Table of Contents
Camera modules in smartphones, automotive systems, and machine vision equipment require small, precise structural components that hold optical elements in alignment under mechanical and thermal stress. Powder metallurgy - particularly metal injection molding (MIM) for very small, complex parts, and conventional PM pressing for larger or simpler structural elements - is used for several positions in these assemblies.
Camera Module Structure and PM Positions
A typical smartphone or automotive camera module consists of:
- Lens barrel: Holds the lens stack; may include a focusing actuator (VCM or liquid lens)
- Autofocus actuator carrier: The moving element in a voice-coil motor (VCM) autofocus system
- Housing / base: Mounts the sensor board, provides optical-mechanical datum surfaces
- Shutter mechanism (if present): Aperture blades and actuator components
- Bracket and retention hardware: Structural clips, spring retainers, mounting brackets
PM metal parts appear primarily in:
- Structural brackets and retention hardware with controlled stiffness
- VCM actuator carrier and magnet holder elements
- Housing components requiring precise mounting surfaces
- Anti-shake actuator structural elements (OIS systems in high-end cameras)
Why Metal PM Is Used
Camera modules are dominated by plastic housings and stamped metal brackets at low cost. PM (including MIM) enters the design when:
Stiffness and dimensional stability matter. Metal structural components maintain their form under thermal cycling and mechanical shock better than equivalent plastic. In automotive camera systems - which experience large temperature swings (鈭?0 deg C to +85 deg C) and vibration - metal structural elements maintain optical alignment more reliably than plastic.
Tight tolerances on small features. MIM can produce complex 3D metal parts in the 0.5 - 0 gram range with dimensional tolerances of +/-0.05 - .15 mm and surface features not achievable in a single die-casting shot. For autofocus carrier guides, stop surfaces, and lens datum seats, MIM achieves the precision required without secondary machining.
Magnetic properties. VCM autofocus systems use a moving metal carrier in a magnetic field. The carrier must be non-magnetic (to not interact with the VCM field) or precisely magnetic (if used as part of the magnetic circuit). PM - both iron-based and stainless - allows specific magnetic requirements to be matched to the component function.
MIM vs. Conventional PM for Camera Components
Most camera module metal structural parts are in the 0.5 - 0 gram range with complex 3D geometry including undercuts, lateral holes, and thin walls below 1 mm. This geometry space belongs to MIM, not conventional die-compaction PM.
| Feature | Conventional PM | MIM |
|---|---|---|
| Minimum wall thickness | ~1.5 - mm | ~0.3 - .8 mm |
| Undercuts | Not possible without secondary | Yes, with tool slides |
| Part weight range | Typically >5 g for cost efficiency | 0.1 - 00 g (sweet spot < 50 g) |
| Density | 85 - 2% TD typical | 96 - 9% TD |
| Dimensional tolerance | +/-0.05 - .15 mm typical | +/-0.05 - .10 mm typical |
| Annual volume minimum | ~10,000 for tooling payback | ~20,000 - 0,000 for tooling payback |
For camera module structural components below ~5 grams with 3D geometry, MIM is typically the correct process. Conventional PM die compaction is appropriate for camera-adjacent parts that are larger, simpler, or axially symmetrical - mounting brackets, structural inserts, support rails, retention clips with uniform cross-section.
SinterWorks PM handles both conventional PM and collaborates with MIM partners for complex small parts depending on customer requirements.
Automotive Camera Applications
Automotive ADAS (advanced driver assistance systems) cameras - rear view, surround view, forward-facing - have specific structural requirements that differ from consumer cameras:
Temperature range. Automotive cameras operate at 鈭?0 deg C to +85 deg C or higher (near-engine positions). Metal structural components maintain dimensional stability across this range; plastics show larger CTE variation that can shift lens alignment.
Vibration and shock. Automotive vibration profiles (road input, engine vibration) require structural components with sufficient fatigue life. Metal PM brackets and housings in automotive cameras are designed to survive the automotive vibration specification (typically 100 - 00 hours vibration testing per ISO 16750 or OEM equivalent).
Optical axis stability. The sensor-to-lens optical distance and axis must be stable over the operating envelope. Metal structural datum surfaces (the lens flange seating face on the housing, the sensor mounting face) maintain tighter dimensional stability than plastic.
