How InPlay Known Good Die Format Enables Sub-$0.50 BLE at Scale

Bare BLE chip dies on a wafer ready for direct integration into low-cost consumer products

Your BLE SoC is 50% of the BOM. The product is a single-use medical patch that has to retail for under $5. Every cent of silicon kills the business case, and you’ve already squeezed the packaged Nordic part as hard as your distributor will let you. The math doesn’t work.

Here’s the gap most engineers miss when they hit this wall: the package itself can be 30 to 50% of what you’re paying for that BLE chip. Molded epoxy, leadframe, test handling, tape and reel. You’re buying silicon plus a lot of plastic and logistics.

That’s where InPlay’s Known Good Die (KGD) program comes in. It’s a different procurement format that strips out the cost structure entirely. Sub-$0.50 BLE pricing is real at qualifying volumes for disposables, smart labels, and high-volume asset tags, but only if your assembly path can handle bare die and you commit to the volume tier. Nordic and TI packaged BLE parts typically anchor between $1.20 and $2.50 at 10K volume on distributor pricing. KGD lives in a different cost regime.

What Known Good Die Actually Means

KGD is unpackaged silicon that’s been wafer-tested for both digital and RF function before it ships to you. You receive it on wafer, in waffle pack, or on tape. There’s no plastic body, no leads, no markings.

The “known good” part matters. Plain “bare die” is just diced wafer with no guarantee that any individual die works. KGD has been through full electrical and RF test coverage at the wafer level, so the die you bond down has the same test pedigree as a packaged part. Without that, your assembly yield falls off a cliff.

Removing the package buys you three things: lower unit cost, much thinner profile (typical KGD is around 150 µm thick versus 2 to 3 mm for a QFN), and assembly flexibility. You can bond directly onto FR4, flex, or a label substrate.

InPlay’s KGD program currently covers parts in their IN100 and IN612 family. Confirm current SKU availability with InPlay sales, since the KGD-available list moves with wafer runs.

Packaged SoC          Known Good Die (KGD)
+-------------+       +-----------+
|  [ die ]    |  -->  |   die     |
|  + leads    |       | (tested)  |
|  + epoxy    |       +-----------+
+-------------+       ~150 µm thin
~2-3 mm thick         no package cost

Why KGD Unlocks Sub-$0.50 BLE for Disposables and Smart Labels

The cost stack on a packaged BLE part isn’t all silicon. You’re paying for the leadframe or laminate, the mold compound, the assembly and singulation steps, final test in the package, tape and reel, and the test handler amortization. Strip those out and a meaningful chunk of the price disappears. A different unit is being shipped.

A few caveats before you put a number in your business case:

  • Pricing tiers and MOQs are negotiated with InPlay directly. Any figure in this article is illustrative. Get a real quote.
  • Sub-$0.50 typically requires committed annual volume. The rule of thumb is 100K+ units per year, but that floor moves with the SKU and the wafer scheduling.
  • The savings are net of added assembly cost, not gross. More on that below.

The applications where this combination actually closes are predictable: smart labels (logistics, retail, cold chain), single-use medical patches, disposable asset tags, and any product where the form factor is already flat and the assembly partner already runs chip-on-board (COB) lines. If you’re shipping into those segments, KGD is probably already in your supply chain somewhere, just not for the BLE part yet.

How to Evaluate InPlay KGD for Your Product

Five steps. Do them in order.

Step 1: Confirm application fit

  • Annual volume of 100K+ (verify the current floor with InPlay)
  • Flat or thin form factor where the 150 µm height is a feature, not a tolerance
  • Existing or available chip-on-board or flip-chip assembly capability

If you’re at 25K units and your assembler only runs SMT reflow, stop here. Packaged parts win.

Step 2: Validate with your assembly partner

Before you talk to InPlay about samples, talk to your contract manufacturer. The questions:

  • Can they take wafer or waffle pack input?
  • Do they have wire bond capability, flip-chip, or both?
  • What’s their experience with glob top and underfill encapsulation?
  • What’s the assembly cost delta versus their SMT line for your volume?

If they hesitate on any of these, you have two options: find a CM that already runs smart label or medical disposable lines, or stay on packaged parts.

