阅读说明：本技术 一种测定键合银丝中掺杂元素和杂质元素含量的方法 (method for measuring contents of doping elements and impurity elements in bonded silver wire ) 是由 颜廷来 宋强 林良 宋丽娜 刘炳磊 韩连恒 于 2019-10-22 设计创作，主要内容包括：本发明公开了一种测定键合银丝中掺杂元素和杂质元素含量的方法,包括样品处理、标准溶液配制、标准系列溶液配制、分析谱线选择、仪器工作参数设置、标准工作曲线绘制、基体影响测试、样品测试以及计算样品中待测元素含量等步骤。本发明的有益效果是：本发明方法所用金属标准贮备液为国家有证标准物质,所用试剂仅有优级纯的盐酸和硝酸,易于获得；采用基体影响测试的方式验证本发明所选定的条件下银基体不影响待测元素的测定；样品处理过程简单,检测周期短。本发明,可以快速全面而准确的测定出键合银丝中掺杂元素和杂质元素的含量,可操作性强,适于普及。(The invention discloses a method for measuring the content of doping elements and impurity elements in a bonded silver wire, which comprises the steps of sample treatment, standard solution preparation, standard series solution preparation, analysis spectral line selection, instrument working parameter setting, standard working curve drawing, matrix influence testing, sample testing, calculation of the content of elements to be measured in a sample and the like. The invention has the beneficial effects that: the metal standard stock solution used in the method is a national certified standard substance, and the used reagents only comprise superior pure hydrochloric acid and nitric acid and are easy to obtain; the method for testing the influence of the matrix is adopted to verify that the silver matrix does not influence the determination of the element to be tested under the selected conditions; the sample treatment process is simple, and the detection period is short. The method can quickly, comprehensively and accurately measure the contents of the doping elements and the impurity elements in the bonding silver wire, has strong operability and is suitable for popularization.)

1. A method for measuring the content of doping elements and impurity elements in a bonded silver wire is characterized by comprising the following steps:

1) Sample processing

Weighing 0.4-0.6g of bonded silver wire sample, accurately weighing the bonded silver wire sample to 0.0001g, placing the bonded silver wire sample in a 100mL quartz beaker, adding 10mL of absolute ethyl alcohol, heating at 45 ℃ for 5min, pouring out the ethyl alcohol, washing the sample with water for 3-5 times, adding 10mL of nitric acid, covering a quartz watch glass, heating on an electric heating plate until the sample is completely dissolved, taking off the watch glass, washing the watch glass and the inner wall of the beaker with water, heating and evaporating until the residual 2-3mL is obtained, cooling to room temperature, transferring the liquid into a 50mL volumetric flask, washing the precipitate with water for 3-5 times, transferring the washing liquid into the volumetric flask, fixing the volume to obtain a to-be-detected liquid A, transferring the 5mL to 50mL volumetric flask from the to-be-detected liquid A, adding 5mL of concentrated nitric acid, diluting with water to fix the volume to obtain a to-; adding 5mL of aqua regia into the precipitate, covering a quartz watch glass, heating on an electric hot plate until the precipitate is completely dissolved, taking down the precipitate when no reddish brown gas exists, cooling to room temperature, washing the inner wall of the watch glass and the beaker with water, transferring the liquid into a 50mL volumetric flask to fix the volume to be used as a liquid C to be detected, transferring 5mL to 50mL volumetric flask from the liquid C to be detected, adding 5mL of concentrated nitric acid, diluting with water to fix the volume to be used as a liquid D to be detected; processing two samples at the same time and making a blank;

2) Standard solution preparation

a. Mixing a standard solution A: respectively transferring 1mL of bismuth, iron, lead, antimony, selenium, tellurium, magnesium, calcium, indium, lanthanum, cerium and yttrium standard storage solution into a 100mL volumetric flask, adding 5mL of concentrated nitric acid, diluting with water, fixing the volume and uniformly mixing;

b. mixing the standard solution B: respectively transferring 5mL of platinum and copper standard stock solutions into a 100mL volumetric flask, adding 5mL of concentrated nitric acid, diluting with water, fixing the volume, and uniformly mixing;

c. Mixing standard solution C: respectively transferring 20mL of gold standard storage solution and 10mL of palladium standard storage solution into a 200mL volumetric flask, adding 10mL of concentrated nitric acid, diluting with water, fixing the volume, and uniformly mixing;

d. Silver standard solution: transferring 20mL of silver standard stock solution into a 200mL volumetric flask, adding 10mL of concentrated nitric acid, diluting with water, fixing the volume, and uniformly mixing;

