CN109487249B - Chemical copper plating activator, preparation method thereof and method for manufacturing circuit by full addition based on activator - Google Patents
Chemical copper plating activator, preparation method thereof and method for manufacturing circuit by full addition based on activator Download PDFInfo
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- CN109487249B CN109487249B CN201910005820.2A CN201910005820A CN109487249B CN 109487249 B CN109487249 B CN 109487249B CN 201910005820 A CN201910005820 A CN 201910005820A CN 109487249 B CN109487249 B CN 109487249B
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- C—CHEMISTRY; METALLURGY
- C23—COATING METALLIC MATERIAL; COATING MATERIAL WITH METALLIC MATERIAL; CHEMICAL SURFACE TREATMENT; DIFFUSION TREATMENT OF METALLIC MATERIAL; COATING BY VACUUM EVAPORATION, BY SPUTTERING, BY ION IMPLANTATION OR BY CHEMICAL VAPOUR DEPOSITION, IN GENERAL; INHIBITING CORROSION OF METALLIC MATERIAL OR INCRUSTATION IN GENERAL
- C23C—COATING METALLIC MATERIAL; COATING MATERIAL WITH METALLIC MATERIAL; SURFACE TREATMENT OF METALLIC MATERIAL BY DIFFUSION INTO THE SURFACE, BY CHEMICAL CONVERSION OR SUBSTITUTION; COATING BY VACUUM EVAPORATION, BY SPUTTERING, BY ION IMPLANTATION OR BY CHEMICAL VAPOUR DEPOSITION, IN GENERAL
- C23C18/00—Chemical coating by decomposition of either liquid compounds or solutions of the coating forming compounds, without leaving reaction products of surface material in the coating; Contact plating
- C23C18/16—Chemical coating by decomposition of either liquid compounds or solutions of the coating forming compounds, without leaving reaction products of surface material in the coating; Contact plating by reduction or substitution, e.g. electroless plating
- C23C18/31—Coating with metals
- C23C18/38—Coating with copper
- C23C18/40—Coating with copper using reducing agents
Abstract
An activating agent for electroless copper plating, a preparation method thereof and a method for manufacturing a circuit by full addition based on the activating agent belong to the technical field of electroless plating and circuit manufacturing. According to the invention, by adding the complexing agent which is mutually soluble with the adhesive and contains unsaturated bonds and the curing agent matched with the adhesive on the basis of the traditional activator, in the curing process after the preset circuit pattern is formed, the adhesive is firmly combined with the base material through physical adsorption and chemical action, and the complexing agent which adsorbs catalyst ions is chemically bonded with the epoxy resin adhesive, so that the catalyst ions are uniformly distributed in the active layer on the surface of the base material, and therefore, a bridging layer and a fixed catalyst are formed on the surface of the base material in one step, and a compact, bright and strong-adhesion coating can be formed by matching with a subsequent chemical plating process, and the problems of metal nanoparticle agglomeration and additive influence on the circuit conductivity, poor universality of the bridging layer on the surface of the base plate, and complex and time-consuming preparation in the existing full-addition circuit manufacturing process are solved.
Description
Technical Field
The invention belongs to the technical field of chemical plating and circuit manufacturing, and particularly relates to a chemical copper plating activator, a preparation method thereof and a method for manufacturing a circuit by full addition based on the activator.
Background
The current mainstream printed circuit board circuit manufacturing methods comprise the following three methods: subtractive, semi-additive and full-additive:
the subtractive method is a method for forming a circuit on a substrate having a copper layer formed on the surface thereof to a predetermined thickness (the thickness is the thickness of the circuit of the copper layer finally required), and comprises the steps of first forming a resist pattern by coating and developing the copper layer, then removing the exposed copper layer by selective etching, and finally removing the resist pattern to obtain the circuit pattern. The method has simple process flow, and can complete the manufacture by a mature etching process. However, the biggest defect of the method is that the exposed copper layer is etched downwards and is also etched laterally in the etching process, if the copper layer is thick, fresh etching liquid is difficult to enter, the water tank effect is obvious, and due to the limit of the etching process capacity, the line width requirement and the width of an anti-corrosion layer, a certain line interval is needed to meet the requirement of timely exchange of liquid medicine when the copper layer is etched to achieve a regular line shape. With the improvement of the integration level of the circuit board, the line width of the copper layer circuit is smaller and smaller, and under the action of side etching, the direct etching method is difficult to meet the manufacturing requirement of the dense copper layer circuit, so that the application of the subtractive method in the fine circuit manufacturing is limited to a great extent.
