[citation][nom]gom99[/nom]@maestintaoliusSince it seems like you're in the business. Is this something that can be mass fabricated easily? How much more time and money would it cost on top of the current Antennae design?What's a good thickness that wouldn't chip?Wouldn't the antennae need to be made smaller to account for the extra dimensions of the finished product since it's a flush fit?[/citation]
Heh, I wish I could give answers like 7, 4 and 8 to all those questions, because they're pretty much the exact ones you need to figure out when designing something. So the answer is, it varies. Well, except on mass production, that I can answer with a definite yes it's mass producible.
Generally, coatings placed on base metals (in my industry) range anywhere from a few mil (1/1000 in) to 30+ mils. The usual driving factor for thickness in our applications is concerns over thermals (so you don't want to go to thick) vs concerns about dielectric (so you don't want to go to thin). A secondary factor on the thin side as a limitation is the particle size of your pigments and other fillers - the rheology of highly filled systems start to get weird below 10x your largest particle size and really weird below 5x. Physical durability generally improves with thinner coatings because the ceramic is able to bend and flex along with the metal more easily (chipping in our cases is usually more prevalent in thick coatings while thin will typically flex and recover). This has to do with angles and distance, you can think of a bend as a arch where the inner surface of the bend experiences compression and the outer surface experiences tension, the greater the difference in radius of those two surfaces from their common center (i.e. the thickness), the higher the force tensors will be on the surfaces. Of course, you can go super thick to the point where things don't flex or bend much at all (but shatter with enough force), but that costs more.
In the case of an handheld antenna, we're not talking real high voltages or parasitic loss (unless you're Emperor Palpatine) so you would ideally go as thinly as possible so fitting tolerances shouldn't be TOO affected. Apple being Apple, they'd probably want to color it, so that'd result in needing to know dimensions of pigment particles/conglomerates and how much thickness/pigment concentration is required to attain the desired color intensity which would put a minimum boundary (plus coating tolerance) on the design thickness.
So, as far as thickness to prevent chipping, well it really depends on if the minimum thickness you can coat is flexible enough to not break under 'typical' use conditions (whatever that means), otherwise you might be forced to go thicker to make it harder, but then it costs more, especially if you have to redesign the phone to fit the new part. Without knowing Apple's tolerances and their suppliers' tolerances, I can't really give a yes or no answer. Dealing with OEMs a lot, the thing that surprises me most is how ridiculously bad the tolerances are on machined parts, especially in Asia (it's not uncommon for me to see board to sink gaps with absolutely silly tolerances like 0.030"±0.020, much to my annoyance).
As far as cost, well I don't know how much simple coatings will cost because my company's materials are designed mostly to deal with high power or high voltage situations. Just based on some simple guessing from the iphone antenna size, our material would range from anywhere from 50 cents to maybe a few dollars an antenna, but that's our material which is designed for significantly different applications. I wouldn't be surprised if Apple could get away with a simple 8-12 mil coating of pigmented enamel or epoxy for 10-20 cents or less an antenna. It may not sound like a lot, but when you start talking millions of phones (not to mention additional testing to verify the fix works and various other regulatory retesting that may or may not be required) the numbers can start to become pretty large. My guess, however, is Apple's margin is large enough on the iPhone4 that they're not going to fret over the cost of coated antennas, if it was something like a low margin, high volume low-end consumer phone, a couple cents can have very large effects on end profits. *disclaimer - these are not guaranteed quotes so anyone interested would need to contact their vendor's sales dept
Anyway, I realize this is a longer answer than 99.4% of the people here will care about or read but I enjoy sharing knowledge of the dark OEM underworld that most consumers never think about (so long as it doesn't get me in trouble heh). It's also serving as a personal distraction from the bad news I got today from the vet that my cat is very, very sick (lots of fluid in his lungs
- he's indoor only, only 5 years old and the tests aren't back yet so with no determined cause of said problems so my engineering brain is very frustrated over a lack of a defined cause and effect situation, not to mention the resulting very upset wife). So you'll have to bare with me that I rambled on for 30 minutes heh.