3) Standard series solution preparation

respectively transferring standard solutions with certain volumes into four groups of 100mL volumetric flasks, adding 5mL concentrated nitric acid, diluting with water to constant volume, and preparing standard series solutions;

4) Analytical line selection

Selecting 3-5 analysis spectral lines for each element to be detected from a spectral line library of the spectrometer according to the influence of interference elements, the luminous intensity and the sensitivity;

5) instrument operating parameter settings

cleaning the pump speed of 100rps, analyzing the pump speed of 50rps, RF power of 1150W, auxiliary air flow of 0.5L/min, cooling air flow of 12L/min and atomizing air flow of 0.7L/min, vertically observing and repeatedly measuring for 3 times;

6) Drawing of standard working curve

According to the analysis method established in the steps 4) and 5), automatically searching peaks by using each series of standard solutions with the highest concentration in the step 3), preliminarily screening out abnormal analysis spectral lines, sequentially measuring the standard series of solutions, drawing a working curve by using the concentration value as a horizontal coordinate and the intensity value as a vertical coordinate, and selecting the analysis spectral lines with linear correlation coefficient not less than 0.9995 and relatively low detection limit;

7) Matrix impact test

respectively adding 40.00mL of silver standard solution with the concentration of 100 mu g/mL into 3 100mL volumetric flasks, sequentially adding 4.00mL of mixed standard solution A, 4.00mL of mixed standard solution B and 10.00mL of mixed standard solution C, and fixing the volume by water to prepare a solution which has the same concentration as Std-2 and contains 40 mu g/mL of matrix silver; under the analysis spectral line screened out in the step 6), Std-0 is used as a blank, Std-2 and the solution added with matrix silver are respectively operated, and according to the measurement result, the analysis spectral line with smaller measurement value difference and close to the standard value of the two solutions is used as the optimal spectral line of sample analysis;

8) Sample testing

under the same operation condition in the step 6), determining a blank and a to-be-detected liquid A, C according to the analysis spectral line determined in the step 7), if the content of the to-be-detected element exceeds the range of the working curve, diluting the to-be-detected element into a to-be-detected liquid B, D according to the step 1), and determining again;

9) Calculating the content of the element to be detected in the sample

Calculating the mass fraction omega (X) of the element to be measured according to the following formula, wherein the numerical value is expressed by percent:

in the formula:

x-the element to be measured,

Rho x is the mass concentration of the element to be detected in the sample solution, and the unit is mu g/mL,

rho 0 is the mass concentration of the element to be detected in the blank solution, and the unit is mu g/mL,

V is the total volume of the test solution, the unit is mL,

m-mass of the sample in g,

the obtained result is usually expressed to two digits after the decimal point, if the content of the element to be detected is less than 0.10%, the result is expressed to three digits after the decimal point, if the content of the element to be detected is less than 0.010%, the result is expressed to four digits after the decimal point, and if the content of the element to be detected is less than 0.0010%, the result is expressed to five digits after the decimal point.

2. The method for determining the content of doping elements and impurity elements in the bonded silver wire according to claim 1, wherein in the step 2), the concentration of the mixed standard solution A is 10 μ g/mL; the concentration of the mixed standard solution B is 50 mug/mL; the concentration of gold in the mixed standard solution C is 100 mug/mL, and the concentration of palladium in the mixed standard solution C is 50 mug/mL; the silver standard solution concentration was 100. mu.g/mL.

3. The method for determining the contents of doping elements and impurity elements in a bonded silver wire according to claim 1, wherein in the step 3), the removal volumes and corresponding concentrations of the standard solution are as follows:

，

And Std-0 is used as a standard blank, only 5mL of concentrated nitric acid is added, and then the mixture is diluted by water to a constant volume.