The semi-additive process is to form circuit on the substrate with one thin base copper layer, which is less than the required copper layer circuit thickness, and includes the first plating resist layer on the base copper layer, the subsequent exposure and development to form plating resist pattern, the subsequent electroplating copper plating to cover part of the plating resist layer, stripping the plating resist layer and etching to eliminate the base copper layer to form circuit. The method generally deposits a base copper layer by electroless copper plating, and the copper layer obtained by electroless copper plating is very thin and easy to etch, so that the side corrosion of the circuit is reduced to a certain extent relatively, but the phenomenon of delamination and blistering caused by insufficient adhesion between the electroless copper plating layer and the substrate is easy to occur when electroless copper is deposited on the insulating substrate.
Both the subtractive method and the semi-additive method have complicated production process and serious material waste, and the used heavy metal ions and corrosive solution can cause environmental pollution. The full addition method is taken as a printed circuit manufacturing process which is formed in recent years, and conforms to the green and efficient development trend of the printed circuit. The full-addition method adopts a process of obtaining a conductor pattern by selectively chemically depositing copper after an insulating substrate containing a photosensitive catalyst is exposed according to a circuit pattern. Is very suitable for manufacturing fine lines. The fabrication of conductive circuits by full-additive process has been developed in recent years, but is still immature, and it is difficult to realize large-scale industrialization. The full-additive process at present is mainly realized by directly printing metal conductive ink or selectively chemically plating metal.
However, the full addition process based on printing of the metal conductive ink has the problems that the conductive ink is easy to agglomerate, so that agglomerated metal nanoparticles are easy to block a nozzle or a mesh during the printing process, and the conductivity of a conductive line is reduced due to a dispersant and a stabilizer in the conductive ink. For example, Chinese patent "a conductive ink and a method for preparing the same" (application publication No. CN107446413A) discloses: mixing the nano-silver particles, the solvent, the cellulose viscosity regulator and the adhesive resin to prepare conductive ink, and then preparing the conductive ink on the surface of the insulating substrate through screen printing to obtain a conductive circuit. The method selects adhesive resin as a bridging material, improves the binding force between the nano-silver particle circuit and the substrate, and the adhesive resin which can exist between the nano-silver particles can influence the conductivity of the circuit; in addition, the method adopts the precious metal nano silver particles to manufacture the conductive circuit, so that the requirement on the consumption of the precious metal is high, and the cost is high.
The main problems faced by the full addition processes based on selective electroless metallisation are: usually, a special substrate is selected or treated specially to realize surface modification, then substances such as polydopamine, photoresist, silane coupling agent, polyacrylic acid, polyelectrolyte and the like are grafted on the surface of the substrate to further adsorb a catalyst as a bridging layer, and the special treatment adopted for realizing the surface modification specifically comprises roughening the surface of the substrate (see the article 'manufacturing process of full-additive laminated printed boards' published by cai celebration), or modifying the surface of the substrate by adopting ultraviolet light, plasma or high-energy radiation of laser (refer to the paper "modified plastic surface laser induced selective chemical copper plating" published in pentsu, the paper "silver selective activation chemical plating on polyimide film" published in cheng-sheng, and the paper "polymethyl methacrylate surface area metallization based on ultraviolet light/ozone chemical modification-selective chemical plating" published in huxian et al, for details). In addition, the bridging layer prepared by the method is not universal, i.e. different bridging layers are often selected for different substrates, and the grafting process is complex in process, time-consuming, high in cost, relatively low in production efficiency and difficult to realize large-scale application. For example, Chinese patent "a method for metallizing a surface of a polymer substrate and its use" (application publication No. CN107012450A) discloses: firstly, grafting modification is carried out on the surface of a polymer substrate, then the polymer surface is enabled to adsorb a catalyst through ink-jet printing or screen printing, and finally chemical plating is carried out to obtain the polymer substrate with a metal conductive pattern. However, the method has the disadvantages of complex surface grafting process for the polymer substrate, long time consumption in the surface grafting process and relatively low production efficiency.
Disclosure of Invention
Aiming at the problems that conductive ink is easy to agglomerate, additives influence the circuit conductivity, a bridging layer on the surface of a substrate has poor universality, the preparation is complex and time-consuming and the like in the conventional full-addition circuit manufacturing process, the invention provides a novel electroless copper plating activator, a preparation method and a full-addition circuit manufacturing method based on the activator.
In order to solve the problems, the invention adopts the following technical scheme:
an activating agent for electroless copper plating, which is characterized by comprising an organic solvent, and a metal ion catalyst, a complexing agent, an adhesive and a curing agent which are dissolved in the organic solvent; the complexing agent contains unsaturated bonds, so that chemical bonds are formed between the complexing agent and the adhesive and are dissolved in a solution system during curing, the complexing agent adsorbs metal ions in the metal ion catalyst, and the complexing agent and the adhesive are mutually soluble, so that the metal ions adsorbed by the complexing agent are uniformly distributed in the adhesive.
Further, the electroless copper plating activator is a uniform, stable solution system. The electroless copper plating activator of the invention is proved to be very stable and still uniform and transparent after being placed for 1 month at room temperature.
