HDI PCB Fabrication for Medical Devices
Standard rigid PCB fabrication hits a ceiling when component density climbs high enough — routing runs out, layer counts keep growing, and BGA packages stop being placeable. HDI is how you get past that ceiling. Sugamed fabricates high density interconnect PCBs for FDA Class I and II medical devices, with the material controls, process documentation, and traceability that medical production requires.
- ✦ ISO 13485 Certified
- ✦ Microvia & Blind/Buried Via Capable
- ✦ Full Lot Traceability
Is HDI Actually What Your Design Needs?
HDI costs more to fabricate than a standard rigid board, and it adds process complexity that isn’t always necessary. Before going down that path, it’s worth being specific about what’s driving the decision. These are the situations where HDI is the right answer — not a preference, but an engineering requirement.
Your BGA or fine-pitch components can't be routed out.
At 0.5mm BGA pitch or below, through-hole vias occupy the space the escape traces need to pass through. There's no routing solution that fixes this — the geometry doesn't work. Laser-drilled microvias placed within the pad are what make sub-0.5mm pitch BGAs manufacturable, and that's HDI territory.
Your layer count keeps going up, but not because of signal requirements.
If you're at 10 or 12 layers because you ran out of routing space — not because you needed signal isolation or specific impedance separation — that's a density problem, not a signal integrity problem. HDI can achieve the same routing capacity in a lower layer count, which means thinner boards, shorter signal paths, and lower fabrication cost over a production run.
The board outline is fixed, and it's too small for what you're trying to fit.
This comes up often in portable diagnostics and handheld instruments — the enclosure is designed first, or constrained by ergonomics, and the PCB has to fit inside it regardless of what the component count requires. When you can't make the board bigger, you have to make the routing denser. That's what HDI is for.
High-speed signal paths are long enough to cause problems.
Processor-to-memory interfaces, ADC front-end routing, and digital imaging signal chains are sensitive to via stub length and parasitic capacitance. Through-hole vias introduce stubs that affect signal integrity at higher speeds — blind vias and via-in-pad eliminate the stub, and HDI is how you get there without redesigning the stack-up around back-drilling.
If none of these apply, standard rigid PCB fabrication is probably the right path — see our [Rigid PCB] page. And if your board also needs to flex or fold to fit the enclosure, HDI design rules can be applied to the rigid zones of a rigid-flex build — see [Flex & Rigid-Flex PCB].
HDI Construction Types — Which One Fits Your Design?
HDI costs more to fabricate than a standard rigid board, and it adds process complexity that isn’t always necessary. Before going down that path, it’s worth being specific about what’s driving the decision. These are the situations where HDI is the right answer — not a preference, but an engineering requirement.
1+N+1 (Single Build-Up)
One layer of laser-drilled blind microvias on each outer layer, with conventional through-hole vias in the core. This is where most portable medical device boards land — it handles BGA escape routing and fine-pitch SMT placement without the cost of sequential lamination. If your design has moderate density requirements and isn't pushing into multi-layer buried via territory, 1+N+1 is usually sufficient.
2+N+2 / i+N+i (Sequential Lamination)
Multiple build-up layers, laminated in sequence. Buried vias connect inner layers without consuming outer layer routing space, and each build-up layer adds another tier of microvia connections. The density gain over 1+N+1 is substantial, but so is the fabrication complexity. Sequential lamination is justified when 1+N+1 genuinely can't support the routing — not as a default choice for complex boards.
1+N+1 (Single Build-Up)
One layer of laser-drilled blind microvias on each outer layer, with conventional through-hole vias in the core. This is where most portable medical device boards land — it handles BGA escape routing and fine-pitch SMT placement without the cost of sequential lamination. If your design has moderate density requirements and isn't pushing into multi-layer buried via territory, 1+N+1 is usually sufficient.
2+N+2 / i+N+i (Sequential Lamination)
Multiple build-up layers, laminated in sequence. Buried vias connect inner layers without consuming outer layer routing space, and each build-up layer adds another tier of microvia connections. The density gain over 1+N+1 is substantial, but so is the fabrication complexity. Sequential lamination is justified when 1+N+1 genuinely can't support the routing — not as a default choice for complex boards.
| Structure | Blind Vias | Buried Vias | Via-in-Pad | Relative Cost | Medical Use Case |
| 1+N+1 | Outer layers only | No | Optional | Low–Mid | Most portable and handheld devices |
| 2+N+2 | Multiple build-up layers | Yes | Optional | Mid–High | Compact imaging, high-density modules |
| Via-in-Pad | Yes | Optional | Yes | Mid (add-on) | Sub-0.8mm pitch BGA designs |
| Any-Layer | All layers | All layers | Yes | High | Extreme miniaturization only |
HDI PCB Capabilities & Specifications
These are our standard production capabilities for medical HDI applications. If your design falls outside these ranges, contact our engineering team before finalizing your stack-up — some parameters can be extended, and it’s better to know that before layout is complete.
