An HDI flex PCB uses laser-drilled microvias and sequential lamination to pack fine-pitch BGA routing into a thin flexible circuit that conventional flex cannot.
FlexiPCB builds 2-10 layer HDI flex with 50μm microvias, 2mil trace/space, copper-filled via-in-pad, and ±25μm layer registration.
Cost and yield are driven by lamination cycle count and microvia structure: a stacked-via build costs more than staggered, so the stackup is chosen from your BGA pitch, not a default.
Send your finest BGA pitch, escape-routing layer, and impedance targets so we propose the lowest lamination-cycle stackup that still breaks out the package.
FlexiPCB manufactures high density interconnect (HDI) flex circuits that pack maximum functionality into minimal board area. Our HDI flex PCB capabilities include stacked and staggered microvias, via-in-pad designs, and sequential lamination processes that enable routing densities far exceeding conventional flex circuits. We process builds from 2 to 10 layers with laser-drilled microvias as small as 50μm, supporting fine-pitch BGA packages down to 0.3mm pitch.
Ultra-thin HDI flex circuits for smartphone camera modules, display interconnects, and smartwatch mainboards requiring maximum component density in minimal space.
Biocompatible HDI flex for cochlear implants, pacemaker leads, endoscopy cameras, and surgical instruments where miniaturization is critical.
Lightweight HDI flex circuits for satellite communication modules, avionics, UAV flight controllers, and radar systems requiring high-reliability interconnects.
High-density flex circuits for LiDAR modules, camera systems, and sensor fusion units in advanced driver assistance systems.
HDI flex circuits with controlled impedance for 5G antenna modules, mmWave front-end modules, and high-frequency signal routing.
Our HDI engineers analyze your design for microvia feasibility, stack-up optimization, and impedance modeling. We recommend the optimal via structure (stacked, staggered, or skip) for your density requirements.
HDI flex builds use sequential lamination cycles — each layer pair is laminated, drilled, and plated before adding subsequent layers. This enables buried and stacked microvia structures.
UV laser drilling creates microvias down to 50μm diameter with precise depth control. Copper-filled vias provide reliable interconnection for via-in-pad and stacking applications.
LDI (Laser Direct Imaging) achieves 2mil trace/space resolution for high-density routing between fine-pitch BGA pads and microvia lands.
Every HDI flex board undergoes TDR impedance verification, microvia cross-section analysis, flying probe electrical testing, and AOI inspection to meet IPC Class 3 standards.
UV laser systems achieve 50μm microvia diameter with ±10μm positional accuracy — enabling the highest routing densities on flex substrates.
Multi-cycle lamination with precise registration (±25μm) for stacked microvias up to 3 levels deep. Full copper fill ensures reliable via stacking.
Our HDI specialists review every design for manufacturability, recommending stack-up changes that reduce cost while maintaining signal integrity.
ISO 9001, ISO 13485, and IATF 16949 certified. Every HDI flex board is cross-sectioned, impedance-tested, and electrically verified.
Pitch, escape, and via-structure data let engineering quote lamination cost instead of guessing.
Gerber, drill, layer stackup, and the finest BGA pitch with ball count and required escape layers
Preferred via structure (stacked, staggered, via-in-pad) or let engineering propose the minimum-cycle option
Microvia capture/target pad sizes, copper-fill requirement, and any blind/buried via depth needs
Single-ended and differential impedance targets, bend radius, fold locations, and surface finish (ENIG/ENEPIG)
MOQ, sample quantity, annual forecast, and required reports: TDR coupon, microvia cross-section, AOI, COC
The response is written for procurement, quality, and engineering review.
DFM comments on microvia structure, BGA breakout, registration, via-in-pad fill, and bend-zone keepout
Proposed stackup with lamination cycle count and the cost impact of stacked versus staggered vias
Quotation with MOQ, sample lead time, production lead time, tooling, and sequential-lamination cost drivers
Inspection plan covering microvia cross-section, TDR impedance, flying-probe test, and AOI to IPC Class 3
Production release checklist for drawing revision, lot traceability, packaging, and repeat-order control
We support fine-pitch BGA down to 0.3mm using 50μm laser microvias and 2mil trace/space, with copper-filled via-in-pad for the tightest packages. The cost driver is not the via diameter but how many sequential lamination cycles your escape routing forces. A 0.4mm BGA often escapes with staggered microvias and fewer cycles; a 0.3mm BGA may require stacked microvias and via-in-pad, adding lamination passes. Send the package pitch, ball count, and which signals must escape on inner layers so we model the minimum-cycle stackup that still routes the part.
Staggered microvias offset each laser via laterally between layers, are more forgiving of registration and lamination stress, and cost less. Stacked microvias sit directly on top of each other (copper-filled) for the densest routing under high-pin-count BGAs but demand tighter ±25μm registration and full copper fill to survive thermal cycling on a flexible substrate. On flex, we lean to staggered unless density forces stacking, because a stacked structure in or near a bend zone is a reliability risk. Tell us the routing density and we recommend the structure that meets density without overbuilding.
No. Microvias, via-in-pad, and stacked structures are rigid stress concentrators and must stay out of any dynamic or tight static bend zone, or they crack after repeated flexing. The HDI density belongs in the component and BGA-escape regions; the bend tail should stay simple flex with balanced copper. During DFM we map your microvia field against the bend geometry and flag any via that falls in the flex zone. Send the bend radius and fold locations with the Gerbers so the high-density area and the flex area are designed separately.
Public references provide context; your drawings and purchase specifications control production acceptance.
High-density interconnect builds use microvias and sequential lamination to achieve routing densities beyond conventional printed-circuit-board construction.
Laser-drilled microvias, stacked and staggered configurations, and via-in-pad are the core interconnect elements of HDI flex builds.
IPC-6013 and IPC-A-600 are used as performance and workmanship references for HDI flexible printed boards.
Written for OEM procurement teams evaluating HDI flex PCB suppliers at RFQ stage.
FlexiPCB manufacturing and sourcing specialist
Hommer Zhao has supported flexible, HDI, and cable-integrated builds for OEM procurement teams since 2008. For HDI flex programs, the engineering review focuses on microvia structure, BGA breakout, lamination cycle count, layer registration, impedance, and keeping the high-density area clear of the flex bend zone.
Capability
2-10 layer HDI flex, 50μm laser microvias, 2mil trace/space, 0.3mm BGA pitch, copper-filled via-in-pad
Process control
±25μm layer-to-layer registration, TDR impedance verification, microvia cross-section on first article
Case evidence
Smartphone camera-module HDI flex escaped a 0.35mm BGA with staggered microvias, avoiding an added lamination cycle and reducing unit cost
Standards
IPC-6013, IPC-A-600 Class 3, ISO 9001, ISO 13485, IATF 16949
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A Singapore robotics OEM required PCB and assembly services for a product rollout, structured as a multi-PO program with split deliveries.
The customer had highly time-sensitive production schedules and required strict delivery visibility; one of the split purchase orders faced a tight timeline risk requiring immediate communication.
Implemented proactive order management by providing same-day payment confirmation and issuing an early delivery timeline warning for the constrained PO, while confirming other POs remained on schedule.
Maintained high customer trust and schedule transparency across the multi-PO program, preventing delivery disputes and ensuring smooth execution without escalating risk signals.
Customer details are anonymized. Numbers and scope are reported as delivered.