Furthermore, the curing agent in the electroless copper plating activator is added and uniformly mixed when being activated again, and then the subsequent operation is carried out.
Further, the metal ion catalyst is any one or more of silver nitrate, silver acetate, silver oxalate, silver benzoate, palladium acetate and palladium oxalate.
Further, the complexing agent is thiourea and derivatives thereof, thiophene and derivatives thereof, 3-mercaptopropyltriethoxysilane, 3-aminopropyltriethoxysilane, cyclopenta-2, 4-dienyl-1-thione (C)5H4S) and 1-pyrrole-1-thiol (C)4H5NS). The complexing agent is mainly used for adsorbing metal ions in a metal ion catalyst, so that the metal ions are prevented from being reduced into metal nano-particles by epoxy groups in the subsequently added epoxy resin adhesive.
Further, the mol ratio of the complexing agent to the metal ion catalyst is not less than 3: 1.
Further, the adhesive is any one or more of bisphenol A epoxy resin, novolac epoxy resin, glycidyl ether epoxy resin, glycidyl ester type epoxy resin, amino epoxy resin and alicyclic epoxy resin.
The invention further requires that the adhesive and the complexing agent are mutually soluble, so that metal ions adsorbed by the complexing agent can be uniformly distributed in the adhesive, and the epoxy resin has physical adsorption on the surface of any substrate, and active epoxy groups in the epoxy resin can be chemically bonded with hydroxyl (-OH), carbonyl (C ═ O) or groups containing lone pair electrons on the surface of the substrate, so that good bonding force is provided for the substrate and the coating when an activated modified layer is formed by using a solution system.
The curing agent is selected according to different base materials and printed circuit application environments, and the dosage of the curing agent is related to the used adhesive.
Further, the organic solvent is any one or more of propylene glycol methyl ether, propylene glycol methyl ether acetate, dipropylene glycol methyl ether acetate and propylene glycol butyl ether. Since these organic solvents have a hydroxyl group (-OH) and an ether group (R-O-R'), a complexing agent having an unsaturated bond and an adhesive having an ether group are easily dissolved therein according to the principle of similar compatibility.
Further, the curing agent is any one or more of an aliphatic polyamine curing agent, an alicyclic polyamine curing agent, an aromatic amine curing agent, an acid anhydride curing agent, a polyamide curing agent, a modified amine curing agent and a synthetic resin epoxy curing agent.
Furthermore, the mole concentration of the complexing agent in the electroless copper plating activator is preferably 0.03-0.6 mol/L, the mole concentration of the metal ion catalyst is preferably 0.01-0.02 mol/L, the mole concentration of the adhesive is preferably 1-5 mol/L, and the mole mass of the curing agent is preferably 0.2-1 mol/L.
The preparation method of the electroless copper plating activator is characterized by comprising the following steps:
step 1: dissolving a complexing agent and a metal ion catalyst in an organic solvent, and uniformly mixing to obtain a solution.
Step 2: and (3) dissolving an adhesive and a curing agent in the solution obtained in the step (1), and uniformly mixing to obtain the chemical copper plating activator.
Further, the electroless copper plating activator needs to be matched with a curing agent when in use, namely the curing agent is added only when the activator needs to be used, and the curing agent and the activating agent are uniformly mixed to form a preset circuit pattern for subsequent electroless copper plating operation.
Further, the electroless copper plating activator is a uniform, stable solution system.
Further, the metal ion catalyst is any one or more of silver nitrate, silver acetate, silver oxalate, silver benzoate, palladium acetate and palladium oxalate.
Further, the complexing agent is thiourea and derivatives thereof, thiophene and derivatives thereof, 3-mercaptopropyltriethoxysilane, 3-aminopropyltriethoxysilane, cyclopenta-2, 4-dienyl-1-thione (C)5H4S) and 1-pyrrole-1-thiol (C)4H5NS). The complexing agent of the invention is mainly used in the catalyst for adsorbing metal ionsAnd the metal ions are further prevented from being reduced into metal nano-particles by epoxy groups in the subsequently added epoxy resin adhesive.
Further, the mol ratio of the complexing agent to the metal ion catalyst is not less than 3: 1.
Furthermore, the mole concentration of the complexing agent in the electroless copper plating activator is preferably 0.03-0.6 mol/L, the mole concentration of the metal ion catalyst is preferably 0.01-0.02 mol/L, the mole concentration of the adhesive is preferably 1-5 mol/L, and the mole mass of the curing agent is preferably 0.2-1 mol/L.
Further, the adhesive is any one or more of bisphenol A epoxy resin, novolac epoxy resin, glycidyl ether epoxy resin, glycidyl ester type epoxy resin, amino epoxy resin and alicyclic epoxy resin.
