Some standard content:
Standard of the Ministry of Electronics Industry of the People's Republic of China Test Methods for Resin-based Fluxes for Soft Soldering
SJ2660-86
This standard mainly stipulates the test methods for resin-based fluxes for soft soldering (hereinafter referred to as fluxes) used for circuit welding of electronic, electrical equipment and instruments.
1 Test items and sampling methods for test materials
Test materials are sampled according to the test items and Table 1. Table 1 Test items and sampling methods of test materials
Appearance of flux
Total amount of flux
Dryness test
Non-stickiness test
Color test
Viscosity test
Specific gravity test
Flux radiation test
Protection test
Seam or plating test
Extreme corrosion test
Copper plate corrosion
Thin copper wire corrosion
Applied voltage
Texture test
Hot plate friction test
Resin core solder wire
Applicable terms
Original Solid
Ministry of Electronics Industry 1986-01-21 Issued
30%
Isopropyl alcohol
Solder paste
Solid flux
Original liquid
Part of the ministry
30%
Liquid flux
Rosin flux
Original solid original
Part of the product
30% isopropyl alcohol solution
1986-10-01 Implementation
Combined element (nitrogen
Au) content test
Acid test| |tt||Direct titration method
Absorptiometry
Applicable clauses
Continued Table 1
SJ2660-86
Test items and sample sampling methods
Fat core solder wire
Original Xiangguo body
Electro-micro-calcination method
Silver chromate red test
Total acid value measurement
Water-soluble acid value
Water-soluble conductive car test film
Insulating electric mouse purchase
30%
Isoprothione
Volatile solder paste
Solid flux
Original Solid Liquid Original
Note: The "O" code in the table indicates the state of the sample to be taken for the test item. Preparation of samples
2.1 Preparation of the solid part of the flux
2.1.1 Resin core solder wire
Part Part
Liquid flux
Rosin flux
30% original solid original
Isopropyl
Part Product
30% isopropyl solution
After cleaning the surface of the resin core solder wire with absorbent cotton dipped in propyl, wash it with distilled water or ion exchange resin water (hereinafter referred to as water). Then wash it with ethanol and then dry it. Cut this resin core solder wire into 2-3mm lengths to make the flux easy to dissolve. Weigh 150g of resin core solder wire and put it into a grease trap (250ml), add 125ml of isopropyl alcohol, and then heat it to about 85℃ to dissolve the flux to form a flux solution. Take about 50g of the flux solution and inject it into a 100ml beaker, then heat it at 80±5℃ to concentrate the flux solution to a near constant weight (the allowable error is less than 2mg before and after 30min), which is the solid part of the flux. 2.1.2 Liquid flux
Inject about 10g of liquid flux into a 50ml beaker, heat it at an appropriate temperature (below 150℃) that does not carbonize the flux, and concentrate the flux to a near constant weight (the allowable error is less than 2mg before and after 30min), which is the solid part of the flux. 2.1.3 Solder Paste
Pour the liquid flux (see 2.2.3) of about 10g solder paste into a 50ml beaker; heat it at a suitable temperature (below 150℃) that does not carbonize the flux, and concentrate it to a constant amount (the allowable error is less than 2mg before and after 30min). This is the solid part of the flux.
Note: With the consent of both parties, the solid part of the flux in the solder pot wire and the solder burnout can be directly used as the bulk flux in the same batch production process. 2.2 Preparation of the Liquid Part of the Flux
2.2.1 Resin Core Solder Wire
Dissolve the solid part of the flux in isopropyl alcohol (analytical grade) to prepare a 30% (weight ratio) isopropyl alcohol solution. 2.2.2 Solid flux
Prepare as per 2.2.1
2.2.3 Solder paste
Put about 100g solder paste into a 100ml beaker, place it in a constant temperature box at about 50℃ for 30min, separate the flux and solder, then slowly pour the clear flux part on the upper part of the beaker into another beaker, which is the liquid part of the solder.
