One of the hardest things to do while developing a new product is to make changes even when something already works.....
Everything in your body is telling you - "If it ain't broke, dont fix it!" - and that is sound advice if you are working on a finished product that someone else has already perfected. On the other hand - when it is your own prototype and you are in early development it is CRITICAL that you try new things - assemble it different ways - try different methods. In my experience the first way I come up with for doing something is usually the slowest, most painful way you could possibly imagine - and the results are about as good. With time though - and a willingness to take risk and try new methods the product slowly starts to get better.
Here is a good example - 50 pin flat flex cables. 100 total solder points. .050 spacing so rework is a nightmare... a mistake spells at least an hour of careful rework and possibly scraping a board (that already has an hour of work into it). These are 4 layer boards with 0.006 traces so if you peel a via you are done.
Notice up at the top... first I was running one flat flex on either side of the PCB. This was actually by design - details I wont go into here - but what I failed to realize is that there would be interference issues with the RJ45 jack
So I made a change on the second from the top by swapping the inner and outer rows. This fixed the problem but it is still a crappy cable exit
By the 3rd from the top I have put both cables on one side. I still have to use the Kapton tape to avoid shorting the cables to via's on the board or eachother
By the bottom I have dialed it in... Cables lay flush and exit at 90 degrees. No tape is visible and it is easy to inspect and trim the pins.
I really was nervous each time I made a change. It seems trivial.... but once you have spent as long as I have soldering 0603 parts - the last thing on earth you want to do is risk scraping a board by making a stupid change that ends up not working (mind you - those cables are staggered and need to interface with another board on the other end)
Anyhow - another big realization I had was which side to solder the ribbons on. If you solder on the "pins" side what happens is that they are so close (0.050) that when you trim the pins all the solder pads mush together and you get shorts all over the place. To get around this I was doing all sorts of stupid stuff like trimming them with razor blades, pre-cutting the pins, etc. It is a total nightmare. Once I started soldering on the back side (non-pin side) I was able to just trim the pins with ease.
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We went on NFEA 2011 Part 2 last weekend (hrm - never posted part one)
We tend to make very large fires by dragging dead trees or branches and just feeding them in as they burn. For this you sometimes need a 10' long stick to cook marshmallows. I made my stick for an even bigger fire - but the wet wood we had was not cooperating.
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