membrane 3 is joined, and it becomes the one-layer plasma polymerization film | membrane 30 (refer FIG.3 (f)). Thereby, the joined body 1 is obtained.

  As a method for imparting energy to the plasma polymerized film 3, any method may be used as long as it can activate the plasma polymerized film 3. (I) A method of irradiating the temporary bonded body 5 with energy rays, (II) A method of heating the temporary joined body 5, (III) a method of applying a compressive force (physical energy) to the temporary joined body 5, and the like. Since these methods can impart energy to the plasma polymerized film 3 relatively easily and efficiently, they are suitable as energy imparting methods.

Hereinafter, each method of (I), (II), and (III) is explained in full detail.
(I) In the case of irradiating the temporary bonded body 5 with energy rays, as the energy rays, for example, light such as ultraviolet rays and laser light, electromagnetic waves such as X-rays and γ rays, or a combination of these energy rays Is mentioned. According to the method of irradiating energy rays, large energy can be applied in a short time. Accordingly, since the molecular structure in the plasma polymerized film 3 is not cut more than necessary, it is possible to avoid the deterioration of the characteristics of the plasma polymerized film 3.

In order to irradiate the plasma polymerized film 3 with energy rays in this way, at least one of the two base materials 2 in the temporary joined body 5 must transmit the energy rays.
From this point of view, when activating the plasma polymerized film 3 by irradiating the temporary bonded body 5 with energy rays, at least one of the two base materials 2 is assumed to be permeable to the energy rays.

For example, when light such as ultraviolet rays or laser light is used as the energy ray, at least one of the two base materials 2 is a light-transmitting material, specifically, a transparent glass-based material or a resin-based material. What is constituted may be used.
When electromagnetic waves such as X-rays and γ-rays are used as energy rays, at least one of the two base materials 2 is composed of a light element material such as a silicon-based material, a glass-based material, or a resin-based material. What is necessary is just to use.
In addition, when irradiating an energy beam to the temporary joined body 5, it cannot be overemphasized that an energy beam is irradiated from the base-material 2 side which has the permeability | transmittance with respect to an energy beam.

  Among these energy rays, it is particularly preferable to use ultraviolet rays having a wavelength of about 150 to 300 nm as shown in FIG. According to such ultraviolet rays, since the applied energy density is optimized, a wide range can be processed in a shorter time without unevenness while preventing the characteristics of the plasma polymerized film 3 from significantly deteriorating. For this reason, the plasma polymerization film 3 can be activated more efficiently. In addition, ultraviolet rays also have an advantage that they can be generated with simple equipment such as a UV lamp.

The wavelength of ultraviolet light is more preferably about 160 to 200 nm.
In the case of using the UV lamp, the output may vary depending on the area of the plasma polymerization film 3 is preferably from ^1mW / cm ^{2 ~1W} / cm 2 ^{approximately, 5mW / cm 2 ~50mW / cm} 2 of about It is more preferable that In this case, the separation distance between the UV lamp and the plasma polymerization film 3 is preferably about 3 to 3000 mm, and more preferably about 10 to 1000 mm.

The time for irradiating with ultraviolet rays is not particularly limited as long as the molecular bond of the plasma polymerized film 3 can be broken, but is preferably about 0.5 to 30 minutes, and preferably 1 to 10 minutes. More preferred is the degree.
Moreover, although an ultraviolet-ray may be irradiated continuously in time, you may irradiate intermittently (pulse form).
On the other hand, examples of the laser light include an excimer laser (femtosecond laser), an Nd-YAG laser, an Ar laser, a CO ₂ laser, and a He—Ne laser.

As described above, according to the method of irradiating the energy beam, it is possible to easily apply energy selectively to the plasma polymerized film 3, and thus, for example, preventing deterioration and deterioration of the base material 2 due to energy application. can do.
In addition, according to the method of irradiating energy rays, a large amount of energy can be applied in a short time, so that energy can be applied more efficiently.

Furthermore, according to the method of irradiating energy rays, the magnitude of energy to be applied can be adjusted easily and accurately. Thereby, the degree of adhesiveness developed in the plasma polymerized film 3 can be easily controlled.
That is, by increasing the energy to be applied, the adhesiveness expressed in the plasma polymerized film 3 can be further increased. On the other hand, the adhesiveness expressed in the plasma polymerization film 3 can be suppressed by reducing the applied energy. Thereby, the joining strength of the joined body 1 finally obtained can be adjusted.
In addition, in order to adjust the magnitude | size of the energy to provide, what is necessary is just to adjust conditions, such as the kind of energy beam, the output of an energy beam, the irradiation time of an energy beam.

  Moreover, it is preferable to irradiate such energy rays so that the energy is concentrated on the interface between the surfaces 31 of the respective plasma polymerization films 3 so as to be focused. In this way, molecular bonds near the surface 31 of each plasma polymerized film 3 can be selectively cut. Thereby, it can prevent more reliably that an energy ray cut | disconnects the molecular structure in the plasma polymerization film | membrane 3 more than necessary. As a result, it can be avoided more reliably that the characteristics of the plasma polymerized film 3 are significantly deteriorated.