3 Test method
3.1 Appearance inspection of flux
3.1.1 Resin core solder wire
Perform as per 3.1 of SJ2659-86 "Resin core solder wire for electronic industry". 3.1.2 Solder paste
Use naked eye to inspect the solder paste. It should be uniform, without agglomeration, and the flux and solder should not be separated. 3.1.3 Solid flux
Solid flux should be uniform and free of inclusions when inspected by naked eyes. 3.1.4 Liquid flux
Liquid flux should be uniform and free of sediment when inspected by naked eyes. 3.1.5 Rosin flux
Rosin flux should meet the requirements of special grade or first grade rosin specified in LY204-63. 3.2 Flux content test
3.2.1 Resin core solder wire
Perform according to the provisions of 3.10 in SJ2659-86. 3.2.2 Solder paste
Weigh 30.000g (ml) of solder paste that has been evenly stirred, and put it into glycerol for heating and melting. After the solder and flux are completely separated, take out the solidified solder, wash it with water, and then wash it with ethanol. Accurately weigh after drying (m2) and calculate the flux content according to the following formula:
Flux content%=ml=mz×100%
Wherein: m——solder paste mass, g,
m.-solder mass after drying, g.
3.2.3 Solids in liquid flux
Accurately weigh 3.000~5.000g (m) of liquid flux into a constant-weight weighing bottle, heat it in a boiling water bath to evaporate and remove most of the volatile substances, then place it in an oven at 110℃ for 3h, take it out and put it in a dryer to cool, weigh it (m2), and calculate the flux content according to the following formula:
Flux content%=㎡2×100%
In the formula, m1—mass of liquid flux, g;
m2—mass of solids in liquid flux, g. 3.3 Dryness test
3.3.1 Resin core solder wire
Perform according to the provisions of 3.11 in JS2659-86.
3.3.2 Solder paste
Weigh 0.300g solder paste and perform according to 3.3.1. 3.3.3 Solid flux, rosin flux
Weigh 0.1g sample and place it on a 30×30×0.3mmT copper plate cleaned with ethanol, and heat it at about 250℃ to melt. Take it out after 5s and solidify it at room temperature to make a sample. After leaving it at room temperature for 30min, sprinkle chalk powder on the surface of the residual flux part of the sample, and then check whether the chalk powder can be removed by gently brushing with a brush. 3.4 Non-stickiness test
Put about 0.1g liquid flux sample on a 0.3×30×30mmT copper plate E cleaned with ethanol and dried, and heat it at about 250℃. Melt it for about 5s and take it out after curing it at room temperature as a sample. Place 6 pieces of 50×50mm gauze on top of each other on the surface of the residual flux of the sample, place a round iron weight with a diameter of 40mm and a mass of 500g and a flat bottom in the center of the gauze, and put the sample into a constant temperature bath at 40±2℃ in the horizontal direction. Keep it for 72 hours and then take it out. Pull the gauze apart from the flux surface to inspect the film surface and check whether the cloth grain marks are obvious. 3.5 Chromaticity Test
3.5.1 Instrument
25ml colorimetric tube
72 type photoelectric colorimeter
3.5.2 Standard Chromaticity
Dissolve 2g of iodine (superior grade) in 100ml 20% potassium iodide (superior grade) solution and titrate with 0.1V sodium thiosulfate (superior grade) solution to determine the iodine concentration. Take the above solutions containing 1mg, 2mg, 3mg of iodine, dilute them to 100ml with water, shake them and use them as standard solutions for chroma 1, chroma 2 and chroma 3.
