International Standard f!@ 2093 0 1 4 4igB INTERNATIONAL ORGANIZATION FOR STANOARDlZATION*MEWlYHAPOilHAR OPrAHM3AUHR n0 CTAH~APTH3AUMH ORGANlSATlON INTERNATIONALE DE NORMALISATION Electroplated coatin[.]
0 International Standard f!@ 2093 14igB INTERNATIONAL ORGANIZATION Electroplated methods D&p&s Hectrolytiques Second UDC edition FOR STANOARDlZATION*MEWlYHAPOilHAR coatings d’htain - - Spdcifications OPrAHM3AUHR of tin et m&odes n0 CTAH~APTH3AUMH.ORGANlSATlON Specification : mete1 coetiWs DE NORMALISATION and test d’essal 1966-12-15 Ref 669.667 Descriptors INTERNATIONALE electrodeposited coatings, tin coatings, classifications, specifications, tests, No determination, IS0 2093-1966 (E) thickness, adhesion Price based on pages Foreword IS0 (the International national standards Standards is normally body interested Organization bodies (IS0 carried out through Draft International technical committees Standards Council adopted They are approved Standard by the technical in accordance latest edition, committees Printed with IS0 by Technical Standards made herein to any other Organization in Switzerland are circulated as International Standards procedures to by requiring at Committee ISO/TC 107, 2093-19731, of which it revision unless otherwise international has govern- coatings Users should note that all International and that any reference Each member organizations, This second edition cancels and replaces the first edition (IS0 a technical of International bodies voting IS0 2093 was prepared and other non-organic constitutes federation has been established International bodies for approval before their acceptance International is a worldwide The work of preparing in liaison with ISO, also take part in the work least 75 % approval by the member Metallic IS0 on that committee mental and non-governmental, the IS0 bodies) in a subject for which a technical committee the right to be represented the member for Standardization) member undergo revision from time to time International stated for Standardization, 1986 Standard implies its INTERNATIONAL Electroplated methods IS0 2093-1966 (El STANDARD coatings of tin - Introduction Specification IS0 2177, Metallic thickness This International Standard specifies requirements IS0 2819, C gives additional information as guidance This International troplated of application Standard specifies requirements coatings of nominally pure tin on fabricated coating on metallic deposited substrates coatings - Elec- -Review of and tables for inspection by at- thickness Metallic - coatings - Measurements X-ray spectrometric IS0 3543, Metallic and non-metallic - Beta backscatter coatings - metal ar- may be dull or bright as electroplated may be flow-melted by fusion after electroplating or coatings - b) tin-coated cl coatings on sheet, strip or wire in unfabricated Measurements method Metallic Neutral IS0 4519, finishes - Electrodeposited metallic coatings and related Sampling procedures for inspection by attributes Metallic salt spray test INSS and other non-organic dioxide test with general condensation threaded coating IS0 3788, test) IS0 8988, It does not apply to a) of methods for elec- ticles The coatings components of to the user of thickness and field Measurement by anodic dissolution available for testing adhesion IS0 3497, Scope coatings and chemically IS0 2859, Sampling procedures tributes 2) It is essential that the purchaser should state the information itemized in 4.1 and, if appropriate, 4.2 Specifying IS0 2093 without this information is insufficient - method that exist in many countries for tin coatings used in the food industry Annex Metallic trodeposited methods is drawn to legislative requirements coatings Coulometric for elec- troplated coatings of tin on fabricated metal articles to protect them from corrosion and to facilitate soldering Attention - and test ; IEC Publication cedures - copper wire ; 88-2-20, Basic coatings - Sulfur of moisture environmental testing pro- Test T: Soldering form, or on articles made from them; d) coatings on coil springs; e) coatings autocatalytic f) applied electroplating 000 MPa” by chemical or “electroless”) means (immersion, Definitions ; of steels with tensile strength greater than (or of corresponding steels are subject to hydrogen hardness), embrittlement For the purpose of this International definitions apply Standard, the following because such (see 8.2) 3.1 significant surface : The part of the article covered or to be covered by the coating and for which the