(II) When heating the temporary joined body 5, it is preferable to set a heating temperature to about 25-100 degreeC, and it is more preferable to set to about 50-100 degreeC. By heating at a temperature in such a range, each plasma polymerization film 3 can be reliably activated while reliably preventing the base material 2 from being altered or deteriorated by heat.
The heating time may be a time that can break the molecular bond in the vicinity of the surface 31 of the plasma polymerized film 3. Specifically, if the heating temperature is within the above range, the heating time is about 1 to 30 minutes. Preferably there is.

The temporary joined body 5 may be heated by any method, but can be heated by various heating methods such as a method using a heater, a method of irradiating infrared rays, and a method of contacting with a flame.
In addition, when using the method of irradiating infrared rays, at least one of the two base materials 2 in the temporary joined body 5 is comprised with the material which has light absorptivity (infrared absorptivity) like a silicon-type material. It is preferable. The base material 2 made of such a material efficiently generates heat by absorbing infrared rays. Thereby, the plasma polymerization film | membrane 3 can be heated efficiently.

  Moreover, when using the method using a heater or the method of making it contact with a flame, at least one of the two base materials 2 is comprised with the material excellent in thermal conductivity like a metallic material. preferable. Thereby, the heat energy of a heater or a flame can be efficiently transmitted with respect to the plasma polymerization film | membrane 3 through the base material 2 comprised with such a material. As a result, the plasma polymerization film 3 can be efficiently heated.

In the case where the thermal expansion coefficients of the two base materials 2 are substantially equal, it is preferable to heat the temporary joined body 5 under the above conditions, but the thermal expansion coefficients of the two base materials 2 are different from each other. In some cases, it is preferable to perform bonding at as low a temperature as possible. By performing the bonding at a low temperature, it is possible to further reduce the thermal stress generated at the bonding interface.
Specifically, although it depends on the difference in thermal expansion coefficient between the two base materials 2, it is preferable to perform the bonding at a temperature of about 25 to 50 ° C, and it is more preferable to perform the bonding at a temperature of about 25 to 40 ° C. . Within such a temperature range, even if the difference in thermal expansion coefficient between the two base materials 2 is large to some extent, the thermal stress generated at the bonding interface can be sufficiently reduced. As a result, it is possible to reliably prevent warpage, peeling, and the like in the joined body 1.
In this case, when the difference in thermal expansion coefficient between the two base materials 2 is 5 × 10 ⁻⁵ / K or more, it is strongly recommended that the bonding be performed at the lowest possible temperature as described above. .

  (III) When compressive force is applied to the temporary joined body 5, it is preferable to compress at a pressure of about 0.2 to 10 MPa in a direction in which the two base materials 2 of the temporary joined body 5 approach each other. It is more preferable to compress at a moderate pressure. Thereby, moderate energy can be easily given with respect to the plasma polymerization film | membrane 3 only by compressing the temporary joining body 5. FIG. As a result, each plasma polymerization film 3 can be activated reliably.

In addition, although compression force may exceed the said upper limit, depending on the constituent material of each base material 2, there exists a possibility that damage etc. may arise in each base material 2. FIG.
Moreover, what is necessary is just to change suitably the time which provides compression force according to the magnitude | size of compression force. Specifically, the time for applying the compressive force can be shortened as the compressive force increases.
Energy can be imparted to the plasma polymerized film 3 by the above methods (I), (II), and (III).

  The application of energy to the plasma polymerization film 3 may be performed in any atmosphere, and specifically, the atmosphere, an oxidizing gas atmosphere such as oxygen, a reducing gas atmosphere such as hydrogen, nitrogen, An inert gas atmosphere such as argon, a reduced pressure (vacuum) atmosphere obtained by reducing these atmospheres, and the like can be given, and it is particularly preferable to perform in an air atmosphere. Thereby, it is not necessary to spend time and cost to control the atmosphere, and energy can be applied more easily.

When energy is applied as described above, adhesiveness develops in the plasma polymerized film 3, and this adhesiveness is manifested in both or one of the following two mechanisms (i) and (ii). Presumed to be based.
(I) Here, as an example, a case where a hydroxyl group is exposed on the surface 31 of each plasma polymerized film 3 by applying energy will be described as an example. When hydroxyl groups are exposed on the surface 31 of each plasma polymerized film 3 in an overlapping state, these hydroxyl groups attract each other by hydrogen bonding, and an attractive force is generated between the hydroxyl groups. It is assumed that the two adherends 41 and 42 are joined by this attractive force.

  Further, the hydroxyl groups attracting each other by this hydrogen bond are cut from each plasma polymerized film 3 with dehydration condensation depending on the temperature condition or the like. As a result, the bonds in which the hydroxyl groups are bonded are bonded between the plasma polymerization films 3. As a result, it is assumed that the first adherend 41 and the second adherend 42 are more firmly joined to form a single-layer plasma polymerization film 30.

