41 battery circuit - opinions wanted


I again received an email from the chinese company that does the flex ciruits. I am not an electronics twinky and so I don't really know how to describe the 41's battery tracings. I suspect Don Wallace or someone of his caliber might be better with this than myself. I am interested in pursuing this, however I wonder if these guys are legit and, if this might be a realistic option.

Anyways, the message follows. The only mention of a company however is at the bottom of the text whom I suspect is only a portal like yahoo.

****** message begins ********************************

Dear sir,
Wish you have good health!

We are glad to introduce a printed circuit (FPC ,PCB) factory. We use
The latest technology make flex(rigid, rigid-flex) printed circuits for use in any
Electronic products.the factory is iso9001:2000 confirmed and IPC
The main capacity:
We can make "ROLL TO ROLL" flexible printed circuits.

We can make very long ( 250 mm x 100 meter) single sided flexible printed circuits item.

We can make 4 layers ,5 layers,6 layers rigid-flex printed circuits.

We can produce 3 layers,4 layers,5 layers,6 layers flexible printed circuits and double side with min 0.06mm trace width. The square hole of the coverlayer can be min 0.4 mm.

We also can produce 4 layers,6 layers,8 layers,10 layers,12 layers rigid printed circuits board(PCB).
and 14 layers,16 layers,18 layers,20 layers HDI rigid printed circuits board.

Our products have exported to USA,Canada,Japan,UK,Germany,France,Australia etc
More then 20 countries.

We would welcome you to visit our factory.

Please e-mail your circuit design by gerber file,or auto cad,or protel files and
advise us of: Fpc size, and number of layers.

You can get the directly factory price!

We can make samples for your approval.

Thank you for your support!

Best regards!

chai ming di



Yes, they are probably legit... but most Chinese compaines only want to do business with you if you want to order a zillion pieces. You can ask them though. There are US companies that will do small lot/prototype orders. Setup charges can be high.


How many do you want to make? If it's only a couple, the setup charges (or having to buy thousands) will be a kiiler, so you might want to get some adhesive-backed copper foil and make (or repair) your own. This kind of material is used for things like connecting top & bottom ground planes on RF stripline or microstrip circuits around the edge of the board-- at least that was my first exposure to it. I got a roll of it for practically nothin' at an electronics swap meet.


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I have not seen the stuff Garth spoke about. Assuming the material was available at reasonable cost, One would have to go to a lot of trouble to actually build a rig to do, say ten, flex PCB's. This is called tooling up. One makes a phtotmask, builds/buys a UV lightbox, makes/buys an ecthing tank, etc.,etc. Once the photomask was made then one could make a hundred, of course. I may consider this if I could get the flexible copper/mylar. Garth, is that stuff etchable (without adhesive failure)?

For just doing one, I would first try to stick the copper foil on the plastic backing and draw the pattern on it and then use an X-Acto knife to make the cuts (being careful not to cut the plastic backing), and peel away the unwanted material. You might have to experiment with different backings to find one that can handle whatever small amount of soldering you need to do. Then I would probably just cover the parts I want insulated with a good transparent packing tape.

I was thinking earlier about whether you could etch this stuff like a PC board. I guess the thing to do would be to experiment. I used to etch my PC boards for home projects (and did many, many of them) but I abandoned that over 20 years ago in favor of off-the-shelf breadboards that are available in different types for different kinds of projects. With the right kind of breadboard, I can usually exceed the density I was getting before (sometimes having to cut a trace here and there), and I no longer have trouble with corrosion. With the home-made ones, it seemed like no matter how well I washed them after etching, some etchant must still have been held in the pores of the board, and a year or two later a tiny bit of corrosion would start to show at the edges of the traces.


At a 2004 electronics industry trade show in Vancouver, I noticed one rep had samples of flex circuits. When I inquired about ballpark setup charges, minimum quantities, etc. for a single sided design, I was astounded.

The fee was around US$400 for setup, plus $150 per (whatever you could fit on an) 11x17" panel.

This was presuming you provided ready-to-use artwork, and yes, this really was flex... copper on kapton. I didn't ask about masking and gold plating, but I did ask about cutting the outline... it could be arbitrarily complex as they etch the kapton.

Perhaps the reality is different from the ballpark guesstimate, but I think it is worth investigating.


Since then, I've been pondering the question of how to attach a 41C replacement flex circuit so that it doesn't require the plastic welds... I think this is key to making a successful retrofit. I have some ideas but whomever is going to take this on probably has their own :-)




I have seen people pay over $100 for a replacement battery contact assembly... too much in my opinion. But I suspect if you can get the costs down to around $50 or so to replace a bad one, that you could sell a good amount of them. Setup charges of a a couple of hundred bucks or so would not be too bad spread out over a run of 100 or so pieces.

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