The tests s own in this stan ard are group d ac ordin to the fol owin prin iples: P: pre aration/con itionin method V: vis al test method D: dimen ional test method C: c emical test meth
General
Measurement processes always involve errors and uncertainties The information provided below allows for accurate estimates of these errors and uncertainties Test data fulfill various purposes, including
– enhancing of confidence in quality conformance;
– arbitration between customer and supplier
In any of these circumstances, it is essential that confidence can be placed upon the test data in terms of
– accuracy: calibration of the test instruments and/or system;
– precision: the repeatability and uncertainty of the measurement;
– resolution: the suitability of the test instrument and/or system.
Accuracy
The quality documentation of the testing supplier or agency must clearly outline the routine calibration procedures for test equipment, ensuring compliance with ISO 9001 standards.
Calibration must be performed by an accredited agency recognized by a national or international measurement standard institute, ensuring a continuous chain of calibration to uphold national or international standards.
Where calibration to a national or international standard is not possible, round-robin techniques may be used and documented to enhance confidence in measurement accuracy
The standard calibration interval is typically one year However, if equipment frequently falls outside acceptable accuracy limits, the calibration intervals will be shortened Conversely, equipment that consistently meets accuracy standards may qualify for extended calibration intervals.
Each instrument must have a comprehensive record of its calibration and maintenance history These records should include the uncertainty of the calibration technique expressed as a ± % deviation, allowing for the aggregation and determination of measurement uncertainties.
A procedure shall be implemented to resolve any situation where an instrument is found to be outside calibration limits.
Precision
The uncertainty budget of any measurement technique is made up of both systematic and random uncertainties All estimates shall be based upon a single confidence level, the minimum being 95 %
Systematic uncertainties are usually the predominant contributor and will include all uncertainties not subject to random fluctuation These include
– errors due to the use of an instrument under conditions which differ from those under which it was calibrated;
– errors in the graduation of a scale of an analogue meter (scale shape error)
Random uncertainties result from numerous sources but can be deduced from repeated measurement of a standard item Therefore, it is not necessary to isolate the individual contributions These may include
– random fluctuations such as those due to the variation of an influence parameter Typically, changes in atmospheric conditions reduce the repeatability of a measurement;
– uncertainty in discrimination, such as setting a pointer to a fiducial mark or interpolating between graduations on an analogue scale
The aggregation of uncertainties can typically be achieved through geometric addition, specifically using the root-sum-square method Additionally, interpolation error is usually considered separately and is often accepted as 20% of the difference between the instrument's finest graduations.
Random uncertainties can be assessed through repeated measurements of a parameter, followed by statistical analysis of the collected data This method relies on the assumption that the data follows a normal (Gaussian) distribution.
U r is the random uncertainty; n is the sample size; t is the percentage point of the t distribution as shown in Table 1 ; σ is the standard deviation (σ n –1).
Resolution 1 0
It is paramount that the test equipment used is capable of sufficient resolution Measurement systems used should be capable of resolving 1 0 % (or better) of the test limit tolerance
It is accepted that some technologies will place a physical limitation upon resolution (for example, optical resolution).
Report 1 0
The report must include essential details beyond the test specification, such as the test method employed, the identity of the sample(s), and the test instrumentation used It should also specify the limits set for the test, provide an estimate of measurement uncertainty along with the working limits, and present the detailed test results Additionally, the report must indicate the test date and include the operators' signatures.