| Parameter | Standard Capability | Advanced Option |
| Layer count | 4 – 16 layers | Up to 20 layers |
| HDI structure | 1+N+1；2+N+2 available | Any-layer on request |
| Microvia diameter (laser drill) | 0.1mm | 0.075mm |
| Microvia capture pad | 0.25mm | 0.20mm |
| Min. trace / space | 2.5/2.5 mil | 2/2 mil |
| Min. mechanical drill | 0.2mm | — |
| Blind via aspect ratio | ≤ 1:1 (diameter:depth) | — |
| Via-in-pad | Resin-filled & copper-capped | Available |
| Stacked microvias | Staggered (standard) | Stacked on request |
| Impedance control | ±10% | ±7% |
| Surface finish | ENIG (recommended)；Immersion Silver | Halogen-free options available |
| Base material | FR4 standard Tg；High-Tg FR4 | See [High-Tg PCB] |
| Board thickness | 0.6mm – 3.2mm | Custom |
| Electrical test | Flying probe (100%) | — |
| AOI | 100% automated optical inspection | — |
For designs that also require RF-specific dielectric materials on high-frequency layers, see our [RF PCB] page. HDI design rules apply to the rigid zones of rigid-flex builds — the flex zone construction is handled separately.
HDI PCBs We Fabricate for FDA Class I & II Medical Devices
The devices below share a common engineering constraint: the board has to carry more than standard rigid PCB construction can support, within a footprint that doesn’t leave much room for compromise.
Portable Ultrasound & Compact Imaging Systems
Handheld ultrasound has compressed what used to require a cart into something a clinician can hold. The signal processing and beamforming boards inside carry high-pin-count BGA processors and high-speed memory in board areas measured in square centimeters. Via-in-pad under BGA packages and 1+N+1 or 2+N+2 HDI construction are standard for this type of board — there isn't a routing solution that doesn't involve microvias at this density.
Point-of-Care Diagnostic Instruments
Portable and benchtop IVD instruments — blood analyzers, coagulation monitors, rapid diagnostic platforms — increasingly run detection, signal conditioning, and connectivity on a single compact board. Putting a fine-pitch analog front-end, a wireless SoC, and a high-speed digital processor on the same layout without blowing the board size is a routing problem HDI solves.
Handheld Patient Monitoring Devices
Multi-parameter monitors, handheld ECG recorders, and compact pulse oximeters fit ADC front ends, display controllers, and wireless stacks into hand-sized housings. Battery placement, display position, and connector locations typically dictate the board outline before routing starts — and those constraints push component density into HDI territory more often than not.
Wearable Medical Monitoring Systems
Long-term monitoring patches for cardiac, neurological, and metabolic conditions need boards thin enough to wear comfortably and small enough for the form factor, while running continuously for days. HDI reduces layer count and board thickness while keeping the routing density these designs need — the two requirements pull in opposite directions with standard construction.
Ophthalmic Imaging & Diagnostic Equipment
OCT systems, fundus cameras, and slit-lamp imaging attachments combine high-resolution image sensors with high-speed data acquisition. The interface between sensor and digital back end — and the signal integrity requirements along that path — benefit from the shorter interconnects and cleaner layer routing that HDI supports.
Audiological & Neurological Diagnostic Devices
EEG systems, audiometers, and nerve conduction devices measure low-amplitude physiological signals alongside digital processing and display circuitry. Getting analog and digital domains routed cleanly in a compact board area — with the layer separation needed to manage crosstalk — is the kind of problem that benefits from HDI's density and precise stack-up control.
If your device has room for a standard multilayer board and doesn’t need microvia construction, Rigid PCB fabrication is the more straightforward path. For designs that need to flex as well, HDI can be applied to the rigid zones of a Flex & Rigid-Flex PCB build.
What Medical Applications Require from HDI Fabrication
HDI fabrication is technically demanding regardless of application. In medical production, the requirements go further — into material sourcing, process verification, and documentation that supports regulatory submissions and post-market obligations. Here’s where those requirements show up in practice.
Laminate sourcing and lot consistency
Dielectric properties in the base laminate affect impedance — and if those properties shift from one material lot to the next, a board that tested correctly in prototyping can behave differently in production. For medical HDI orders, we source laminates from qualified suppliers with documented material certifications, and those certifications are tied to each production batch through our traceability system. Halogen-free laminates are available where environmental compliance or patient proximity is a factor.
