1、STD-BSI BS EN IS0 9455-b-ENGL 1997 lb2VbbS b05582 bll m BRITISH STANDARD Soft soldering fluxes - Test methods Part 6. Determination and d.etection of halide (excluding fluoride) content The European Standard EN IS0 94556 : 1997 has the status of a British Standard ICs 25.160.50 BS EN IS0 9455-6 : 19
2、97 TED BY COPYRIGHT LAW - STD-BSI BS EN IS0 9455-b-ENGL 1997 1b24bbS Ob05583 558 W Amd. No. BS EN IS0 9455-6 : 1997 Date Text affected - This British Standard, having been prepared under the direction of the Engineering Sector Board, was published under the authority of the Standards Board and comes
3、 int effect on 15 April 1997 O BSI 1997 ISBN O 580 26522 6 National foreword This British Standard is the En- language version of EN IS0 94556 : 1997. It is identical with IS0 9455-6 : 1995. It partially supersedes BS 5625 : 1986 which will be withdrawn following publication of other European standa
4、rds in this series. The UK participation in its preparation was entrusted by Technid Committee NM7, lin and tin alloys, to Subcommittee NM7/4, Solders and soldering flurpes, .$ which has the responsibility to: - aid enquirers to understand the text; - present to the responsible internationaUEuropean
5、 committee any enquiries on the interpretation, or proposals for change, and keep the UK interests informed; - monitor related international and European developments and promulgate them in the UK. A list of 0rg;uiizatiOns represented on this committee can be obtained on request. Cross-references At
6、tention is drawn to the fact that annex ZA lists normative references to international publications with their corresponding European publications. The British Standards which implement these international or European publications may be found in the BSI Stankc method. Method C is a titration method
7、 for the determination of the halide (excluding fluoride) content of water- soluble fluxes containing phosphates and is applica- ble to flux class 3.2.1 .A, as defined in IS0 9454-1. Method D is a qualitative test, using silver chromate test paper, for the presence of ionic halides. The technique ma
8、y be used for all classes of flux. 3 Method A: Potentiometric method (Reference method) 3.1 Principle 2 Normative references The following standards contain provisions which, through reference in this text, constitute provisions A prepared, weighed sample of the flux is dissolved in a suitable solve
9、nt. The resulting solution is titrated with standard silver nitrate solution, using a silver electrode, the mV readings being recorded simul- 1 STD.BS1 BS EN IS0 9455-b-ENGL 1997 1b29bbS Ob05590 798 BS EN IS0 9466-6 : 1997 taneously. From the graph of volume of titrant readings against mV readings,
10、the point of inflexion is determined and the percentage halide content, ex- pressed as chloride, is calculated. The method is not suitable for the determination of fluoride. This method is applicable to flux classes 1 and 2, as defined in IS0 9454-1. 3.2 Reagents 3.2.1 General Only reagents of recog
11、nized analytical quality and distilled or deionized water with a conductivity less than 10 pS/cm are to be used. 3.2.2 Propan-2-01. 3.2.3 Silver nitrate solution (0.02 mol/). 3,4 g of silver nitrate (ASNO,) are dissolved in water (see note 1) then transferred to a 1 litre volumetric flask and dilute
12、d to the mark with water. It is mixed thoroughly. Alternatively a commercially available concentrate is used to prepare 0,02 mol/ standard silver nitrate sol- ution. The silver nitrate solution is standardized using the method given in annex A, to derive the correlation factorf,. This is stored in a
13、n amber glass bottle. NOTES 1 The silver nitrate (ASNO,) should be dried at 110 “C I 5 C for 16 h and cooled in a desiccator before weighing. 2 1 ml of silver nitrate solution (3.2.3) is equivalent to 0,000 709 xfi g of chloride ion. 3.3 Apparatus Ordinary laboratory apparatus and 3.3.1 Millivott me
14、ter. 3.3.2 Silver electrode. 3.3.3 Mercury/mercurous sulfate 1 mol/l so- dium sulfate electrode, or a reversible hydrogen electrode. 3.3.4 Magnetic or mechanical stirrer, with variable speed drive, the stirrer bar to be PTFE-coated. 3.4 Procedure Carry out the following procedure, in triplicate, on
15、the flux sample. Weigh, to the nearest 0,001 g, approximately 0.5 g of the solid flux sample or 2 g of the liquid flux sam- ple, avoiding loss of volatile matter during the weigh- ing, and transfer it to a 250 ml low-form beaker. NOTE 3 This procedure is suitable for halide ion concen- trations gene
16、rally within the range 0.1 % (m/m) to 1 % (m/m) in the non-volatile content of the solution to be titrated. For flux samples having halide ion concentrations outside this range, the sample mass taken should be ad- justed, as follows: a) for flux samples having a halide ion concentration in the range
17、 0,05 K (m/m) to 0.1 % (m/m), the mass of sample taken should be double; and b) for flux samples having a halide ion concentration in the range 1 % (m/m) to 2 % (m/m), the mass of sample taken should be halved. Add 100 mi of propan-2-01 (32.2). or water, according to the solubility characteristics o