4. the method for determining the contents of doping elements and impurity elements in a bonded silver wire according to claim 1, wherein in step 7), the optimum analytical lines are selected as follows:

，

When the analysis spectral line is selected, the influence of the silver matrix on the numerical value of the standard solution is within +/-5%.

5. The method for determining the contents of the doping elements and the impurity elements in the bonded silver wire according to claim 1, wherein in the step 8), if the contents of the elements in the solution A to be detected and the solution C to be detected are within the range of the working curve, the solution B to be detected and the solution D to be detected do not need to be prepared; and if the element contents of the liquid A to be detected and the liquid C to be detected are not within the range of the working curve, preparing a liquid B to be detected and a liquid D to be detected.

6. The method for determining the contents of the doping element and the impurity element in the bonded silver wire according to claim 1, wherein in the step 9), if the solution a to be measured and the solution C to be measured do not need to be diluted again, V is 50.00 mL; if the solution a and the solution C to be tested need to be further diluted into solution B and solution D to be tested, V is 500.00mL, and the average value of two parallel samples is taken as the final result.

Technical Field

The invention relates to the field of integrated circuits, in particular to a method for measuring the content of doping elements and impurity elements in bonded silver wires.

background

The bonding wire is one of five major structural materials for microelectronic packaging, is a main connection mode for realizing a chip and an external packaging substrate and/or a multilayer circuit board, and mainly comprises a gold wire, a copper wire, an aluminum wire, a silver wire and a precious base metal composite wire material at present. In recent years, the traditional bonding gold wire in the LED and IC industries is gradually replaced by the bonding silver wire with the advantages of low cost, excellent electric conduction and heat conduction performance, good light reflection, mechanical property similar to that of the gold wire, no need of protective gas in the bonding process and the like. However, since the silver wire is soft and has low strength, the wire is easy to break under high-speed bonding conditions and is easy to be vulcanized and oxidized. Therefore, trace elements or surface coatings are usually doped into silver wires to reduce the formation of metal compounds, prevent the generation of interfacial oxides and cracks, reduce the degradation of bonding properties, and stabilize the bonding properties as same as gold wires.

under the condition of little influence on the electric and heat conductivity of the silver wire, each doping element plays different roles on other properties of the silver wire. For example, alkaline earth elements of calcium and magnesium can improve plasticity and reduce oxygen content; the third main group indium can passivate the surface and reduce the sulfuration corrosion; the transition metal elements such as gold, palladium, platinum and copper can increase the ductility and improve the oxidation resistance and the sulfuration resistance; the rare earth elements of lanthanum, cerium and yttrium can prevent segregation, refine crystal grains and improve mechanical properties. The kind and content of the doping elements directly influence the mechanical property, oxidation and vulcanization resistance and processability of the bonding silver wire. In addition, impurity elements such as palladium, copper, bismuth, iron, lead, antimony, selenium, tellurium and the like from the raw silver ingot also affect the performance of the bonded silver wire. With the increasing demand for high-performance bonding silver wires, how to rapidly monitor the types and contents of elements in the bonding silver wires is particularly important.

at present, methods for simultaneously and rapidly determining the content of doping elements and impurity elements in bonded silver wires are rarely reported, and if a national standard is adopted for single analysis, multiple technicians are required to cooperate to complete the analysis; the standard method can only use ICP to measure trace impurities in the raw material silver ingot, and the matrix silver needs to be removed during sample treatment, thereby greatly prolonging the detection time.

Disclosure of Invention

The invention provides a method for measuring the content of doping elements and impurity elements in a bonded silver wire, aiming at the problem that the doping elements and the impurity elements in the existing bonded silver wire are difficult to detect.

