nRF52 WLCSP PCB Cost Very High: How to Reduce?

[Bill Finger]

We have recently completed the design for a product prototype using the 0.4 mm pitch nRF52832 WLCSP. When we sent it to the board production house, the cost to produce it was exorbitant, particularly when compared with our previous prototype which used the QFN part.

It seems that there are challenges using typical low cost PCB assembly techniques with 0.4mm pitch devices. Yet it would seem that this product is intended for low cost applications. How can we use this form factor and still produce inexpensive devices?

[AmbystomaLabs]

I disagree strongly that flip chip parts are intended for inexpensive applications. They are intended first for small form factor not necessarily low cost. For comparison, some of the least expensive products on the market are still using through hole parts. Very large form factor but super cheap.

However, you should research other board vendors. My favorite is Pentalogix. Their offshore service offers 3 mil traces with 3.5 mil spaces, 8 mil drills and even 3 mil laser drills if you choose to do an HDI design.

Just running some guesses on their quote engine produced prices of under $0.50USD a board on an 8-up array with 4 day lead time at qty 500.