18、f the flux (see note 4). Cover with a watch glass and allow to dis- solve with gentle agitation. NOTE 4 For fluxes of class 1.2, as defined in IS0 9454-1 the choice of solvent should be agreed between the flux manufacturer and the user. Place the beaker on the stand of the titration as- sembly with
19、the electrodes, stirrer and burette in position. Adjust the speed of the stirrer to give vigor- ous stirring without splashing. Titrate with the silver nitrate solution (3.2.31, adding 1 ml portions and re- cording the mV meter readings after each addition. As the end-point is approached, reduce the
20、 additions of titrant to 0.1 ml and continue titrating past the end-point. Plot the potential values against the volume of titrant added to obtain the titration curve. The point of in- flexion of the curve corresponds to the end-point of the titration. NOTE 5 veniently be determined by using the der
21、ivative curve. The point of inflexion of the curve may con- Carry out a blank determination, using all reagents, for comparison purposes. 2 BS EN IS0 9465-6 : 1997 3.5 Calculation of results The halide (excluding fluoride) content, expressed as the percentage, by mass, of chloride in the flux, is gi
22、ven by: The test is applicable to fluxes of classes 2.1.2.A and 3.1 .I .A only, as defined in IS0 9454-1. Some liquid fluxes Contain free hydrochloric acid and the halide content will, consequently, be greater than the amount equivalent to the zinc and other chlorides present. 0,070 9 x V mft where
23、V is the volume, in millilitres, of silver nitrate solution used, less the volume needed to titrate the blank; fi is the correlation factor for the silver nitrate solution (see 3.2.3); is the mass, in grams, of the sample taken The halide content of the flux sample is given by the mean of the three
24、results obtained on the triplicate test samples. The halide content may also be expressed as the percentage, by mass, of chloride in the non-volatile matter by: 7,09 x V mS m fi where S is the percentage non-volatile matter con- tent of the sample, determined as de- scribed in IS0 94551 or IS0 9455-
25、2. For solid flux samples, S = 100. 4 Method 6: Titration method for halide (excluding fluoride) content of water- soluble fluxes 4.1 Principle A prepared sample of the flux is diluted to a known volume with water and a specified volume of sulfuric acid of known concentration. The solution is then t
26、reated with a known quantity of silver nitrate solution and the excess silver nitrate is titrated with am- monium thiocyanate. A blank determination using water in place of the flux is carried out simultaneously and the percentage halide content, expressed as chloride, is calculated. The method is n
27、ot suitable for the determination of fluoride. 4.2 Reagents 4.2.1 General Only reagents of recognized analytical quality and distilled or deionized water with a conductivity less than 10 pS/cm are to be used. 4.2.2 Silver nitrate solution (0.1 mol/l). 16,99 g of silver nitrate (ASNO,) are dissolved
28、in water (see note 1) then transferred to a 1 litre volu- metric flask and diluted to the mark with water. This is mixed thoroughly. Alternatively, a commercially available concentrate is used to prepare 0,l mol/l standard silver nitrate sol- ution. The silver nitrate solution is standardized using
29、the method given in annex A, to derive the correlation factorf,. This is stored in an amber glass bottle. NOTES 6 The silver nitrate (ASNO,) should be dried at 11 O “C I 5 “C for 16 h and cooled in a desiccator before weighing. 7 1 ml of silver nitrate solution (4.2.2) is equivalent to 0,003 545 xfi
30、 grams of chloride ion. 4.2.3 Ammonium thiocyanate solution (approxi- mately O, 1 mol/l). 8 g of ammonium thiocyanate (NH,CNS) are dissolved in water then transferred to a 1 litre volumetric flask and diluted to the mark with water. This is mixed thoroughly. Alternatively, a commercially available c
31、oncentrate is used to prepare 0.1 mol/l standard ammonium thio- cyanate solution. 4.2.4 Sulfuric acid solution 20 % (V/V). 200 ml of sulfuric acid (density 1,84 glrnl) is cautiously added, with stirring, to 400 ml of water. It is then mixed, cooled, diluted to 1 litre and mixed thoroughly. 3 STD-BSI
32、 BS EN IS0 7455-b-ENGL 1997 W Lb24bb7 Ob05592 SbD W BS EN IS0 9455-6 : 1997 4.2.5 Ammonium fen% sulfate indicator solution. 1 O g of ammonium ferric sulfate NH4Fe(S04),.12H,0 are dissolved in 1 O0 ml water. 4.2.6 Nitrobenzene WARNING - Care should be exercised in the handling and disposal of this ha
33、zardous reagent. 4.2.7 Nitric add (density 1.42 g/ml). 4.3 Apparatus Ordinary laboratory apparatus. 4.4 Procedure Carry out the following procedure, in triplicate, on the flux sample. By means of a pipette, transfer 25 ml of the sample to a 500 ml volumetric flask. Add 10 ml of sulfuric acid solutio
