CN115198323A - Conductive assistant composition for high-speed silver plating of lead frame and electroplating solution containing conductive assistant composition - Google Patents

Abstract

The application relates to a conductive assistant composition for high-speed silver plating of a lead frame and an electroplating solution containing the composition, wherein the composition comprises the following raw materials in concentration: 56-84g/L of conductive mixed salt; 16-24g/L of buffer; 7-9g/L of auxiliary agent; 1-3g/L of regulator; the solvent is water; the conductive mixed salt comprises potassium nitrate and potassium sulfate; the buffer comprises potassium borate, dipotassium hydrogen phosphate and potassium chloride; the auxiliary agent is potassium pyrophosphate; the regulator comprises one or more of 2-butyne-1, 4-diol, urea, furfuryl thiocarbamate, ammonia methosulfate or isomeric alcohol polyoxyethylene ether. The method has the advantages of improving the performances of the plating solution and the plating layer, and further improving the conductivity and usability of the product.

Description

Conductive assistant composition for high-speed silver plating of lead frame and electroplating solution containing same

Technical Field

The application relates to the technical field of high-speed silver plating, in particular to a conductive assistant composition for high-speed silver plating of a lead frame and an electroplating solution containing the composition.

Background

Leadframes are a key component of integrated circuits that form electrical circuits. Lead frames are used in most semiconductor packages and are used as important basic materials in the electronic information industry. High-speed electroplating refers to a process of obtaining a high-quality coating by performing high-speed deposition under a very high cathode current density by adopting special measures, wherein the deposition speed of the high-speed deposition is several times or even hundreds times of that of common electroplating. In the manufacturing process of the lead frame, the functional silver deposition layer is required to reach 1-5 microns so that the lead frame is suitable for loading a chip and bonding wires, and in the process, the silver deposition layer is required to reach the functional silver deposition layer in a short time at a high speed so as to achieve the lead frame suitable for chip bonding and bonding wires. The biggest characteristic of high-speed electroplating is that the adopted cathode current density is high, and the plating solution flows at high speed; compared with the plating layer obtained by the common electroplating mode, the plating layer obtained by high-speed electroplating has higher hardness and better corrosion resistance.

The plating solution in the existing high-speed silver plating treatment comprises a basic solution and an additive, wherein the basic solution generally comprises open-cylinder salt (a conductive aid composition), main salt and free potassium cyanide, and the types and the contents of the basic solution and the free potassium cyanide have direct influence on the stability, the conductivity and the production speed of the plating solution; the open-vat salt mainly plays the roles of conducting, buffering, auxiliary complexing, stabilizing the plating solution and the like in the high-speed silver plating solution, and the production and use find that when the main body in the open-vat salt selects dipotassium phosphate, an obtained silver plating layer is fine and uniform, but the conductivity of the plating layer and the dispersibility of the plating solution are poor; when the potassium phosphate is used as the main body in the open-cylinder salt, the plating layer has good conductivity but the plating solution has poor stability; because the selection of different open-cell salts has a non-uniform effect on the performances of the plating solution and the plating layer, the inventor considers that the conductive aid composition (open-cell salt) capable of better improving the performances of the plating solution and the plating layer is needed to improve the conductivity and the usability of the product.

Disclosure of Invention

In order to better improve the performances of a plating solution and a plating layer and further improve the conductivity and the usability of a product, the application provides a conductive assistant composition for high-speed silver plating of a lead frame and a plating solution containing the composition.

In a first aspect, the conductive aid composition for high-speed silver plating of the lead frame provided by the application adopts the following technical scheme:

the conductive assistant composition for high-speed silver plating of the lead frame comprises the following raw materials in concentration:

56-84g/L of conductive mixed salt; 16-24g/L of buffer; 7-9g/L of auxiliary agent; 1-3g/L of regulator; the solvent is water;

the conductive mixed salt comprises potassium nitrate and potassium sulfate;

the buffer comprises potassium borate, dipotassium hydrogen phosphate and potassium chloride;

the adjuvant is potassium pyrophosphate;

the regulator comprises one or more of 2-butyne-1, 4-diol, urea, furfuryl thiocarbamate, ammonia methosulfate or isomeric alcohol polyoxyethylene ether.