Further, the organic solvent is any one or more of propylene glycol methyl ether, propylene glycol methyl ether acetate, dipropylene glycol methyl ether acetate and propylene glycol butyl ether. Since these organic solvents have a hydroxyl group (-OH) and an ether group (R-O-R'), a complexing agent having an unsaturated bond and an adhesive having an ether group are easily dissolved therein according to the principle of similar compatibility.
Further, the curing agent is any one or more of an aliphatic polyamine curing agent, an alicyclic polyamine curing agent, an aromatic amine curing agent, an acid anhydride curing agent, a polyamide curing agent, a modified amine curing agent and a synthetic resin epoxy curing agent.
Furthermore, the curing agent in the electroless copper plating activator is added and uniformly mixed during activation, and then subsequent operation is carried out.
A method for manufacturing a circuit by full addition is characterized by comprising the following steps:
forming a preset circuit pattern with catalytic activity on the surface of a base material by adopting a chemical copper plating activating agent; and after the preset circuit pattern is solidified, chemically plating copper, thereby forming a target circuit on the surface of the base material.
Further, the electroless copper plating activator for the method for fabricating a full-additive circuit according to the present invention is not described herein again.
Further, the substrate is a rigid insulating substrate or a flexible insulating substrate, the rigid insulating substrate comprising: FR-4 substrate, glass substrate, alumina ceramic or aluminum nitride ceramic substrate; the flexible insulating substrate includes: paper-based films, Polyethylene terephthalate films (PET), Polyimide films (PI), or polytetrafluoroethylene films (PTFE).
Further, the preset circuit pattern is prepared on the surface of the base material in an ink-jet printing or silk-screen printing mode.
Furthermore, the base material needs to be cleaned before the activating agent is subjected to ink jet printing or screen printing, the used cleaning reagents are deionized water and absolute ethyl alcohol, and a cleaning instrument is an ultrasonic cleaning instrument; the specific operation of substrate cleaning is as follows: under the ultrasonic cleaning condition, firstly putting the base material into deionized water for cleaning for 5-10 min, then putting the base material into absolute ethyl alcohol for cleaning for 5min, and finally putting the base material into deionized water for cleaning for 5 min; the power of the ultrasonic cleaner is 110W, and the frequency is 40 KHz.
Furthermore, in order to ensure that the activating agent can be manufactured on the base material, the viscosity of the activating agent for ink-jet printing or silk-screen printing is controlled to be 50-80 mPa.S, and the surface tension is controlled to be 25-45 mN/m.
According to the embodiment of the invention, the formula of the copper plating solution for electroless copper plating is as follows: potassium sodium tartrate tetrahydrate (32g/L), disodium ethylenediaminetetraacetate dihydrate (2.5g/L), copper sulfate pentahydrate (12.5g/L), nickel sulfate hexahydrate (3.5g/L), 2' -bipyridine (10mg/L), potassium ferrocyanide trihydrate (23mg/L), sodium hydroxide (10g/L), and formaldehyde solution (12 ml/L).
Preferably, air is blown into the copper plating solution in the electroless copper plating process to improve the stability of the plating solution, the air flow is preferably 2.5-5 cm3/min, the temperature of the plating solution is controlled between 36-45 ℃, and the electroless plating time is controlled between 30-60 min.
The principle of the invention is as follows:
firstly, a complexing agent is added into the activating agent system, on one hand, the complexing agent is utilized to adsorb catalyst ions (namely metal ions) so as to stably exist in the system, thereby avoiding the catalyst ions from being reduced into metal nano particles by epoxy groups in epoxy resin, causing catalyst agglomeration of the metal nano particles to cause uneven distribution of the catalyst, and preventing the activating agent from being blocked in the ink-jet printing or silk-screen printing process and preventing an electroless plated copper layer from being uneven. The ionic activator can ensure that catalyst ions are uniformly distributed, and in the chemical copper plating process, the reducing agent firstly reduces the catalyst metal ions into metal atoms in situ, and then the metal atoms are used as catalytic nuclei to catalyze the copper ions to be reduced into metal copper by the reducing agent to be deposited on the surfaces of the catalytic nuclei to form uniform copper plating layers; on the other hand, the complexing agent contains unsaturated chemical bonds, and in the curing process, the unsaturated bonds in the complexing agent and epoxy groups in the adhesive can be chemically bonded. Compared with complexing agents without saturated double bonds, only physical adsorption exists between the complexing agents and the adhesive, and the complexing agents adsorbing catalyst ions can be dissolved in the chemical copper plating solution in the chemical copper plating process, so that the plating solution is scrapped. Therefore, the method can avoid the scrapping of the plating solution caused by the loss of the subsequent plating solution system due to the incapability of curing the complexing agent adsorbed with the catalyst ions, and ensure that the surface of the substrate has enough catalytic sites to further realize the subsequent chemical copper plating.
