[PinkFloyd]

Ouch!

 

[PinkFloyd]

Quote:

Originally Posted by tkerby Could I refer you all to the following article: Long Term Mechanical Reliability with Lead-Free Solders You can sign up for a free trial on this site allowing you to download 5 articles free of charge. The article fully investigates 'tin pest' formation and other issues surrounding a number of new alloys. Some of the pictures are quite disturbing

Excellent find tkerby! that article is well worth a read for sure.

 

[tkerby]

I should note that the picture PinkFloyd has shown is showing tin pest formation on a 99.5% Sn - 0.5% Cu solder sample aged at -18 degrees to speed up the formation process

 

[Captain Scarlet]

Rule: Energy exists. It cannot be created and therefore cannot be destroyed. It can only be transformed.

Before man started interfering, the atmosphere simply had to dissipate the heat originating from the earths core. Heat energy is dissipated as wind energy. The winds evaporate the seas. We have weather. Simple!

Man made his own fire (he transformed the energy locked up in carbon into heat energy). Man started global warming.

Man is now racing headlong to transform energy into sufficient heat energy to destroy the planet and him.

Global warming causes freak weather. Freak weather is worsening. Boscastle, England: Virtually washed away - this week. Landslip in Scotland: 53 motorists have to be rescued - this week. Freak storms in Asia: Some people killed in Japan - this week.

What has this to do with Lead?

Lead is a gift of creation. It is a cooling element. It allows us to do many things without transforming as much energy into heat as would happen without it. It is only dangerous if man does not use it with care. Man has no respect for Lead. He has not used it with care.

We removed it from fuel because we couldn't be bothered looking at the alternatives (using it with care). Now engines run hotter (FACT). More heat = more global warming.

We will now remove it from solder because we can't be bothered looking at the alternatives (using it with care). Mass production plants all over the globe will therefore pump out 10% more heat instead. More heat = more global warming.

For the minority who would like to heed the warnings carried by this thread, the information is available by the thousand via the miracle of the Internet.

However, I now realise I am wasting my time trying to educate man.

Bye!

Captain Scarlet (Off back to Mars - I may have more success with the Mysterons…)

 

[Nisbeth]

Quote:

Originally Posted by Captain Scarlet We removed it from fuel because we couldn't be bothered looking at the alternatives (using it with care). Now engines run hotter (FACT). More heat = more global warming.

I think it is more complex than that, because the newer engines are far more efficient than older ones and that has to pull in the other direction (a lot in the other direction actually)

/U.

 

[aos]

Captain Scarlet, now THAT was a good post. Rest assured that a lot of us think the same way (or at least acknowledge the side effects). However, also rest assured that most of people don't care. They will not stop until this planet is turned into Hell (pun intended).

 

[PinkFloyd]

Quote:

Originally Posted by Captain Scarlet Captain Scarlet (Off back to Mars - I may have more success with the Mysterons…)

Wishing you a safe lift off Captain Scarlet and give my regards to all those on Cloudbase, especially Captain Blue, Lieutenant Green and Doctor Fawn. Spectrum has been warned of a mysteron plot which will involve them attempting to sabotage the Angel Interceptor fighter jets, the bullet proof Spectrum Pursuit Vehicle, gas powered Spectrum Saloon Cars and Magnacopters. The sabotage will involve resoldering the vital panel with lead free solder so please check all your vital panels for lead content before lifting off.

May you return to Cloudbase fully leaded.

Captain Pink.

 

[Alick]

S.I.G.

 

[PinkFloyd]

Quote:

Originally Posted by Alick S.I.G.

S.I.G

 

[PinkFloyd]

This is the article tkerby referred to and it's a pretty informative read.

This does not infringe on copyright and is inkeeping with Emeralds copyright policy summary:

"Fair Dealing (Fair Use) for the purpose of non-commercial research, private study, criticism or review, instruction or examination does not infringe copyright. An author's moral rights are

to be identified as the author
to object to derogatory treatment of their work and
not to have work falsely attributed to them"



[size=large]Long term mechanical reliability with lead-free solders[/size]

[size=large]By W.J Plumbridge Department of Materials Engineering, The Open University, UK[/size]




ABSTRACT:

The decision to move to lead-free solders has been made, but processing and performance challenges remain. This paper considers the transition in terms of performance, with particular emphasis on long term, high reliability applications. Comparison of key mechanical properties indicates generally beneficial outcomes of the transition to lead-free alloys, although there is a lack of understanding surrounding "anomalous" observations, such as the effects of the bismuth. The lower melting point of Sn-Zn-Bi alloys, together with their comparable mechanical properties, provide further impetus to address their shortcomings during processing. Some lead-free alloys, such as Sn-0.5Cu, are susceptible to tin-pest formation following prolonged exposure below 13°C, and this possibility remains for the more concentrated Sn-3.8Ag-0.7Cu alloy.