By adopting the technical scheme, the conductive mixed salt compounded by combining potassium nitrate and potassium sulfate mainly plays a role of conductivity in the plating solution, so that the conductivity of the plating solution can be improved; the buffering agent mainly plays a role in stabilizing the pH value of the plating solution in the plating solution, and can narrow the change range of the pH value of the plating solution; the auxiliary agent mainly plays a role in auxiliary complexation in the plating solution, and can be complexed with metal ions in the plating solution to increase the polarization effect of a cathode and enable a plating layer to be crystallized and refined; various salts in the conductive mixed salt, the buffering agent and the auxiliary agent are combined and compounded according to a specific proportion range, so that a rapid and stable ion transmission channel can be formed, the movement of ions is accelerated, the stability of silver ions in a system is improved, the conductivity of a plating solution is further improved, and the product has better conductivity; the synergistic compounding of the components is also beneficial to improving the stability of the plating solution, the cathode current efficiency of the plating solution is higher, and the high-speed silver plating production efficiency is improved; the plating solution can be uniformly dispersed, so that a fine and uniform plating layer is obtained, and the plating layer has good performance.

The conductive mixed salt, the buffering agent and the auxiliary agent have a large amount of conductive salt, a certain inhibiting effect can be generated among various conductive salts, the solubility of different salts in a system can be reduced, the plating solution can be opacified at a lower temperature, the performance of the plating solution can be seriously affected, the inhibiting effect among different salts can be relieved by the regulator, the better dissolution of different salts is promoted, the content of the conductive salt in the plating solution is improved, the synergistic effect of different salts is promoted, and the gain of the performance of the plating solution and the improvement effect of the conductive performance of a product are realized.

Preferably, the conductive mixed salt is 70-80g/L; 18-20g/L of buffering agent; 7-9g/L of auxiliary agent; 1-3g/L of regulator.

Preferably, the conductive mixed salt is 78g/L; 19g/L of a buffering agent; 8g/L of auxiliary agent; 3g/L of regulator.

By adopting the technical scheme, the component proportion of the conductive mixed salt, the buffering agent, the auxiliary agent and the regulator in the system is further limited, substances in each component, particularly different salts can be better cooperated, the inhibition effect among different salts is reduced to the maximum extent, and the gain effect of the conductive auxiliary composition on the plating solution is improved.

Preferably, the concentration of potassium nitrate in the conductive mixed salt is 39-59g/L, and the concentration of potassium sulfate in the conductive mixed salt is 17-25g/L.

Through adopting above-mentioned technical scheme, potassium nitrate and potassium sulphate mix, have increased the ionic concentration in the plating bath, and then help strengthening the electric conductivity of plating bath, and wherein the electric conductivity of potassium nitrate is stronger than the electric conductivity of potassium sulphate to the potassium nitrate is the main part, helps the promotion of bigger degree promotion electrically conductive mixed salt to plating bath electric conductivity.

Preferably, the concentration of the potassium borate in the auxiliary salt is 7-10g/L, the concentration of the dipotassium phosphate in the auxiliary salt is 7-10g/L, and the concentration of the potassium chloride in the auxiliary salt is 2-4g/L.

By adopting the technical scheme, the buffer agent adopts weak acid salt, so that the influence of the conductive mixed salt on the pH value of the plating solution can be counteracted and reduced to a certain extent, and the pH value of the plating solution is kept relatively stable; the potassium borate, the dipotassium hydrogen phosphate and the potassium chloride are matched with each other according to specific concentrations to form a stable buffer system, the pH value of the plating solution is further stabilized in a stable and proper range, the plating solution can be ensured to have better cathode current density, the stability of free cyanogen in the plating solution can be better maintained, the potassium chloride can provide certain osmotic pressure, the movement of ions is accelerated, and the conductivity-assisting performance of the conductivity-assisting composition on the plating solution is further improved.

Preferably, the regulator is prepared from 2-butyne-1, 4-diol, urea and isomeric alcohol polyoxyethylene ether according to the concentration ratio of (0.5-0.7): (0.8-1.2): (1.3-1.5) mixing.

By adopting the technical scheme, the 2-butyne-1, 4-diol, the urea and the isomeric alcohol polyoxyethylene ether are compounded according to a certain proportion, and added into the conductive salt solution, so that the effect of slowing down the solubility inhibition among different salts can be achieved, the compatibility among the components is promoted, the content and the stability of the salt components in a system are further improved, and the plating solution is stable in performance.

Preferably, the preparation method of the conductive assistant composition comprises the following steps:

s1, uniformly mixing potassium nitrate and potassium sulfate, and dissolving in deionized water to obtain a base solution;

s2, adding the auxiliary agent and the buffer agent into the base solution, stirring and dissolving, and uniformly mixing;

and S3, adding the regulator into the base solution, and uniformly mixing to obtain the conductive composition.