The technical scheme for solving the technical problems is as follows: a method for measuring the content of doping elements and impurity elements in a bonded silver wire is characterized by comprising the following steps:

1) sample processing

weighing 0.4-0.6g of bonded silver wire sample, accurately weighing the bonded silver wire sample to 0.0001g, placing the bonded silver wire sample in a 100mL quartz beaker, adding 10mL of anhydrous ethanol, heating at 45 ℃ for 5min, pouring out the ethanol, washing the sample with water for 3-5 times, adding 10mL of nitric acid (1+1), covering the quartz cuvette, heating the sample on an electric heating plate until the sample is completely dissolved, taking off the cuvette, washing the inner wall of the cuvette and the beaker with water, heating and evaporating until the residual 2-3mL is obtained, cooling to room temperature, transferring the liquid to a 50mL volumetric flask, washing the precipitate with water for 3-5 times, transferring the washing liquid to the volumetric flask and fixing the volume to obtain a to-be-measured liquid A, transferring the 5mL to 50mL volumetric flask from the to-be-measured liquid A, adding 5mL of concentrated nitric acid, and diluting the to fix the volume with water to obtain a to-be; adding 5mL of aqua regia into the precipitate, covering a quartz watch glass, heating on an electric hot plate until the precipitate is completely dissolved, taking down the precipitate when no reddish brown gas exists, cooling to room temperature, washing the inner wall of the watch glass and the beaker with water, transferring the liquid into a 50mL volumetric flask to fix the volume to be used as a liquid C to be detected, transferring 5mL to 50mL volumetric flask from the liquid C to be detected, adding 5mL of concentrated nitric acid, diluting with water to fix the volume to be used as a liquid D to be detected; processing two samples at the same time and making a blank;

2) Standard solution preparation

a. Mixing a standard solution A: respectively transferring 1mL of bismuth, iron, lead, antimony, selenium, tellurium, magnesium, calcium, indium, lanthanum, cerium and yttrium standard storage solution into a 100mL volumetric flask, adding 5mL of concentrated nitric acid, diluting with water, fixing the volume and uniformly mixing;

b. Mixing the standard solution B: respectively transferring 5mL of platinum and copper standard stock solutions into a 100mL volumetric flask, adding 5mL of concentrated nitric acid, diluting with water, fixing the volume, and uniformly mixing;

c. Mixing standard solution C: respectively transferring 20mL of gold standard storage solution and 10mL of palladium standard storage solution into a 200mL volumetric flask, adding 10mL of concentrated nitric acid, diluting with water, fixing the volume, and uniformly mixing;

d. Silver standard solution (100. mu.g/mL): transferring 20mL of silver standard stock solution into a 200mL volumetric flask, adding 10mL of concentrated nitric acid, diluting with water, fixing the volume, and uniformly mixing;

3) Standard series solution preparation

respectively transferring standard solutions with certain volumes into four groups of 100mL volumetric flasks, adding 5mL concentrated nitric acid, diluting with water to constant volume, and preparing standard series solutions;

4) analytical line selection

selecting 3-5 analysis spectral lines for each element to be detected from a spectral line library of the spectrometer according to the influence of interference elements, the luminous intensity and the sensitivity;

5) instrument operating parameter settings

Cleaning the pump speed of 100rps, analyzing the pump speed of 50rps, RF power of 1150W, auxiliary air flow of 0.5L/min, cooling air flow of 12L/min and atomizing air flow of 0.7L/min, vertically observing and repeatedly measuring for 3 times;

6) drawing of standard working curve

According to the analysis method established in the steps 4) and 5), automatically searching peaks by using each series of standard solutions with the highest concentration in the step 3), preliminarily screening out abnormal analysis spectral lines, sequentially measuring the standard series of solutions, drawing a working curve by using the concentration value as a horizontal coordinate and the intensity value as a vertical coordinate, and selecting the analysis spectral lines with linear correlation coefficient not less than 0.9995 and relatively low detection limit;

7) matrix impact test

Respectively adding 40.00mL of silver standard solution with the concentration of 100 mu g/mL into 3 100mL volumetric flasks, sequentially adding 4.00mL of mixed standard solution A, 4.00mL of mixed standard solution B and 10.00mL of mixed standard solution C, and fixing the volume by water to prepare a solution which has the same concentration as Std-2 and contains 40 mu g/mL of matrix silver; under the analysis spectral line screened out in the step 6), Std-0 is used as a blank, Std-2 and the solution added with matrix silver are respectively operated, and according to the measurement result, the analysis spectral line with smaller measurement value difference and close to the standard value of the two solutions is used as the optimal spectral line of sample analysis;