The die is cast! Lead-free solders are being introduced at different rates across the world. Japan is ahead; for Europe, 1 July 2006 has been set as the deadline for the transition, and the US is making rapid progress towards this goal. The alloys likely to be the initial replacements for Sn-37 Pb are Sn-0.5 Cu, Sn-3.5 Ag and Sn-3.8 Ag-0.7 Cu or slight variations of them. More uncertainty and debate exists around zinc and bismuth-containing systems (Richards et al., 1999).

Once that decision was made, two further challenges had to be faced; the implementation of lead-free processing/manufacturing to achieve an efficient transition in production, and the assurance of the reliability of lead-free solders during performance in service. The present paper addresses the second point, particularly with regard to long term mechanical reliability. It takes the opportunity, presented by the hiatus surrounding the transition to lead-free solders, of reappraising the situation from both a metallurgical and an engineering prespective.

At the outset, two questions should be considered. What is meant by "long term" reliability? and Can long term reliability be assumed with traditional Sn-Pb solders, which have been in use in electronics equipment for many decades?

INTRODUCTION:

The answer to the first of these is very much application-specific, and may range from 5 to 50 years accordingly. In this writer's opinion, the answer to the second question is a resounding "No"! unless the excessive conservatism incorporated in design prior to miniaturisation is permitted. Although the volume of data on the mechanical properties of lead-containing solders is orders of magnitude greater than that available for the new lead-free alloys, much of it has little value in design and life prediction for the commonest cause of service failure - thermomechanical fatigue (TMF). In essence, the argument here is that it is not yet possible to ensure long term reliability, irrespective of the nature of the solder alloy. With that caveat, the key questions to be addressed are:

What are the differences between lead-free solders (those alloys cited above) and the established Sn-37 Pb alloy? and

How do these differences affect the properties that influence service performance?

The present paper considers various aspects that require closer scrutiny, with regard to long term reliability, and draws attention to the significant differences that can arise in the behaviour of broadly similar alloys. While examples from the literature are used to demonstrate the points made, a comprehensive review is not attempted.

THE METALLURGICAL PERSPECTIVE:

Most solders are currently tin-based alloys, and an overview of the physical metallurgy of lead-free alloy development has recently been produced by Subramanian and Lee (2003). Apart from a reduction in density (and hence more solder per unit mass), the removal of lead produces a quite different alloy from Sn-37 Pb. The amount of solute for the popular lead-free systems mentioned above varies between 7 (Sn-3.8Ag-0.6Cu) and 70 (Sn-0.5Cu) times less than in Sn-37Pb. This raises the melting point by some 30-40°C, taking processing temperatures perilously close to those that might damage the board or components. In addition, the category of the alloy is changed from a conventional two-phase system (as in Sn-37 Pb) to a particle-strengthened system, and this has significant ramifications on mechanical behaviour, as will be evidenced later. While both types of solder are based upon tin, alloys in the more dilute lead-free group are more likely to exhibit the intrinsic characteristics of that metal. Of particular relevance are its allotropy and anisotropy.


THE ALLOTROPY OF TIN:

Pure tin undergoes a transition in crystallographic structure at 13°C from body-centred tetragonal, bct, (white tin) to a diamond cubic (grey tin) form at lower temperatures. The 26 per cent volume change accompanying this transformation results in local cracking and eventual disintegration of the sample. The product is known as tin pest. Such an effect has never been observed in Sn-37 Pb alloys, but has been reported for the Sn-0.5 Cu solder alloy (Kariya et al., 2001) which is the most dilute of the lead-free family. Figure 1 shows the severe damage to a massive tensile test piece. In pure tin, the process involves nucleation and growth with a protracted incubation period (Burgers and Green, 1957). Once nucleation has taken place, the growth of grey tin is relatively rapid and the maximum rate of transformation occurs at -40°C (Hedges, 1960). However, the timescales shown in the figure do fall easily within the definition of long term. Formation of tin pest in the less dilute Sn-Ag based solders has yet to be established but long term ageing tests at -18°C indicate that this is a possibility (Plumbridge and Gagg, 2004). Figure 2 shows discoloured surface regions which may be the beginning of tin pest formation. The dark regions on the flat indicate almost total transformation in this location. Their location on the machined area of the cylindrical sample concurs with previous findings that the presence of residual stress or strain promotes the transformation.


