JP2904613B2 - Cover tape film and mounted component package using the same - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a package for mounting and transporting various electronic components, precision components and surface mounting components such as ICs, especially active components vulnerable to electrostatic damage such as ICs, and a packaging device for the same. It relates to the cover tape film used.

[0002]

2. Description of the Related Art In general, as a cover tape film for a carrier tape, a conventional biaxially stretched polyester film having a thickness of 10 to 50 .mu.m or a two-layer coextruded film of polyester / polyolefin is used as a base film, and an easy-open adhesive layer is formed. Styrene-butadiene-
Styrene block copolymer resin, ethylene-vinyl acetate copolymer resin alone or blended with polybutene, nylon resin and polyurethane resin
Those formed by a film laminating method or a coating method to a thickness of 30 μm are widely used.

[0003] The cover tape film has a concave portion (hereinafter referred to as a cavity) for accommodating a surface mount component, which is covered with a carrier tape formed continuously on an antistatic or conductive resin sheet and then covered with a lid. The cover tape film is heat-sealed at both ends to the carrier tape to prevent parts from falling off during storage and transport, and to be removed from the carrier tape body when parts are mounted by an automatic mounting machine such as a chip mounter. Is used.

[0004]

As described above, the cover tape film is unwound in the manufacturing process and the use process, and
The film is peeled off from the carrier tape at the same time that it is wound up several times, so that the transfer of electric charge occurs at the time of peeling, the film itself is easily charged, and when it is charged, it is stored when the cover tape is peeled off from the carrier tape. There is a problem that parts are electrostatically adhered to the cover tape film side and fall off from the cavity of the carrier tape, or the position is shifted, making it difficult to automatically mount. Complementary MOS-IC, transistor, transistor logic , Field-effect MO
Semiconductor devices (generally referred to as active components), such as S-transistors, bipolar transistors, and Schottky diodes, which are susceptible to static electricity, have a problem in that when they come into contact with a charged cover tape film, they are electrostatically damaged by discharge. Therefore, these cover tape films are generally formed by kneading an antistatic agent into the heat seal adhesive layer, depositing a metal or metal oxide on the surface, or coating the antistatic agent on the surface to form a thin film. Used as In addition, it is said that the surface resistance of the cover tape film for achieving an antistatic effect is required to be 10 ⁹ Ω or less, preferably 10 ⁷ Ω or less.

An effective means for providing such an antistatic effect is to add a conductive powder such as carbon black or metal fine powder to the adhesive layer. Since it is necessary to confirm the characters and visually inspect the characters, transparency is required, so that they cannot be practically adopted. Therefore, as a method for increasing the conductivity of the surface of the top tape film, an antistatic method using a transparent or translucent surfactant, that is, an anionic surfactant, a cationic surfactant, a nonionic surfactant, an amphoteric surfactant, etc. Are generally kneaded into the adhesive layer of the film or coated on the film surface to impart hydrophilicity and ionicity to the cover tape film surface. Examples of the surfactant used for such an antistatic agent include aliphatic quaternary ammonium salt type cationic surfactants, carboxybetaine type amphoteric surfactants, and anionic surfactants such as higher alcohol phosphate esters and sodium salts. And nonionic surfactants such as polyoxyethylene sorbitan fatty acid ester and polyoxyethylene alkylamine.

The above antistatic agent is commercially available as a powder, an aqueous solution, or an oil solution, and is used by kneading it into the heat-sealable adhesive layer or coating it on the surface of the film. However, in general, the surfactant is -COO ^- M ⁺ , -OSO ₃ ^- M ⁺ , (where M is an element atom such as H, Na, K), [-N (CH ₃ ) ₂
−] ⁺ X ⁻ (X is a halogen atom such as Cl or Br), hydrophilic groups such as —OH and — (CH ₂ CH ₂ O) _n — are arranged toward the atmosphere, and the electric resistance is determined by the hygroscopic property. , It is easily influenced by atmospheric humidity, and at room temperature and normal humidity (5-35 ° C., 45-85%
RH) has a surface resistance of 10 ⁹ Ω or more and is not useful for preventing the above-mentioned electrostatic breakdown of the semiconductor element. When kneading into the adhesive layer, the compatibility between the adhesive resin and the antistatic agent is a problem. If the compatibility is poor, it may bleed to the surface of the adhesive layer and deteriorate the heat seal adhesion performance.The coating on the film surface will dissolve in moisture and lose the antistatic effect. Cheap,
And so on.