coating is essential References IS0 1483, for serviceability Metallic coating thickness and - oxide coatings Microscopical - Measurement of (Definition and/or taken from IS0 2064.1 method 3.2 flow-melting A process thickness ability (see clause C.4) MPa desirable by which ; fusing ; flow-brightening IS0 2084, Metallic and other non-organic coatings - Definitions and conventions concerning the measurement of II appearance properties a coating is melted such as brightness ; reflowing : in order to impart or improved solder- = N/mm2 21 At present at the stage of draft (Revision of IS0 2859.1974.) IS0 2093-1986 (El Information to be supplied by the purchaser Classification to the electroplater 7.1 4.1 Essential Service condition The service condition The following information the electroplater shall be supplied by the purchaser to vice conditions number indicates the severity of the ser- in accordance with the following scale : : : a) number information the number of this International exceptionally severe - severe corrosive Standard; for example service outdoors in conditions or contact with food or drink b) the nature of the basis material (see clause 5) ; where a complete cover of tin has to be maintained corrosion and abrasion (see C.l l) cl the service condition 3: number (see 7.1) or the classifi- severe cation code of the coating required (see 7.2) ; temperate d) 2: the significant indicated, surface of the article to be electroplated for example, by drawings or by the provision of - for example service outdoors against in typical conditions moderate - for example service indoors with some condensation suitably marked samples; 1: e) the sampling f) the procedure positions where to be adopted unavoidable other defects are acceptable (see clause 6) ; contact marks 4.2 the method Additional and of adhesion testing to be used (see 10.3) information b) any requirements c) any requirement methods for solderability e) a sample showing f) any special pretreatment g) any specific requirements testing for undercoats Coating gives guidance and minimum on the relation between (see clause 9) ; classification code code shall consist of four parts, the by an oblique stroke, as where a indicates the chemical symbol for the basis metal (or for the main constituent if an alloy); required; for the purity of the coating indicates the chemical for its minimum requirements for plated symbol for the undercoat (or for the main constituent omitted com- ponents; c coating if no undercoat d thickness, Basis material indicates An example in micrometres, and is is required [see 4.2 d)] ; thickness, the surface finish, by a in micrometres; by the symbol m if the or f if it is is This international Standard specifies no requirements for the condition, finish or surface roughness of the basis material prior Fe/Ni 2.5 Sn f to electroplating which (see C.2.1) metal by a figure indicates the chemical symbol for tin, Sn, followed figure for its minimum treatment if an alloy) followed coating is matt, or b if it is bright electroplated flow-melted ser- thickness a/b c d (see clauses and C.5); any special post-plating require- and the test b i) number The coating classification the required finish (see 10.1) ; packaging See 10.2, which first two of which shall be separated follows : to be applied (see 10.5) ; any special requirements any special - vice condition 7.2 for porosity testing (see 10.4) ; d) h) is the primary may be required and, if so, required (see clause 8) ; and conditions solderability c.1.1 shall be specified by the purchaser: any heat treatment where When specifying the service condition number or coating classification code, it should be noted that tin is susceptible to damage in abrasive environments or in those containing certain organic vapours See also The following additional information a) for example service indoors in dry atmospheres (see 10.1); NOTE g) mild - or applications ment represents nickel undercoat, an iron or steel basis metal, tin electroplated with a 2,5 urn to a coating thickness of urn and flow-melted Sampling procedures The method between Sampling are specified in IS0 2859 and IS0 4519 of sampling and acceptance purchaser and supplier levels shall be agreed 8.1 Heat treatment Stress relief Severely cold-worked electroplating of steel before electroplating steel parts shall be stress relieved before by heating for h at 190 to 220 OC IS0 2093-1986 (E) The properties of some steels which flame-hardened or ground would be impaired 10 have been