By adopting the technical scheme, the conductive mixed salt, the buffering agent and the auxiliary agent are added firstly, so that different salts can be uniformly mixed to obtain a salt solution, and then the regulator is added to regulate the compatibility among the components, so that the prepared conductive assistant composition can fully exert the conductivity assisting performance in the plating solution, and can stabilize silver ions, so that the plating solution has good conductivity and high plating layer quality.

In a second aspect, the electroplating solution containing the conductive assistant composition for high-speed silver plating of the lead frame adopts the following technical scheme:

an electroplating solution containing a conductive assistant composition for high-speed silver plating of a lead frame comprises the following raw materials in concentration:

80-120g/L of conductive assistant composition; 90-120g/L of silver potassium cyanide; 3-7g/L of potassium cyanide; 0.3-0.5g/L of wetting agent; 8-12ml/L of brightener; the solvent is water;

the cathode current density of the electroplating solution is 80A/dm ² -100A/dm ² (ii) a The temperature is 60 ℃; the pH was 9.5.

The concentration of the conductive assistant composition added into the plating solution needs to be proper, when the concentration is too low, the conductivity and the dispersion capability of the plating solution are poor, and the performance of the obtained silver plating layer can not meet the actual requirement; when the concentration is too high, the conductive salt is easy to separate out, so that the pipeline is blocked; by adopting the technical scheme, the conductive assistant composition is added into the plating solution according to a certain concentration, so that a good conductive assistant effect can be achieved, the prepared plating solution has good conductivity and dispersing capacity, the obtained silver plating layer is uniform and fine, and the product has strong conductivity.

In summary, the present application includes at least one of the following beneficial technical effects:

1. the conductive-aid composition comprises conductive mixed salt, a buffering agent, an auxiliary agent and a regulator, wherein the conductive mixed salt compounded by combining potassium nitrate and potassium sulfate mainly plays a conductive role in plating solution, so that the conductivity of the plating solution can be improved; the buffering agent mainly plays a role in stabilizing the pH value of the plating solution in the plating solution, and can reduce the change range of the pH value of the plating solution; the auxiliary agent mainly plays a role in auxiliary complexation in the plating solution, and can be complexed with metal ions in the plating solution to increase the polarization effect of a cathode and enable a plating layer to be crystallized and refined; the existence of the regulator can relieve the inhibition effect among the components, promote the better dissolution of different salts and improve the content of conductive salt in the plating solution; various salts in the conductive mixed salt, the buffering agent and the auxiliary agent are combined and compounded according to a specific proportion range, and the regulation assistance of the regulator is added, so that a rapid and stable ion transmission channel can be formed in the plating solution, the movement of ions is accelerated, the stability of silver ions in a plating solution system is improved, the conductivity of the plating solution is further improved, and the product has better conductivity; the components are cooperatively compounded, so that the stability of the plating solution can be improved, the plating solution can be uniformly dispersed, a fine and uniform plating layer can be obtained, and the plating layer has good performance; the product performance is stable;

2. the regulator is prepared by mixing 2-butyne-1, 4-diol, urea and isomeric alcohol polyoxyethylene ether according to a certain concentration ratio; the conductive salt solution is added, so that the effect of slowing down the dissolution inhibition among different salts can be achieved, the compatibility among the components is promoted, the content and the stability of the salt components in the system are further improved, and the performance of the plating solution is stable;

3. the concentration range of the conductive assistant composition in the plating solution is 80-120g/L, the conductive assistant composition is added into the plating solution according to proper concentration, good conductive assistant effect can be achieved, the conductivity and the dispersing capacity of the plating solution are improved, the obtained silver plating layer is uniform and fine, and the product has strong conductivity.

Detailed Description

Examples

Examples 1 to 5

Embodiments 1-5 disclose a conductive aid composition for high speed silver plating of lead frames comprising the following raw materials in concentrations:

56-84g/L of conductive mixed salt; 16-24g/L of buffer; 7-9g/L of auxiliary agent; 1-3g/L of regulator; the solvent is water; wherein the conductive mixed salt comprises potassium nitrate and potassium sulfate; the buffer comprises potassium borate, dipotassium hydrogen phosphate and potassium chloride; the auxiliary agent is potassium pyrophosphate; the regulator comprises one or more of 2-butyne-1, 4-diol, urea, furfuryl thiocarbamate, ammonia methosulfate or isomeric alcohol polyoxyethylene ether.