(Ii) When energy is applied to the plasma polymerized film 3 in the temporary joined body 5, dangling bonds are generated on the surface 31 and inside of each plasma polymerized film 3. And when a dangling bond arises in each plasma polymerization film 3 which overlapped, adjacent dangling bonds will recombine. Since this recombination occurs in a complicated manner so as to overlap (entangle) with each other, a network-like bond is formed at the bonding interface. Accordingly, it is presumed that the respective base materials constituting each plasma polymerized film 3 are directly bonded to each other, and the respective plasma polymerized films 3 are integrated to form one plasma polymerized film 30.
By the mechanism (i) or (ii) as described above, the joined body 1 as shown in FIG.

  The bonded body 1 thus obtained is not bonded mainly based on a physical bond such as an anchor effect, as in an adhesive used in a conventional bonding method, but is a short time such as a covalent bond. The two adherends 41 and 42 are joined based on the strong chemical bond generated in step (b). For this reason, the bonded body 1 can be formed in a short time, is extremely difficult to peel off, and is difficult to cause uneven bonding.

Further, according to the bonding method of the present invention, unlike the conventional solid bonding, a heat treatment at a high temperature (for example, 700 ° C. or higher) is not required. Can be used for joining.
Moreover, since the two base materials 2 are joined to each other through the plasma polymerization film 3, there is an advantage that there is no restriction on the material of the base material as in the conventional solid joining.
From the above, according to the present invention, the range of selection of the constituent material of the substrate 2 can be expanded.

  Further, in the conventional solid bonding, since the bonding is not performed through the bonding layer, when there is a large difference in the coefficient of thermal expansion between the two base materials 2, when these are bonded, a large stress based on the difference is generated. Concentration at the bonding interface may cause problems such as peeling, but according to the present invention, stress concentration is mitigated through the plasma polymerized film 3, and peeling in the bonded body 1 is reliably prevented. Can do.

  Moreover, the plasma polymerization film | membrane 3 becomes a solid thing which does not have fluidity | liquidity. For this reason, by using the plasma polymerized film 3 as a bonding layer, the thickness and shape of the bonding layer (plasma polymerized film 3) hardly change compared to a conventional liquid or viscous liquid adhesive. Thereby, the dimensional accuracy of the joined body 1 obtained using the plasma polymerized film 3 is remarkably higher than the conventional one. Furthermore, since the time required for curing the adhesive is not required, strong bonding can be achieved in a short time.

The bonded body 1 thus obtained preferably has a bonding strength between the substrates 2 of 5 MPa (50 kgf / cm ² ) or more, more preferably 10 MPa (100 kgf / cm ² ) or more. The bonded body 1 having such bonding strength can sufficiently prevent the peeling. As will be described later, when the droplet discharge head is configured using the joined body 1, a droplet discharge head having excellent durability can be obtained. Moreover, according to the joining method of the present invention, the joined body 1 in which the two base materials 2 are joined with such a large joining strength can be efficiently produced.
After obtaining the joined body 1, at least one of the following three steps ([5A], [5B], and [5C]) is performed on the joined body 1 as necessary. You may do it. Thereby, the joint strength of the joined body 1 can be further improved.

[5A] As shown in FIG. 3G, the obtained bonded body 1 is pressurized in a direction in which the base materials 2 approach each other.
Thereby, the surfaces of the respective plasma polymerization films 3 are closer to each other. As a result, for example, dehydration condensation and recombination of binding activity in the step [4] are promoted. Then, the integration of the two plasma polymerized films 3 further proceeds, and the bonding strength in the bonded body 1 can be further increased.
At this time, the pressure at the time of pressurizing the bonded body 1 is a pressure that does not damage the bonded body 1 and is preferably as high as possible. Thereby, the joint strength in the joined body 1 can be increased in proportion to the pressure.

In addition, what is necessary is just to adjust this pressure suitably according to conditions, such as a constituent material and thickness of the base material 2, and a joining apparatus. Specifically, although it varies slightly depending on the constituent material and thickness of the substrate 2, it is preferably about 0.2 to 10 MPa, more preferably about 1 to 5 MPa. Thereby, the joining strength of the joined body 1 can be reliably increased. In addition, although this pressure may exceed the said upper limit, depending on the constituent material of the base material 2, there exists a possibility that damage etc. may arise in the base material 2. FIG.
The time for pressurization is not particularly limited, but is preferably about 10 seconds to 30 minutes. In addition, what is necessary is just to change suitably the time to pressurize according to the pressure at the time of pressurizing. Specifically, the higher the pressure at which the bonded body 1 is pressed, the better the bonding strength can be achieved even if the pressing time is shortened.

