Embodiment
Below in conjunction with embodiment, film with electromagnetic shielding action that the technical program provides and preparation method thereof is further described in detail.
Refer to Fig. 1, the technical program provides a kind of film 100, and it comprises the release substrate layer 110, epoxy resin composite material layer 120 and the release separator 130 that stack gradually.
Release substrate layer 110 is for load-carrying ring epoxy resin composite material layer 120.Release substrate layer 110 can be PET release film, and namely its base material is PET, one or two relative surfaces of base material is coated with the materials such as silicone oil and forms release surface.Described release surface can cling epoxy resin composite material layer 120 formed thereon, but is easy to release substrate layer 110 is separated with epoxy resin composite material layer 120.In the present embodiment, release substrate layer 110 adopts one side PET release film, and it has the first release surface 111.The material of release substrate layer 110 is not limited to the PET release film provided in the present embodiment, and it also can have the material of release surface, as release liners etc. for other.Described release liners can be silicone oil paper or leaching membrane paper.
Release separator 130 is for by guard ring epoxy resin composite material layer 120.When the film 100 produced does not need transport or preserves for a long time, film 100 also can not comprise release separator 130.The material of release separator 130 can with the material of release substrate layer 110 just as, namely it can be PET release film, and it also can have the material of release surface, as various release liners etc. for other.Release separator 130 has the second release surface 131, second release surface 131 contacts with each other with epoxy resin composite material layer 120, thus carrying out transporting or in storage process, when multifilm 100 mutual stacking time, it is inter-adhesive to avoid that release separator 130 can isolate the film 100 contacted with each other.And release substrate layer 110 and release separator 130, in transport and storage process, also can make epoxy resin composite material layer 120 be isolated from the outside, prevent the contaminated or moisture absorption of epoxy resin composite material layer 120.
Epoxy resin composite material layer 120 is for playing electromagnetic shielding action.The power of the electromagnetic interference that the thickness of epoxy resin composite material layer 120 can shield according to actual needs sets.Epoxy resin composite material layer 120 is arranged between the first release surface 111 of release substrate layer 110 and the second release surface 131 of release separator 130, and its thickness is about 8 microns to 25 microns.Epoxy resin composite material layer 120 is semi-cured state.Epoxy resin composite material in epoxy resin composite material layer 120 comprises the epoxy resin of end carboxyl polymer modification, carbon nano-tube, inorganic dispersion, curing agent, catalyst, solvent and defoamer.
The epoxy resin of described end carboxyl polymer modification is the product after epoxy resin and end carboxyl polymer generation copolymerization, namely the carboxyl of the epoxy radicals of epoxy resin end and the end of end carboxyl polymer reacts and generates an ester group, thus obtains the polymer of the repetitive comprising epoxy resin repetitive alternately and end carboxyl polymer.Wherein, epoxy resin can be bisphenol A type epoxy resin, and end carboxyl polymer can be liquid polybutadiene acrylonitrile (CTBN).In the present embodiment, the epoxy resin of the employing epoxide equivalent before unmodified is 180 to 195, and be preferably 188, the oxygen equivalent of going back of the epoxy resin that carboxyl polymer is modified is 323 to 352, is preferably 337.The mass percent of epoxy resin in epoxy resin composite material of end carboxyl polymer modification is about 55% to 65%, is preferably about 60%.
Carbon nano-tube is as electric conducting material, and it is dispersed in the epoxy resin of end carboxyl polymer modification, to play electromagnetic shielding action.The shared in the composite mass percent of carbon nano-tube is 4.6% to 16%.The electric conductivity that in composite material, how much content of carbon nano-tube can obtain composite material is according to actual needs determined.In epoxy resin composite material, the content of carbon nano-tube is more, and the resistance of epoxy resin composite material is less, and in composite material, the content of carbon nano-tube is fewer, and the resistance of epoxy resin composite material is larger.
Inorganic dispersion is used for dispersing Nano carbon tubes, can be uniformly distributed in epoxy resin composite material to make carbon nano-tube.Described inorganic dispersion is nanoclay or nano mica powder.Described nanoclay is the phyllosilicate of 2: 1, and it is specifically as follows montmorillonite, and (Montmorillonite, molecular formula is M
x(Al
4-xmg
x) Si
8o
20(OH)
4), (Hectorite, molecular formula is M to hectorite
x(Mg
6-xli
x) Si
8o
20(OH)
4) or saponite (Saponite, molecular formula is M
xmg
6(Si
8-xal
x) O
20(OH)
4) etc.Wherein, carbon nano-tube is 8 to 12 to 1 with the mass ratio of inorganic dispersion.Described inorganic dispersion is preferably nano mica powder.
Described curing agent is used for playing induration to composite material.In the present embodiment, the curing agent of employing is dicyandiamide (Dicyandiamine), and described curing agent is about 5% in the mass percent shared by epoxy resin composite material.The consumption of curing agent should be corresponding with the epoxy resin of end carboxyl polymer modification, and wherein the epoxy resin of end carboxyl polymer modification is about 13 to 14 to 1 with the mass ratio of curing agent.