The invention selects various epoxy resins as bridging layers between electroless copper plating and base materials, on one hand, the epoxy resin is used as an adhesive and can adsorb the surfaces of various base materials, and on the other hand, epoxy groups in the epoxy resin can be chemically bonded with hydroxyl, carbonyl and groups containing lone-pair electrons on the surfaces of the base materials. Therefore, the epoxy resin is selected as the bridge layer bridging layer, so that the universality is realized.
And thirdly, the complexing agent and the adhesive are mutually soluble, so that catalyst ions can be uniformly distributed in the adhesive under the action of the complexing agent and further uniformly distributed in an activator system, a bridging layer can be generated on the surface of the insulating base material and the catalyst ions can be uniformly fixed in one step by ink-jet printing or silk-screen printing, the production process is greatly simplified, and finally, the conductive pattern required by the process can be obtained by matching with chemical copper plating.
Compared with the prior art, the invention has the following beneficial effects:
according to the invention, by adding the mutually soluble complexing agent, the adhesive and the curing agent matched with the adhesive on the basis of the traditional activator, and selecting the complexing agent containing unsaturated bonds, the complexing agent adsorbing the catalyst can generate a chemical reaction with the adhesive and stably exist on the surface of the base material in the curing process after a preset circuit pattern is formed; because the bonding force between the adhesive and the base material is good, and the catalyst is uniformly distributed in the activating agent on the surface layer of the base material, the invention realizes that the bridging layer and the catalyst are formed on the surface of the base material in one step, and a compact, bright and strong-adhesion coating can be formed by matching with the subsequent chemical plating process. Compared with the existing method for manufacturing the circuit by full addition, the method for manufacturing the circuit does not need to prepare a bridging layer independently, has strong applicability of base materials, simplifies the operation flow, has short manufacturing period and obviously improves the production efficiency; meanwhile, by using the circuit manufacturing method, when the preset circuit pattern is formed, the adhesive acts to ensure that the bonding force between the activation layer and the surface of the base material is good, and the activation sites on the surface of the subsequent activation layer catalyze copper deposition to form a compact and uniform copper layer, so that the conductivity of the circuit is not influenced by using the insulating resin material for adhesion as the traditional conductive ink. The electroless copper plating activator is a uniform and stable solution system, the raw materials are cheap and easy to obtain, only a small amount of noble metal is used as a metal ion catalyst, the cost is low, and no nano metal particles exist, so that the problem that the traditional conductive ink is easy to block equipment does not exist.
Drawings
FIG. 1 is a schematic view of the process of electroless copper plating activator and full-additive process for manufacturing printed circuit according to the present invention.
FIG. 2 is an analysis chart of the composition and crystallization of the plating layer after electroless copper plating according to the present invention: (a) EDS energy spectrum analysis chart; (b) is an XRD pattern.
FIG. 3 is an SEM image of conductive traces after electroless copper plating in accordance with the present invention.
FIG. 4 is a 3M tape test chart of the conductive traces after electroless copper plating according to the present invention.
FIG. 5 is a diagram of forming conductive traces on a curved substrate surface according to the present invention.
Fig. 6 shows the fatigue resistance test of the present invention on the flexible substrate conductive circuit with radius r of 2mm and bending angle of 180 °.
Detailed Description
The technical scheme of the invention is explained in detail by combining the specific embodiment and the attached drawings of the specification:
the invention provides an activating agent for electroless copper plating, which comprises an organic solvent, a metal ion catalyst, a complexing agent, an adhesive and a curing agent, wherein the metal ion catalyst, the complexing agent, the adhesive and the curing agent are dissolved in the organic solvent; the complexing agent contains unsaturated bonds, so that chemical bonds are formed between the complexing agent and the adhesive and are dissolved in a solution system during curing, the complexing agent adsorbs metal ions in the metal ion catalyst, and the complexing agent and the adhesive are mutually soluble, so that the metal ions adsorbed by the complexing agent are uniformly distributed in the adhesive.
The invention also provides a full-addition circuit manufacturing process, the process flow is shown as figure 1, and the full-addition circuit manufacturing process specifically comprises the following steps:
(a) dissolving a complexing agent in an organic solvent under room temperature and magnetic stirring;
(b) adding a catalyst, and keeping magnetic stirring until the catalyst is completely dissolved;
(c) adding an adhesive, and continuing to magnetically stir until the adhesive is completely dissolved;
(d) adding a curing agent, and magnetically stirring for 1 h; cleaning the base material, firstly putting the base material into deionized water for ultrasonic treatment for 5-10 min, then putting the base material into absolute ethyl alcohol for ultrasonic treatment for 5min, then washing the base material with the deionized water, and finally putting the base material into an oven for drying;
(e) printing an activator on the surface of a clean insulating substrate by means of ink-jet printing equipment or silk-screen printing to form a preset circuit pattern with catalytic activity;
(f) after room temperature curing, the required conductive pattern is obtained by matching with chemical copper plating.