8) Sample testing

under the same operation condition in the step 6), determining a blank and a to-be-detected liquid A, C according to the analysis spectral line determined in the step 7), if the content of the to-be-detected element exceeds the range of the working curve, diluting the to-be-detected element into a to-be-detected liquid B, D according to the step 1), and determining again;

9) Calculating the content of the element to be detected in the sample

calculating the mass fraction omega (X) of the element to be measured according to the following formula, wherein the numerical value is expressed by percent:

In the formula:

x-the element to be measured,

Rho x is the mass concentration of the element to be detected in the sample solution, and the unit is mu g/mL,

Rho 0 is the mass concentration of the element to be detected in the blank solution, and the unit is mu g/mL,

v is the total volume of the test solution, the unit is mL,

m-mass of the sample in g,

The obtained result is usually expressed to two digits after the decimal point, if the content of the element to be detected is less than 0.10%, the result is expressed to three digits after the decimal point, if the content of the element to be detected is less than 0.010%, the result is expressed to four digits after the decimal point, and if the content of the element to be detected is less than 0.0010%, the result is expressed to five digits after the decimal point.

in the step 2), the concentration of the mixed standard solution A is 10 mug/mL; the concentration of the mixed standard solution B is 50 mug/mL; the concentration of gold in the mixed standard solution C is 100 mug/mL, and the concentration of palladium in the mixed standard solution C is 50 mug/mL; the silver standard solution concentration was 100. mu.g/mL.

in step 3), the volume of the standard solution removed and the corresponding concentration are as follows:

And Std-0 as a standard blank, adding only 5mL of concentrated nitric acid, and diluting with water to a constant volume.

in step 7), the selected optimal analysis spectral lines are as follows:

The influence of the silver matrix on the standard solution values was within + -5% when the following analytical lines were chosen.

In the step 8), if the element contents in the solution A to be detected and the solution C to be detected are within the range of the working curve, the solution B to be detected and the solution D to be detected do not need to be prepared; and if the element contents of the liquid A to be detected and the liquid C to be detected are not within the range of the working curve, preparing a liquid B to be detected and a liquid D to be detected.

in the step 9), if the solution a to be detected and the solution C to be detected do not need to be diluted again, V is 50.00 mL; if the solution a and the solution C to be tested need to be further diluted into solution B and solution D to be tested, V is 500.00mL, and the average value of two parallel samples is taken as the final result.

the invention has the beneficial effects that: the metal standard stock solution used in the method is a national certified standard substance, and the used reagents only comprise superior pure hydrochloric acid and nitric acid and are easy to obtain; the method for testing the influence of the matrix is adopted to verify that the silver matrix does not influence the determination of the element to be tested under the selected conditions; the sample treatment process is simple, and the detection period is short. The method can quickly, comprehensively and accurately measure the contents of the doping elements and the impurity elements in the bonding silver wire, has strong operability and is suitable for popularization.

Detailed Description

The present invention is described below with reference to examples, which are provided for illustration only and are not intended to limit the scope of the present invention.

Equipment used for the experiment: U.S. Thermo Fisher6300DUO full spectrum direct reading inductively coupled plasma atomic emission spectrometer.

Reagents used for the experiment: standard stock solutions of gold, silver, palladium, platinum, copper, magnesium, calcium, indium, lanthanum, cerium, yttrium, bismuth, iron, lead, antimony, selenium and tellurium (national analysis and test center for nonferrous metals and electronic materials), 1000 μ g/mL; hydrochloric acid (guaranteed purity), 36.0% -38.0%; nitric acid (super pure), 65.0% -68.0%; the water used in the experiment was deionized water.

Setting working parameters of the instrument: 100rps of cleaning pump speed, 50rps of analyzing pump speed, 1150W of RF power, 0.5L/min of auxiliary air flow, 12L/min of cooling air flow and 0.7L/min of atomizing air flow, vertically observing and repeatedly measuring for 3 times.