Student’s t distribution 1 0
Table 1 gives values of the factor t for 95 % and 99 % confidence levels, as a function of the number of measurements
Suggested uncertainty limits 1 1
The following target uncertainties are suggested: a) Voltage < 1 kV: ± 1 ,5 % b) Voltage > 1 kV: ± 2,5 % c) Current < 20 A: ± 1 ,5 % d) Current > 20 A: ± 2,5 %
Resistance e) Earth and continuity: ± 1 0 % f) Insulation: ± 1 0 % g) Frequency: ± 0,2 %
Time h) Interval < 60 s: ± 1 s i) Interval > 60 s: ± 2 % j) Mass < 1 0 g: ± 0,5 % k) Mass 1 0 g – 1 00 g: ± 1 % l) Mass > 1 00 g: ± 2 % m) Force: ± 2 % n) Dimension < 25 mm: ± 0,5 % o) Dimension > 25 mm: ± 0,1 mm p) Temperature < 1 00 °C: ± 1 ,5 % q) Temperature > 1 00 °C: ± 3,5 % r) Humidity 30 % to 75 % RH: ± 5 % RH
Plating thicknesses s) Backscatter method: ± 1 0 % t) Microsection: ± 2 àm u) Ionic contamination: ± 1 0 %
Test 5-2C01 : Corrosion, flux 1 2
This test method evaluates the corrosive properties of flux residues in extreme environmental conditions A solder pellet is melted with the test flux on a sheet metal piece, followed by exposure to specific humidity levels The resulting corrosion is then assessed visually.
To ensure proper soldering, a minimum of 0.035 g of flux solids, along with 1 g of solder paste, wire, or preform containing an equivalent amount of solids, is required Flux solids refer to the residue from the solid content as outlined in section 4.1 of the flux test It is essential that all solvents are completely evaporated from the specimen in a chemical fume hood prior to use.
To conduct the experiment, the following equipment and materials are required: a solder pot, a humidity chamber that can maintain a temperature of (40 ± 1) °C and a relative humidity of (93 ± 2) %, an air-circulating drying oven, and a microscope with a minimum magnification of 20× All chemicals must be reagent grade and free from contamination, including ammonium persulphate, sulphuric acid (v/v), a degreasing agent such as acetone or petroleum ether, and distilled or deionized water Additionally, an analytical balance with a precision of 0.001 g and a copper sheet measuring (0.50 ± 0.05) mm in thickness and 99% purity are necessary for the procedure.
4.1 4.1 Chemicals a) Ammonium persulphate (25 % m/v in 0,5 % v/v sulphuric acid) Dissolve 250 g of ammonium persulphate in water and add cautiously 5 ml of sulphuric acid (density
To prepare a 5% v/v sulfuric acid solution, cautiously add 50 ml of sulfuric acid (density 1.84 g/cm³) to 400 ml of water After mixing, allow the solution to cool, then dilute it to a total volume of 1 liter and mix thoroughly It is important to prepare this solution fresh for optimal results.
To prepare the test panels, cut 50 mm × 50 mm squares from a copper sheet Create a 3 mm deep circular depression in the center of each panel by pressing a 20 mm diameter steel ball into a 25 mm diameter hole Finally, bend one corner of each panel upwards to allow for easier handling with tongs.
Before conducting the test, ensure proper preconditioning by using clean tongs First, degrease the sample with a suitable neutral organic solvent like acetone or petroleum ether Next, immerse the sample in a 5% sulfuric acid solution at a temperature of (65 ± 5) °C for 1 minute to eliminate any tarnish film Finally, immerse the sample in a solution of 25% m/v ammonium persulfate with 0.5% v/v sulfuric acid.
To achieve a uniform etching of the surface, maintain a temperature of (23 ± 2) °C for 1 minute Subsequently, wash the surface in running tap water for a maximum of 5 seconds Next, immerse the surface in a 5% sulfuric acid solution at the same temperature for 1 minute, followed by another 5-second wash in running tap water and a thorough rinse in deionized water After rinsing with acetone, allow the surface to dry in clean air It is recommended to use the test piece promptly or store it in a closed container for up to 1 hour.
To prepare the test solder, weigh a specimen of solder between 0.95 g and 1.05 g for each test and position it at the center of the depression on each test panel Next, degrease the solder specimen using an appropriate neutral organic solvent, such as acetone or petroleum ether The solder can be utilized in the form of pellets or by tightly coiling solder wire into spirals.