Embodiments 1 to 5 also disclose a method for preparing the conductive composition for high-speed silver plating of lead frames, comprising the following steps:

s1, dissolving conductive mixed salt in deionized water, and stirring until the conductive mixed salt is completely dissolved to obtain a base solution;

s2, adding the auxiliary agent and the buffer agent into the base solution, and mixing and stirring until the auxiliary agent and the buffer agent are completely dissolved;

and S3, adding the regulator into the base solution, uniformly mixing, and stirring until the regulator is completely dissolved to obtain the conductive aid composition.

The concentration ratios (unit: g/L) of the respective raw materials of examples 1 to 5 are specified in Table 1.

TABLE 1

Examples 6 to 8

Examples 6 to 8 disclose a conductive aid composition for high-speed silver plating of a lead frame, which is different from example 5 in that: the concentration ratios of the components in the regulator are different, and the details are shown in table 2.

TABLE 2

Comparative example

Comparative examples 1 to 8

The conductive assistant composition for high-speed silver plating of the lead frame is different from the conductive assistant composition in example 5 in that: the components in the composition and the concentration ratios of the components are different, and the details are shown in table 3.

TABLE 3

Application example

Application examples 1 to 14

Application examples 1 to 14 disclose an electroplating bath containing a conductive assistant composition for high-speed silver plating of lead frames, which comprises the following raw materials in concentration:

the assistant conductive composition is 80-120g/L; 90-120g/L of silver potassium cyanide; 3-7g/L of potassium cyanide; 0.3-0.5g/L of wetting agent; 8-12ml/L of brightener; the solvent is water;

wherein the wetting agent is ethyl hexanol polyoxyethylene ether (HA-10), and the brightening agent is tellurium dioxide; the conductive assistant compositions prepared in examples 1-8 and comparative examples 1-6 are selected respectively;

the cathode current density of the plating solution is 80A/dm ² -100A/dm ² (ii) a The temperature is 60 ℃; the pH was 9.5.

Comparative application example

Comparative application example 1

The difference from application example 1 is that: the conductive aid composition prepared in comparative example 7 was selected as the conductive aid composition; namely, the concentration of the conductive assistant composition in the plating solution is 60g/L.

Comparative application example 2

The difference from application example 1 is: the conduction-assisting composition prepared in the comparative example 8 is selected; namely, the concentration of the conductive assistant composition in the plating solution is 140g/L.

Performance test

Electroplating the plating solution prepared by the application example by adopting a high-speed silver plating process of the lead frame, wherein the process flow is as follows: (wherein D =100A/dm at high-speed silver plating ² ，t＝5s)

Loading → electrolytic degreasing (degreasing) → washing → acid washing activation → washing → preplating copper → washing → immersion of silver displacement agent → washing → high-speed silver plating → washing → silver removing → washing → copper discoloration prevention → washing by cold water → washing by hot water → drying → unloading.

1. And (3) testing the conductivity of the plating layer: and (3) carrying out conductivity test on the silver plating layers of the products prepared by adopting the high-speed silver plating process by adopting a conductivity meter corresponding to the examples 1-14 and the comparative application examples 1 and 2, wherein the test is in accordance with the international annealed copper standard.

2. And (3) testing the dispersing ability of the plating solution: the dispersing ability of the high-speed silver plating solutions prepared in application examples 1 to 14 and comparative application examples 1 and 2 was measured according to the Hall cell template method in the "test for dispersing ability of electroplating solution test" of Standard JB/T7704.4. The dispersing capacity of the plating solution is also called the uniform plating capacity of the plating solution, and can reflect the capacity of the electrolyte for ensuring the thickness uniformity of the plating layer on the surface of a plated part. If the thickness of the plating layer on the surface of the plated part is uniform, the good dispersion capability of the plating solution is shown; on the contrary, if the thickness of the plating layer on the surface of the plated part is not uniform, the poor dispersion capability of the plating solution is indicated; the process conditions of the hall cell are I =15a, t =15s.

3. And (3) testing the cathode current efficiency of the plating solution: measuring the cathode current efficiency of the high-speed silver plating solution prepared in the application examples 1-14 and the comparative application examples 1 and 2 according to a standard JB/T7704.3 cathode current efficiency test of electroplating solution test method; the cathode current efficiency of the plating solution is an important index of the performance of the plating solution, and reflects the cathode deposition speed in the electroplating process, and the higher the cathode current efficiency is, the higher the production efficiency is; the cathodic current efficiency was measured by the copper coulometer method. In the experiment, the current density D of silver plating _{Silver (Ag)} ＝100A/dm ² The energization time was 250 seconds.