Example 1:
selecting thiourea as a complexing agent, and stirring the thiourea at room temperature and magnetic force for 200r/minDissolving the mixture in propylene glycol methyl ether under the condition of low temperature to obtain a solution with the thiourea concentration of 0.03 mol/L; adding catalyst AgNO3Completely dissolving the silver ions under magnetic stirring to obtain a solution with the silver ion concentration of 0.01 mol/L; then adding 1.5mol/L bisphenol A epoxy resin, and completely dissolving under magnetic stirring; then adding a proper amount of 593 curing agent, and magnetically stirring uniformly until the viscosity is 50-80 mPa.S and the surface tension is 25-45 mN/m; printing an activating agent on the surface of the epoxy glass fiber substrate by using an ink-jet printing device to form a preset circuit diagram with catalytic activity; and (5) curing at room temperature, and then matching with chemical copper plating to obtain the required conductive pattern.
FIG. 2a is an EDS spectrum analysis of a copper layer after electroless copper plating showing that only the peaks of the copper spectrum are known to show that only copper is deposited in the conductive traces, and FIG. 2b is an XRD diffraction analysis of the copper layer after electroless copper plating showing that the peaks of the crystalline planes of copper are sharp to show that the copper is crystallized well during electroless copper plating.
FIG. 3 is an SEM image of the conductive circuit after electroless copper plating, in which it can be seen that the grains of the plating layer are uniformly distributed, the grain size is 300-400 nm, and the crystallization is dense. Tests show that the resistivity of the copper conductive circuit is about 2.8 multiplied by 10-6Omega cm, and has good conductivity.
Example 2:
the operation of this example is essentially the same as example 1, except that the electroless copper plating activator is specifically composed of: the organic solvent is propylene glycol methyl ether acetate, the concentration of the 3-mercaptopropyltriethoxysilane is 0.1mol/L, AgNO3The concentration of the phenolic epoxy resin is 0.015mol/L, the concentration of the phenolic epoxy resin is 2mol/L, a proper amount of curing agent 593 is added, and the mixture is magnetically stirred uniformly until the viscosity is 50-80 mPa & S, and the surface tension is 25-45 mN/m.
Cyclopenta-2, 4-dienyl-1-thiones (C)5H4S) and 1-pyrrole-1-thiol (C)4H5NS)
Example 3:
the operation of this example is essentially the same as example 1, except that the electroless copper plating activator is specifically composed of: the organic solvent is dipropylene glycol methyl ether, 3-aminopropyl triethyl etherThe concentration of the oxysilane is 0.5mol/L, AgNO3The concentration of the epoxy resin is 0.02mol/L, the concentration of the glyceryl ether epoxy resin is 3mol/L, a proper amount of curing agent 593 is added, and the mixture is magnetically stirred uniformly until the viscosity is 50-80 mPa & S, and the surface tension is 25-45 mN/m.
Example 4:
the operation of this example is essentially the same as example 1, except that the electroless copper plating activator is specifically composed of: the organic solvent is dipropylene glycol methyl ether acetate, the concentration of the cyclopentyl-2, 4-dienyl-1-thioketone is 0.4mol/L, AgNO3The concentration of the epoxy resin is 0.01mol/L, the concentration of the alicyclic epoxy resin is 5mol/L, a proper amount of curing agent 593 is added, and the mixture is magnetically stirred uniformly until the viscosity is 50-80 mPa & S, and the surface tension is 25-45 mN/m.
Example 5:
the operation of this example is essentially the same as example 1, except that the electroless copper plating activator is specifically composed of: the organic solvent is propylene glycol methyl ether, the concentration of the thiosemicarbazide is 0.5mol/L, and AgNO3The concentration of the curing agent is 0.02mol/L, the concentration of the bisphenol A epoxy resin is 3mol/L, a proper amount of 593 curing agent is added, and the mixture is magnetically stirred uniformly until the viscosity is 50-80 mPa & S, and the surface tension is 25-45 mN/m.
Example 6:
the operation of this example is essentially the same as example 1, except that the electroless copper plating activator is specifically composed of: the organic solvent is propylene glycol butyl ether, the concentration of alpha-chloromethyl thiophene is 0.05mol/L, AgNO3The concentration of the epoxy resin is 0.01mol/L, the concentration of the glyceryl ether epoxy resin is 6mol/L, a proper amount of curing agent 593 is added, and the mixture is magnetically stirred uniformly until the viscosity is 50-80 mPa & S, and the surface tension is 25-45 mN/m.
Example 7:
this example is different from example 1 in that: example 2A polyimide film (PI) with a substrate thickness of 125 μm was selected, and the remaining procedure was the same as in example 1.
As can be seen from FIG. 4a, after electroless copper plating, the conductive traces are uniformly distributed on the surface of the PI, and as can be seen from FIG. 4b, no copper scrap is stuck on the 3M adhesive tape after the 3M adhesive tape test, which indicates that the copper conductive traces prepared by the method have good adhesion with the substrate.