THE ANISOTROPY OF TIN:

A variation in properties with crystallographic direction is known as anisotropy. At room temperature, the body-centred tetragonal structure of tin provides ample opportunity for this. For example, the coefficient of thermal expansion (CTE) may change by a factor of two according to the direction in which it is measured, and Young's modulus may experience a threefold variation. Significant stresses may develop at grain boundaries, according to the orientation of the neighbouring grains (Lee et al., 2002; Subramanian and Lee, 2004). When samples contain large numbers of grains which, by definition, have different crystalline orientations from their neighbours, the net effect is reduced. However, in modern microelectronics actual joints may comprise a few grains, and exposure to temperature change, or repeated thermal cycling, can cause surface roughening or extrusion and cracking as shown in Figure 3 (Liu and Plumbridge, 2003).

It must be emphasised that this phenomenon is intrinsic to the material itself. The presence of an interface, as in a solder joint, or the mechanical leverage associated with adjacent joints on a printed circuit board are additional strain-producing effects during service, and originate from mismatch between CTEs of different materials in contact. The consequences of dilute alloy addition, as in lead-free solders, or higher levels of solute, as in Sn-37 Pb, are unknown, and the distinctly two-phase microstructure of the latter further impedes direct comparison. Various situations arising from anisotropy during TMF have been considered in more detail by Lee et al. (2002).


THE ENGINEERING PERSPECTIVE:

Modelling TMF behaviour requires knowledge of the following.

The solder properties over the temperature range of the cycle.
How the rate of temperature change (or strain rate) affects these values.
The detailed temperature-time profile.
The degree of instability of the microstructure, which is largely determined by its prior thermal history.
The mechanical properties that influence performance are the following.

Strength - It is denoted by yield, proof or ultimate stress, and indicates the load-bearing capacity, impact resistance and the low strain fatigue (predominantly elastic cycles such as vibration) calibre of a material.
Ductility - The amount of strain that can be accommodated prior to failure determines the high strain (predominantly plastic cycles) fatigue behaviour.
Fatigue - Mechanical, thermal and thermomechanical sources of cyclic failure involve the initiation and growth of a crack until fracture results. The amplitude of stress, strain or temperature is the principal determinant of fatigue life, although other factors may have a significant role. There is no simple correlation between TMF and isothermal fatigue at the same strain range.
Creep - A time, rather than cycle-dependent process under constant load or stress which may be deformation or crack dominated. The equivalent mechanism when the strain limits are fixed is known as stress relaxation. Both processes may occur in a solder joint subjected to thermal cycles, especially when the temperature-time profile contains dwell periods.
According to the component and the operating conditions these properties have a significant effect on performance. The underlying question in the present context is the comparative behaviour of lead-free solders and those containing lead. This point is now addressed.


MONOTONIC TENSILE PROPERTIES:

The effects of temperature and strain rate on strength

An increase in temperature reduces the strength of all engineering materials but in a manner that is specific to the material under consideration, and in particular, the homologous temperature range involved. For solders, an increase from -10 to 75°C (0.55<Th<0.70, where Th is the homologous temperature) produces effects of significantly different magnitude according to the particular alloy and the strain rate at which strength is determined. For example, the tensile strength of Sn-37 Pb, measured at a strain rate of 1×10-1 s-1 is approximately halved on increasing the temperature from -10 to 75°C, and the effect is enhanced at diminishing strain rates (Plumbridge and Gagg, 1999) (Figure 4). While the trends are generally similar for the lead-free alloys, both Sn-0.5 Cu and Sn-3.5 Ag appear less sensitive to temperature. Proof stress values follow a similar pattern. The salient point is that accurate values of strength pertaining to the alloy, temperature and strain rate are necessary for reliable modelling.

Even when temperature is fixed, a change in the rate of deformation may have a significant effect on strength, with the lower strain rates associated with reduced strength (Figure 5). For example, at -10°C, a reduction in strain rate from 10-1 to 10-6 s-1 produces a greater than threefold fall in tensile strength for Sn-37 Pb, whereas the lead-free alloys are less sensitive, exhibiting strength reductions of around 2-2.5 times (Plumbridge et al., 2003). In long term applications, strain rates may be extremely low, so the use in modelling of strength data determined from higher strain rate tests may be severely non-conservative. However, the lower sensitivity of lead-free alloys is some consolation.