[0007] In order to solve these problems, the inventor of the present invention has proposed a method in which the organic conductor 7,7,8,8, -tetracyanoquinodimethane complex (hereinafter abbreviated as TCNQ complex) has a donor. Attempts to improve heat resistance and reliability by mixing several kinds of the different complexes, and alkyl group-substituted TCNQ
Attempts have been made to use complexes. However, these TC
When an NQ complex is used, the TCNQ complex is
Because of the ionic bond of NQ, high temperature and high humidity conditions (60
(95 ° C, 95% Rh), the conductivity decreases when stored for a long time. At the same time, those using these TCNQ complexes dissolve the TCNQ complex in a solvent solution of a polymer matrix, Coating on the base film
The solvent is volatilized and dried to precipitate needle-like crystals in the matrix resin, and the needle-like crystals are brought into contact to obtain conductivity. For this reason, the needle-like crystals protrude from the polymer matrix resin layer, and when heat sealing is performed for a long time in actual use, the heated seal head surface
The needle-shaped crystals protruding from the matrix resin layer are broken and adhere to the seal head, and the adhered crystals become tacky due to the heat of the seal head and lift the cover tape, making it impossible to seal. It was necessary to clean the seal head. Furthermore, at the stage where the electronic component is embedded in the cavity of the carrier tape, the cover tape is sealed, and taping is completed, an inspection for visually confirming the orientation of the internal electronic component and the presence or absence of unfilling is performed. At the time of this inspection, the needle-like crystals of the TCNQ adhere to gloves of the inspector, and at the same time, fine crystals of the TCNQ complex adhere to the electronic component, thereby deteriorating the solderability. There was such a problem.

In addition, instead of the above-mentioned organic conductor such as the TCNQ complex, improvement in reliability under high-temperature and high-humidity conditions,
In order to solve problems such as adhesion to the seal head, various studies were conducted on metal oxide conductive materials.
Although there is no problem in terms of reliability, conductivity and adhesion to the seal head under high temperature and high humidity conditions, there is a problem that sufficient transparency cannot be obtained.

[0009]

The present inventors SUMMARY OF THE INVENTION In order to solve these above problems, as a result of carrying out intensive studies for the kind and particle size of the transparent conductive materials described above, the surface of the transparent plastic film, a heterologous Doped by elements
The average particle size of a transparent conductive resin layer made of a conductive fine powder and the binder resin of the following tin oxide compound and / or indium oxide compounds 0.3 [mu] m, the transparent having a hot-melt adhesive layer on the back surface And a carrier tape in which concave portions for accommodating mounted components are continuously provided in an antistatic or conductive resin sheet, and the hot melt adhesive layer heats the carrier tape so that it can be easily opened. The present invention has been completed by finding a packaged packaging component characterized by being sealed.

Hereinafter, the present invention will be described in detail with reference to the drawings. As shown in FIG. 1 (a), the cover tape film of the present invention comprises a transparent plastic film 1, a transparent conductive resin layer 2 on the front surface, and an easy-open hot-melt adhesive layer 3 on the back surface.
As shown in (b), the carrier tape 5 provided with the concave portions 4 for accommodating the mounted components is heat-sealed thereby. As described above, the transparent conductive material is a tin oxide compound or an indium oxide compound, and these compounds include tin oxide or indium oxide alone and tin oxide or indium oxide doped with a different element. As the different element to be doped, in addition to antimony, fluorine, phosphorus, and the like, tin is used for indium, indium is used for tin, and the conductivity can be improved by doping these different elements. When the particle size of these transparent conductive materials is too large, when blended with a binder resin to form a transparent conductive resin layer,
Visible light is irregularly reflected by the conductive material particles and the light transmittance decreases, and the conductive material particles protrude from the surface of the binder resin to form fine irregularities and increase the haze (haze) of the film. In order to cause a problem that transparency is reduced, the average particle size of the transparent conductive material is 0.3 μm or less, which is shorter than the wavelength of visible light, and 90% or more of the particles is in a range of 0.5 μm or less. I just need. However, when the average particle size is smaller than 0.05 μm, the surface resistance of the obtained transparent conductive resin layer may significantly increase and become higher than the necessary surface resistance described above. It is preferable that the thickness be in the range of 0.05 to 0.3 μm.