Step 3: Request samples and the KGD design package from InPlay

The design package is what makes the integration tractable. You want:

  • Wafer map and bond pad coordinates
  • ESD handling guidelines (KGD is more sensitive than packaged parts)
  • Recommended bonding diagram and pad metallurgy
  • Reference layouts for COB and flip-chip

Step 4: Build the cost comparison properly

This is where most evaluations go wrong. Engineers compare the KGD unit price to the packaged unit price and stop. That overstates the savings because KGD adds assembly and encapsulation cost. Build a fully-loaded comparison:

Cost Element           Packaged    KGD
---------------------  ---------  --------
SoC unit price          $1.50      $0.45*
PCB / substrate area    $0.08      $0.02
Assembly delta          $0.03      $0.06
Encapsulation           $0.00      $0.04
---------------------  ---------  --------
Loaded BOM impact       $1.61      $0.57

* illustrative; confirm pricing with InPlay

The savings are real but smaller than the headline price suggests. At these illustrative numbers, you’re saving about $1.04 per unit, not $1.05. Across 500K units a year that’s still half a million dollars, which is why the format exists.

Step 5: Run an RF validation build

KGD on a substrate behaves differently than a packaged part on PCB. Antenna tuning, ground plane assumptions, and matching network values all need re-validation. Plan for at least one spin between your first bond-down build and a frozen design. If you’re building on a Hubble-connected device, the terrestrial transmission guidance gives a sane baseline for output power and antenna efficiency targets.

Light Integration Walkthrough

Once you’ve made the call, the integration itself is well-trodden in the smart label and medical disposable industries. Here’s the shape of it.

Substrate choice. FR4 works for asset tags. Flex PCB works for patches and wearables. For smart labels, you’re typically on a label-grade laminate with printed conductors. Talk to your CM about pad finish; ENEPIG is common for wire bond.

Bond pad layout. Use InPlay’s pad map exactly. Don’t optimize the layout to save substrate area before you’ve confirmed bond yield with your CM.

Wire bond vs. flip-chip. Most smart label lines use wire bond plus glob top because the equipment is cheaper and the process is forgiving. Flip-chip gives you better RF performance and a thinner stack but needs underfill and tighter substrate tolerances. For a first KGD product, wire bond is the safe choice unless you have flip-chip already running.

Antenna integration. Three options: PCB trace antenna (cheapest, biggest), chip antenna on the substrate (smaller, adds BOM), or printed antenna for label products (cheapest at scale, requires tuning expertise). Re-tune for the substrate stackup. Don’t reuse the packaged-part reference design without measurement.

Test access. Keep SWD pads accessible during development and pilot production. Once the firmware is locked, you can drop them for the production stencil to save area. If you’re doing over-the-air provisioning, see Hubble’s end-device provisioning guide for how to avoid needing physical test access in the field.

Encapsulation. Glob top is the default for disposables. For medical patches, validate against your sterilization process (EtO, gamma, or autoclave each have different effects). For cold-chain smart labels, check moisture ingress over the product life.

First-build checklist.

  • Bond pull tests on a sample of units, target above your CM’s spec
  • RF output power and frequency centering verification across the band
  • Current consumption sanity check in sleep, advertising, and TX states
  • Drop and flex testing if the product is wearable

When KGD Is Not the Right Answer

KGD is the wrong path if any of these are true:

  • Annual volumes below 100K. The integration overhead doesn’t amortize.
  • No existing COB or flip-chip capability in your supply chain, and no appetite to qualify a new CM.
  • Designs needing field rework, sockets, or modular replacement.
  • Harsh environments where you can’t commit to a qualified encapsulation strategy.

In all of those cases, packaged parts from InPlay or another vendor are the better answer. KGD is a high-volume, high-commitment format.

Volume >100K/yr? --no--> Use packaged
     |yes
COB capable? ----no--> Use packaged or qualify new CM
     |yes
Flat form factor? --no--> Evaluate case-by-case
     |yes
     v
  KGD candidate

Getting a Real Quote From InPlay

The numbers in this article are illustrative. To build a real business case, contact InPlay directly for current KGD pricing tiers, the design package, and sample wafers for your target SKU. Bring your annual volume forecast and your CM’s COB capability sheet to the first call. Both questions will come up in the first 10 minutes.

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