Ductility
Ductility is considerably less sensitive to temperature and strain rate than strength. Solders operate at temperatures well above the possibility of any ductile - brittle transition (as occurs in steels) and can be regarded as ductile materials. Ductility measurements, either from strain to fracture or reduction in area, are generally less precise than strength determinations. Figure 6 indicates that Sn-37 Pb and Sn-0.5 Cu are more ductile than the silver-containing alloys, although few points fall below a 20 per cent ductility level. Within the range examined, there are no clear trends regarding the influence of temperature or strain rate.

CREEP:

Creep can be manifested by excessive deformation and fracture in unconstrained situations or by stress relaxation, internal cracking and failure where geometrical constraint exists. It is a time-dependent, thermally-activated, process and extremely temperature sensitive. For example, the creep rupture lives of Sn-37Pb at -50, 22 and 125°C with a constant stress of 10 MPa are roughly 104, 30 and 0.1 h, respectively (Figure 7) - a variation of 105 times (Plumbridge and Gagg, 2002). Lead-free alloys are similarly sensitive to temperature, although direct comparisons on the basis of applied stress are sometimes difficult due to extended rupture times. With an applied stress of 30 MPa, for example, the rupture times of an as-cast Sn-3.8Ag-0.7Cu solder at 125°C, RT and -10°C are approximately 0.1, 200 and 8×104 (Plumbridge et al., 2001a). These differences can be seen in the different slopes of the stress vs rupture time plots at various temperatures. The creep properties of Sn-0.5Cu are broadly similar to those of Sn-37Pb, but the resistances of the binary and ternary silver-containing alloys are much higher and their sensitivity to temperature is greater (Plumbridge et al., 2001a). From the modelling and reliability perspectives, the need to know creep properties over the range of the service cycle is therefore most important in these alloys.

The benefits of greater creep resistance in the silver-containing alloys arise at the expense of ductility. For example, creep strain to fracture in the ternary alloy is usually below 20 per cent at temperatures between -10 and 125°C but rarely falls below 10 per cent.

An important consequence of the difference in nature between Sn-37Pb and the lead-free alloys, is that the dispersion strengthened characteristics of the latter result in very high stress exponents in the minimum strain rate - applied stress relationship (m=Cσn). While those for tin-lead are in the range 3-7, n values for the ternary Sn-3.8Ag-0.7Cu alloy generally exceed 10 and increase with diminishing temperature to 18 at -10°C (Plumbridge et al., 2001a). Such high values cause problems for reliable modelling and may lead to convergence difficulties in finite element analysis.

Creep behaviour may be used as a vehicle for two other points of debate. The first relates to prior thermal history and Standards for Evaluation of Mechanical Properties. Due to the low melting point of solders, their microstructure in the as-cast condition is inherently unstable at ambient temperature (Th0.6). Consequently, significant variability may be observed in determined properties. Some workers and proposed standards advocate a stabilisation anneal (such as 1 h at 100°C) to produce a microstructure which will remain essentially constant during testing. The contrary view is that since joints are small castings and experience no further heat treatment, it is more realistic to assess properties in the as-cast condition. Creep tests on Sn-3.5Ag at 75°C indicate a potentially significant effect of a factor of about seven times increase in the minimum creep rate after annealing (Plumbridge et al., 2001b). This was not translated into a proportional effect of the creep life, because the changes in ductility opposed the effects of those in strain rate thereby reducing the overall effect (Figures 8 and 9). This emphasises the importance of selecting the salient parameter in design-strain to failure or lifetime.

A second factor which has attracted much debate is the potential of tin-zinc based solder alloys. Although having melting points much closer to that of Sn-37Pb, they are reportedly prone to oxidation and fluxing problems (Richards et al., 1999) and have been investigated sparingly in Europe. In terms of creep, Figure 10 shows that for lives of up to 100 h they can match the silver-containing alloy but at longer lives (lower stresses) they are intermediary between, Sn-3.5Ag and Sn-0.5Cu (Shoji et al., 2004). With further stress reduction (lives above 1,000 h) their creep performance becomes progressively more inferior to the silver-containing alloys. This is a good example of the need to carry out realistically timed creep tests and, perhaps further impetus for tackling the oxidation/fluxing challenge?