34、n (4.2.41, dilute to the mark with water and mix. By means of a pipette, transfer 10 ml of this solution to a glass-stoppered 500 ml conical flask and add 50 ml of water, followed by 5 ml of nitric acid (4.2.7). To a similar flask transfer 60 ml of water and 5 ml of nitric acid (4.2.7) and carry out
35、, simultaneously, a blank determination following the same procedure and using the same quantities of reagents as used for the flux sample. By means of a burette or a pipette, add 50 ml of silver nitrate solution (4.2.2) to the contents of the flask. NOTE 8 assist coagulation of the precipitate. 2 m
36、l of nitrobenzene (4.2.6) may be added to Re-stopper the flask and shake it vigorously. Add 5 ml of ammonium ferric sulfate indicator solution (4.2.5) and titrate with ammonium thiocyanate sol- ution (4.2.3). shaking the flask vigorously between additions of the titrant. The end-point is indicated w
37、hen a faint orange-red colour first persists through- out the solution in the flask. 4.5 Standardization of the ammonium thiocyanate solution (4.2.3) Transfer 70 ml of water and 5 ml of nitric acid (4.2.7) to a 500 ml conical flask. By means of a pipette, add 25 ml of silver nitrate solution (4.2.2)
38、. Add 5 ml of ammonium ferric sulfate indicator solution (4.2.5) and titrate with the ammonium thiocyanate solution (42.3). as in the procedure given in 4.4. Calculate the correlation factor f3 for the ammonium thiocyanate, as follows: 25 xf2 f3 = volume of NHCNS 4.6 Calculation of results The halid
39、e (excluding fluoride) content, expressed as the percentage by mass of chloride in the flux, is given by the following formula: XI00 (titre, - titremnipie) x 0,003 545 x f3 0,5 d which simplifies to: 0,709 x V d i3 where: V is the volume, in millilitres, of ammonium thiocyanate solution (4.2.3) used
40、 in the titration of the blank, minus the volume used in the titration of the flux sample; is the density, in grams per millilitre, of the original flux sample, at 20 OC, determined by the use of a hydrometer; is the correlation factor for the ammonium thiocyanate obtained in 4.5. d f3 The halide co
41、ntent of the flux sample is given by the mean of the three results obtained on the triplicate test samples. NOTE 9 As an alternative practice the original 25 ml sample may be weighed and the final calculation adjusted accordingly. 5 Method C: Titration method for the determination of halide (excludi
42、ng fluoride) content of water-soluble fluxes containing phosphates 5.1 Principle Oxalic acid is added to complex any copper which may be present in the flux and then ferric nitrate is added to complex the phosphate. The halide content of the flux, calculated as chloride, is then determined volumetri
43、cally using silver nitrate and ammonium 4 STD.BSI BS EN IS0 7455-6-ENGL 1797 Lb24bb7 b05593 4T7 thiocyanate. The method is not suitable for the deter- mination of fluoride. This method is applicable to fluxes of class 3.2.1 .A as defined in IS0 9454-1. BS EN IS0 9455-6 : 1997 5.2.7 Nitrobenzene. WAR
44、NING - Care should be exercised in the handling and disposal of this hazardous reagent. 5.3 Apparatus 5.2 Reagents Ordinary laboratory apparatus 5.2.1 General Only reagents of recognized analytical quality and distilled or deionized water with a conductivity less than 10 pS/cm are to be used. 5.2.2
45、Silver nitrate solution (0,02 mol/l). 3,4 g of silver nitrate (AgNO,) are dissolved in water (see note 1) then transferred to a 1 litre volumetric flask and diluted to the mark with water. This is mixed thoroughly. Alternatively, a commercially available concentrate is used to prepare 0,OZ moll1 sta
46、ndard silver nitrate sol- ution. The silver nitrate solution is standardized using the method given in annex A, to derive the correlation - factorf,. This is stored in an amber glass bottle. NOTES II - E - I - 10 The silver nitrate (AgNO,) should be dried at 110 “C k 5 “C for 16 h and cooled in a de
47、siccator before * cr * weighing. 11 0,000 709 xfi grams of chloride ion. 1 ml of silver nitrate solution (5.2.2) is equivalent to 5.2.3 Ammonium thiocyanate solution, (approxi- mately 0.02 mol/). 1,6 g of ammonium thiocyanate (NH,CNS) are dis- solved in water then transferred to a 1 litre volumetric
48、 flask and diluted to the mark. This is mixed thoroughly. This solution is standardized with 0,02 mol/l silver nitrate solution (5.2.2). as described in 5.5. 5.2.4 Nitric acid solution (10 % V/V). 100 ml of nitric acid (density 1,42 glml) are diluted to 1 litre and mixed thoroughly. 5.2.5 Oxalic aci
49、d. WARNING - Care should be exercised in the handling and disposal of this toxic reagent. 5.4 Procedure Carry out the following procedure, in triplicate, on the flux sample. Weigh, to the nearest 0,001 g, approximately 10 g of the flux sample. Transfer it to a 100 ml volumetric flask, add approxi- mately 70 ml of water, stopper the flask and mix. Add oxalic acid (5.2.5) in increments of approximately 02 g and mix well, until the blue copper colour just disappears. Dilute to the mark and mix thoroughly. Allow to stand for approximately 10 min and filter t
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