As a method for producing these fine particles, a tin or indium compound which is water-soluble and can be hydrolyzed in a weak alkaline region of PH = 8 to 12, for example, potassium stannate, sodium stannate, indium nitrate or sulfuric acid It can be obtained by hydrolyzing indium or the like in the weak alkaline region to form a sol, filtering this, and then drying and firing. In addition, when it is desired to dope a different element as described above, the water-soluble doping element compound, for example, antimony potassium tartrate for antimony, and ammonium fluoride for fluorine, each element is doped by dissolving. Fine powder can be obtained.

The cover tape of the present invention is obtained by mixing and dispersing the transparent conductive fine powder obtained as described above in a binder resin dissolved in an appropriate solvent or the like to obtain a conductive ink, It is obtained by applying a suitable method to a film to form a transparent conductive resin layer, and forming an easily-openable hot-melt adhesive layer on the opposite surface of the plastic film. The binder resin for blending and dispersing the transparent conductive powder needs to have high adhesion and transparency to the transparent plastic film to be used. Further, since the method of forming the transparent conductive resin layer is preferably formed by coating as described above, the binder resin needs to be dissolved in a general-purpose solvent, and is heat-sealed in actual use. Therefore, if the binder resin softens and becomes tacky when it comes into contact with the heated seal head, a sticking phenomenon occurs in which the cover tape film adheres to the seal head, which hinders the operation, so that the sealing is performed. It is necessary to have heat resistance so that it does not become tacky even if it is brought into contact with the head for a predetermined time.

Examples of such a binder resin include thermosetting polyurethane (PU), saturated copolymerized polyester having a high glass transition point, epoxy resin (EP), phenol resin (PF), and polymethyl methacrylate (PMMA). Polyacrylate, polycarbonate (P
C), urea resin, melamine resin, alkyd resin, nylon 11 and 12, polyvinyl butyral (PV
B), a simple substance such as polyvinyl alcohol (PVA), a fluororesin, a silicone resin (SR), or a mixture of two or more kinds thereof is preferably used. In order to improve the heat resistance of these resins, isocyanate or acid anhydride is used. Stuff,
It is optional to appropriately mix a curing agent such as an amine compound, and when an isocyanate-based curing agent is used, the obtained top tape films are heated and aged at 60 ° C. for 72 hours to accelerate the curing. It is also optional to add an anti-blocking agent or the like exemplified in the block copolymer containing a perfluoroalkyl group so as to prevent blocking.

Further, an ultraviolet curable resin or an electron beam curable resin may be used as the binder resin because of its merit that it can be applied without a solvent and at the same time that its processing speed can be improved.

If the proportion of the transparent conductive fine powder to be added to the binder resin is too small, the desired conductivity cannot be obtained, and if it is too large, the adhesion of the transparent conductive resin layer to the plastic film of the base material is insufficient. At the same time, there is a problem that the binder resin cannot be filled between the conductive particles and a gap is formed, resulting in a decrease in transparency.Therefore, the conductive fine powder is added to the total weight of the conductive fine powder and the binder resin. The content may be 40 to 85% by weight.

The solvent for dissolving the binder resin may be appropriately selected from general-purpose solvents in consideration of the solubility of the resin and the solvent resistance of the plastic film to be coated. ,ethanol,
alcohols such as n-propanol, i-propanol, n-butanol, i-butanol, diacetone alcohol, cyclohexanol, acetone, cyclohexanone, methyl ethyl ketone, methyl isobutyl ketone, holone, ketones such as isophorone, ethylene glycol monomethyl ether, Ethers such as carbitol and dioxane; esters such as ethyl acetate, butyl acetate and isopropyl acetate; aromatics such as toluene, xylene and solvent naphtha; dimethylformamide, dimethylacetamide, propylene carbonate, γ-butyrolactone and dimethylsulfo Polar solvents such as oxide, sulfolane, formamide, N-methyl-2-pyrrolidone, acetonitrile, propionitrile and water alone or as a mixture of two or more Agents are exemplified.