3.5.3 Methods
a. Visual colorimetry
Inject the sample and the color standard solution into 25mg colorimetric tubes respectively for visual colorimetry. The sample and the standard colorimetric solution with the same thickness of liquid layer are visually compared. The colorimetric of the sample is expressed by the number of milligrams of iodine contained in 100ml of the standard colorimetric solution with the same color and brightness as the sample. b. Photoelectric colorimetry
Put the standard colorimetric solution and the sample into 1ml of colorimetric solution respectively, and perform photoelectric colorimetry at a wavelength of 420-450μ. The colorimetric value of the sample is obtained on the standard 4
colorimetric curve. SJ2660-86
Standard colorimetric curve: Take the colorimetric 1, colorimetric 2, and colorimetric 3 standard colorimetric solutions and perform photoelectric colorimetric determination according to the above method to make a standard colorimetric curve.
3.6 Viscosity test
Measure the viscosity of the liquid flux at about 30℃ and express it as absolute viscosity. 3.7 Specific gravity test
Pour the liquid flux into a clean and dry glass cylinder for measuring specific gravity, and then put it into a constant temperature bath at 30℃. Put the hydrometer into the sample, and measure its specific gravity value when the sample temperature is about 30℃. Read the scale at the upper edge of the curved liquid surface. 3.8 Flux sputtering test
3.8.1 Sample preparation
Put three 40×40×1.5mmT copper plates into trichloroethane or acetone to remove oil, and then put them into 1% fluoroboric acid to immerse them in bright water, then take them out and rinse them with running water, and then wipe them thoroughly dry with a clean cloth. 3.8.2 Test steps
Put 0.3g solder wire or solder paste (solid flux, rosin flux, liquid flux, take 0.05g plus 0.3g solid solder) in the center of each sample, put the sample into a 315±15℃ oven or heat it with a 200W electric soldering iron to melt the solder, and keep the temperature at 285～330℃ until the solder on the copper plate no longer flows. Take out the sample and visually inspect the thickness of the edge of the melted solder and the spatter of the flux. wwW.bzxz.Net
During the inspection, the complete edge of the melted solder should be clearly visible through the flux residue. There should be no obvious spatter. If there is spatter, there are particles of flux residue outside its edge. The spatter of flux is used as a reference when selecting flux. 3.9 Extended test
3.9.1 Resin core solder wire, solder paste
3.9.1.1 Sample preparation
Use 500* sandpaper to polish the surface of 0.3×50×50mm T copper plate, remove the oxide film with hydrochloric acid (1:2), and then rinse with water. Then clean with ethanol. Let it dry in the air. Then put it in a 150±5℃ oven (the sample should be kept at the same horizontal position) for 15 minutes of oxidation treatment, take it out and put it in a tight glass bottle for use. 3.9.1.2 Test material
a. Solder ring Wrap 0.300±0.002g of resin core solder wire on a rod with a diameter of 3mm to make a solder ring, and each sample shall be tested in parallel for no less than 3 times. b. Solder paste Take about 0.300g of solder paste as the test material. 3.9.1.3 Test steps
Use a plier to bend a small corner of the test plate prepared in 3.9.1.1 upwards, place the test ring in the center of the test plate, clamp the small corner of the test plate with tweezers, and place it in a tin-lead alloy bath for heating (the liquidus temperature of the tin-lead alloy should be lower than 200°C, the bath pot diameter should be no less than 120mm, and the alloy bath height should be no less than 40mm). The temperature of the alloy bath should be controlled at 40-50°C higher than the melting temperature of the solder. The solder melts and expands within 30 seconds, cools at room temperature, removes the residue with ethanol, and measures the expansion area of the solder with transparent coordinate paper; and measures the height of the solder. A grade 1 micrometer must be used to measure the high temperature of the solder. Calculate the expansion rate as follows: Dh
=×100%
Expansion rate (%)=
SJ2660-86
Where: h is the height of the expanded solder, mm;
D---the diameter of the test solder converted into a sphere, mm; D=1.2407V/3,
Where:
Where: V-solder volume, cm\
m--mass of the obtained sample, g;
d-reported material density, g/cm.
Put the prepared solder rings in the center of the test board, and then put them horizontally in a circulating air oven at 205±5℃ for 6min±10s, then take them out to cool, and wash the residual flux with ethanol. The height h of the solder joint must be measured accurately to 0.001cm, and the average value is taken.
