The electroplate liquid that a kind of PCB Hole Metallization ionic liquid is gold-plated and electro-plating methodTechnical field
The present invention relates to a kind of gold plating liquid and gold-plating process thereof, especially relate to a kind of without cryanide ion liquid gold plating liquid and in this plating solution to the method for PCB Hole Metallization electrogilding.
Background technology
Gold plate has good outward appearance, and discoloration-resisting is good, is widely used as decorative coating.Meanwhile, gold plate good conductivity, contact resistance are little, weldability good, have anti-oxidant, acid-alkali-corrosive-resisting, the premium properties such as wear-resistant in addition, can be used as protectiveness and functional coating.Therefore, gold plate is widely used in electronics, aerospace, instrument, military project and some special dimensions.
The main gold plating liquid adopted containing prussiate in traditional gold plating method, the advantages such as prussiate is gold-plated has that bath stability, current efficiency are high, Deposit appearance and good mechanical property, thus become the longest, the most widely used gold plating method of history.But well-known, prussiate has severe toxicity, all can cause huge harm to operator and environment.Along with the raising of people's environmental consciousness and the development of science and technology, non-cyanogen gold-plating technique and technique are constantly being explored and perfect, and at present, cyanogen-less gold mainly adopts the gold-plated salt such as sulphite, thiosulphate, halogenide.But cyanogen-less gold liquid often employs organic additive, the less stable of plating solution.
In recent years, ionic liquid is as a class novel green medium, and its discovery and application cause the whole world and pay attention to widely.Ionic liquid is a kind of salt, and reach its corresponding fusing point when heating and melt or liquefy, it only includes ion, without any molecular solution.Form eutectic solution with it by adding other salt, this can reduce the fusing point of system.Ionic liquid compares traditional aqueous plating because of its environmental protection, stable in properties, can the advantage such as room temperature use, becomes the study hotspot of metal current electrodeposition.In data disclosed at present: (1) publication number is in the Chinese invention patent of CN101092725, be golden salt with Au (PPh3) Cl or Au (PPh3) Br, carry out electrochemical plating gold at ionic liquid [bmim] BF4 or [bmim] PF4; (2) publication number is in the Chinese invention patent of CN101319339, is golden salt, carries out the galvanic deposit of room temperature gold in ionic liquid Reline with Au (PPh3) Cl or Au (PPh3) Br.But the price of these ionic liquids is higher, preparation is difficulty comparatively.
For above-mentioned ionic liquid Problems existing, the exploration of novel ion liquid just seems extremely important.
Summary of the invention
The present invention is intended to improve the problems referred to above, proposes the electroplate liquid that a kind of a kind of PCB Hole Metallization ionic liquid that is simple, environmental protection is gold-plated, and utilizes this electroplate liquid to carry out the method for printed circuit board Gold plated Layer.The printed circuit board stable performance that the method is obtained and quality is good.
The technical scheme that electroplate liquid of the present invention adopts is: this electroplate liquid comprises golden salt and ionic liquid, and described golden salt is KAuCl4, ionic liquid is choline chloride 60-ethylene glycol ionic liquid, KAuCl4concentration be 4 g/L ~ 16 g/L.
Further, the step preparing described electroplate liquid is:
A, add in beaker by choline chloride 60 and ethylene glycol according to the ratio of mol ratio 1:2, be positioned over by beaker in oil bath pan and be heated to 60 ~ 80 ° of C magnetic agitation, insulation Keep agitation 2 h is until form the liquid of uniform colorless.Then ionic liquid is put into vacuum drying oven insulation 60 ° of C stand-by;
B, to be added in choline chloride 60-ethylene glycol ionic liquid according to certain mass ratio by golden salt in beaker, be positioned over by beaker in oil bath pan and be heated to 60 ~ 80 ° of C magnetic agitation, Keep agitation 2h is until form uniform liquid in insulation;
C, gained solution in step b is put into vacuum drying oven constant temperature 60 ° of C, continue 24h, to remove the moisture in solution, obtain electroplate liquid.
The technical scheme that electro-plating method of the present invention adopts is, the method comprises the following steps:
(1) thin gold process is plated to printed circuit board, obtain the printed circuit board with thin layer gold;
(2) in a cell, to contain golden salt KAuCl4choline chloride 60-ethylene glycol ionic liquid be gold plating liquid, platinum titanium net is anode, printed circuit board after step (1) process is negative electrode, adopt the mode of direct current electrode position, the concentration of gold salt in ionic liquid is 4 g/L ~ 16 g/L, during plating, the temperature of plating tank is 50 ~ 90 ° of C, and volts DS is 1.5 ~ 2.5 V, and current density is 1 ~ 5 mA/cm2, anode and cathode distance are 5 cm, electroplating time 5 ~ 20min;
(3) printed circuit board processed through step (2) is used deionized water successively, EtOH Sonicate cleans, and cold wind blows, and obtains finished product.
Further, described step (1) is specially: printed circuit board is just expected cold wind blows into row surface cleaning successively with deionized water, EtOH Sonicate cleaning; In reactive tank, add the citric acid gold potassium that concentration is 2 g/L, concentration is the ammonium dihydrogen citrate of 50 g/L, and concentration is the ammonium hypophosphite of 10 g/L, concentration is the nickelous chloride of 2 g/L and concentration is the ammonium chloride of 75g/L, solution ph is 5 ~ 6, and temperature is 35 ~ 50 ° of C, and the time is 2min.
