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Emerald Group Publishing Limited
Copyright © 2004, Emerald Group Publishing Limited
There’s a cool Web of language
Keywords: Internet, Security products, Cleaning, Solvents
Over the past few issues, my major concern has been one of security. I’ll just mention one point about it, here. I recommended the ZoneAlarm firewall in the past. If you took my advice, you may have seen that the authors have issued a version 5.0.590.015. Do not install this version, it has some severe bugs that can crash Windows and stop e-mail downloading (the voice of experience!). Hopefully, by the time you read this, there will be a new version with a higher number which will have been tested before issue. However, I’ll discuss Web site design, this time round. Regular readers from a few years ago will remember my concerns about the speed of downloading Web sites. They may also be able to recall that I promoted the use of meta functions to improve search engine performance. Things have changed, but not that much.
Let us keep in mind an inescapable fact: only about five per cent of users connected to the Internet have broadband connections. As a case in point, I do not have one, although I requested it nearly three years ago. DSL hardware, at the exchange level, is simply not available where I live. The same applies to many countries; for example, my daughter in Switzerland cannot obtain an ADSL connection, even though she lives in a dormitory village just outside a large city. The same applies to cable systems. So, I appeal to everybody who designs a Web site, or who orders a Web site to be designed, to remember that the vast world uses telephone line modems which are limited in speed and bandwidth. Furthermore, in some developing countries, these may be operating at much smaller rates than you may think. It is certainly not unknown to have connections at 14 kilobits/second or even less. I’m lucky, in one way, that the cost of online work is low, at CYP 0.20/hour (GBP 0.22, USD 0.35); my daughter is less so at CHF 4.80/hour (GBP 2.10, USD 3.30) during working hours. So, don’t forget that your viewers may be paying through the nose for the privilege of looking at your site.
Of course, if you can be absolutely sure that every single one of the persons you wish to view your Web site has wideband connections, then please feel free to ignore my remarks! What I would recommend to all the others is to check your Web site out with a telephone line modem; if you find that the download times are excessive, then you know that something has to be done if you do not wish to antagonise those who come to your site. Bear in mind that the patience of surfers is limited and that they will often abort a visit if they cannot see what they wish to see within a matter of 15 seconds or so.
This general message has not changed over the past years, although the reasons behind it are slightly different. Please allow me to give a few hints how to attract more people to your site.
A couple of years ago, I ranted against those with enormous numbers or sizes of graphics, especially on the Home Page. This is still valid and I recommend a total graphics size of less than 30 kilobytes. As an illustration, just open Google at http://www.google.com. No matter how slow your connection, it will come up rapidly, simply because the page has been well designed. Yet the title is in the form of a graphics. What else do you notice about the page? It has no unnecessary advertisements, while the links are in text form.
The important thing with graphics is to minimise them. Some Web site authoring programs will allow you to physically reduce the size of a graphics and then automatically reduce the file size commensurate with the physical size. This technique can make dramatic improvements to the download time. Another possibility, where a photograph or a detailed drawing is required to be shown, is to simply have a thumbnail image linked to the full-sized one. This can also be done automatically with some authoring programs.
There is nothing new about what I have said up to now. What is perhaps new is what I detest most! This is the Home Page with a Flash image. I would guess that I abort downloading a site nine times out of ten, if I see a Flash image starting to load, without a link to bypass it. I always know that I’m in for a long wait if I let it go on. My advice is to avoid Flash like the plague; if you must have it, make absolutely sure that your viewers can disable it. The same applies to video techniques.
Another problem which appears very regularly is that many designers like to show off their prowess by doing everything in enormously long scripts. More often than not, there are simpler methods of achieving the same ends. In fact, it is probable that, if a Home Page has more than a few kilobytes of script, it is very badly designed.
My faithful readers will remember that I used to rant about not having meta keywords and descriptions. These are somewhat less important today because the spiders used by search engines for cataloguing their links are much more sophisticated, by parsing the real meaning of the text in the pages of a Web site. It is still useful to have them, although far less essential.