Determination of solder ball volume: Weigh 1.500g of sample and prepare solder according to the method for determining flux content specified in 3.2, measure the mass lost in water, and calculate the solder ball volume V according to the following formula, and the expansion rate is calculated according to the method. V=m-m2
Where: m-solder mass, g:
-mass lost by solder in water, g:
dH20-density of water, g/cm
5--ratio of 1.500g sample to 0.3g solder ring, V-solder ball volume, cm.
3.9.2 Solid flux, liquid flux, rosin flux Take about 0.05 flux and test according to the method in 3.9.1; but the solder ring should be Sn60 solid core solder wire. 3.10 Corrosion Test
3.10.1 Copper Mirror or Copper Plate Corrosion Test
3.10.1.1 Sample Preparation
The solid part of the flux is prepared according to 2.1. The liquid part of the flux is prepared according to 2.2. Preparation of Rosin Ethanol Solvent Dissolve 30g of rosin in 90ml of isopropyl alcohol (or anhydrous ethanol) to prepare it. 3.10.1.2 Preparation of Sample Plate
a. Preparation of Copper Mirror Place a photographic plate of about 1.5×50×100mm under a pressure of 6.666×10-4Pa and vacuum copper-plate it to a thickness that has a transmittance of 10±5% for 500nm normal incident light. The prepared copper mirror is stored in a sealed bottle filled with dry nitrogen or stored in a desiccator for future use. During the test, first place the copper mirror in 5% ethylenediaminetetraacetic acid or a chelating agent that can form a copper complex. After removing the oxide film, immediately take it out and rinse it thoroughly with running water, then immerse it in clean ethanol or methanol, take it out and dry it in clean oil-free air. Identify the copper film under good light, and the copper mirror with no visible oxide film and scars is qualified. b. Preparation of copper-plated plate: A steel plate of 0.5×50×150 mm is pickled according to the general pickling process, immersed in 6
SJ2660-86
hydrochloric acid (1:2) for 20s (if sulfuric acid electrolysis is performed immediately after pickling, this process can be omitted), then electrolyzed with 5% sulfuric acid for 3min, immersed in salt (1:2) for 15~20s, and then copper plated for 2.5min at a current of 110mA. The copper plating solution formula is as follows:
Copper sulfate (industrial pure)
Ammonium sulfate (industrial pure)
Sodium potassium tartrate (industrial pure)
Use 5~10% ammonia water or sulfuric acid to adjust the electroplating solution to PH=7.7. After plating, take it out and wash it thoroughly with running water. Blow dry with compressed air for use.
3.10.1.3 Test steps
On the test board of a or b in 3.10.1.2, drop 2 drops of flux, about 35mm apart, and dry for about 5 minutes at room temperature. Then put it in a constant temperature and humidity box with a temperature of 23±2℃ and a humidity of 50±5% for 24 hours, take it out and remove the flux residue with isopropyl alcohol, put it under the substrate, and observe and compare it with the sample of 30% rosin isopropyl alcohol solution (treated in the same way as the above test board).
3.10.1.4 Evaluation of corrosion results
If the copper film under the flux disappears, it is unqualified (see Figure 1). If the copper mirror changes color due to surface reaction or the thickness of the copper film changes partially, the flux is still qualified.
Solder flux qualified
3.10.2 Copper plate corrosion test
3.10.2.1 Sample preparation
a, test material
Copper mirror or copper-plated extreme corrosion test acid results
(a) 0.1g resin core solder wire or solder paste. Unqualified solder
(b) 0.1 solid solder wire, add 0.005g solid flux or rosin flux during the test. (c) 0.1g solid solder wire, add 1 drop of liquid flux during the test. 7
SJ2660-86
(a) Use 500 sandpaper to polish the surface of 0.3×30×30mmT copper plate, put it in hydrochloric acid (1:2) to remove the simplified film, rinse with water, then clean with ethanol, and place it in the air to dry thoroughly. Put about 0.1g of the sample is placed on the surface of the copper plate, and heated for about 5s at a temperature 40°~50℃ higher than the melting temperature of the solder (the maximum heating temperature of the resin core solder wire shall not exceed 270℃, and the heating temperature of the solid flux, liquid flux, and rosin flux shall be 250℃) to melt the sample, and then used as a sample after cooling at room temperature. Four samples must be prepared, three of which are used as corrosion samples, and one sample is kept in a dry state at room temperature as a control sample.