FATIGUE:

Owing to their small yield stress, the vast majority of conditions experienced by solders in service fall into the high-strain category, i.e. there is significant plasticity involved. An exception is high frequency vibration involving numerous elastically-dominated cycles, with the performance of a material governed by its strength. Since ductility is a principal factor in determining high strain fatigue life (Plumbridge et al., 2003) it is not surprising, from the previous comments regarding that property, that low cycle fatigue endurance is relatively insensitive to temperature, composition and many other parameters. This is shown well in Figure 11 which demonstrates that the continuous cycling fatigue life of bulk Sn-37Pb varies by less than an order of magnitude in the temperature range -40-150°C (Shi et al., 2000). Lead-free solders containing bismuth, however, are very sensitive to composition. At room temperature, the fatigue life of Sn-3.5Ag diminishes progressively with bismuth content, until at 10 per cent bismuth it is 3-4 orders of magnitude lower than the pure binary alloy (Kariya and Otsuka, 1998) (Figure 12). In contrast to bismuth, Kariya and Otsuka (1998) also found that additions of copper, zinc or indium had little effect on fatigue performance of the alloy. These exceptional data indicate the potential pitfalls of thinking across behaviour and properties from one alloy to another. Service cycles which include dwell periods or asymmetric heating/cooling rates may result in life reductions of a factor a 10 or higher, although there appears little consistency in the observed trends to date.

When the performance of joints is considered, the observed behaviour becomes even more specific, involving additional factors such as joint geometry, thickness and profile of the intermetallic compound (IMC). When thermal effects are constrained, as after a few thermal cycles, the location and accumulation of damage in mechanical shear fatigue and in thermomechanical cycling are similar (Chen et al., 2002; Howell et al., 2002). Failure generally occurs by the initiation and growth of cracks in the highly strained regions in the solder, adjacent to the IMC. While some findings suggest that solder type has little effect on the joint strength after thermal cycling (Harrison et al., 2001), other data with different joints and solders seem able to discriminate the effects of small compositional changes (Kariya et al., 1999), for example, compare Figures 13 and 14. Again, addition of bismuth has a significant effect, leading to as much as a halving of residual joint strength. It is evident from such, often conflicting, information that ab initio design and modelling is a long way off. There is much to understand.


SUMMARY

The purpose of this paper has been to raise the profile of factors that may be safely neglected in routine applications operating in a benign environment. There is an inherent conservatism built into these. However, for long term usage, there is an automatic requirement for higher reliability but it is under these very conditions of prolonged exposure to temperature, cyclic temperature and extended times that the additional factors described above may come into play. The natural reflex of thinking across from one alloy to another, or from one set of operating conditions to another, is common and understandable but it can be dangerous. Each specific combination of solder alloy, joint type and service conditions should be considered on its own merits. The current paucity of understanding of the mechanical behaviour of solder alloys and solder joints demands this.

Several of the features considered here cannot be identified and evaluated by accelerated testing. For example, the incubation period for tin pest formation may be several years (Hedges, 1960) and the balance between thermodynamics and kinetics indicates that the transformation in pure tin occurs "most rapidly" at -40°C. At the Open University, both bulk and board samples have experienced low temperature (-18 and -40°C) ageing for several years, but the results are far from complete. While it would be imprudent to say at this stage that tin pest will become a serious problem for extended low temperature (sub-zero) applications involving some of the most common lead-free solder alloys, it is appropriate to highlight the possibility. For example, failure of a satellite, after half of its projected 20-year life, due to disintegrating solder joints would be a costly exercise.

With regard to service performance and long term reliability, the prognosis for the implementation of lead-free solders appears optimistic. Despite the difference in the intrinsic type of alloy, the influential mechanical properties of the more dilute lead-free systems are similar to, or exceed those of traditional Sn-37Pb. Substantial advantages accrue with the silver-bearing alloys in terms of strength and creep resistance, at the expense of a slight loss of ductility.

However, within that generalisation many factors remain unresolved. For example, the profound effect of bismuth on mechanical and TMF is exceptional. There is a pressing need to understand the reasons for this and to identify other additions that may produce similar effects. Further, since the properties of the Sn-Zn-Bi alloys are adequate and there are no material cost penalties, there seems further impetus for solving the processing difficulties associated with them to enable their lower melting points to be exploited.