To conduct the solder testing, heat the solder pot to stabilize at (235 ± 5) °C for Sn63Pb37 and Sn60Pb40 alloys, or at (255 ± 3) °C for Sn96.5Ag3Cu0.5, or 35 ± 3 °C above the liquidus temperature for other alloys as agreed upon For alloys other than Sn63Pb37 and Sn60Pb40, the solder pot temperature may be approximately 40 °C higher than the liquid temperature Next, place 0.035 g of liquid flux solids into the test panel's depression, followed by the solder sample For solder paste, cored wire, or cored preform, use 1 g in the same manner Using tongs, lower the test panel onto the molten solder and maintain contact until the solder melts, approximately (5 ± 1) seconds Afterward, examine the test panel at 20× magnification for discoloration and other observations Preheat the test panel to (40 ± 1) °C for (30 ± 2) minutes, then set the humidity chamber to (40 ± 1) °C and (93 ± 2) % relative humidity Suspend each test panel vertically in the chamber and expose them for 72 hours Both moderately active and highly active fluxes may be tested in cleaned and uncleaned conditions.
Carefully examine test panels prior to placing them in the environmental chamber Note any discoloration
After the appropriate exposure period, remove test panels from humidity chamber, examine at
20× magnification and compare with observations noted prior to exposure
Corrosion is described as follows
– Excrescences at the interfaces of the flux residue and copper boundary or the residues or discontinuities in the residues
– Discrete white or coloured spots in the flux residues
When soldering, an initial color change of the test panel is typically overlooked; however, the later appearance of green-blue discoloration accompanied by pitting on the copper panel is considered a sign of corrosion.
Corrosion is defined as the chemical reaction that occurs between copper, solder, and the components of flux residues after soldering, particularly when exposed to specific environmental conditions.
Colour photos before and after the test are valuable tools in identifying corrosion
Observe all appropriate precautions on material safety data sheets (MSDS) for chemicals involved in this test method.
Test 5-2C02: Determination of acid value of liquid soldering flux
Object 1 4
This test method specifies two methods for the determination of the acid value of a flux of types L, M or H
Method A is a potentiometric titration method and is to be considered as the reference method Method B is an alternative, visual end-point, titration method
Test specimen 1 4
A minimum of 2,0 g of liquid flux, 1 0 g of solder paste, 1 50 g of cored wire or 1 0 g of solder preforms.
Apparatus and reagents 1 4
4.2.3.1 General a) Use only reagents of recognized analytical quality and only distilled or deionized water b) Ordinary laboratory apparatus c) The term “M” represents molarity of a solution and is calculated by taking the moles of solute and dividing by the litres of solution, e.g 1 ,00 mole of sucrose (about 342,3 g) mixed into a litre of water equals 1 ,00 M (1 ,00 mol/l)
4.2.3.2 Potentiometric titration method (Method A) a) Tetrabutyl ammonium hydroxide 0,1 M (0,1 mol/l) Use a commercially available standard solution or one prepared from a commercially available concentrated standard solution by dilution with propan-2-ol Standardize this solution against an accurately weighed amount of benzoic acid (about 0,5 g) dissolved in dimethylformamide, previously neutralized to thymol blue b) Propan-2-ol: neutralized with tetrabutyl ammonium hydroxide solution to a faint pink colour using phenolphthalein as an indicator c) Ethanol 96% by volume: neutralized with tetrabutyl ammonium hydroxide solution to a faint pink colour using phenolphthalein as an indicator d) Toluene: neutralized with tetrabutyl ammonium hydroxide solution to a faint pink colour using phenolphthalein as an indicator e) Ethanol/toluene mixture: mix equal volumes of the ethanol 96 % by volume and toluene f) Millivoltmeter or pH meter g) Glass electrode h) Saturated calomel, or silver chloride/silver, electrode i) Magnetic or mechanical stirrer with variable speed drive
4.2.3.3 Titration with visual end-point (Method B) a) Ethanol 96 % by volume: neutralized with potassium hydroxide, 0,1 M in alcohol, to a faint pink colour using phenolphthalein as an indicator b) Toluene: neutralized with potassium hydroxide, 0,1 M in alcohol, to a faint pink colour using phenolphthalein as an indicator c) Ethanol/toluene mixture: mix equal volumes of the ethanol 96 % by volume and toluene d) Propan-2-ol: neutralized with potassium hydroxide, 0,1 M in alcohol, to a faint pink colour using phenolphthalein as an indicator e) Potassium hydroxide solution: 0,1 M in alcohol Use a commercially available standard solution or one prepared from a commercially available concentrated standard solution by dilution with ethanol Standardize this solution against an accurately weighed amount of benzoic acid (about 0,5 g) dissolved in ethanol f) Phenolphthalein indicator solution: Add 1 g of phenolphthalein to approximately 50 ml methanol and mix When dissolved, dilute to 1 00 ml with methanol and mix.