Example 8:
this example is compared with example 1, except that in example 3, a polyethylene terephthalate film (PET) with a substrate thickness of 125 μm is selected, an activator is printed on the surface of the substrate by ink-jet printing, and the rest of the operation steps are the same as in example 1.
It is seen from fig. 5 that the conductive traces can be prepared on the curved PET surface, which illustrates that the present invention can prepare the conductive traces on the surface of not only the planar substrate but also the three-dimensional substrate.
The copper wiring fabricated on the concave surface of the PET was further subjected to a bending test, and the test results are shown in fig. 6. FIG. 6a is a drawing and pressure bending test performed on a copper conductive trace with a radius of 2mm and a bending angle of 180 degrees; FIG. 6b is a graph showing the ratio of the resistance to the initial resistance (R) after 1000 180 degree pulling and pressing bends, respectively, were applied to the copper wire0Representing the initial resistance and R the resistance after a certain number of bends), as can be seen in fig. 6 b: R/R after 1000 times of 180 DEG pressure bending test01.006, R/R after 1000 times 180 DEG tensile bending test0When the 180 ° compression bending test and the tensile bending test were performed 1000 times, the change in resistance was very small as 1.034. Therefore, the flexible copper circuit manufactured by the method has certain application value.
Example 9:
this example is compared with example 1, except that the substrate selected in example 4 is a glass substrate, and the rest of the operation is the same as example 1. As demonstrated by EDS, XRD, SEM and 3M tape tests identical to examples 1 and 2: the metal deposited on the conductive pattern obtained on the glass substrate is only metal copper, the crystallization of copper crystal grains is uniform and compact, the conductivity is good, and the copper conductive circuit and the substrate have good binding force.
Example 10:
this example studies the effect of the ratio of complexing agent to metal ion catalyst:
in the present example, under the conditions of room temperature and magnetic stirring at 200r/min, in the range of 10ml propylene glycol methyl ether solubility, when n (thiourea): n (silver nitrate) < 3: 1, white precipitate is generated in the solution, the white precipitate is preliminarily inferred to be a product generated by combining silver ions and propylene glycol methyl ether, and the white precipitate is ((1-methoxypropan-2-yl) oxy) silver through XRD test and thermogravimetric analysis (TGA); under the same conditions, in the solubility range of 10ml propylene glycol methyl ether, when n (thiourea): n (silver nitrate) is more than or equal to 3: 1, a colorless transparent solution was obtained. When n (thiourea): n (silver nitrate) is more than or equal to 3: 1, all silver ions in the solution are complexed with thiourea, and free silver ions do not exist, so that the silver ions and a solvent propylene glycol methyl ether are prevented from generating white precipitates. Therefore, to ensure the stability of the activators of the invention, n (thiourea) is required: n (silver nitrate) is more than or equal to 3: 1.
example 11:
this example studies the principle of action of different complexing agents in the system:
in this embodiment, thiourea or thiophene with a double bond in the structure is selected as a complexing agent, an activator is prepared according to the process flow of the present invention, a transparent solution is also obtained, the activator is printed into a preset circuit, and infrared spectrum testing is performed after the activator is cured. The test result shows that double bonds in the complexing agent and epoxy groups in the adhesive disappear, which indicates that the adhesive is chemically bonded with the complexing agent in the curing process, so that a copper layer with good bonding force can be obtained by matching with subsequent chemical copper plating.
Comparative example 1:
in the embodiment, 3-aminopropyltriethoxysilane of which the molecular structure only contains a single bond is selected as a complexing agent, an activating agent is prepared according to the process flow of the invention to obtain a transparent solution, a preset circuit pattern is prepared through inkjet printing or silk screen, and chemical copper plating is carried out after the activating agent is cured.
Comparative example 2:
in the embodiment, carboxyl thiophenol of which the molecular structure only contains a single bond is selected as a complexing agent, an activating agent is prepared according to the process flow of the invention to obtain a transparent solution, a preset circuit pattern is prepared through ink-jet printing or silk screen, and chemical copper plating is carried out after the activating agent is cured.
Through research on the two comparative examples, the fact that the complexing agent only containing single bonds is adopted for full-addition line production is found that the used chemical plating solution is scrapped quickly, and no copper layer is deposited on the surface of the activation layer; the existence of the complexing agent in the chemical copper plating solution is found through infrared spectrum tests, which shows that only physical adsorption exists between the adhesive and the complexing agent, and the complexing agent can be dissolved in the chemical copper plating solution during chemical copper plating.
In conclusion, the chemical copper plating activator and the full-addition printed circuit manufacturing method have universality for different base materials, are simple to operate, economical and environment-friendly, and have bright and compact surfaces, excellent conductivity, good bonding force between the circuit and the base material, capability of manufacturing conductive circuits on the surfaces of three-dimensional base materials and certain large-scale popularization value.