(b) Use 500* sandpaper to grind a 50×150mm single-sided copper foil phenolic glass cloth laminate, put it in hydrochloric acid (1:2) to remove the oxide film, rinse it with water, and then clean it with ethanol, place it in the air to fully dry, and use a 75w soldering iron to solder 5 solder joints. A total of four samples are prepared, three of which are used as corrosion samples, and one sample is kept in a dry state at room temperature as a control sample. 3.10.2.2 Test steps Place three corrosion samples prepared by methods (a) and (b) in 1: in a constant temperature bath at a temperature of 40±2℃ and a humidity of about 90.3%. Place them for 72 hours and then take them out and compare them with the control sample to check whether they are corroded or not. 3.10.2.3 Evaluation of corrosion results
Magnify the corrosion sample and the control sample by 20 times. If there is no obvious change, it can be considered as no corrosion. However, if one of the following phenomena occurs when comparing the sample with the control sample, it is considered as corrosion: a. The color produced by the sample during welding can not be judged as corrosion, but when it produces green-blue color under humid conditions or the color is enlarged compared with the control sample, it is considered as corrosion. b. When white spots and color shifts are produced in the flux residue or the flux is hydrated, it is considered as corrosion. 3.10.3 Thin copper wire corrosion test
Wipe a soft copper wire with a diameter of 0.3mm and a length of 150mm with a cloth soaked in ethanol, and then soak the copper wire in a liquid flux at 30±2℃ for 1min, carefully and slowly take it out of the flux, and dry it at room temperature to form a sample. Put the sample into a constant temperature and humidity chamber with a temperature of 40±2℃ and a humidity of 90%, take it out after 72h, set the gauge length (calculated length) to 100mm, and perform a tensile test at a speed of 10±5mm per minute, and compare it with the tensile strength of the soft copper wire before coating. And calculate the corrosion rate according to the following formula: Corrosion rate % = 81-82
×100%
Wherein; 8 is the tensile strength of the copper wire before coating, kg/mm\, 8 is the tensile strength of the copper wire after coating and corrosion, kg/mm2. 3.10.4 Corrosion test with applied voltage
As shown in Figure 2, on one side of a 3mm thick phenolic resin board, small grooves with an interval of 6mm are cut to allow T soft copper wires to be embedded in parallel. Then a layer of polyester film is placed on the entire board surface. The above copper wire is laid in the groove without being subjected to excessive tension. Then a layer of flux is evenly applied and dried at room temperature for 1h as a sample. The wire of each sample is connected to the cathode and anode of a DC 250±5V, and placed in a constant temperature and humidity chamber with a temperature of 40±2℃ and a humidity of about 90%. After being placed for 72 hours, the tensile strength of each sample is measured and the corrosion rate is calculated according to the following formula: Corrosion rate % = - "ming-°yang = × 100%
SJ2660-86
Where: o tensile strength of cathode sample, kg/mm\, a tensile strength of anode sample, kg/mm2. Solder
Copper wire
Vinegar film
Powdered resin board
250±5V
Figure 2 Corrosion test of applied voltage
3.10.5 Corrosion test of copper plate
3.10 .5.1 Preparation of standard flux
For standard flux containing 0.1% chlorine, weigh 30g of special grade rosin and dissolve it in 90ml of isopropanol or anhydrous ethanol, add 0.090g of diethylamine hydrochloride to dissolve and mix.