Procedures 1 5
4.2.4.1 Potentiometric titration (Method A) a) By preliminary experiments, determine whether the specimen is soluble in propan-2-ol, ethanol 96 % by volume, toluene or the ethanol/toluene mixture If it is not completely soluble in any of these solvents, select the one in which it appears to be the most soluble
To analyze the flux specimen, use propan-2-ol if it is equally soluble in all four solvents Weigh 2.0 g to 5.0 g of the liquid flux specimen, ensuring minimal loss of volatile matter, and transfer it to a 250 ml low form beaker Dilute the specimen to 100 ml with propan-2-ol or the chosen solvent, then cover with a watch glass and gently agitate to dissolve the flux Position the beaker in the titration assembly with the electrodes, stirrer, and burette, adjusting the stirrer for vigorous mixing without splashing Titrate with tetrabutyl ammonium hydroxide solution, adding 1 ml portions while recording pH or mV readings after each addition As the endpoint nears, decrease the titrant additions to 0.1 ml and continue past the endpoint Finally, plot the pH or potential values against the volume of titrant to create the titration curve, identifying the endpoint at the curve's point of inflection Additionally, perform a blank determination with all reagents for comparison.
4.2.4.2 Visual titration (Method B) a) By preliminary experiments, determine whether the specimen is soluble in propan-2-ol, ethanol 96 % by volume, toluene or the ethanol/toluene mixture If it is not completely soluble in any of these solvents, select the one in which it appears to be the most soluble
When selecting a solvent, choose ethanol if it is equally soluble in all four options Conduct the procedure in triplicate on the flux specimen, weighing approximately 1 g of non-volatile matter to the nearest 0.001 g, while ensuring that liquid flux specimens do not lose volatile matter during weighing Transfer the weighed specimen to a suitable flask or beaker, add 100 ml of the selected solvent, and stir until the specimen is fully dissolved without applying heat Then, introduce 3 drops of phenolphthalein indicator and titrate with potassium hydroxide until a faint pink color remains for 15 seconds Additionally, perform a blank determination with all reagents for comparison.
4.2.4.3 Calculation of results a) The acid value is expressed in milligrams of potassium hydroxide per gram of non-volatile matter, regardless of the alkali used to perform the titration b) The acid value (expressed in milligrams of potassium hydroxide per gram of non-volatile matter) is given by: mS
V is the volume, in ml, of alkali used (tetrabutyl ammonium hydroxide for method A, potassium hydroxide for method B);
M is the molarity of the alkali used; m is the mass, in grams of the specimen taken;
S is the percentage non-volatile matter determined as described in test method 6C03 of this standard
The acid value (expressed in milligrams of potassium hydroxide per gram of flux) is given by: m
The acid value of the flux under test is calculated as the mean of the results obtained on each of the three test specimens.
Additional information 1 6
Operators must be trained and knowledgeable about the hazards associated with the chemicals they are using and analyzing It is essential to utilize appropriate personal protective equipment, including safety glasses, gloves, and splash aprons, along with ensuring adequate ventilation in the workspace.
Test 5-2C03: Acid number of rosin 1 6
Test 5-2C04: Determination of halides in fluxes, silver chromate method 1 6
Object 1 6
This test method is designed to determine the presence of chlorides and bromides in soldering flux by visual examination after placement of the flux on test paper.
