Appendix 1: Coefcient of (Linear) Thermal Expansion for Selected Materials (COE or CTE) Coefficient of (linear) thermal expansion, α, for selected (continued) − − materials (COE or CTE) (units are ×10 6 °C 1 (i.e. ppm/°C)) Indium–lead 33.0 Lead (95 %) tin solder 28.0 Tin–lead solder 60/40 25.0 A. Pure metals Magnesium, AZ31B 26.0 Aluminium 25 Ni-clad Molybdenum 5–6 Chromium 6 Steel, 1020 12.0 Cobalt 12 Stainless steel (18-8) 17.0 Copper 17 Tungsten/copper (90/10) 6.5 Gold 14 Aluminium MMC with SiC particles 6–14 Iron 12 (80–50 % reinforcement) Lead 29 C. Insulators and substrate materials (for electronic systems)a Magnesium 25 E glass 5.5 Molybdenum 5 S glass 2.6 Nickel 13 Glass–ceramic >3.0 Platinum 9 Silicon 2.6 Silver 19 Diamond 0.9 Tantalum 7 Aluminium nitride 4.5 Tin 20 Silicon nitride 3.7 Titanium 9 Quartz, fused silica 0.5 Tungsten 5 Kevlar 49 –5 Zinc 35 Beryllia 6–9 B. Alloys and MMCs Cubic boron nitride Alloy 42 4.4 x–y 3.7 Aluminium (40 % silicon) 13.5 z 7.2 Aluminium, AA 6061 23.6 E glass/epoxy Aluminium, AA 3003 23.2 x–y 14–17 Aluminium, AA 2017 22.9 z 80–280 Boron aluminium (20 %) 12.7 E glass/polyimide Brass 18.0 x–y 12–16 Copper/invar/copper 20/60/20 thick 5.8 z 40–80 Copper/molybdenum/copper 20/60/20 7.0 E glass/PTFE thick x–y 24 Graphite/aluminium 4–6 z 260 Invar 36 1.6 Kevlar/epoxy Invar 42 4.5 x–y 5–7 Inconel 600 13.0 z 70 Kovar (Fe–Ni–Co) 5.0 (continued) Kevlar/polyimide (continued) © Springer International Publishing Switzerland 2016 557 B.D. Dunn, Materials and Processes, Springer Praxis Books, DOI 10.1007/978-3-319-23362-8 558 Appendix 1: Coefficient of (Linear) Thermal Expansion for Selected Materials (COE or CTE) (continued) (continued) x–y 3.4–6.7 Si3N4 (α-phase) 2.9 z 83 Si3N4 (β-phase) 2.3 Quartz/polyimide Spinel (MgAl2O4) 7.6 x–y 5–8 Soda–lime–silicate glass 9.2 (used in lightbulbs) z 68.4 Borosilicate glass 4.6 (used with Kovar) Quartz/bismaleimide Silica (96 % pure) 0.8 x–y, 35 % resin 6.2 Silica (99.9 % pure) 0.55 z 35 % resin 41 Zerodur Class 2 0.1 Alumina (90 %) TF substrate 7.0 Zerdur Class 0 Extreme 0.007 Alumina (ceramic chip carrier) 5.9–7.4 E. Polymers (unorientated) Epoxy (70 % silica) plastic packaging 20–23 Polyethylene 100–200 Mulite co-fired 4.2 Polypropylene 58–100 Gallium arsenide 5.7 Polystyrene 60–80 Silicon carbide 3.6 Polytetrafluoroethylene 100 Carbon fibre 60 %–epoxy −1.1 Polycarbonate 66 D. Other ceramics Nylon (6/6) 80 A12O3 6.5–8.8 Cellulose acetate 80–160 BeO 9 Polymethylmethacrylate 50–90 MgO 13.5 Epoxy 45–90 SiC 4.8 Phenolformaldehyde 60–80 Silicon 2.6 Silicones 20–40 (continued) aFor temperature range −55 to +100 °C Appendix 2: Properties of Printed Circuit Laminates Material Thermal Mechanical Conductivity CTE CTE Max. use Glass Tensile Yield Elongation W/M-K X, Y Dir. Z. Dir Temperature transition strength strength % ppm/°C ppm//° °C Temperature °C MPa MPa C Polymer composites Polyimide glass 0.35 12–16 40–60 215–280 250–260 345 – Epoxy glassa 0.16–0.2 14–18 180 130–160 125–135 276 – Modified epoxyb – 14–16 –– 140–150 –– PTFEe glass, 0.1–0.26 20 – 230–260 ––– non-woven PTFEe glass, 419–837 10–25 – 248 – 38–52 – woven Epoxy aramid 0.12 6–866– 125 68–103 –– Epoxy quartz – 6–13 62 – 125 –– Polyimide aramid 0.28 5–883– 250 –– Polyimide quartz 0.35 6–12 35 – 188–250 207 – Epoxy—cordierite 0.9–1.3 3.3–3.8 –– – ––– Modified epoxy – 5.5–5.6 100 – 137 –– aramid PTFEe quartz – 7.5–9.4 88 – 19d –– Polyimide 4.3–11.8 45–50 – 260–315 –––6–7 Metal composites Cu/Invar/Cu 15–18c 5.3–5.5 16 – N/A 310–414 170–270 36 (20/60/20) Cu/Invar/Cu 14c 4.4 –– N/A 380–480 240–340 (12.5/75/12.5) Cu/Mo/Cu 90–174 2.6 –– N/A –– Ni/Mo/Ni 129.8c 5.2–6 5.2–6 – N/A 621 552 50 Published with permission from the IPC, 2215 Sanders Road, Northbrook, Illinois, USA. (Table from IPC-D-279 Design Guidelines for Reliable Surface Mount Technology Printed Circuit Board Assemblies, July 1996) aFR-4, G-10 bPolyfunctional FR-4 cZ-direction dPolymorphic p ePTFE=Polytetrafluoroethylene © Springer International Publishing Switzerland 2016 559 B.D. Dunn, Materials and Processes, Springer Praxis Books, DOI 10.1007/978-3-319-23362-8 Appendix 3: Reagents for Microetching Metals and Alloys A wide variety of techniques may be used for the identifi- Each chemical must be stored and handled according to the cation of grain structures, phases, and other constituents in manufacturer’s recommendations. All chemicals are poten- metals and alloys. Metallographers are often able to predict tially dangerous and it is assumed that the person mixing, the chemical composition and processing