The invention has the beneficial effects as follows: ionic liquid of the present invention has unique physics and chemistry character, has merged the advantage of high-temperature molten salt and the aqueous solution: (1) has wider electrochemical window, generally all far above 1.23 V.(2) deposition process and conventional media (as water) are different, at room temperature i.e. the metal that obtains of electrodepositable and alloy, effectively can reduce the intensity of consumption of the energy.The character of ionic liquid is gentle, does not have the severe corrosive that high-temperature molten salt is such.(3) can obtain great majority can the metal that obtains of galvanic deposit in aqueous, but does not produce hydrogen and analyse, and avoids hydrogen embrittlement; Can also the many unavailable active metals in aqueous of galvanic deposit; (4) volatility is low, does not have the strong volatility and toxicity etc. of organic solvent; Choline chloride 60-glycol system of the present invention carries out the galvanic deposit of gold, and compare general ionic liquid, electroplate liquid of the present invention is with low cost, and manufacture craft is simple, is easy to batch production; Electroplate liquid has good electroconductibility, anhydrous system, avoids the precipitation of hydrogen; Electroplate liquid toxicity is property very, is easy to biological degradation, is the green plating solution of environment-friendly type.So the present invention utilizes that the preparation of choline chloride 60-glycol system is simple, cost is low, nontoxic, biological degradation, empty G&W stablized etc. to advantage and promote that the whole method preparing printed circuit board is more simple, the circuit card stable performance of producing, quality is good.
Embodiment
Described in detail by specific embodiment according to inventive method below.Following embodiment just in order to better by clear for the explaination of the technology of the present invention principle, do not represent the present invention and only limits this embodiment of use.
embodiment one:
According to described chemical gilding formula above, to the thin gold of printed circuit board pore structure electroless plating to be plated.Then, in plating tank, the KAuCl that concentration is 4 g/L is added4choline chloride 60-ethylene glycol ionic liquid 100 ml, is placed in oil bath pan by electrolyzer, is warming up to 50 ° of C, and with platinum titanium net for anode, the printed circuit board after the thin gold of electroless plating is negative electrode, and anode and anode distance are 5 cm.Logical direct current plating, current density 3 mA/cm2, electroplating time 20 min.
embodiment two:
According to described chemical gilding formula above, to the thin gold of printed circuit board pore structure electroless plating to be plated.Then, in plating tank, the KAuCl that concentration is 4 g/L is added4choline chloride 60-ethylene glycol ionic liquid 100 ml, is placed in oil bath pan by electrolyzer, is warming up to 70 ° of C, and with platinum titanium net for anode, the printed circuit board after the thin gold of electroless plating is negative electrode, and anode and anode distance are 5 cm.Logical direct current plating, current density 3 mA/cm2, electroplating time 10 min.
embodiment three:
According to described chemical gilding formula above, to the thin gold of printed circuit board pore structure electroless plating to be plated.Then, in plating tank, the KAuCl that concentration is 4 g/L is added4choline chloride 60-ethylene glycol ionic liquid 100 ml, is placed in oil bath pan by electrolyzer, is warming up to 90 ° of C, and with platinum titanium net for anode, the printed circuit board after the thin gold of electroless plating is negative electrode, and anode and anode distance are 5 cm.Logical direct current plating, current density 3 mA/cm2.Electroplating time 10 min.
embodiment four:
According to described chemical gilding formula above, to the thin gold of printed circuit board pore structure electroless plating to be plated.Then, in plating tank, the KAuCl that concentration is 8 g/L is added4choline chloride 60-ethylene glycol ionic liquid 100 ml, is placed in oil bath pan by electrolyzer, is warming up to 70 ° of C, and with platinum titanium net for anode, the printed circuit board after the thin gold of electroless plating is negative electrode, and anode and anode distance are 5 cm.Logical direct current plating, current density 5 mA/cm2.Electroplating time 10 min.
embodiment five:
According to described chemical gilding formula above, to the thin gold of printed circuit board pore structure electroless plating to be plated.Then, in plating tank, the KAuCl that concentration is 16 g/L is added4choline chloride 60-ethylene glycol ionic liquid 100 ml, is placed in oil bath pan by electrolyzer, is warming up to 90 ° of C, and with platinum titanium net for anode, the printed circuit board after the thin gold of electroless plating is negative electrode, and anode and anode distance are 5 cm.Logical direct current plating, current density 3 mA/cm2.Electroplating time 5 min.
Through experiment, the test performance index that above-described embodiment obtains is as shown in table 1.
Table 1
As shown in Table 1, choline chloride 60-glycol system of the present invention carries out the galvanic deposit of gold, compares general ionic liquid, the preparation of choline chloride 60-glycol system is simple, cost is low, nontoxic, biological degradation, to advantages such as empty G&W are stable.Also ensure that the circuit card performance that the present invention obtains is more excellent also more stable, quality is higher.
Above-mentioned example to invention has been detailed description, but and does not mean that the present invention is only confined to this four kinds of examples.When not departing from the technology of the present invention principle, making improvements and being out of shape within the claims in the present invention and technology, also should belong to protection scope of the present invention.