carburized, induction-hardened and by this treatment be stress relieved at a lower temperature, and shall instead 10.1 embrittlement relief after Appearance any visible defects such cracks or unelectroplated electroplating as blisters, areas, pits, roughness, and shall not be stained of hydrogen through for hydrogen embrittlement tin is very slow, The acceptability heat and defects relief after electroplating and positions of unavoidable on non-significant contact marks surfaces shall be specified The finished article shall be clean and free from damage surface Requirements Undercoats for undercoats If necessary, a) to prevent diffusion b) to retain solderability (see C.2.2 and C.2.3) ; c) to ensure adhesion d) to improve protection (see C.2.2, brittlement 10.2 areas by the purchaser Thickness Tin coatings condition an undercoat are classified by thickness (see 7.11, minimum and for each service values are specified in the table (see also C.3.2) against corrosion to select The free from nodules and, C.2.3 and C.2.4) ; (see C.2.4 and C.2.5) ; system that will not confer undesirable texture, a sample showing the required finish shall be sup- plied or approved reasons : be taken shall be of a smooth where fused, shall be free from dewetted may be necessary on certain basis materials for any of the following Care should by the purchaser is impractical or discoloured Because diffusion treatment coatings When examined by the unaided eye or corrected vision the significant surfaces of the electroplated article shall be free from Hydrogen for for example at 130 to 150 “C for not less than h 8.2 Requirements subsequently The thickness of the coating shall be measured over a reference or undercoat area (see IS0 2064) properties such as em- by the appropriate method given in an- nex A on any part of the significant surface that can be touch- of the basis material or finished article For example the use of highly stressed nickel should be avoided ed with a 20 mm diameter ball In the case of articles having a significant surface area of 100 mm* or greater, the minimum If the basis material is a copper alloy containing zinc as an alloy- thickness ing constituent, thickness or copper and solderable properties are required, a nickel undercoat essential in addition (see C.2.3); of minimum to the specified such coatings good appearance local thickness coating thickness 100 mm*, regarded as the minimum of tin as the minimum value In the case of articles having a significant area of less than 2,5 pm is may also be necessary shall be regarded the minimum thickness of local surface shall be value of average thickness to retain In the case of printed circuit boards with electroplated-through and adhesion holes, the requirements shall apply to the surfaces within the holes, as well as to the areas that can be touched with a 20 mm diameter ball If an undercoat is specified, its nature (see annex Cl and minimum local thickness (see 10.2) shall be specified by the purchaser In the case of flow-melted The thickness measured of the undercoat by the appropriate method or undercoats shall (See C.3.2., specified in annex A Table - Coating (Partial) classification code 1) Mm 10 Sn 12 12 5 is drawn to the essential See C.2.4 and C.2.5 requirement w 30 Sn zinc as an alloying Minimum thickness Sn 30 Sn 20 Attention (Partial) classification code 15 that contain 21 Minimum thickness 30 prior to flow-melting clause C.4 and annex A.) Other basis materials*) Sn 30 Sn 15 Sn the thickness requirements condition, thicknesses Copper basis materials’) Service condition number coatings, apply to the as-electroplated be Sn in clause for undercoats on copper 20 alloy basis materials constituent regarding the need to undercoat certain basis materials IS0 2093-1966 (El In case of dispute, the referee methods 10.3 Adhesion When tested by one of the methods 10.5 are as given in A.0.2 10.5.1 specified by the purchaser, described in annex B, as the coating shall not show signs of detachment 10.4 Solderability General materials and piece parts If specified by the purchaser, solderability shall be tested in ac- cordance with method of test Ta of IEC Publication using non-activated flux If accelerated Porosity (see clause A.21 ageing before the test is required, 6B-2-20, the procedure shall be specified by the purchaser If specified thickness by the purchaser, of 10 urn or greater coatings having shall be subjected a minimum to a test as follows: 10.5.2 a) for ferrous basis materials, b) for Printed