Typical materials for automotive camera PM:
- Stainless 316L: For external exposure with corrosion requirement (mirror camera systems, exterior-mount cameras)
- Iron-copper (FC-0208): For internal structural elements with no corrosion requirement
- 17-4PH (MIM): High-strength stainless for small, high-load structural elements
Tolerances for Optical Applications
Camera module structural tolerances are tighter than most industrial PM applications because small dimensional errors translate directly into optical axis error:
| Feature | Typical Tolerance | Functional Impact |
|---|---|---|
| Lens seat OD / bore | +/-0.010 - .025 mm | Lens centration on optical axis |
| Sensor mounting face flatness | <=.010 - .020 mm | Sensor tilt relative to optical axis |
| Lens-to-sensor distance (axial) | +/-0.05 - .10 mm | Back focus distance |
| Mounting hole position (true position) | +/-0.05 - .10 mm | Module alignment on PCB or bracket |
| Housing OD/ID for retention snap | +/-0.025 - .075 mm | Assembly retention force |
Achieving +/-0.010 - .025 mm on small bores requires sizing or secondary machining on PM parts. For MIM parts, the sintering shrinkage variability means tight tolerances typically need secondary machining or coining as well.
Design Considerations
Anisotropic CTE. Metal PM and MIM parts have isotropic CTE close to the base alloy. Plastic housings have anisotropic CTE that varies with fiber fill direction. When metal PM inserts are bonded or assembled into plastic housings, CTE mismatch can generate stress at the interface over the temperature range. Design clearances and bonding methods should account for this.
Non-magnetic requirement. If the structural component is adjacent to a VCM actuator magnet or hall sensor, ferromagnetic PM material can interfere with the magnetic circuit. In these positions, specify non-magnetic stainless (316L) or aluminum.
Cleanliness. Camera module assembly is conducted in controlled-environment conditions. PM and MIM parts must be delivered clean, dry, and packaged to prevent contamination. Oil-impregnated PM parts are generally not suitable for direct assembly into camera modules - the oil can contaminate optical surfaces and cleaning is difficult.
Getting a Quote
For camera module structural PM or MIM component inquiries:
- Part geometry (3D STEP file preferred)
- Annual volume
- Material requirement (non-magnetic, corrosion class, strength)
- Critical tolerances for optical alignment features
- Surface finish requirements
- Cleanliness and packaging requirements
- Operating temperature range (especially for automotive applications)
Contact SinterWorks PM to discuss your camera module structural component requirements.
Frequently Asked Questions
Q: What PM parts are used in camera modules?
A: Structural brackets, alignment features, magnetic shield inserts, and reinforcement components in smartphone, automotive, and industrial camera modules may use PM or MIM when net-shape metal is required near sensors or actuators.
Q: When is PM preferred over plastic for camera module structure?
A: Metal PM or MIM is chosen when stiffness, wear resistance, magnetic shielding, or CTE matching to adjacent metal parts matters more than minimum weight. Plastic remains dominant for cosmetic housings; metal inserts handle load and alignment.
Q: Are oil-impregnated PM parts suitable for camera modules?
A: Generally no. Oil from impregnated bearings can contaminate optical paths and cleanroom assembly. Specify dry, clean sintered stainless or non-magnetic grades with packaging suited to controlled assembly environments.
Q: What tolerances are needed for optical alignment features?
A: Bore and mounting feature tolerances often fall in the ±0.01–0.05 mm range depending on module tier. Tight bores may require sizing or secondary machining on PM or MIM parts—confirm feasibility early with STEP data.
Q: Which stainless grade is used near magnets?
A: Non-magnetic 316L stainless PM is typical adjacent to VCM magnets or Hall sensors. Ferromagnetic grades can disturb the magnetic circuit and should be avoided in those positions.
Q: What should RFQs include for camera module PM?
A: Provide STEP geometry, annual volume, material and non-magnetic requirements, critical tolerances, surface finish, cleanliness and packaging rules, and operating temperature range for automotive programs.
Related Resources
Use these internal links to keep moving through the most relevant guides, service pages, and technical references for this topic.
Consumer Electronics PM Parts
Review where miniature PM parts fit smartphones, wearables, and high-volume consumer hardware programs.
Camera Module Structural Components Case Study
See a representative PM example focused on precision structural parts for compact camera assemblies.
Smartphone Vibration Motor Case Study
Compare another compact consumer-electronics PM program where miniaturization and stable production volume both matter.
Request a Quote
Send your camera module structural part, tolerance stack, and material target for PM feasibility review and quotation support.