While the present invention has been particularly shown and described with reference to the preferred embodiments, it will be understood by those skilled in the art that various changes in form and details may be made therein without departing from the spirit and scope of the invention as defined by the appended claims.
Claims (10)
1. An activating agent for electroless copper plating, which is characterized by comprising an organic solvent, and a metal ion catalyst, a complexing agent, an adhesive and a curing agent which are dissolved in the organic solvent;
the complexing agent adsorbs the metal ion catalyst, so that the metal ion catalyst can stably exist in the chemical copper plating activating agent, and the complexing agent and the adhesive are mutually soluble, so that the metal ions adsorbed by the complexing agent are uniformly distributed in the adhesive;
the complexing agent contains unsaturated bonds, and in the curing process, the unsaturated bonds in the complexing agent and epoxy groups in the adhesive can be chemically bonded; meanwhile, an epoxy group in the adhesive can be chemically bonded with hydroxyl, carbonyl and a group containing lone pair electrons on the surface of the base material, so that the adsorption force between the adhesive and the base material is enhanced; the chemical copper plating activator finally ensures that the surface of the base material has enough catalytic sites to further realize the subsequent chemical copper plating, and avoids the phenomenon of plating solution scrapping caused by the loss of the complexing agent adsorbed with catalyst ions in the subsequent plating solution system.
2. The electroless copper plating activator according to claim 1, wherein the metal ion catalyst is any one or more of silver nitrate, silver acetate, silver oxalate, silver benzoate, palladium acetate and palladium oxalate.
3. The electroless copper plating activator of claim 1, wherein the complexing agent is any one or more of thiourea and its derivatives, thiophene and its derivatives, and cyclopenta-2, 4-dienyl-1-thione.
4. The electroless copper plating activator of claim 1, wherein the molar ratio of complexing agent to metal ion catalyst is not less than 3: 1.
5. The electroless copper plating activator according to claim 1, wherein the adhesive is an epoxy resin adhesive comprising any one or more of bisphenol a epoxy resin, novolac epoxy resin, glycidyl ether epoxy resin, glycidyl ester epoxy resin, amino epoxy resin, and alicyclic epoxy resin.
6. The electroless copper plating activator according to claim 1, wherein the organic solvent is any one or more of propylene glycol methyl ether, propylene glycol methyl ether acetate, dipropylene glycol methyl ether acetate, and propylene glycol butyl ether.
7. The electroless copper plating activator according to claim 1, wherein the curing agent is any one or more of an aliphatic polyamine-type curing agent, an alicyclic polyamine-type curing agent, an aromatic amine-type curing agent, an acid anhydride-type curing agent, a polyamide-type curing agent, a modified amine-type curing agent, and a synthetic resin-type epoxy curing agent.
8. The electroless copper plating activator according to claim 1, wherein the electroless copper plating activator has a complexing agent molar concentration of 0.03 to 0.6mol/L, a catalyst molar concentration of 0.01 to 0.02mol/L, an adhesive molar concentration of 1 to 5mol/L, and a curing agent molar concentration of 0.2 to 1 mol/L.
9. A process for preparing an electroless copper plating activator according to any of claims 1 to 8, comprising the steps of:
step 1: dissolving a complexing agent and a metal ion catalyst in an organic solvent, and uniformly mixing to obtain a solution;
step 2: and (3) dissolving an adhesive and a curing agent in the solution obtained in the step (1), and uniformly mixing to obtain the chemical copper plating activator.
10. A method for forming a circuit based on the full addition of an electroless copper plating activator according to any of claims 1 to 8, comprising the steps of: forming a preset circuit pattern with catalytic activity on the surface of a base material by adopting a chemical copper plating activating agent; and after the preset circuit pattern is solidified, chemically plating copper, thereby forming a target circuit on the surface of the base material.
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| CN115087541B (en) * | 2020-01-31 | 2024-03-26 | 三井化学株式会社 | Anisotropic conductive sheet, electrical inspection device, and electrical inspection method |
| CN113485581A (en) * | 2021-07-02 | 2021-10-08 | 浙江鑫柔科技有限公司 | Method for forming metal grid on substrate |
| CN115233200B (en) * | 2022-06-23 | 2023-09-01 | 东莞市正为精密塑胶有限公司 | Antenna surface metallization plating solution and metallization method thereof |
| CN115537788A (en) * | 2022-08-29 | 2022-12-30 | 深圳大学 | Chemical plating activator and preparation method and application thereof |
| CN115976501A (en) * | 2022-12-27 | 2023-04-18 | 电子科技大学 | Metal pattern on surface of insulating base material and additive manufacturing method |
| CN116782516B (en) * | 2023-07-13 | 2024-01-23 | 南华大学 | Universal process for preparing copper printed circuit based on homogeneous ion type catalytic ink |
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