No matter what, a good Web site is always legible. This means that the text should appear with a good contrast against the background, have an easily read type face and be neither too large nor too small. Personally, I dislike white text on a black background, or anything similar, because I do not find it easy to read. The only excuse for a dark background is to show off a gallery of photographs, but certainly not for text. I’m not over keen on pure white backgrounds, either, because they can be somewhat dazzling; a muted light shade is better. If you have a pattern or a watermark in the background, please make sure that it does not interfere with the legibility of the text.
What should the Home Page contain? The most important thing is, of course, a menu of some description, which will link you to at least the important pages of your site. Text should be fairly short, half a screen at the most, giving a very brief description of what the site is all about. If it is for commercial purposes, then I strongly recommend that the full name and address, telephone number, fax number and general e-mail address be added to the Home Page. The telephone and fax numbers should include the international dialling codes preceded by a plus sign, such as +357 22 532 762.
Other pages can relax these rules somewhat but, if a page is excessively heavy, it is a good idea to warn users of the fact in hyperlinks, especially if the link goes to a file, such as PDF documents or streaming video. Talking of video, the recent fine imposed on Microsoft by the EU, for their media player may be a two-edged sword. Much as I detest Microsoft’s policy of imposing their applications technology as part of their operating systems, it must be admitted that their Window’s Media Player 9 is good (perhaps apart from the hideous “skins”, designed, I think, to appeal to five-year old kiddies) and a distinct improvement on the Real and QuickTime competition for streaming. Unfortunately, the WMV format for the video is not yet universally cross-platform, as the others are.
May I make one last appeal? On your Contact us page, even if you have a form for doing so, please, please, please, also give the e-mail addresses of your key personnel or, at least, departments. Filling out forms, often requiring a lot of irrelevant information, is much less “user-friendly” and time consuming than a quick e-mail; worse, it doesn’t leave a copy in the sender’s Sent e-mail box, so he has no record of what he said or when he said it. Also, make sure that every message received, whether by e-mail or via the form, is answered (not by an automatic acknowledgement, which only wastes bandwidth) within one working day or two, at the most. There is nothing more frustrating than to send a message requiring a response, and not to receive one – and its very bad for your corporate image (I’ve blacklisted suppliers and potential ones for just that). If you don’t have the answer immediately at hand or you cannot give a valid reply don’t hesitate to say so – at least, the receiver will know. Do not just ignore an e-mail. And don’t, for Goodness’ sake, do what a supplier has just done to me; he acknowledged my order via his secure Web site by ordinary e-mail, complete with my full credit card details, for anyone to use.
My theme for the review section, this time, is one of my favourites, cleaning solvents, specifically for defluxing. There has been considerable change since I last wrote on this subject, several years ago. As cleaning is my speciality, along with its environmental effects, I intend to add some personal comments within and between the reviews. Other than the first commentary, which is something very exceptional for these columns, I’ll concentrate for this issue on the halogenated solvents and, next time, I’ll look at some of the other cleaning products.
Of course, it is impossible to find out much about water for this application, other than purification in open or closed circuits. If you use Google and type in “water”, it comes up with about 109,000,000 pages; I challenge anyone to sort that lot out! I therefore make no apology for recommending you have a look at what is possibly one of the best spoof sites (Figure 1) on the Internet, a complete story of the most common defluxing solvent used in our industry, dihydrogen monoxide (DHMO). A 30 minute digression through the many pages will surely lighten your heart. Of course, wherever there is a controversial subject, there are arguments on both sides, so you can counter the propaganda element of the DHMO argument at: http://www.armory.com/~crisper/DHMO/. If these two sites are of interest, it must be mentioned that DHMO is, by far, the best solvent for removing that most insidious contaminant from electronics assemblies, monosodium chloride (MSC). I wrote a page on MSC in similar vein a few years ago, to be found at http://www.bnellis.com/msc/ with an MSDS at http://www.bnellis.com/msc/MSC_MSDS.htm. Of course, MSC is also a common contaminant of DHMO as supplied to many factories in our industry and is also found in sea water used for bathing. It is incontrovertible that the MSC/DHMO combination is fatal for thousands, every year! Incidentally, shortly after publishing this page, I received an e-mail from a well-known international eco-political NGO, informing me that they were passing the reference to their scientific committee to determine what action should be taken to limit the use of MSC!