The conductive fine powder can be obtained by blending into a binder resin solution dissolved in the above-mentioned solvent and then uniformly dispersing the same. The dispersion method includes a spiral mixer, a planetary mixer, and a disperser. After performing pre-mixing with a blade-type stirring and kneading device such as a parser and a hybrid mixer, thoroughly disperse using a ball-type kneading device such as a ball mill, a vibration mill, and a sand mill or a roll-type kneading device such as a three-roll. Is desirable.

In order to improve the dispersibility, various anionic, nonionic and cationic surfactants and various coupling agents such as silane, titanium and aluminum are incorporated as dispersants. It is optional.

The viscosity and solid content of the transparent conductive ink thus adjusted are appropriately adjusted in accordance with the following various coating methods, and thereafter, a known coating method, specifically, a gravure coater is used. Roll coater such as three reverse coater, offset gravure coater and meyer bar,
A bar coater, a comma coater and an air knife coater, as well as a dip coater or a spray coater or the like, may be applied to a thickness at which an appropriate surface resistance is obtained and dried, but if this thickness is too thick, the cost increases, Preferably, the dry film thickness is in the range of 0.2 to 1.0 μm.

As the transparent plastic film used in the present invention, a general-purpose plastic film having high transparency is used. Specific examples thereof include a single film of a polyethylene film, a polyvinyl chloride film, a polypropylene film, a polystyrene film, a polyethylene terephthalate film, a polycarbonate film, a polyarylate film, a polyvinylidene fluoride film, a polyamide film, and a composite film thereof. Since these transparent plastic films form a transparent conductive resin layer, it is preferable to perform a corona discharge treatment or a plasma treatment on the surface for the purpose of improving the adhesion.

The cover tape film of the present invention is obtained by forming an easy-opening hot-melt adhesive layer on the opposite surface of the film obtained as described above. , Saturated copolymerized polyester resin,
Polyvinyl butyral, vinyl chloride resin, ethylene-vinyl acetate copolymer resin, polybutadiene resin, ethylene-
Ethyl acrylate copolymer resin, polyvinyl acetate resin, ionomer resin, styrene-butadiene-styrene copolymer resin, styrene-isobutylene-styrene copolymer resin, styrene-ethylene / butylene-styrene copolymer resin, nylon resin, polyvinyl butyral resin Or a complex of two or more. It is optional to add a filler such as hydrophilic or hydrophobic silica to these hot melt adhesive resins in a range that does not reduce the transparency in order to suppress the peel strength of the resin.

As a method for forming the hot melt adhesive resin layer on the base film, the hot melt adhesive resin is melted from a T-die and extruded to coat the base film. The resin is dissolved in an appropriate solvent to form a varnish, and may be formed by coating by selecting an appropriate method from the above-mentioned coating method. Further, when the adhesive is in the form of a film, a hot roll Or may be formed by bonding using an adhesive.

The thickness of this hot melt adhesive is as follows:
Since the adhesive also requires transparency, if it is too thick, the transparency will be reduced, and if it is too thin, sufficient adhesive strength will not be obtained, so that it is in the range of 0.5 to 30 μm, preferably 1.
What is necessary is just to make it the range of 0-20 micrometers. Also, since this cover tape needs to be peeled off from the carrier tape when mounting the internal electronic components, the base film may be broken if the adhesive strength of the hot melt adhesive is excessively large. It is necessary to make it easy to open, and the specific peel strength is 10 to 180 peel.
100 gf / mm, preferably 20 to 70 gf / mm.

[0024]