[5B] As shown in FIG. 3G, the obtained bonded body 1 is heated.
Thereby, for example, dehydration condensation of hydroxyl groups further proceeds at the interface of each plasma polymerized film 3. As a result, the bonding strength in the bonded body 1 can be further increased.
At this time, the temperature at the time of heating the bonded body 1 is not particularly limited as long as it is higher than room temperature and lower than the heat resistance temperature of the bonded body 1, but is preferably about 25 to 100 ° C., more preferably 50 to 100 ° C. About ℃. By heating at a temperature in such a range, it is possible to reliably increase the bonding strength of the bonded body 1 while reliably preventing the bonded body 1 from being altered or deteriorated by heat.

The heating time is not particularly limited, but is preferably about 1 to 30 minutes.
Moreover, when performing both said process [5A] and [5B], it is preferable to perform these simultaneously. That is, as shown in FIG. 3G, it is preferable to heat the bonded body 1 while applying pressure. Thereby, the effect by pressurization and the effect by heating are exhibited synergistically, and the joint strength of the joined body 1 can be particularly increased.

[5C] The obtained bonded body 1 is irradiated with ultraviolet rays (or other energy rays) (not shown).
Thereby, the chemical bond formed between each plasma polymerization film | membrane 3 can be increased, and the joining strength of the conjugate | zygote 1 can be raised especially.
The conditions of the ultraviolet rays irradiated at this time may be equivalent to the conditions of the ultraviolet rays shown in the step [4]. Moreover, when performing this process [5C], it is required that at least one of the two base materials 2 has translucency. Then, by irradiating ultraviolet rays from the translucent substrate 2 side, the plasma polymerization film 3 can be reliably irradiated with ultraviolet rays.

By performing the steps as described above, the two plasma polymer films 3 are almost completely integrated into one plasma polymer film 30. As a result, a bonded body 1 ′ with higher bonding strength can be obtained.
Each of these steps [5A], [5B] and [5C] may be performed continuously in time after the completion of the step [4], or after a certain time. It may be.
The joining method according to the present embodiment as described above can be used to join various members.

  Examples of members used for such bonding include semiconductor elements such as transistors, diodes, and memories, piezoelectric elements such as crystal oscillators, optical elements such as reflectors, optical lenses, diffraction gratings, and optical filters. , Optical conversion elements such as solar cells, semiconductor substrates and semiconductor elements mounted thereon, insulating substrates and wiring or electrodes, inkjet recording heads, microreactors, microelectromechanical systems (MEMS) components such as micromirrors, pressure Sensor parts such as sensors, acceleration sensors, package parts for semiconductor elements and electronic parts, magnetic recording media, magneto-optical recording media, recording media such as optical recording media, liquid crystal display elements, organic EL elements, electrophoretic display elements Such display element parts, fuel cell parts, and the like.

<Droplet ejection head>
Here, an embodiment in which the joined body of the present invention is applied to an ink jet recording head (droplet ejection head) will be described.
FIG. 4 is an exploded perspective view showing an ink jet recording head (droplet discharge head) obtained by applying the joined body of the present invention, and FIG. 5 shows a configuration of a main part of the ink jet recording head shown in FIG. FIG. 6 is a schematic view showing an embodiment of an ink jet printer including the ink jet recording head shown in FIG. Note that FIG. 4 is shown upside down from the state of normal use.

An ink jet recording head (droplet discharge head of the present invention) 10 shown in FIG. 4 is mounted on an ink jet printer (droplet discharge apparatus of the present invention) 9 as shown in FIG.
The ink jet printer 9 shown in FIG. 6 includes an apparatus main body 92, a tray 921 in which the recording paper P is installed at the upper rear, a paper discharge port 922 for discharging the recording paper P in the lower front, and an operation panel on the upper surface. 97.

The operation panel 97 includes, for example, a liquid crystal display, an organic EL display, an LED lamp, and the like, and a display unit (not shown) for displaying an error message and the like, and an operation unit (not shown) configured with various switches and the like. And.
Further, inside the apparatus main body 92, mainly a printing apparatus (printing means) 94 provided with a reciprocating head unit 93 and a paper feeding apparatus (paper feeding means) for feeding recording paper P to the printing apparatus 94 one by one. 95 and a control unit (control means) 96 for controlling the printing device 94 and the paper feeding device 95.

  Under the control of the control unit 96, the paper feeding device 95 intermittently feeds the recording paper P one by one. The recording paper P passes near the lower part of the head unit 93. At this time, the head unit 93 reciprocates in a direction substantially orthogonal to the feeding direction of the recording paper P, and printing on the recording paper P is performed. That is, the reciprocating motion of the head unit 93 and the intermittent feeding of the recording paper P are the main scanning and sub-scanning in printing, and ink jet printing is performed.

The printing apparatus 94 includes a head unit 93, a carriage motor 941 that is a drive source of the head unit 93, and a reciprocating mechanism 942 that reciprocates the head unit 93 in response to the rotation of the carriage motor 941.
The head unit 93 includes an ink jet recording head 10 (hereinafter simply referred to as “head 10”) having a large number of nozzle holes 111 at a lower portion thereof, an ink cartridge 931 that supplies ink to the head 10, the head 10 and And a carriage 932 on which the ink cartridge 931 is mounted.