Described catalyst is 2-undecyl imidazole (2-Undecylimidazole), and the content of catalyst is mutually corresponding with the content of the epoxy resin of end carboxyl polymer modification.The mass percentage of catalyst shared by epoxy resin composite material is about 0.5% to 1%, is preferably 0.65%.Described solvent is diethylene glycol ether acetate alone (Diethylene glycol monoethyl ether acetate), and the content of described solvent in epoxy resin composite material is about 20% to 25%, is preferably 24%.This solvent for dissolving other components above-mentioned, to form uniform liquid dispersed system.Described defoamer is for eliminating the foam in above-mentioned epoxy resin composite material, and the mass percent of described defoamer in epoxy resin composite material is about 2%.Described defoamer can be the 2183H defoamer that commercially available Taiwan Chun Zheng company produces.
Preferably, in epoxy resin composite material, the mass percentage of the epoxy resin of end carboxyl polymer modification is about 60.3%, the mass percentage of carbon nano-tube is about 7.8%, the mass percentage of inorganic dispersion is about 0.6%, the mass percentage of curing agent is about 4.5%, the mass percentage of catalyst is about 0.65%, and the mass percentage of solvent is about 24.3%, and the mass percentage of defoamer is about 1.85%.Inorganic dispersion selects mica powder.The viscosity of the epoxy resin composite material in the present embodiment can reach 60000 to 75000 centipoises, and it can bond with coverlay in circuit board or other glue-line easily mutually.Preferably, the viscosity of epoxy resin composite material is about 70000 centipoises.
The technical program also provide a kind of described in there is the manufacture method of the film 100 of electromagnetic shielding action, described manufacture method comprises the steps:
The first step, makes described epoxy resin composite material.
State epoxy resin composite material in the present embodiment and can adopt making with the following method:
First, adopt end carboxyl polymer modification epoxy resin to obtain the epoxy resin of end carboxyl polymer modification.
End carboxyl polymer and epoxy resin are positioned over and are jointly positioned in reaction vessel, and to maintain reaction temperature be 120 degrees Celsius, under the condition stirred, react about 3 hours, thus epoxy resin after obtaining end carboxyl polymer modification.In the present embodiment, the epoxy resin of employing is bisphenol A type epoxy resin, and its epoxide equivalent is 188.The end carboxyl polymer adopted can be liquid polybutadiene acrylonitrile (CTBN), and the epoxide equivalent of the modified epoxide resin obtained after reaction is 337.Through above-mentioned reaction, an epoxy radicals of epoxy resin end and a carboxyl of end carboxyl polymer ends be combined with each other, and remove the water of a molecule, thus obtain an ester group.Thus compared to not carrying out the epoxy resin of modification, modified epoxy resin has good flexibility.Certainly, the epoxy resin of employing is not limited to the bisphenol A type epoxy resin that the present embodiment provides, and it also can be the epoxy resin of other types.The end carboxyl polymer adopted also is not limited to the liquid polybutadiene acrylonitrile provided in the present embodiment, and it also can be the polymer such as terminal carboxyl polyester.
Then, even carbon nanotube is scattered in inorganic dispersion to form finely dispersed CNT (carbon nano-tube) dispersion.
Adopt physics mode by carbon nanotube dispersed in inorganic dispersion.Described inorganic dispersion can be layered nanoclay or mica powder.In the present embodiment, the inorganic dispersion selected is layered nanoclay.The CNT (carbon nano-tube) of configuration quality than 8 to 1 to 12 to 1 and layered nanoclay, and mixed by the mode stirred or shake, even carbon nanotube is scattered in layered nanoclay.The layered nanoclay adopted can be the phyllosilicate of 2: 1, and it is specifically as follows montmorillonite, hectorite or saponite etc.The carbon nano-tube adopted can be Single Walled Carbon Nanotube, also can be multi-walled carbon nano-tubes.
Finally, the epoxy resin of end carboxyl polymer modification, CNT (carbon nano-tube) dispersion, solvent, curing agent, catalyst and defoamer are carried out mixing and grinding distribution, thus obtain epoxy resin composite material.
In the present embodiment, three drum-type grinding distribution machines are adopted to carry out grinding distribution to described end carboxyl polymer modification epoxy resin, CNT (carbon nano-tube) dispersion, solvent, curing agent, catalyst and defoamer.Above-mentioned end carboxyl polymer modification epoxy resin, CNT (carbon nano-tube) dispersion, solvent, curing agent, catalyst and defoamer are devoted in three drum-type grinding distribution machines according to above-mentioned respective content, start three drum-type grinding distribution machines to carry out grinding distribution, thus solid content in above-mentioned each composition is dispersed in liquid component, thus form finely dispersed epoxy resin composite material.In the present embodiment, in above-mentioned each composition, the mass percentage of the epoxy resin of end carboxyl polymer modification is about 60.3%, the mass percentage of carbon nano-tube is about 7.8%, the mass percentage of inorganic dispersion is about 0.6%, the mass percentage of curing agent is about 4.5%, the mass percentage of catalyst is about 0.65%, and the mass percentage of solvent is about 24.3%, and the mass percentage of defoamer is about 1.85%.