For standard flux containing 0.5% chlorine, weigh 30g of special grade rosin and dissolve it in 90ml of isopropanol or anhydrous ethanol, add 0.45g of diethylamine hydrochloride to dissolve and mix.
For standard flux containing 1.0% chlorine, weigh 30g of special grade rosin and dissolve it in 90ml of isopropanol or anhydrous ethanol, add 0.900g of diethylamine hydrochloride to dissolve and mix.
3.10.5.2 Test steps
Take 16 copper plates with a size of 0.3×50mmT, polish them with 500 sandpaper, and immerse them in 1 :2 Remove the oxide film in hydrochloric acid, rinse with water, dehydrate with ethanol, dry in a desiccator for 2h, or put in a 60±2℃ oven for 10min, and then put in a lower desiccator for 0.5h, weigh on a 1/10,000 scale (m,), divide the 16 sample plates into 4 groups and put them into the sample flux and the standard flux containing 0.1%, 0.5% and 1.0% chlorine respectively: take them out after 48h, wash and dry with ethanol, weigh on the above scale (m2), and calculate the loss per unit area of the copper plate in the flux at room temperature (g/cm\): Copper plate loss/unit area = ml = m2-g/cm*S
Where: m, the mass of the copper plate before dipping in flux, name; 9
mr the mass of the copper plate after no flux, g;|| tt||S-total area of copper plate, cm.
3.10.5.3 Evaluation
SJ2660-86
If the loss per unit area of copper plate in the sample flux is less than the loss per unit area of copper plate in the standard flux containing 0.1% chlorine, the flux is considered to be basically non-corrosive and is a first-level flux. If the loss per unit area of copper plate in the sample flux is greater than the loss per unit area of copper plate in the standard flux containing 0.1% chlorine and less than the loss per unit area of copper plate in the standard flux containing 0.5% oxygen, the flux is considered to have slight corrosion and is a second-level flux. If the loss per unit area of copper plate in the sample flux is less than the loss per unit area of copper plate in the standard flux containing 0.5% chlorine and less than the loss per unit area of copper plate in the standard flux containing 1.0% chlorine, the flux is moderately corrosive and is a third-level flux. 3.11 Test for halogen (chlorine, bromine) content
3.11.1 Direct titration method
3.11.1.1 Resin core solder wire
a. Reagents and instruments
Methanol (analytical grade)
Ether or benzene (analytical grade)
Nitrobenzene (analytical grade)
Nitric acid: (d=1.42) (analytical grade)
Potassium chromate, 2% aqueous solution (analytical grade)
Iron ammonium sulfate solution: Weigh 6g analytical grade ammonium ferric sulfate and dissolve it in 100ml 6N nitric acid (boil to remove nitrous acid) and mix well. Silver nitrate: 0.02N standard solution, accurately weigh 3.398g analytical grade silver nitrate in a 11 volumetric flask, dissolve it in water and dilute to the scale and shake well.
Calibration: Weigh 1.65g of high-grade pure sodium nitride correctly, dissolve it in water in a 11-volume flask and dilute it to the mark, shake well (1ml=0.001g chlorine), take 10ml of this solution in a 250ml conical flask, use potassium chromate solution as an indicator, and titrate with 0.02N silver nitrate solution until it turns pale yellow-red as the end point.
Calculate the coefficient C according to the following formula,
Where: c-the amount of chlorine equivalent to 1ml silver nitrate solution, g/ml0.01-the amount of standard chlorine, more,
V-the volume of silver nitrate consumed in titration, ml.
Potassium thiocyanate: 0.02N solution, accurately weigh 1.942g of analytical pure potassium thiocyanate in a 11-volume flask, dissolve it in water and dilute it to the mark.
Calibration: Accurately pipette 25ml silver nitrate solution into a 250ml conical flask, add 50ml water, 5ml nitric acid, shake the hook, add 1ml iron ammonium alum solution indicator, and titrate with 0.02N potassium thiocyanate solution until the end point is light yellow-red. Calculate the conversion factor K according to the following formula.