Ink cartridge 931 is filled with four color inks of yellow, cyan, magenta, and black (black), thereby enabling full color printing.
The reciprocating mechanism 942 includes a carriage guide shaft 943 whose both ends are supported by a frame (not shown), and a timing belt 944 extending in parallel with the carriage guide shaft 943.

The carriage 932 is supported by the carriage guide shaft 943 so as to be able to reciprocate and is fixed to a part of the timing belt 944.
When the timing belt 944 travels forward and backward via a pulley by the operation of the carriage motor 941, the head unit 93 reciprocates as guided by the carriage guide shaft 943. During this reciprocation, ink is appropriately discharged from the head 10 and printing on the recording paper P is performed.

The sheet feeding device 95 includes a sheet feeding motor 951 serving as a driving source thereof, and a sheet feeding roller 952 that is rotated by the operation of the sheet feeding motor 951.
The paper feed roller 952 includes a driven roller 952a and a drive roller 952b that are vertically opposed to each other with a recording paper P feeding path (recording paper P) interposed therebetween. The drive roller 952b is connected to the paper feed motor 951. As a result, the paper feed roller 952 can feed a large number of recording sheets P set on the tray 921 one by one toward the printing apparatus 94. Instead of the tray 921, a configuration in which a paper feed cassette that stores the recording paper P can be detachably mounted may be employed.

The control unit 96 performs printing by controlling the printing device 94, the paper feeding device 95, and the like based on print data input from a host computer such as a personal computer or a digital camera.
Although not shown, the control unit 96 mainly includes a memory that stores a control program for controlling each unit, a piezoelectric element driving circuit that drives the piezoelectric element (vibration source) 14 to control the ink ejection timing, A driving circuit for driving the printing device 94 (carriage motor 941), a driving circuit for driving the paper feeding device 95 (paper feeding motor 951), a communication circuit for obtaining print data from the host computer, and these electrically And a CPU that is connected and performs various controls in each unit.
Further, for example, various sensors that can detect the remaining ink amount of the ink cartridge 931, the position of the head unit 93, and the like are electrically connected to the CPU.

  The control unit 96 obtains print data via the communication circuit and stores it in the memory. The CPU processes the print data and outputs a drive signal to each drive circuit based on the process data and input data from various sensors. The piezoelectric element 14, the printing device 94, and the paper feeding device 95 are each activated by this drive signal. As a result, printing is performed on the recording paper P.

Hereinafter, the head 10 (the droplet discharge head of the present invention) will be described in detail with reference to FIGS.
The head 10 includes a head main body 17 including a nozzle plate 11, an ink chamber substrate 12, a vibration plate 13, and a piezoelectric element (vibration source) 14 bonded to the vibration plate 13, and a base body that houses the head main body 17. 16. The head 10 constitutes an on-demand piezo jet head.

The nozzle plate 11 is made of, for example, a silicon-based material such as SiO ₂ , SiN, or quartz glass, a metal-based material such as Al, Fe, Ni, Cu, or an alloy containing these, or an oxide-based material such as alumina or iron oxide. The material is composed of carbon-based materials such as carbon black and graphite.
A number of nozzle holes 111 for discharging ink droplets are formed in the nozzle plate 11. The pitch between these nozzle holes 111 is appropriately set according to the printing accuracy.

An ink chamber substrate 12 is fixed (fixed) to the nozzle plate 11.
The ink chamber substrate 12 includes a plurality of ink chambers (cavities, pressure chambers) 121 and a reservoir chamber that stores ink supplied from the ink cartridge 931 by the nozzle plate 11, side walls (partition walls) 122, and a vibration plate 13 described later. 123 and a supply port 124 for supplying ink from the reservoir chamber 123 to each ink chamber 121 are partitioned.

Each ink chamber 121 is formed in a strip shape (cuboid shape), and is disposed corresponding to each nozzle hole 111. Each ink chamber 121 has a variable volume due to vibration of a diaphragm 13 described later, and is configured to eject ink by this volume change.
As a base material for obtaining the ink chamber substrate 12, for example, a silicon single crystal substrate, various glass substrates, various resin substrates and the like can be used. Since these substrates are general-purpose substrates, the manufacturing cost of the head 10 can be reduced by using these substrates.

On the other hand, a vibration plate 13 is bonded to the ink chamber substrate 12 on the side opposite to the nozzle plate 11, and a plurality of piezoelectric elements 14 are provided on the vibration plate 13 on the side opposite to the ink chamber substrate 12.
A communication hole 131 is formed at a predetermined position of the diaphragm 13 so as to penetrate in the thickness direction of the diaphragm 13. Ink can be supplied from the ink cartridge 931 to the reservoir chamber 123 through the communication hole 131.