Microvia reliability beyond dimensional inspection
A microvia that passes dimensional inspection at delivery can still fail during thermal cycling if the copper fill quality or aspect ratio is marginal. Medical HDI boards go through multiple reflow passes during assembly and then operate across temperature cycles in clinical environments — both of which stress the via structure. We run cross-section analysis on coupon samples from each production run to verify copper quality in the microvia barrel. The results are part of the production record.
Via-in-pad surface quality
Filled and capped vias under BGA packages require consistent resin fill and a flat copper cap — any void in the fill or surface relief at the pad edge affects solder joint formation during assembly. Our via-in-pad process is verified through cross-section and surface profilometry. This isn’t a step we add for medical orders specifically; it’s part of how the process is controlled.
Lot traceability
Every HDI medical order runs under a unique batch identifier. Laminate and prepreg certifications, laser drill parameters, plating records, impedance coupon test data, AOI results, and flying probe test reports are all linked to that identifier and retained for a minimum of 10 years. If a quality question surfaces two years after delivery, the full production record is accessible.
Impedance verification on production coupons
Controlled impedance structures are tested on coupons fabricated alongside the production panels — not estimated from simulation or assumed from stack-up calculations. Coupon test data (target, measured value, pass/fail) ships with the order documentation. If your design has multiple impedance targets across different layer pairs, each is tracked and reported separately.
Why Choose Sugamed?
HDI fabrication has more process variables than standard rigid board work — blind via aspect ratios, laser drill parameters, sequential lamination adhesion, plating chemistry in high-aspect structures, via-in-pad fill consistency. When any of those variables are marginal, the failure doesn't usually show up at incoming inspection. It shows up later, under thermal or mechanical stress. Getting the design right before production starts is where most of that risk gets managed.
DFM Review on Every Order
Before production starts, we check bend radius compliance, coverlay opening dimensions, copper distribution across flex zones, and via placement in rigid-to-flex transition areas. If anything needs adjustment, you hear from us first — not after the boards are made.
Engineering Involvement Early
If your flex design is still being finalized, our engineers can review your stack-up concept before Gerber files exist. The earlier we see the mechanical intent, the easier it is to advise on material choices and layer structure — before those decisions are locked in.
Full Lot Traceability Documentation
Every medical flex order generates a complete set of records: polyimide and coverlay material certifications, plating process logs, AOI and electrical test reports — all linked to a unique batch identifier, retained for a minimum of 10 years to support DHR and post-market requirements.
One Contact from Quote to Delivery
A single project engineer manages your order end to end — file review, DFM feedback, production progress, and shipment confirmation. You don't re-explain your project at each handoff, because there are none.
NDA Before File Transfer
We regularly work with medical OEMs and development teams under non-disclosure agreements. If confidentiality is a requirement before sharing design files, we put the NDA in place first — no exceptions made for convenience.
7–10 Days for Rigid-Flex Builds
Standard rigid-flex designs (4–8 layer combinations) are typically delivered within 7–10 business days. Expedited options are available for time-sensitive development milestones — discuss this with your engineer before placing the order.
Need Something Different?
HDI solves routing density and miniaturization. If your design has requirements that go beyond that, these pages cover the relevant fabrication approaches in detail.
→ Rigid PCB
If your board has the area to support standard multilayer routing — no microvias needed, no sequential lamination — rigid PCB fabrication is the more cost-effective path. Most fixed-enclosure medical device boards don't need HDI. [Explore HDI PCB →]
→ Flex & Rigid-Flex PCB
If the board also needs to bend or conform to a three-dimensional enclosure, HDI design rules can be applied to the rigid zones of a rigid-flex build. The flex zones use standard flex PCB construction. [Explore Flex & Rigid-Flex PCB →]
→ RF PCB
If your HDI design includes high-frequency signal layers that require low-loss dielectric materials — Rogers or similar rather than FR4 — RF PCB fabrication covers those material and process requirements. [Explore RF PCB →]
→ High-Tg PCB
If your HDI board will go through multiple reflow passes or operate near heat-generating components over long service periods, high-Tg FR4 is the appropriate base material. Standard FR4 Tg may not be sufficient. [Explore High-Tg PCB →]
Start Your Medical HDI PCB Project
Describe your design requirements or upload your Gerber files — our engineering team will review the project and respond with pricing, lead time, and DFM feedback within 24 hours.
☑ HDI-specific DFM review included at no extra charge
☑ Stack-up and via strategy consultation available before Gerber files
☑ Impedance test coupon data included with every shipment
☑ Full lot traceability documentation for ISO 13485 / DHR compliance
☑ NDA available before any file transfer
☑ Response within 24 business hours
Request Your HDI PCB Quote
Share your project details below. We’ll respond with pricing, lead time, and engineering feedback within 24 hours. Gerber files are optional but help us give you a more accurate quote.