In order to obtain the epoxy resin composite material of different surfaces resistivity, when can be fed intake by change, the consumption of CNT (carbon nano-tube) dispersion controls.The mass percent accounting for composite material when carbon nano-tube is between 4.6% to 16%, and epoxy resin composite material surface resistivity constant interval is about between 100,000 ohm to ten ohm.Wherein, in epoxy resin composite material, the content of carbon nano-tube is larger, and the surface resistivity of epoxy resin composite material is less.
By the epoxy resin composite material that described method makes, its viscosity can reach 70000 centipoises, and outward appearance presents black, faint reflective.Under microscope amplifies 100 times of observations, without hole.And there is good attachment characteristic and soldering property, and can the corrosion of acid and alkali resistance and solvent.When temperature is 25 degrees Celsius, mass percentage be 10% hydrochloric acid or mass percentage be in the sodium hydroxide solution of 10% soak 0.5 hour, all without peeling phenomenon.Soak in acetone after 17 hours and carry out hundred lattice attachment tests, also without peeling phenomenon.
Refer to Fig. 2, second step, release substrate layer 110 is provided.
In the present embodiment, release substrate layer 110 is PET release film, and it has the first release surface 111.
Refer to Fig. 3, the 3rd step, described epoxy resin composite material is coated the first release surface 111 to form epoxy resin composite material layer 120.
In the present embodiment, slit type coater is adopted the epoxy resin composite material of liquid state to be coated the first release surface 111 of release substrate layer 110, to form epoxy resin composite material layer 120.Owing to adopting slit type coater to be coated with in the present embodiment, the thickness that can control the epoxy resin composite material layer 120 formed meets the demands and coating uniform.In the present embodiment, the thickness of the epoxy resin composite material layer 120 of formation is 8 microns to 25 microns, is preferably 10 to 20 microns.Epoxy resin composite material layer 120 has the first surface 121 away from release substrate layer 110.
4th step, processes the epoxy resin composite material layer 120 the first release surface 111 of release substrate layer 110 being coated with formation, to make epoxy resin composite material layer 120 semi-solid preparation.
In the present embodiment, the method that epoxy resin composite material layer 120 semi-solid preparation adopts is prebake conditions process.
Be about 15 minutes in the time continued of epoxy resin composite material layer 120 being carried out to prebake conditions, the temperature kept during prebake conditions is about 80 degrees Celsius to 90 degrees Celsius.By carrying out prebake conditions process, the partial solvent in epoxy resin composite material layer 120 being volatilized, makes epoxy resin composite material layer 120 be in semi-cured state.
Be understandable that, the temperature of carrying out prebake conditions duration and baking can be determined according to the thickness of the epoxy resin composite material layer 120 of reality, when epoxy resin composite material layer 120 thickness is larger, the time proper extension of process or temperature suitably can be heightened, and when epoxy resin composite material layer 120 thickness is less, the time of process suitably can be shortened or temperature suitably reduces, to ensure that epoxy resin composite material layer 120 can form semi-solid preparation membrane structure.
See also Fig. 3 and Fig. 1, the 5th step, release separator 130 that the first surface 121 of epoxy resin composite material layer 120 is fitted.
The release separator 130 of laminating for protecting epoxy resin composite material layer 120 in storage and transportation.Release separator 130 can be release PET film, and it can be various release liners.It is bonded to each other with the first surface 121 of epoxy resin composite material layer 120 that release separator 130 has the second release surface 131, second release surface 131.When making the film 100 formed and being directly used in circuit board making, release separator 130 that the first surface 121 of epoxy resin composite material layer 120 also can not be fitted.
After this step, can further include and film 100 is cut, film 100 is made into the shape of needs, with easy to use.When the film 100 that making is formed directly is not applied, store under film 100 can being positioned over low temperature environment, the temperature of storage can be approximately 5 degrees Celsius.When film 100 is applied to circuit board making, the release separator 130 of film 100 can be removed, then epoxy resin composite material layer 120 is directly pressed on the surface of the coverlay of the circuit board being formed with conducting wire, to play the effect of electromagnetic shielding.And release substrate layer 110 is separated with epoxy resin composite material layer 120.The film 100 that the technical program provides also can be formed between the two adjacent insulating barriers of multilayer circuit board, to play electromagnetic shielding action.
The film that the technical program provides, it comprises epoxy resin composite material layer, in described epoxy resin composite material layer, there is finely dispersed carbon nano-tube and there is electromagnetic shielding action, described film can directly be fitted in the surface of circuit board or is arranged in the internal layer of multilayer circuit board, and described film has the effect of electromagnetic shielding.Compared to stainless steel substrates of the prior art, the performance of destroying or force to yield of flexible PCB can be increased, and the production cost of circuit board can be reduced.The manufacture method of the film that the technical program provides, can simply produce the film with electromagnetic shielding action.
Be understandable that, for the person of ordinary skill of the art, other various corresponding change and distortion can be made by technical conceive according to the present invention, and all these change the protection range that all should belong to the claims in the present invention with distortion.