Where:
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K--1ml potassium thiocyanate solution is equivalent to the number of liters of silver nitrate, ml25-the number of milliliters of 0.02N silver nitrate, ml, V--the number of milliliters of potassium murate consumed, ml.
Condenser
Separatory funnel
b, Test steps
Wash the surface of the solder wire with ethanol, then wash it with nitrogen-free distilled water, and then wash it with ethanol and dry it. Cut into 2~3mm lengths, weigh about 2g of clean solder wire equivalent to flux into a flask, add 50ml of methanol and install a condenser, dissolve for 15min, until the flux is completely dissolved, pour the clear liquid into a 150ml beaker, and use 10ml of methanol to wash the residual flux and combine the solutions. Heat and evaporate this solution to about 10ml, pour it into a separatory funnel, wash the beaker with 5ml of methanol, and then wash it with 25ml of ether or benzene, and combine the washing liquid into the separatory funnel. Extract the mixed solution twice with 50ml of distilled water, and place the extract into a 250ml conical flask. Use a pipette to draw 25ml of 0.02N silver nitrate and inject it, then add 25ml of nitric acid and 5ml of nitrobenzene and mix thoroughly to form a silver fluoride precipitate, add 1ml of ferric ammonium alum indicator and use 0.0.02N potassium sulfate solution is titrated until the yellowish red color does not disappear. The empty door test is carried out according to the above operation.
Flux mass determination: Place the above solder wire that has been desoldered and washed in a 100℃ oven and dry for 1 hour, then cool and weigh. The difference in mass before and after the flux is dissolved is the flux mass. Calculate the chlorine content of the flux according to the following formula:
C1% =C×(V/-KV)×100%
Where: C1m0.02N silver nitrate solution equivalent to chlorine content, g/ml, V1-the number of milliliters of 0.02N silver nitrate solution, ml, V,-the number of milliliters of 0.02N potassium thiocyanate solution consumed, ml, K-the conversion coefficient of potassium thiocyanate to silver nitrate. m flux mass, g.
3.11.1.2 Solder paste, solid flux, liquid flux Pour 2g of solid flux into a 100ml beaker, and add 10ml of industrial methanol to dissolve the flux. Use this as the test solution and proceed according to the method specified in 3.11.1.1b. 3.11.2 Absorptiometry
3.11.2.1 Resin core solder wire
a. Reagents and instruments
Mercuric thiocyanate solution: Weigh 0.3g of analytically pure thiocyanate and dissolve it in 100ml of nitrogen-free anhydrous ethanol and mix. Ammonium ferric sulfate solution: Weigh 6g of analytically pure ammonium ferric sulfate and dissolve it in 100ml of 6N nitric acid (boiled to remove nitrous acid) and mix. Ethanol-benzene mixture: Mix 7 parts of ethanol (analytical pure) with 3 parts of benzene (analytical pure). Standard solution of chlorine: weigh 1.65g of high-grade pure sodium chloride and dissolve it in water, dilute it to 1000ml, take out 10ml of solution, add nitrogen-free ethanol-benzene mixture to make it reach 1000ml (1ml is equivalent to 0.01mg chlorine). 72 type spectrophotometer
b. Test steps
Use ethanol to clean the surface of the resin solder wire, wash it with nitrogen-free distilled water, and then rinse it with ethanol. Then cut the clean solder wire into 2~3mm lengths, weigh 3.000~5.000g (m) and put it into a 100ml beaker, and pour 30ml of ethanol-benzene mixture, stir it at room temperature for 15min to make the flux solution. Pour the solution into a 100ml volumetric flask, rinse the solder wire with ethanol-benzene mixture 3-4 times, add the rinse solution into the volumetric flask, dilute to the mark with ethanol-benzene mixture, and use this as the test solution. Dry the solder wire that has been dissolved and cleaned of flux at 100℃ for 1h, and weigh it accurately (m2). The mass difference (m, ~m2) before and after the solder wire treatment is the mass of the flux. Pipette 10ml of the above flux solution into a colorimetric tube, accurately add 1ml of mercuric thiocyanate and 2ml of ammonium ferric alum solution, cover the stopper and shake the mixing spoon, use the one that develops color in 10min as the standard, add 10ml of ethanol-benzene mixture and mix well, then select a colorimetric colorimetric with a wavelength of 460n, 1cm, and use rosin with equivalent content as the blank solution for photoelectric colorimetry. The chlorine content of the sample is obtained by checking the standard auxiliary line. Calculate as follows:
C1%=-_mc1.