The performance test data for application examples 1-14 and comparative application examples 1, 2 are detailed in table 4.

TABLE 4

According to the detection data of application examples 1-8 in table 4, the conductive compositions of examples 1-8 can be used to prepare plating solutions with dispersion capability of more than 67% and cathode current efficiency of more than 98%, and the plating layer obtained after the plating solutions are used for half a year has stable performance, which indicates that the plating solutions have good dispersion and stability and higher working efficiency, and the silver plating layer obtained by plating with the plating solutions has conductivity of more than 94%, bright, uniform, fine and non-plating-leakage phenomenon, and good conductivity and usability of the product.

The conductive assistant mixture prepared in the embodiments 1 to 5 is added into the electroplating solution according to a certain concentration range, so as to form the electroplating solution of the application examples 1 to 5, wherein the conductive assistant mixture comprises conductive mixed salt, a buffering agent, an auxiliary agent and a regulator, different salts in the conductive mixed salt, the buffering agent and the auxiliary agent are compounded in a combination manner, so that different properties of different salts on the electroplating solution and the plating layer can be gained, the regulator realizes the regulation of compatibility of different salts, the solubility inhibition caused by the compounding of different salts is further slowed down, and the components in the conductive assistant composition are mixed according to a specific concentration ratio, so that the synergistic effect is fully exerted, the movement rate of ions in the electroplating solution is further improved, the stability of silver ions is improved, and the improvement of the properties of the electroplating solution and the plating layer can be realized by adding the proper concentration range, so as to finally improve the conductivity and the usability of the product.

The comparative examples 1 and 2 replace the internal components of the conductive mixed salt, so that only a single component of potassium nitrate or potassium sulfate exists in the conductive mixed salt, the performance data of the electroplating solution prepared by the application examples 9 and 10 by adopting the conductive assistant composition of the comparative examples 1 and 2 is compared with that of the electroplating solution prepared by the application examples 1 to 5, the problems of reduced dispersing capacity of the electroplating solution, reduced cathode current efficiency, reduced conductivity and uneven thickness of the coating are solved, and the data of the application examples 9 and 10 also reflect that when a single component is used as the conductive salt, the performance of the electroplating solution and the coating cannot be well improved by the single component, so that the limitation is large.

The internal components of the buffer are adjusted and replaced in comparative examples 3 and 4, the buffer only contains one or two components of potassium borate, dipotassium hydrogen phosphate and potassium chloride, the performance data of the electroplating solutions prepared by the conductive assistant compositions of the comparative examples 3 and 4 in application examples 11 and 12 are compared with the performance data of the electroplating solutions prepared by the application examples 1 to 5, the dispersing capacity and the cathode current efficiency of the electroplating solutions are reduced, the conductivity of the plating layers is reduced, the problems of uneven thickness and plating leakage of the plating layers occur, and the data of the application examples 11 and 12 reflect that after the internal components of the buffer are adjusted and replaced, the components in the buffer cannot generate good matching effect, so that the capacity of buffering the pH value of the plating solution is weakened, and the dispersing stability of the plating solution and the performance of the plating layers are influenced to a certain extent.

Through comparison of performance data of application examples 1-5 and application examples 9-12, the conductive mixed salt and the components in the buffering agent have specific combination proportion relationship, and the combination proportion relationship between the components is damaged, so that the performance of the electroplating solution and the performance of the plating layer are influenced.

In examples 6 to 8, the component proportion of the regulator in the conductivity-assisting composition is further improved, and the compatibility regulation of other components in the conductivity-assisting composition system is more prominent by mixing 2-butyne-1, 4-diol, urea and isomeric alcohol polyoxyethylene ether according to a specific concentration ratio compared with the combination proportion of other substances, so that the inhibition effect of different salts on the solubility can be well relieved, and the plating solution prepared by applying the conductivity-assisting composition in examples 6 to 8 and the plating layer formed by the plating solution have better performance.

The conductive assistant composition prepared in comparative example 5 was not added with a conditioning agent, and the dispersion ability and the cathode current efficiency of the plating solution prepared in application example 13 of comparative example 5 were significantly reduced, the plating layer was rough and uneven, there was a phenomenon of more plating omission, and the plating layer conductivity was significantly reduced.

