Common detachable microphone flex

One assembly for either band MIC socket (J103/J203): 40mm overall, a 3mm flexible neck, and 5 × 7mm mic island. The 5.5mm tongue and its fanout taper into the narrow neck; rounded transitions avoid sharp re-entrant corners. There are no mounting holes. This is a standalone KiCad 10 project; open espurr-mic-flex.kicad_pro. It does not alter the parent project hierarchy.

Circuit and physical map

• U1: Gettop MD-DRA371-H10 / C50275760, nominal 3.3V.
• C1: Samsung CL05B104KO5NNNC / C1525, 100nF, 16V, X7R, 0402.
• J1: integral front-copper fingers, not a purchased socket. Excluded from assembly BOM/CPL by Assembly=Copper and the footprint position flag.
• No SEL strap, SEL pull, DATA pull or clock resistor on this flex. The band owns opposite 100k SEL pulls and separate 100Ω clock-source resistors.

Viewed from the component/finger side, tip upwards, contacts run left to right:

Contact	Net	Mic pin
1, 10	VDD	4
2, 9	GND	3
3, 8	DATA	5
4, 7	CLK	1
5, 6	SEL	2

The symmetric map agrees with the saved band J103/J203 pads and the native schematic XML export checked 2026-10-29. Turning the flex over reverses the contact numbering but retains each function; the FH34SRJ has top and bottom contacts. Only one flex face has exposed fingers. Check physical continuity, actuator access, retention and acoustic orientation on both mounted sides. Do not plug this into an EAR or BAND socket, despite the identical socket.

The microphone symbol/footprint derive from the accepted rigid prototype assets, with the same five electrical lands, upper-left pin 1 at front-view 0°, annular ground seal, Ø0.8mm NPTH and three paste sectors. The port centre is (102.75,137.68) in board coordinates; the body centre is (102.75,137). C1 is at (102.75,134.1). Local footprint variants omit cramped silk and explicitly expand the component coverlay openings by 0.1mm; electrical lands, hole and paste sectors are held. Each of the ten fingers uses two joined copper pad primitives with the same number: an exposed 2.3mm contact and a covered 0.4mm retention section. These are ten physical contacts, not twenty. The exposed copper now runs from 0.2mm to 2.5mm behind the tip, with 0.4mm retained under coverlay. An explicit full-width mask rectangle removes coverlay over the first 2.5mm. The adopted 3.3V supply/tolerance assumption is unchanged from the band design.

Fabrication construction

Use JLCPCB's standard 0.11mm, two-layer PI flex, 25µm core, nominal 12µm copper per side, yellow coverlay, ENIG and front SMT assembly. Do not use the thicker white-coverlay ear stack. CAD board thickness is 0.11mm; the supplier stack and finished tolerances remain the manufacturing authority.

The rear 0.225mm PI stiffener is represented by positive filled artwork on User.1 (Rear_PI_0.225mm), exported as pib_0.225.gbr. It has two separate pieces: the 3.5mm-long insertion support and the supported mic island. The mic piece includes a Ø2.4mm opening through PI and its adhesive around the Ø0.8mm acoustic hole. No added mounting adhesive is specified. Keep the port open to air; do not cover it with tape, fur backing, enclosure walls or fixtures. Do not bend the mic island or at the stiffener edges. Provide external strain relief and a gentle installed bend; this is a static flex, not a qualified repeated-bend hinge.

The tongue drawing uses 0.5mm pitch, 0.30mm-wide fingers, 5.5 ±0.05mm width, a 2.5 ±0.3mm coverlay window and at least 3.5mm reinforcement length, following Hirose's FH19SC compatibility note. Nominal overlap P is 1.0mm, above the 0.5mm minimum. Fingers start 0.2mm behind the laser-cut tip, as explicitly retained for JLC fabrication; Hirose's illustration shows flush copper, so this setback is a documented manufacturing departure. Copper extends 0.4mm under the coverlay for retention. FH19SC pin numbering changes; the symmetric flex map is preserved, but host connector numbering and physical fit still need checking if that connector is substituted. Retain covered rear copper beneath the contact area. JLC's calculation for a 0.11mm construction with rear copper is 0.11 - 0.0275 + 0.225 = 0.3075mm nominal at the uncovered contact area. Request 0.30 ±0.03mm finished mating thickness; the selected PI thickness alone does not establish this tolerance. The covered mic island is about 0.335mm nominal with the same PI reinforcement.

JLC's ordinary outline tolerance is ±0.1mm; the Hirose tongue drawing requires ±0.05mm. Request/confirm the tighter tongue width, stiffener registration, finished contact thickness and clear acoustic opening with the supplier. The native rules retain ≥0.15mm track/space, ≥0.55/0.30mm regular vias, 0.30mm copper/outline clearance (0.20mm for the integral fingers) and the Gettop-mandated 0.20mm hole-to-seal clearance. Coverlay windows and fine mic paste geometry require supplier review; assembly panel/carrier design is not implied by an individual-board outline.

Reproducible outputs and remaining gates

From the repository root, run just mic-flex <fresh-build-output>. It copies this project under build/, refills there, runs native physical/map checks, ERC and DRC with schematic parity, then uses kikit fab jlcpcb for the standard Gerbers, separate PTH/NPTH drills, BOM and CPL (excluding the integral J1 fingers from assembly). A supplementary native export adds User.1 as pib_0.225.gbr and updates the Gerber job before packaging fabrication.zip. The workflow checks the exported acoustic opening, coverlay, stiffeners and placement data, and creates a schematic PDF and layer previews. Source hashes must match on success and failure; no source is restored over another edit. A completion manifest appears only after the checks pass.

Generated CAM is for supplier review. It does not establish JLC assembly acceptance, panel handling, component stock, placement rotations, acoustic sealing, flex retention or mounted audio performance. Inspect U1 pin 1 and the open port in JLC's component preview. Verify both insertion orientations before power, then check stereo channel selection and clock/data waveforms with the actual band. No firmware changes or order are included.

Sources checked 2026-10-29: Gettop datasheet, pp. 8 and 13, Hirose FH34SRJ product and current drawing/catalogue, JLC flex capabilities, PI thickness calculation, stiffener layer naming, FPC clearance guide.

The 2026-10-30 routing revision holds component placement, board outline and the microphone land/port geometry. Four straight front-layer traces cross the neck; the rear ground plane is continuous there. Connector crossovers and vias stay in the end regions. There are 47 track segments, down from 103, and 11 regular through vias. The VDD neck run is 0.25mm; signal runs are 0.15mm. The shared footprint library is staged alongside disposable projects for export.

Saved-source validation: KiCad 10.0.7 ERC and DRC (including schematic parity), native placement/connector checks and exported CAM checks must pass. This is electrical/CAD evidence, not supplier or physical acceptance.