×100%
Where: mc1-free nitrogen content in flux, gsm1-weighed solder wire mass, g;
m2-weight of solder wire after treatment, g.
Drawing of standard curve:
Weigh rosin equivalent to the flux in the sample (about 0.1g) and dissolve it in ethanol-benzene mixed solution, and dilute it to 100ml with the mixed solution. Take 10ml of the above solution, add six portions of 0, 1, 2, 3, 5, 7ml chlorine standard solution respectively, and then add 10, 9, 8, 7, 53ml ethanol-benzene mixed solution respectively, perform colorimetry according to the sample operation steps, and draw a standard curve. 3.11.2.2 Solder paste, solid flux and liquid flux Put the flux equivalent to 0.1g of the solid part into a 100ml beaker, add ethanol-benzene mixture (ethanol:benzene = 7:3) to dissolve the flux, transfer it to a 100ml volumetric flask and dilute it to 100ml with the mixture (and dissolve the flux completely), which is the test solution, and then test it according to the method in 3.11.2.1. 3.11.3 Potentiometric titration method
3.11.3.1 Resin core solder wire
a. Reagents and instruments
Ethanol-benzene mixture, anhydrous ethanol (analytical grade): benzene (analytical grade) = 10:1. 0.02N sodium chloride standard solution: weigh 1.169g of standard sodium chloride (pre-dried at 550℃ for 2h), dissolve it in 10ml of distilled water, transfer it to a 11 volumetric flask, dilute it to the scale with water, and shake it. 0.02N potassium bromide solution: weigh 2.38g (analytical grade) potassium bromide and prepare it with sodium nitride standard solution. 0.05N silver nitrate solution: prepare according to 3.11.1.1 (accurately weigh 8.494g silver nitrate), calibrate according to 3.11.1.1.4. Potentiometric titrator
a silver electrodeReagents and instruments
Ethanol-benzene mixture, anhydrous ethanol (analytical grade): benzene (analytical grade) = 10:1. 0.02N sodium chloride standard solution: weigh 1.169g of standard sodium nitride (pre-dried at 550℃ for 2h), dissolve it with 10ml of distilled water, transfer it to a 11 volumetric flask, dilute it with water to the scale, and shake it. 0.02N potassium bromide solution: weigh 2.38g (analytical grade) potassium bromide and prepare it with sodium nitride standard solution. 0.05N silver nitrate solution: prepare according to 3.11.1.1 (accurately weigh 8.494g silver nitrate), and calibrate according to 3.11.1.1.4. Potentiometric titrator
One silver electrodeReagents and instruments
Ethanol-benzene mixture, anhydrous ethanol (analytical grade): benzene (analytical grade) = 10:1. 0.02N sodium chloride standard solution: weigh 1.169g of standard sodium nitride (pre-dried at 550℃ for 2h), dissolve it with 10ml of distilled water, transfer it to a 11 volumetric flask, dilute it with water to the scale, and shake it. 0.02N potassium bromide solution: weigh 2.38g (analytical grade) potassium bromide and prepare it with sodium nitride standard solution. 0.05N silver nitrate solution: prepare according to 3.11.1.1 (accurately weigh 8.494g silver nitrate), and calibrate according to 3.11.1.1.4. Potentiometric titrator
One silver electrode
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