Figure 1 Partial screen capture of www.dhmo.org Home Page. This is a fantastic spoof site
OK, let’s become serious. I don’t propose discussing anything to do with Annex A (CFC-113), Annex B Gp. 1 (CFC-112), Gp. II (carbon tetrachloride) or Gp. III (1,1,1-trichloroethane) controlled substance solvents under the Montreal Protocol. These are already phased out in all developed countries and well on the way towards phase-out in developing countries. On the other hand, Annex C controlled substances (HCFCs) are still in use in both developed and developing countries, with phase-out schedules between 2010 and 2050. However, some countries have introduced voluntary reductions or phase-out schedules, especially for HCFC-141b, which has a high Ozone-depleting Potential (ODP), comparable with that of 1,1,1-trichloroethane.
This is a site for HCFC-141b-based solvents. Downloading the data sheet for Genesolv 2004 reveals the data for the most popular blend for defluxing, although the page warns that its production in the USA ceased on 1 January 2003. Personally, I do not recommend using this type of solvent, even where it is still permitted; it is not very good for rosin-based fluxes and it is environmentally dangerous. The MSDS can be downloaded directly from the site without any formality. Not only is it very complete, it has been very recently updated, even though it is obsolescent.
This is a data sheet for a blend based on HCFC-225. This has characteristics quite similar to those of some CFC-113 blends. The Asahi Glass Web site at http://www.ak-225.com, specific to HCFC-225 products, is quite user-unfriendly, but this data sheet (if you can find it) is very complete and informative. In developed countries, where its use is still permitted, it will be phased out by 2010, so it cannot be considered a long term solution. Like many of the low-volume speciality solvents, it is quite expensive to fill a machine, although the losses are minimised by modern low-emission vapour degreasers, so that running costs are quite acceptable. For this reason, it should not be used as a “drop-in” replacement for CFC-113 in an older machine, otherwise running costs become exorbitant. A good MSDS is available online, but requires logging in.
Another class of speciality solvent class, also expensive to purchase but economical to use in appropriate equipment, is that of hydrofluorocarbons and derivatives. These solvents have no ODP but they are responsible for climate change and are mentioned in the Kyoto Protocol. Most of them have a Global Warming Potential between 300 and 1,000 (CO2=1), so emissions must be minimised, economic factors apart. As pure solvents, their performance is totally inadequate for many applications, but blends are available for defluxing.
This is the data sheet for the DuPont product, Vertrel-SMT, which is a blend of approximately 53 per cent HFC-43-10mee (1,1,1,2,2,3,4,5,5,5-decafluoropentane, if you want the full chemical name!), 43 per cent of a chlorinated solvent (trans-1,2-dichloroethylene) and 4 per cent methanol plus a stabiliser. It is an azeotrope with a slightly lower boiling point than CFC-113 blends. It cannot really be considered as a drop-in replacement, though, because the high content of a chlorocarbon renders many plastics incompatible with it. A 13-page MSDS is available without logging-in. It is very complete, to the extent that it would scare the pants off any user! However, this kind of information will become the norm as, for example, the future REACH directive will impose additional information, not to mention the question of civil liabilities. I can’t help but compare it favourably to some other enterprises’ MSDSs, where they bend over backwards to release the bare minimum of safety information.
Sorry about the length of the URL; the 3M Webmaster must be in the throes of an organizational nightmare! The product information sheet and MSDS for 3M’s Novec HFE-71DA are downloadable from this page. This solvent is a blend of two hydrofluoroethers, trans-1,2-dichloroethylene and ethanol in fairly similar proportions to the last one. Its characteristics and properties are also similar. The data presented is, perhaps, slightly less complete, but sufficient for most purposes.
Finally, I propose we have a look at the most controversial halogenated solvent on the market, n-propyl bromide, 1-bromopropane or nPB. Personally, I am very opposed to its use for two, very good, reasons and a number of less important ones:
its toxicity has not been fully established; and
it is ozone-depleting.