circuit boards the test given in IS0 3768; If specified non-ferrous basis material, the test given in in accordance IS0 6966 In either case, there shall be no evidence substrate when viewed with a magnification by the purchaser, International of corrosion of the of X3 (see C 1.1) If accelerated Standard a coating complying with this on printed circuit boards shall be tested with test Tc of IEC Publication 68-2-20 ageing before the test is required, the procedure shall be specified by the purchaser IS0 2093-1986 (E) Annex Determination A of coating thickness (This annex forms an integral part of the Standard.) A.0 Introductory A.O.l Routine All the methods A.0.2.6 Thickness of circuit boards notes methods given in this annex are those which are con- sidered to have an adequate accuracy when properly used with samples suitable for the particular method The method chosen of tin in electroplated-through holes Use the microscopical method specified in A.1 l The microsection shall be parallel to the axis of the hole and perpendicular to the surface measured (see IS0 where the coating or layer is to be 1463) for routine test purposes shall be one which is expected to yield the most reliable results considering thickness, shape of component, composition, basis material, such factors as coating size of component, coating A.1 Measurement etc A.l.l Other test methods may be used if it can be demonstrated A.0.2.1 Referee In cases of dispute, the methods designated with A.0.2.2 and analytical methods, as 7.30 g/cm3 even for referee pur- to A.0.2.6 For the the density of the tin shall though this may result A.0.2.3 method specified thickness use the A.l.4 method specified in IS0 3543, its operation can be determined is dependent X-ray Use the method value A.0.2.4 steel A.2.1 of tin on copper, nickel or to to within specified in A 1.2 if the coating surface is sufficiently smooth and flat so that there is no leakage of the electrolyte at the cell-probe; otherwise use the microscopical method specified in A.I The microsection shall traverse the centre of the test specimen, and at least five evenly spaced microsection measurements shall be requires the the coating 10 % of its true value; atomic number of the basis material method in IS0 3497, which A.2 Measurement of average requires the in- thickness Principle coating by chemical dissolution A.0.2.5 Average thickness of undercoat and of tin on undercoats on basis material such as aluminium method that on the mass per unit area of the spectrometric specified which be such A suitable coated specimen for number of specimens, if small) of known surface area is cleaned, weighed, stripped of its method specified in A.2 Use the coulometric 10 % strument, its calibration and its operation to be such that the coating thickness can be determined to within 10 % of its true NOTE - For the coulometric measurement of undercoats, it is essential to remove the tin first This can be accomplished by the coulometric dissolution of the tin coating or by stripping as described for the analytical method specified in clause A.2 Use the analytical and coating and the effective Use the coulometric method specified in A.1.2 if the coating surface is sufficiently smooth and flat so that there is no thickness to within Beta backscatter this accuracy Local thickness less than urn Average method Use the method specified in IS0 2177 This method is stated to Use the method otherwise the overplating is stated to have an accuracy of f 0,8 pm or, for be normally accurate equipment in A 1.1 leakage of the electrolyte at the cell-probe; microscopical method specified in A 1.1 1463, with greater than 25 pm, to within % Coulometric A.l.3 Local thickness greater than pm Use the microscopical in IS0 with not less than 10 urn of copper in a thickness value less than the true thickness A.0.2.2 method specified overplating thicknesses A.l.2 poses shall be in accordance be taken Use the method procedure, This method methods General coulometric Microscopical that they are as good as or better than the methods given in this annex for the particular application A.0.2 of local thickness made along the and re-weighed The method is not generally suitable for coatings on small parts or on certain metals (see C.2.5) In appropriate cases, the average of a number of microsection determinations should be used for the determination A.2.2 of average thickness (see IS0 2064) Reagents During the analysis, use only reagents of recognized analytical grade and only