history of a pouring, or etching is thoroughly familiar with their use. If metallic sample by selectively etching its polished surface there is any uncertainty about their use, toxicity, or means of and comparing the microstructure to those of reference disposal, the user’s Chemical and Safety Department should samples in conjunction with published phase diagrams. be contacted. The following chemical reagents (etch compositions) are The concentrations of acids are given in terms of specific recommended by the author for the etching of metals and gravity (s.g.), or as a percentage (%) of the fully concen- alloys commonly encountered during the metallurgical trated value. assessment of electrical and structural spacecraft materials. © Springer International Publishing Switzerland 2016 561 B.D. Dunn, Materials and Processes, Springer Praxis Books, DOI 10.1007/978-3-319-23362-8 562 No. Reagent composition Remarks Metal Aluminium and its alloys 1 Hydrofluoric acid (40 %) 0.5 ml 15 s immersion is recommended. Particles of all common microconstituents are outlined. Colour indications Hydrochloric acid (1.19) 1.5 ml Nitric acid (1.4) 2.5 ml Water 95.5 ml Mg2Si and CaSi2 Blue to brown α (AlFeSi) and (AlFeMn) Darkened β (AlCuFe) Light brown (Keller’s etch) MgZn2, NiAl3, (AlCuFeMn), Al2Cu Mg and Al6CuMg Brown to black α (AlCuFe) and (AlCuMn) Blackened Al3Mg2 Heavily outlined and pitted The colours of other constituents are little altered. Not good for high Si alloys Desmut in 50 % nitric acid if necessary 2 Sodium hydroxide 1 g Specimens are etched by swabbing for 10 s. All usual constituents are heavily outlined, except for Al3Mg2 Water 99 ml (which may be lightly outlined) and (AlCrFe) which is both unattacked and uncoloured. Colour indications FeAl3 and NiAl3 Slightly darkened (AlCuMg) Light brown α (AlFeSi) Dull brown α (AlFeSi) Rough and attacked; slightly darkened MnAl6 and (AlFeMn) Coloured brown to blue (uneven attack) MnAl4 Tends to be darkened The colours of other constituents are only slightly altered Beryllium 3 Hydrofluoric acid (40 %) 10 ml Etch by immersion for 10–30 s to outline grain boundaries and microconstituents Ethyl alcohol 90 ml Appendix 3: Reagents for Microetching Metals and Alloys 4 Water 95 ml Be alloys may be etched in the reagent (1–15 s) Sulphuric acid (1.84) 5 ml Note: during the preparation of beryllium samples, do not breathe dust, as this is extremely toxic. Cutting operations must be done under controlled conditions, preferably in a glove box. See text for the removal of mechanical twins. Polishing cloth will be contaminated with beryllia and needs to be disposed of according to local health and safety requirements. Metallographers should wear rubber gloves and avoid contact with etchants Chromium 5 Hydrochloric acid (concentrated) Shows striations in electrodeposits Copper, copper alloys, brass, bronze, etc. 6 Ammonium hydroxide 50 ml Used for copper, many copper-rich alloys Water 50 ml Gives a grain boundary etch, and also tends to darken the α solid solution, leaving the β solid solution lighter. The Hydrogen peroxide (30 vol.) 20 ml hydrogen peroxide content may be varied. Less is required the lower the copper content 7 Ferric chloride, various strengths and compositions Used as a general reagent for copper, brass, bronze, nickel–silver, aluminium–bronze, and other copper-rich alloys. It β To 100 parts of water are added darkens the constituent in brasses and gives grain contrast following ammoniacal or chromic acid etches. The most suitable composition should be found by trial and error in specific cases. This reagent generally emphasizes scratches Hydrochloric acid (1.19) Ferric chloride (g) in imperfectly prepared specimens, and tends to roughen the surface. For sensitive work it is frequently a great 20 1 advantage to replace the water in the reagent by a 50:50 water–alcohol mixture or by pure alcohol 10 5 50 5 (continued) (continued) Appendix 3: Reagents for Microetching Metals and Alloys No. Reagent composition Remarks 8 Potassium dichromate 2 g Used for copper, and copper alloys with beryllium, manganese, and silicon. Also suitable for nickel–silver, bronzes, – Water 100 ml and chromium copper alloys. This reagent should be followed by a ferric chloride etch to give added contrast Sodium chloride (saturated) 4 ml Sulphuric acid (s.g. 1.84) 8 ml Gold 9 Hydrochloric acid (concentrated) 60 ml Use under a hood, immerse for a few seconds Nitric acid (concentrated) (Aqua Regia) 40 ml 10 Potassium cyanide, 10 % in water 10 ml Used for gold and its alloys.