There is little doubt that nPB is toxic, affecting mainly the central nervous system and the sperm count and motility. Where there is doubt is a safe operator exposure level. In a matter of a few years, the recommended time-weighted average exposure level, according to various sources, has dropped from 200 to 100 ppm to 50 to 25 ppm. To cap it all, two manufacturers recommend 10 and 5 ppm. This has recently come to a head with the very serious and independent American Conference of Governmental Industrial Hygienists (ACGIH) proposing a recommendation of 10 ppm (http://groups.yahoo.com/group/solvents_group/files/Download%20files/April-may%20\2004.pdf). However, the Department of Health Services in California recommend a limit as low as 1 ppm, although I believe this is somewhat exaggerated with little scientific base (http://www.hsia.org/updates/hesis%20npb.pdf ). I suspect that it is merely a misguided political ploy to prevent the use of this substance, altogether. Of course, this kind of exaggeration is a pure scare tactic but its lack of scientific base causes these authorities to lose all credibility (that is, if they had any beforehand!). To the best of my knowledge, no country has legislated mandatory exposure levels, yet. I don’t know what data were used by the ACGIH to reach this conclusion, but there are a number of animal results available, including a two-generation reproductive test, and some anecdotal cases with humans. In the absence of definitive data, I feel that the precautionary principle should apply. What does this mean, in practice? Well, a level of 50 ppm, with a batch vapour degreaser, is fairly easy to maintain with good, modern, low-emission, equipment, a good installation and adequate operator training. Even 25 ppm is possible, with good caution. I would say that 10 ppm is almost impossible to maintain, even with so-called zero-emission machines, because solvent vapour is often trapped under and even in the components, to be released after the assembly has been cleaned.
As for the ozone-depletion, nPB has not yet been accepted as a controlled substance in the Montreal Protocol by a technical quirk. Its atmospheric decomposition is relatively rapid, but not rapid enough for some of the substance and its decomposition products not to reach the ozone layer. Scientists have not been able to model the exact process because this is the first time that this kind of situation has arisen. What is known is that various figures for the ODP have been calculated, depending largely on the place where it is released. In polar regions, the ODP must approach zero, while it is probably larger than 0.1 (comparable to controlled 1,1,1-trichloroethane) in the Intertropical Convergence Zone (ITCZ) (typically about Å10° round the latitude where the sun is at zenith). This means that the North American continent (including the non-industrialised regions of N. Canada and the Mid-West) has an average ODP of 0.01-0.02 (still significant and similar to that of many controlled substances) but probably peaks close to 0.1 in summer in Florida and South California. However, the scientific proof of this does not exist and the Parties to the Protocol do not appear to wish to apply the precautionary principle. It should also be mentioned that one of the major production centres of nPB is in Guangdong province, which lies well within the ITCZ for about three to four months of the year, so that the inevitable production emissions would be detrimental to the health of the ozone layer. If the global demand increases from the current 10,000-15,000 tonnes/year, I fear a lot of the good work we have achieved by phasing out CFC-113 and 1,1,1-trichloroethane will be undone.
This is an eight-page document extolling the virtues of three nPB solvents, two of which are formulated for defluxing. Of course, this represents only one of a dozen or so international suppliers, so should be compared with that of others. It rather plays down the disadvantages that I’ve outlined above, but that can be expected; after all, the company does want to sell its products! The solvents are quite similar to 1,1,1-trichloroethane defluxers in performance and compatibility, and are therefore more aggressive than CFC-113 blends or any of the others I’ve reviewed earlier (perhaps only marginally so for HCFC-141b). I spent 20 minutes trawling through the Abzol site trying to find an MSDS, but did not succeed. I find this hard to accept.
Further commercial links to nPB-based solvents for defluxing can be found at (non-exhaustive list in alphabetical order):
If you examine and compare all these links, you will find that there is a lot of contradictory information, sometimes verging on the unethical. For example, one document cites its ODP at 0.002, which is sheer nonsense, even by the most optimistic calculations.
Note1. There’s a cool Web of language winds us in … Robert Graves, The Cool Web (1927)