distilled water or water of equivalent purity IS0 2093-1966 (El A.2.2.1 For stripping nickel undercoats from iron basis materials and immersed for after brushing off any smut Dissolve 20 g of antimony trated hydrochloric NOTE - Articles using this solution A.2.4.2 mav not be suitable for reprocessing in running water, Dry and weigh to the nearest 0,001 g For copper and copper alloys Weigh the 0,001 g, For stripping from copper and copper alloys Wash cleaned immerse remove A.2.2.2 of gas has ceased wash thoroughly trioxide in 000 ml of cold concen- acid (Q = 1,16 to 1,18 g/ml) stripped the evolution Remove from the solution, immediately thoroughly test specimen it in the the (A.2.3) stripping coating in running to solution the has completely water, nearest (A.2.2.2) and dissolved dry and weigh to the nearest 0,001 g Hot (minimum 90 OC) concentrated hydrochloric acid (Q = I,16 to I,18 g/ml) A.25 A.2.3 Expression The coating thickness, Use a test specimen or specimens of total surface area suffi- cient to give a mass loss of not less than 0,l which can be measured to an accuracy Remove all soil from the test specimen suitable solvent or by vapour degreasing A.2.4 (m, g, the area of of % where m2 cleaned 103 A it in a Procedure the is given by the formula m.J x 137 x or better by washing - in micrometres, m, is the mass, in grams, of the test specimen ing ; A.2.4.1 For iron basis materials on copper and copper alloys Weigh of results Test specimen test and nickel undercoats A before stripp- is the mass, in grams, of the test specimen after stripping ; is the surface area, in square millimetres, of the test specimen ; specimen (A.2.3) to the 0,001 g, immerse it in the stripping solution fA.2.2.1) nearest and leave Annex Adhesion 137 x lo3 tin is a factor based on the density, 7,30 g/ems, B tests (This annex forms an integral part of the Standard.) 6.1 Burnishing vice) Bend the sample through 90’ and back to its original position Carry out this procedure three times Examine the test Apply the method described in IS0 2819 to an area of not more than 600 mm* of the significant surface NOTE - An agate dental spatula radiused nishing tool B-2 Bend edge has been found and sharpened to be a very satisfactory to a bur- test Place the sample in a suitable machine, capable of applying a bend of radius mm to the sample (or in the jaws of a suitable for signs of detachment of the coating with a handle 60 to 1M) mm long and agate blade 30 to 50 mm long, to 10 mm wide, slightly specimen B.3 Thermal shock test CAUTION - This test may have an adverse effect on the mechanical properties of the article tested Accordingly, the thermal shock test specimen shall not be used for other tests Use the method described in IS0 2819 of IS0 2093-1986 (E) Annex Guidance C notes (This annex does not form part of the Standard.) These notes are intended to draw the attention a) certain properties b) properties and preparation c) electroplating practice C.l Properties of the C.l.l General Tin coatings therefore, of tin which, if not understood, may lead to inappropriate use of the coating ; of the substrate; coating are soft and easily abraded deposit of the user to thicknesses Some considerably corrosion greater than of tin may be expected those specified in certain for a given service outdoor exposure condition conditions and, may be required The thicknesses specified in the table are minimum values and the use of thicknesses greater than those specified may be required In normal indoor exposure, tin gives protection to most metals except, especially on ferrous metals, at discontinuities and pore sites in the coating The porosity of an electroplated coating is governed not only by its thickness but also by such variables as the condition of the basis material and general electroplating Electroplated practice, coatings covered by this International and this should be borne in mind when specifying Standard the porosity test can provide thinner or thicker coatings than those normally obtained by hot-dipping C.1.2 Whisker Electroplated growth tin is liable to the spontaneous of whisker growth is considered sidered The use of suitable undercoats, C.1.3 Allotropic High-purity growth of metal ‘whiskers’ to be a liability, flow-melting (filaments), of the coatings especially on stressed coatings If the possibility or the use of tin-lead alloy coatings should be con- for example nickel, may retard the growth of whiskers changes tin coatings are subject to allotropic change (to CL-or grey-tin) if