The present invention will be described in detail below with reference to examples and comparative examples. Using Example 1 polyester film having a thickness of 25μm as the transparent substrate "Lumirror ^R T type" (manufactured by Toray Co., Ltd., trade name) as a base film. As easy-open hot-melt adhesive, the glass transition point 2 ° C., Ring and Ball softening point of 115 ° C. saturated copolymerized polyester "elitel ^R U
E-3221 "(trade name, manufactured by Unitika Co., Ltd.) and 100 parts by weight of this" Elitel ^R UE-3221 "were used in toluene / methyl ethyl ketone (50/50% by volume).
Was dissolved in 233.3 parts by weight of a mixed solvent using a high-speed disperser to prepare a coating solution A having a viscosity of 150 cP. Then, a glass transition point of 90 ° C. and a softening point of a ring and ball method of 1
85 ° C., saturated copolymerized polyester "elitel ^R UE-
3690 ”(trade name, manufactured by Unitika Ltd.) was dissolved in 70 parts by weight of a mixed solvent of methyl ethyl ketone / toluene (50/50) using a high-speed disperser, and a binder resin solution having a solid content of 30% by weight was dissolved. It was adjusted. 30 parts by weight of the antimony-doped tin oxide compound fine powder produced by the following process was added to 30 parts by weight of this binder resin solution, and methyl ethyl ketone / toluene = 1/1.
After 240 parts by weight of the mixed solvent was mixed, the mixture was stirred using a disperser, and then subjected to sand mill treatment to complete the dispersion, thereby preparing a transparent conductive ink B having a solid content of 13.0% and a viscosity of 200 cp.

The antimony-doped tin oxide compound fine powder is prepared by dissolving 300 g of potassium stannate and 36.0 g of potassium antimonyl tartrate in 664 g of distilled water, and then dissolving the aqueous solution in 2 liter of distilled water adjusted to 45 ° C. A sol solution in which conductive particles are dispersed by hydrolysis while adding nitric acid so as to adjust the pH of the temperature-controlled water bath to 8.5 so as to adjust the pH of the water bath to 8.5 while stirring and applying an ultrasonic wave is applied. After filtration, the residue on the filter paper was washed with distilled water, and the resulting particles were dried and then dried at 200 ° C. in air.
To 600 ° C over 4 hours, and further 650 ° C.
Calcination was performed at 2 ° C. for 2 hours to prepare a fine powder of a tin oxide compound having an average particle diameter of 0.17 μm and particles of up to 90% within 3.3 μm.

Each of the coating solution A and the transparent conductive ink B prepared above was coated with a gravure plate having a line number of 150 mesh, a depth of 50 μm and a line number of 200 mesh, and a depth of 2 mesh.
A 5 μm gravure plate was placed on a two-color gravure coater capable of simultaneous coating on both sides, and one side of the polyester film was reversed in the order of A → B to perform double-side coating and drying, and then aging at 40 ° C. for 3 days. Was carried out.
At this time, with respect to 100 parts by weight of the transparent conductive ink B, 1.0 part by weight of an isocyanate-based curing agent "CAT-10" (trade name, manufactured by Toyo Morton Co., Ltd.) was added and stirred for use.

The thickness of the obtained dried coating film was 3 μm for the coating liquid A and 0.2 μm for the coating liquid B.
D is added to the transparent conductive resin layer of the obtained cover tape film.
When the surface resistance was measured by applying C100V, the average value was 5.0 × 10 ⁶ Ω, the maximum value was 6.0 × 10 ⁶ Ω, and the minimum value was 4.5 × 10 ⁶ Ω, which was very stable. The light transmittance was 82%, the haze was 10 or less, and the abrasion resistance was tested by applying a load of 100 gf and rubbing the nonwoven fabric against the transparent conductive resin layer. The resin layer does not adhere,
No significant change was observed in the conductivity. Then, a slit is formed to a predetermined width, and a carrier tape for IC made of polyvinyl chloride "Shin-Etsu Carrier" (Shin-Etsu Polymer Co., Ltd.) is formed by a 1 mm-wide heat seal head
The seal was repeated at a seal head temperature of 180 ° C and a crimping time of 0.3 seconds.
In the case of using the NQ complex, the sticking phenomenon occurred at about 6000 shots, and it was necessary to clean the seal head. On the other hand, the cover tape film of the present invention showed that the seal head became dirty even after 100,000 shots. No sticking phenomenon was observed. The average peel adhesive strength is 38 gf / mm, and the maximum is 64 gf / m.
m, a minimum of 25 gf / mm, indicating good strength.

