Case study
A camera module stack had 0.4 mm of vertical budget for four screws. Wafer-head M1.0 screws with ±0.02 mm head height made the stack fit without a housing redesign.
0.35
Head height achieved (mm)
±0.02
Head height tolerance (mm)
M1.0
Screw diameter
0
Housing redesigns required
Client: Consumer electronics OEM, Tier-1 camera module supplier · Industry: Smartphones & Wearables
The challenge
The module stack — lens barrel, OIS actuator, sensor board and shield can — had 0.4 mm of vertical clearance for the fasteners. The existing M1.2 pan head screws were 0.65 mm high, so the shield can would not seat and the autofocus actuator hit its travel limit.
The obvious answer was to redesign the housing, but tooling was already cut. The team needed a fastener that recovered 0.3 mm without changing the screw diameter or the thread engagement.
At a glance
Products specified
Machine Thread · PVD Coated · Precoated
The approach
Each change addresses a specific failure mechanism rather than tightening a specification in general.
01
A wafer head with a 0.35 mm height and a 2.0 mm diameter recovered 0.30 mm while keeping the same M1.0 thread and drive size.
02
Head height was specified at ±0.02 mm and measured on 100% of parts by vision, because a 0.04 mm spread would consume a fifth of the remaining budget.
03
Reducing head height reduces recess depth. We used a Phillips 000 drive rather than a Torx T2, which would have been too shallow to transmit torque reliably at this height.
04
The underside of the head was coined flat to 0.01 mm so that clamp load was distributed evenly and the actuator plate did not tilt.
The result
01
The module stack fitted without a housing change, avoiding a tooling modification estimated at several weeks.
02
Autofocus travel was restored to full range with no interference.
03
Head height Cpk was 1.67 over the first three production lots.
04
The wafer head became the standard for two subsequent module generations.
Products used
These families carried the joint. A different combination may suit your assembly — the engineering method is the same.
Micro Screws · M0.5 – M6
Precision machine screws from M0.5 to M6 with rolled Class 6g threads, tight head concentricity and clean drive recesses for automated driving.
Micro Screws · M0.8 – M6
Physical vapour deposition coatings that add 2–5 µm of hard ceramic film — for driver wear resistance, low friction and decorative black or gold finishes.
Micro Screws · M0.8 – M6
Screws with a factory-applied locking or sealing element, so the assembly line receives a ready-to-drive fastener with no liquid adhesive and no cure time.
Send the joint drawing, the cycle count and the failure mode. We will tell you whether the fix is a fastener, a tolerance or a design change.