For high reliability, long term applications, the capability of empirical approaches, however, extensive and accelerated, must be in question. They will become uneconomic at best and potentially unreliable. In many cases, available mechanical property data have "runaway" from the understanding of the mechanisms that are responsible for them. The effects of bismuth are a classic example of this. A greater understanding of the physical metallurgy-mechanical property relationship in solders is required to underpin design and lifetime prediction. It is a global challenge with enormous scope for international collaboration. The absence of consistent standards for determining properties is an additional difficulty that should be addressed with urgency.

Paper by W.J. Plumbridge

 

[rsaavedra]

Quote:

Originally Posted by Captain Scarlet Mass production plants all over the globe will therefore pump out 10% more heat instead. More heat = more global warming.

I'm sorry, but this is seriously going down the drain of material for yellowish newspapers talking about the chupacabras. I hope you are not serious pretending to associate increased global warning with the temperature difference soldering each soldering joint in plants in the whole world switching from lead-based to lead-free solder.

 

[PinkFloyd]

Quote:

Originally Posted by rsaavedra I hope you are not serious pretending to associate increased global warning with the temperature difference soldering each soldering joint in plants in the whole world switching from lead-based to lead-free solder.

If it takes 10% more heat to melt lead free solder then that is 10% more heat being generated period. every little bit of extra heat goes toward global warming (global "flooding" in Scotland) whether it's from coal fired power stations, electric kettles, cars, cigarettes, industry, heating systems..... you name it, they all contribute to global warming and 10% temperature increase to melt unleaded solder will only "add" to global warming....... it can't be denied.

Look around your home and count the number of appliances that contain PCB's with hundreds of solder joints...... your computer, your TV, your Hi-Fi, your microwave, your car, your fridge, your freezer, your hoover, your hairdryer, your electric toothbrush, your shaver, your remote controls etc. etc. etc etc.................

Now, if you were the only person in the world who owned these items then a 10% increase in solder melting temperature would be highly insignificant.

There are, however, 6 BILLION people in the world and if only 2 billion of those people owned the same stuff that is in the average home then I think you can accept that a [size=x-large]hell[/size] of a lot of heat is generated by soldering.........

Go sit in a room and solder together a TV, a computer, a hi-fi etc etc and then imagine the heat that would be generated if you were soldering BILLIONS of them.

It's easy to forget that there are BILLIONS of consumers on the planet and not just you so, yes, I agree with Captain Scarlet and 10% extra heat from soldering will make a big impact on global warming.

 

[rsaavedra]

Quote:

Originally Posted by PinkFloyd If it takes 10% more heat to melt lead free solder then that is 10% more heat being generated period.

Yes so what, now every localized heat increase in the world will be connected to global warming, and therefore prevented or regarded as environmentally hazardous???? Hey don't go out and do exercise, the extra heat you are generating will be hazardous to the environment as well. Don't turn on your kitchen, or even your audio equipment, hey for goodness sake don't dare to turn on your heating system in winter... and so and so forth. There are matters of scale here that are being ridiculously ignored.

 

[cosmopragma]

Quote:

Originally Posted by rsaavedra Yes so what, now every localized heat increase in the world will be connected to global warming, and therefore prevented or regarded as environmentally hazardous???? Hey don't go out and do exercise, the extra heat you are generating will be hazardous to the environment as well. Don't turn on your kitchen, or even your audio equipment, hey for goodness sake don't dare to turn on your heating system in winter... and so and so forth. There are matters of scale here that are being ridiculously ignored.

Well, and don't breathe, exhaling carbon dioxide should at least been taxed.

 

[PinkFloyd]

Quote:

Originally Posted by rsaavedra Yes so what, now every heat increase in the world will be connected to global warming

No, every heat increase will "contribute" toward global warning..... each small candle lights a corner of the dark but each small candle can also make a big fire.


Quote:

Originally Posted by rsaavedra Hey don't go out and do exercise, the extra heat you are generating will be hazardous to the environment as well.

Why shouldn't Europe tax joggers? It may be their most sensible idea yet

Quote:

Originally Posted by rsaavedra Don't turn on your kitchen

That could be taken 3 ways and I shall answer all three:

1: I never feed my kitchen mind altering drugs

2: I never sexually excite my kitchen

3: I am never angry to my kitchen



Quote:

Originally Posted by rsaavedra There are matters of scale here that are being ridiculously ignored.

Yep six billion "consumers" who are each impervious to the existance of the other 5,999,999,999 people who are all "consuming" the same as they are and think that a 10% temperature rise in solder melting point is inconsequential.

Give me cool water out of lead pipes anyday.