[0028] [Comparative Example 1] Instead of the transparent conductive ink B of Example 1, as a polymer matrix, the glass transition point 90 ° C., a ring and ball softening point of 185 ° C., saturated copolymerized polyester "Elitel ^R UE-3690" 10 parts by weight (produced by Unitika Ltd., trade name) of cyclohexanone /
It is dissolved in 500 parts by weight of a mixed solvent of toluene (70/30) using a high-speed disperser, and Nn-butylisoquinolinium-methyl-TCNQ complex (prototype manufactured by Nitto Chemical Industry Co., Ltd.) ) 5.3 parts by weight and 2.7 parts by weight of Nn-butyl-N-methylmorpholinium-methyl-TCNQ complex (prototype manufactured by Nitto Chemical Industry Co., Ltd.) were added, and a disperser was used. After stirring and dissolving, the mixture was subjected to a sand mill treatment, and further filtered through filter paper (Whatman filter paper No. 3). To 100 parts by weight of the obtained liquid, 0.25 part by weight of toluene diisocyanate-trimethylpropane adduct prepolymer "Coronate L" (trade name, manufactured by Nippon Polyurethane Industry Co., Ltd.) and 0.25 parts by weight of a blocking inhibitor "MODIPA F" (Nippon Oil & Fats Co., Ltd.) ), Trade name) was added and stirred again with a disperser to prepare a coating solution C having a viscosity of 20 cP. Others were carried out in the same manner as in Example 1, and the coating liquid C had a dry film thickness of 0.1 μm. When DC 100 V was applied to the coating film of the obtained top tape film with the coating liquid C to measure the surface resistance, the average value was 2.5 × 10 ⁶ Ω, and the maximum value was 3.0 ×.
10 ⁶ Ω, and the minimum value was 2.0 × 10 ⁶ Ω. FIG. 2 shows changes in surface resistance under high temperature and high humidity, and Table 1 shows the results of the rubbing test and the long run test.

[0029]

[Table 1]

[0030]

Cover tape film of the present invention according to the present invention uses a transparent conductive tin oxide compound reliability under high temperature and high humidity conditions is a high metal oxide in the resin layer a fine powder and / or indium oxide fine powder, further Different elements to these
As shown in FIG. 2, the surface resistance does not increase even during long-term storage under high-temperature and high-humidity conditions, and the particles are made smaller than the conventional conductive fine powder. The transparency can be greatly improved compared to the transparent conductive resin layer of, and the visibility in confirming the marking of electronic parts etc. can be greatly improved, thus enabling automatic recognition of these confirmation processes It is assumed that. In addition, regarding the problem of the conventional TCNQ complex and the like, the contamination and sticking of the seal head and the problem of adhesion of conductive materials such as gloves during long-time heat sealing, the transparent conductive fine powder used in the present invention is Since it is a fine powder of a tin oxide compound or an indium oxide compound, and is an inorganic conductor, it does not melt or soften and becomes tacky even when it comes into contact with a seal head in heat sealing, so that sticking does not occur. Further, since the particles used are smaller than the conventional ones as described above and do not crystallize like the TCNQ complex, even if the conductive material is exposed on the surface, it protrudes from the transparent conductive resin layer. Even in the long-term seal test (long run test), the period until the seal head is cleaned is significantly extended, and the number of lots sealed by one seal head is 10,000 to 100,000 shots. The trouble of stopping and cleaning can be eliminated. Similarly, visual inspection and the like also confirmed that there was no dirt due to the adhesion of the conductive material to gloves and the like.

[Brief description of the drawings]

FIG. 1A is a longitudinal sectional view of a cover tape film of the present invention, and FIG. 1B is a longitudinal sectional view of a mounted component package made of a carrier tape heat-sealed with a cover tape.

FIG. 2 is a graph showing a change in surface resistance of the mounted component package of the present invention under high temperature and high humidity conditions (60 ° C.-95% Rh).

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Transparent plastic film 2 Transparent conductive resin layer 3 Easy-opening hot-melt adhesive 4 Depression 5 Carrier tape

Claims (2)

(57) [Claims] Claims: 1. The surface of a transparent plastic film has a different shape.
Of a tin oxide compound and / or an indium oxide compound having an average particle diameter of 0.3 μm or less doped with a seed element
The conductive fine powder and the transparent conductive resin layer made of a binder resin is provided, the transparent composite cover tape film characterized in that a hot-melt adhesive layer on the back surface. 2. A hot-melt adhesive comprising a transparent composite cover tape film according to claim 1, and a carrier tape having a concave portion for accommodating a mounted component in an antistatic or conductive resin sheet. A package for a mounted component, wherein the carrier tape is heat-sealed with an agent layer so as to be easily opened.