Each piezoelectric element 14 has a piezoelectric layer 143 interposed between the lower electrode 142 and the upper electrode 141, and is disposed corresponding to the substantially central portion of each ink chamber 121. Each piezoelectric element 14 is electrically connected to a piezoelectric element drive circuit and is configured to operate (vibrate, deform) based on a signal from the piezoelectric element drive circuit.
Each piezoelectric element 14 functions as a vibration source, and the diaphragm 13 vibrates due to vibration of the piezoelectric element 14 and functions to instantaneously increase the internal pressure of the ink chamber 121.
The base body 16 is made of, for example, various resin materials, various metal materials, and the like, and the nozzle plate 11 is fixed and supported on the base body 16. That is, the edge of the nozzle plate 11 is supported by the step 162 formed on the outer periphery of the recess 161 in a state where the head body 17 is housed in the recess 161 provided in the base body 16.

Among the above-described bonding between the nozzle plate 11 and the ink chamber substrate 12, bonding between the ink chamber substrate 12 and the vibration plate 13, and bonding between the nozzle plate 11 and the substrate 16, the bonding according to the present invention is performed. The method is used.
In other words, the present invention is provided in at least one place among the joined body of the nozzle plate 11 and the ink chamber substrate 12, the joined body of the ink chamber substrate 12 and the vibration plate 13, and the joined body of the nozzle plate 11 and the substrate 16. The joined body is applied.

Such a head 10 is joined by interposing a plasma polymerization film at the joining interface. For this reason, the bonding strength and chemical resistance at the bonding interface are increased, and thereby the durability and liquid-tightness of the ink stored in each ink chamber 121 are increased. As a result, the head 10 becomes highly reliable.
In addition, since highly reliable bonding can be performed at a very low temperature, it is advantageous in that a large-area head can be formed even with materials having different linear expansion coefficients.

  Such a head 10 is in a state where a predetermined ejection signal is not input via the piezoelectric element driving circuit, that is, in a state where no voltage is applied between the lower electrode 142 and the upper electrode 141 of the piezoelectric element 14. The piezoelectric layer 143 is not deformed. For this reason, the vibration plate 13 is not deformed, and the volume of the ink chamber 121 is not changed. Therefore, no ink droplet is ejected from the nozzle hole 111.

  On the other hand, in a state where a predetermined ejection signal is input via the piezoelectric element driving circuit, that is, in a state where a constant voltage is applied between the lower electrode 142 and the upper electrode 141 of the piezoelectric element 14, the piezoelectric layer 143 is applied. Deformation occurs. As a result, the diaphragm 13 is greatly deflected, and the volume of the ink chamber 121 is changed. At this time, the pressure in the ink chamber 121 increases instantaneously, and ink droplets are ejected from the nozzle holes 111.

When the ejection of one ink is completed, the piezoelectric element driving circuit stops applying the voltage between the lower electrode 142 and the upper electrode 141. As a result, the piezoelectric element 14 returns almost to its original shape, and the volume of the ink chamber 121 increases. At this time, a pressure (pressure in the positive direction) from the ink cartridge 931 toward the nozzle hole 111 acts on the ink. Therefore, air is prevented from entering the ink chamber 121 from the nozzle hole 111, and an amount of ink corresponding to the amount of ink discharged is supplied from the ink cartridge 931 (reservoir chamber 123) to the ink chamber 121.
In this manner, in the head 10, arbitrary (desired) characters and figures can be printed by sequentially inputting ejection signals to the piezoelectric elements 14 at the positions to be printed via the piezoelectric element driving circuit. it can.

The head 10 may have an electrothermal conversion element instead of the piezoelectric element 14. That is, the head 10 may have a configuration (so-called “bubble jet method” (“bubble jet” is a registered trademark)) that ejects ink using thermal expansion of a material by an electrothermal transducer.
In the head 10 having such a configuration, the nozzle plate 11 is provided with a coating 114 formed for the purpose of imparting liquid repellency. Thus, when ink droplets are ejected from the nozzle holes 111, it is possible to reliably prevent ink droplets from remaining around the nozzle holes 111. As a result, the ink droplets ejected from the nozzle hole 111 can be reliably landed on the target area.

As described above, the bonding method, the bonded body, the droplet discharge head, and the droplet discharge apparatus of the present invention have been described based on the illustrated embodiments, but the present invention is not limited thereto.
For example, in the bonding method of the present invention, one or more optional steps may be added as necessary.
Moreover, although the said embodiment demonstrated the method to join two to-be-adhered bodies (a 1st to-be-adhered body and a 2nd to-be-adhered body), when joining three or more to-be-adhered bodies, this You may apply the joining method of invention.

Next, specific examples of the present invention will be described.
1. Manufacture of joined body (Example 1)
First, a single crystal silicon substrate having a length of 20 mm × width of 20 mm × average thickness of 1 mm and a glass substrate of length 20 mm × width 20 mm × average thickness of 1 mm were prepared.

Next, each of these substrates was accommodated in the chamber 101 of the plasma polymerization apparatus 100 shown in FIG. 1, and surface treatment with oxygen plasma was performed.
Next, a plasma polymerization film having an average thickness of 200 nm was formed on the surface subjected to the surface treatment. As a result, a first adherend and a second adherend were obtained. The film forming conditions are as shown below.

