Not really, I was pretty specific. Wanted to know what people knew about vias. My iPhone is IP rated, though no one really touts it as a submersible phone.
They actually use that in the marketing for the phone I have. In the ad it goes into multiple situations including full submersion.
Now on to what op is asking:
Which style vias/PCB will be cheaper?
If you are curious on the price difference of the different via technologies then just quote the four PCBs at volume. My gut tells me that plugged vias will be the cheapest and buried vias will probably be the most expensive. Again this really depends on the application. You may be able to spin a smaller PCB if you go 4 layers with buried vias.
Which will be most reliable?
You really have not talked about the environment or device life cycle this PCB will be subjected to. This can be determined by testing. Buy all four types and subject them to aggressive environmental aging. This will also very dramatically with material types.
Which will be easiest to manufacture, or find manufacturers to be capable?
Quoting the four types again will tell you. Since you did not really specify what industry this if for it really depends. A generic commercial PCB suppliers you would go to for a cheap product capabilities will be different than a supplier you would go to for automotive or aerospace.
Thanks for the reply. Of course testing all options would be desirable, but since time and money are always limited, I was hoping for some experience from others to narrow the field a bit.
Here is a bit more background. Maintaining the internal moisture levels to "very low" is desired. Desiccant is fitted internally during manufacture, and the device is submerged for leak testing. This ensures a dry environment inside the unit. It is a 15 year product in an outdoor environment. It is not our first.
We have previously used a PCB with gold pins soldered to it to interface power and comms to the outside world, but never needed to run tracks under the seal, as the pins are through hole. In an effort to improve the BOM cost and ease of manufacture, the one time use comm port interface has been designed onto pads instead of gold pins, in the same area that the gold power pins are located. A battery connects to this location, and covers it, but doesn't seal it airtight, just shields it from direct exposure to light, dust and rain. Moisture does not pool in this area, it is designed to dry following high humidity.
This design is in use in another 15 year product. The BOM cost is low, the parts always engage correctly, and we already have the pins (albeit a few bucks a mating pair). The new parts are the use of pads for the factory load (pogo pins on the factory loader - low volume), and the tracks routing under the seal if no vias are used. All other issues regarding the use of the pins, FR4's hygroscopic properties (which is practically non existent by the way - it is an excellent insulator and absorbs very little moisture -
https://en.wikipedia.org/wiki/FR-4), the seal material and clamping force of the seal, have been tested and work as designed. Re-engineering is expensive.
I am nervous about the pads, hard gold plated or not, i think salt fog testing will kill these, even though these pins are not powered after the initial load. We will see.
The Mech Eng is nervous about the long term seal if there are tracks running under the seal. Hard to test in a short amount of time. We would prefer to avoid than test this.
That is what lead to my specific request for experience with alternatives for the tracks (ie via options). Truth is, if the pads are a no go, I will probably use IrDA from inside the sealed area and the sealing problem disappears, but would prefer to keep it simple for both hardware and firmware.
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