subjected to subzero temperatures For such conditions the use of tin-lead or other suitable tin alloy coatings should be considered C.2 Properties and Surface condition C.2.1 preparation of the basis material The surface condition of the coating will depend partly on the surface condition C.2.2 of intermetallic Formation The interdiffusion compounds of the coating with copper and copper-base alloys by a solid/solid temperature, and can lead to darkening and poor solderability with thin coatings conditions but in poor conditions storage life may be only a few months C.2.3 Diffusion hesion and appearance “Difficult” diffusion process is dependent The rate of deterioration on time and depends on the storage of zinc Zinc, from zinc-containing C-2.4 of the basis material alloys such as brass, diffuses through the tin coating to the surface and degrades the solderability, ad- (see clause 9) basis materials Some basis materials, for example phosphor-bronze, beryllium-copper and nickel-iron alloys, are difficult to prepare chemically clean because of the nature of the surface oxide film If solderability is a requirement of the tin coating, an undercoat of nickel or copper of a minimum local thickness of 2,5 pm may be advantageous IS0 2093-1986 C.2.5 (El Aluminium, magnesium These alloys are readily attacked and zinc alloys by dilute acids and/or relatively thick (IO to 25 urn) undercoat C.3 Electroplating C.3.1 alkalis and therefore special pretreatments, is a requirement of the coating, can be deleterious to the solderability C.3.2 thickness Except where otherwise rinsing with a suitable solution such as a % (m/m) coating thickness defined in IS0 2054, it should be noted that the deposit thicknesses specified in this International conforms both of the article being electroplated to a normal (gaussian) be assessed by the solderability Co-deposition The average thickness required to give a minimum by flow-melting because of the formation of a meniscus In relevant cases, the performance can matter used in tin plating solutions the coating during the subsequent C.4 in distribution taken in the choice of the organic additive and co-deposition specified organic compounds bath with regard to the pos- (especially of small parts), the variation requirement of organic Organic additives are sometimes Standard local thickness on the significant and of the electroplating It should also be borne in mind that, with barrel electroplating The thickness of coatings is affected C.3.3 solution of citric or tartaric acid, if allowed to dry on the surface of the coating, requirements surfaces will depend upon the geometry itions of the electrodes of a with tin of that surface local and not average thicknesses are minimum the deposition rinse may be included in the washing cycle to ensure removal of hydrated tin salts which, Coating including bronze or nickel is necessary before the article can be electroplated practice Post-electroplating If solderability of copper, If solderability fusing or soldering operation may enhance the mechanical is the main requirement should be minimized, However, properties of the coating, as these may lead to “out-gassing” if sliding contacts are being electroplated, care should be or bubbling of the presence of of the coating Flow-melting Tin coatings may be readily flow melted by procedures sing hot vapour solderability It can be advantageous will also result in dewetting such as immersion in hot oil or by exposure to infra-red radiation or to conden- to flow melt tin coatings as any defects of the coating on flow-melting in the substrate Coating thicknesses that would give rise to poor in the region of 20 urn can be success- fully flow melted but, if there is a possibility of the melted coating draining to an edge during the flow-melting, the deposit thickness should be limited to about urn to avoid the formation of “blips” on the edge of the work Flow-melting is not recommended for electroplated C.5 C.5.1 tin coatings that are already bright Tin coatings Organic in contact with food brighteners If bright coatings are to be used in contact with food, the possibility of co-deposited in mind as this could lead to contamination C.5.2 Tin content National legislative requirements should contain may be applicable not less than 99,75 % (m/m) organic material being extracted should be borne of the food in particular countries of tin and should contain but, in general, tin coatings for use in contact with food not more than 0.2 % (m/m) of lead