<Film formation conditions>
-Source gas composition: Octamethyltrisiloxane-Source gas flow rate: 50 sccm
Carrier gas composition: Argon Carrier gas flow rate: 100 sccm
・ High frequency power output: 100W
-Chamber pressure: 1 Pa (low vacuum)
・ Processing time: 15 minutes ・ Substrate temperature: 20 ° C.
Subsequently, the silicon substrate (first adherend) on which the plasma polymerized film is formed and the glass substrate (second adherend) on which the plasma polymerized film is formed so that the plasma polymerized films are in close contact with each other. Superimposed. Thereby, a temporary joined body was obtained.

Next, the obtained temporary joined body was irradiated with ultraviolet rays under the following conditions. Thereby, the plasma polymerization films in the temporary joined body were joined together to obtain a joined body.
<Ultraviolet irradiation conditions>
-Atmospheric gas composition: Air (air)
・ Atmospheric gas temperature: 20 ℃
・ Atmospheric gas pressure: Atmospheric pressure (100 kPa)
UV wavelength: 172 nm
-Ultraviolet irradiation time: 5 minutes Next, the obtained joined body was heated at 80 ° C while being pressurized at 3 MPa, and maintained for 15 minutes. Thereby, the joint strength of the joined body was improved.
(Example 2)
A joined body was obtained in the same manner as in Example 1 except that the heating temperature was changed from 80 ° C to 25 ° C.

(Example 3)
The constituent material of the base material of the second adherend is changed to the material shown in Table 1, and instead of the method of irradiating with ultraviolet rays, the temporary bonded body is heated under the following conditions, except for the above. A joined body was obtained in the same manner as in Example 1.
<Heating conditions>
・ Heat source: Heater ・ Heating temperature: 80 ℃
・ Heating time: 5 minutes ・ Heating atmosphere: air (air)

(Examples 4-5, 12)
A joined body was obtained in the same manner as in Example 3 except that the constituent materials of the respective base materials were changed to the materials shown in Table 1, respectively.
(Examples 6 to 11)
A joined body was obtained in the same manner as in Example 1 except that the constituent materials of the respective base materials were changed to the materials shown in Table 1, respectively.

(Examples 13 to 15)
A joined body was obtained in the same manner as in Examples 1, 3, and 4 except that the raw material gas was changed to the gas having the composition shown in Table 1 and the composition of the plasma polymerized film was changed.
(Comparative Examples 1-3)
A joined body was obtained in the same manner as in Examples 1, 3, and 4 except that the substrates were bonded with an epoxy adhesive.

2. 2. Evaluation of Bonded Body 2.1 Evaluation of Bonding Strength (Split Strength) The bonding strength was measured for each of the bonded bodies obtained in each Example and each Comparative Example.
The measurement of the bonding strength was performed by measuring the strength immediately before each substrate was peeled off. Then, the bonding strength was evaluated according to the following criteria.

<Evaluation criteria for bonding strength>
◎: 10 MPa (100 kgf / cm ² ) or more ○: 5 MPa (50 kgf / cm ² ) or more, less than 10 MPa (100 kgf / cm ² ) Δ: 1 MPa (10 kgf / cm ² ) or more, less than 5 MPa (50 kgf / cm ² ) ×: Less than 1 MPa (10 kgf / cm ² )

2.2 Evaluation of dimensional accuracy The dimensional accuracy in the thickness direction was measured for each joined body obtained in each of the examples and the comparative examples.
The measurement of the dimensional accuracy was performed by measuring the thickness of each corner of the square joined body and calculating the difference between the maximum value and the minimum value of the thicknesses at the four locations. This difference was evaluated according to the following criteria.
<Evaluation criteria for dimensional accuracy>
○: Less than 10 μm ×: 10 μm or more

2.3 Evaluation of chemical resistance The joined bodies obtained in each of Examples and Comparative Examples were immersed in ink for inkjet printers (manufactured by Epson Corporation, HQ4) maintained at 80 ° C for 3 weeks under the following conditions. Thereafter, each base material was peeled off, and it was confirmed whether or not ink entered the bonding interface. The results were evaluated according to the following criteria.

<Evaluation criteria for chemical resistance>
◎: Not penetrated at all ○: Slightly penetrated into the corner △: Infiltrated along the edge ×: Intruded inside As described above, each evaluation result of 2.1 to 2.3 Is shown in Table 1.

As is clear from Table 1, the joined bodies obtained in each Example exhibited excellent characteristics in all items of joining strength, dimensional accuracy, and chemical resistance.
On the other hand, the joined bodies obtained in the respective comparative examples have insufficient dimensional accuracy and chemical resistance, and the tendency is particularly remarkable in dimensional accuracy.

It is a longitudinal cross-sectional view which shows typically the plasma polymerization apparatus used for the joining method of this invention. It is a figure (longitudinal sectional view) for demonstrating the joining method of this invention. It is a figure (longitudinal sectional view) for demonstrating the joining method of this invention. It is a disassembled perspective view which shows the inkjet recording head (droplet discharge head) obtained by applying the conjugate | zygote of this invention. FIG. 5 is a cross-sectional view illustrating a configuration of a main part of the ink jet recording head illustrated in FIG. 4. It is the schematic which shows embodiment of an inkjet printer provided with the inkjet recording head shown in FIG.