Test specimen 1 7
The test specimen must include at least 100 ml of liquid flux, along with a representative container of solder paste, paste flux for reflow soldering, extracted solder preform flux, or extracted flux-cored wire.
Apparatus and reagents 1 7
a) Six pieces of silver chromate test paper 51 mm × 51 mm b) 0,25 l of reagent grade (highly pure, without contamination) propan-2-ol.
Procedure 1 7
4.4.4.1 Preparation a) The silver chromate paper is extremely light sensitive and shall be stored in a closed container away from light until used for testing b) To avoid contamination, the paper shall be handled with forceps and shall never be touched with bare hands
4.4.4.2 Test for liquid flux or flux extract solution a) Place one drop of test flux or flux extract (approximately 0,05 ml) on each piece of silver chromate test paper Allow the droplet to remain on each test paper for a minimum of 1 5 s b) After the 1 5 s, immediately immerse each test paper in clean propan-2-ol to remove the residual organic materials c) Allow each test paper to dry for 1 0 min, then examine for colour change
4.4.4.3 Test for paste flux or solder paste flux as obtained from the supplier a) Clean a glass microscope slide with propan-2-ol and air dry b) Moisten a piece of silver chromate reagent paper of suitable size with deionized water c) Apply the wet paper to the glass slide and remove the excess water with blotting paper d) Using a spatula, apply a thin coating of the paste flux or solder paste flux directly to the moist reagent paper e) Allow the paste flux or solder paste flux to remain in contact with the paper for 1 min, then remove the flux with propan-2-ol without disturbing the paper.
Evaluation 1 7
Carefully examine each test sheet for possible colour change A change to off-white or yellow- white indicates the presence of chlorides or bromides (see Figure 1 )
Interferences in testing can arise from various chemicals, including amines, cyanides, and isocyanates, which may lead to test failures Additionally, certain acidic solutions can react with reagent paper, causing a color change that mimics the presence of chlorides and bromides When such a color change is noted, it is essential to assess the acidity of the area using pH indicating paper If the pH is found to be below 3, further verification of chlorides and bromides should be conducted using alternative analytical methods.
Additional information 1 7
Safety: Observe all appropriate precautions on the material safety data sheets (MSDS) for chemicals involved in this test method
Source for silver chromate test paper:
Quantek, PO Box 1 36, Lyndhurst, NJ 07071 , (201 ) 935-41 03
FAIL Figure 1 – Chlorides and/or bromides test results
Test 5-2C05: Solids content, flux 1 8
Object 1 8
This test method is designed to determine the residual solids content of the liquid flux after evaporation of the volatile chemicals from the liquid flux; typically 1 5 % by weight minimum.
Test specimen 1 8
The test specimen shall consist of a minimum of 6 g per test of liquid flux or flux extracted from solder paste, solder preforms or flux-cored wire.
Apparatus and reagents 1 8
a) a circulating air drying oven capable of maintaining a temperature of (1 1 0 ± 5) °C; b) analytical balance capable of weighing 0,000 1 g; c) glass pipettes; d) glass petri dishes, 30 ml capacity; e) silica gel desiccant, or equivalent, in a glass desiccator
Procedures 1 9
Carry out the following procedures in triplicate
4.5.4.2 Preparation a) Dry three empty glass petri dishes in the drying oven, then cool in the desiccator to room temperature b) Weigh each dish to the nearest 0,001 g
4.5.4.3 Test a) Pipette approximately 6 g of test flux specimen into each petri dish and weigh to the nearest 0,001 g b) Heat in the drying oven for 1 h, then re-weigh after allowing the specimen to come to room temperature c) Repeat heating and drying procedure until the weight is constant to within 0,005 g.
Evaluation 1 9
Calculate the residual solids as follows:
C s are the residual solids; m 2 is the mass of residual after drying, in g; m 1 is the mass of original test flux specimen, in g.
Additional information 1 9
Larger specimen sizes may be required to obtain accurate data on low solids (