Through comparative analysis of performance data of application examples 6-8 and application example 13, the regulator plays an important role in a conduction-assisting composition system, the combination proportion of the regulator is related to the stability of coordination among other components in the system, the regulator is absent, and the inhibition effect generated by different salts in the system can cause the dispersion stability of the plating solution to be reduced, the plating solution is salted out, so that the quality of the plating layer is caused to be in a problem, and the performance of a product is further influenced.

In the application example 14 of the conduction aid composition prepared in the comparative example 6, the concentration of the conduction aid composition in the plating solution is unchanged, and the concentration ratio of the components in the plating solution is changed, so that the conduction aid composition system is disordered, the function of the conduction aid composition is further disabled, and the performances of the plating solution and the plating layer are interfered.

Compared with application examples 1 and 2, the assistant conductive compositions prepared in comparative examples 7 and 8 are respectively adopted, so that the concentration ratio of the assistant conductive compositions in the plating solution exceeds the range defined by the application, the concentration range is too low, the working efficiency and the dispersing capacity of the plating solution are poor, the obtained silver plating layer has poor conductivity, and the performance can not meet the actual requirement; when the concentration is too high, the salt in the conductive assistant composition is easily precipitated, and the plating solution and the plating properties are also affected.

The above embodiments are preferred embodiments of the present application, and the protection scope of the present application is not limited by the above embodiments, so: all equivalent changes made according to the structure, shape and principle of the present application shall be covered by the protection scope of the present application.

Claims (8)

1. The utility model provides a lead frame is conductive composition that helps for silver-plating at a high speed which characterized in that: comprises the following raw materials in concentration:

56-84g/L of conductive mixed salt; 16-24g/L of buffer; 7-9g/L of auxiliary agent; 1-3g/L of regulator; the solvent is water;

the conductive mixed salt comprises potassium nitrate and potassium sulfate;

the buffer comprises potassium borate, dipotassium hydrogen phosphate and potassium chloride;

the adjuvant is potassium pyrophosphate;

the regulator comprises one or more of 2-butyne-1, 4-diol, urea, furfuryl thiocarbamate, ammonia methosulfate or isomeric alcohol polyoxyethylene ether.

2. The conductive aid composition for high-speed silver plating of lead frames according to claim 1, characterized in that: the composite material comprises the following raw materials in parts by mass:

70-80g/L of conductive mixed salt; 18-20g/L of buffer; 7-9g/L of auxiliary agent; 1-3g/L of regulator.

3. The conductive auxiliary composition for high-speed silver plating of lead frames according to claim 2, characterized in that: the composite material comprises the following raw materials in parts by mass:

78g/L of conductive mixed salt; 19g/L of a buffering agent; 8g/L of auxiliary agent; 3g/L of regulator.

4. The conductive-aid composition for high-speed silver plating of lead frames according to any one of claims 1 to 3, wherein: the concentration of potassium nitrate in the conductive salt is 39-59g/L, and the concentration of potassium sulfate in the conductive salt is 17-25g/L.

5. The conductive aid composition for high-speed silver plating of lead frames according to any one of claims 1 to 3, wherein: the concentration of potassium borate in the auxiliary salt is 7-10g/L, the concentration of dipotassium hydrogen phosphate is 7-10g/L, and the concentration of potassium chloride is 2-4g/L.

6. The conductive-aid composition for high-speed silver plating of lead frames according to any one of claims 1 to 3, wherein: the regulator is prepared from 2-butyne-1, 4-diol, urea and isomeric alcohol polyoxyethylene ether according to the concentration ratio of (0.5-0.7): (0.8-1.2): (1.3-1.5) mixing.

7. The conductive-assistant composition for high-speed silver plating of lead frames according to claim 1, wherein: the preparation method of the conductive assistant composition comprises the following steps:

s1, dissolving conductive mixed salt in deionized water, and stirring until the conductive mixed salt is completely dissolved to obtain a base solution;

s2, adding the auxiliary agent and the buffer agent into the base solution, stirring and dissolving, and uniformly mixing;

and S3, adding the regulator into the base solution, and uniformly mixing to obtain the conduction aid composition.

8. An electroplating bath comprising the conductive aid composition for high speed silver plating of lead frames according to any of claims 1 to 7, wherein: comprises the following raw materials in concentration:

the assistant conductive composition is 80-120g/L; 90-120g/L of silver potassium cyanide; 3-7g/L of potassium cyanide; 0.3-0.5g/L of wetting agent; 8-12ml/L of brightener; the solvent is water;

the cathode current density of the electroplating solution is 80A/dm < 2 > -100A/dm < 2 >; the temperature is 60 ℃; the pH was 9.5.