Explanation of symbols

  DESCRIPTION OF SYMBOLS 1, 1 '... Bonded body 2 ... Base material 21 ... Bonding surface 3, 30 ... Plasma polymerization film 31 ... Surface 41 ... First adherend 42 ... Second adherend 5 ... ... Temporary joined body 100 ... Plasma polymerization apparatus 101 ... Chamber 102 ... Ground wire 103 ... Supply port 104 ... Exhaust port 130 ... First electrode 139 ... Electrostatic chuck 170 ... Pump 171 ... Pressure Control mechanism 180 …… Power supply circuit 182 …… High frequency power supply 183 …… Matching box 184 …… Wiring 190 …… Gas supply unit 191 …… Liquid storage unit 192 …… Vaporizer 193 …… Gas cylinder 194 …… Piping 195 …… Diffusion Plate 10: Inkjet recording head 11 ... Nozzle plate 111 ... Nozzle hole 114 ... Coating 12 ... Ink chamber substrate 121 ... Ink chamber 122 ... Wall 123 …… Reservoir chamber 124 …… Supply port 13 …… Vibration plate 131 …… Communication hole 14 …… Piezoelectric element 140 …… Second electrode 141 …… Upper electrode 142 …… Lower electrode 143 …… Piezoelectric layer 16 ... Base 161 ... Concave 162 ... Step 17 ... Head body 9 ... Inkjet printer 92 ... Device main body 921 ... Tray 922 ... Paper discharge port 93 ... Head unit 931 ... Ink cartridge 932 ... Carriage 94 …… Printing device 941 …… Carriage motor 942 …… Reciprocating mechanism 943 …… Carriage guide shaft 944 …… Timing belt 95 …… Feeding device 951 …… Feeding motor 952 …… Feeding roller 952a …… Following roller 952b …… Drive roller 96 …… Control unit 97 …… Operation panel P …… Recording Paper

Claims (22)

A first step of preparing a first adherend and a second adherend comprising a plasma polymerized film on a substrate;
A second step of superimposing the first adherend and the second adherend so as to bring the plasma polymer films into close contact with each other to obtain a temporary joined body;
And a third step of joining each of the plasma polymerized films to obtain a joined body by applying energy to the plasma polymerized film.   The bonding method according to claim 1, wherein each of the plasma polymerized films is composed of polyorganosiloxane as a main material.   The joining method according to claim 2, wherein the polyorganosiloxane is mainly composed of a polymer of octamethyltrisiloxane.   The joining method according to any one of claims 1 to 3, wherein the average thickness of each plasma polymerization film is 1 to 1000 nm.   The application of the energy in the third step is performed by at least one of a method of heating the temporary bonded body and a method of applying a compressive force to the temporary bonded body. The joining method according to any one of the above.   The joining method according to claim 5, wherein the heating temperature is 25 to 100 ° C.   The joining method according to claim 5 or 6, wherein the compressive force is 0.2 to 10 MPa. At least one of the base material provided in the first adherend and the base material provided in the second adherend has energy ray permeability,
The joining method according to any one of claims 1 to 7, wherein the application of the energy in the third step is performed by a method of irradiating the energy beam from the side of the base material having the permeability of the temporary joined body. . At least one of the base material provided in the first adherend and the base material provided in the second adherend has translucency,
The joining method according to any one of claims 1 to 8, wherein the application of the energy in the third step is performed by a method of irradiating ultraviolet rays from the translucent substrate side of the temporary joined body.   The bonding method according to claim 9, wherein the wavelength of the ultraviolet light is 150 to 300 nm.   The bonding method according to claim 1, wherein the third step is performed in an air atmosphere.   The joining method according to claim 1, further comprising a step of heating the joined body after the third step.   The joining method according to claim 12, wherein the heating temperature is 25 to 100 ° C.   The joining method according to claim 1, further comprising a step of pressurizing the joined body after the third step.   The bonding method according to claim 14, wherein a pressure when the bonded body is pressurized is 0.2 to 10 MPa.   The first adherend or the second adherend is preliminarily subjected to surface treatment for improving adhesion with the plasma polymerized film on the substrate, and then the region is subjected to the surface treatment. The bonding method according to claim 1, wherein a plasma polymerization film is formed.   The bonding method according to claim 16, wherein the surface treatment is a plasma treatment.   The joining method according to any one of claims 1 to 17, wherein a base material included in the first adherend and a base material included in the second adherend have different rigidity.   Two bonded substrates are bonded by the bonding method according to any one of claims 1 to 18.   The joined body according to claim 19, wherein the joining strength between the two base materials is 5 MPa or more.   21. A droplet discharge head comprising the joined body according to claim 19.   A droplet discharge apparatus comprising the droplet discharge head according to claim 21.

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