What are micro screws?

Micro Screws are a type of high-precision threaded fasteners with a diameter usually less than M2 (2 mm), used to connect or fix small and micro parts. According to ISO standards, screws with thread diameters between M0.6 and M2 are generally called micro screws, and some manufacturers even produce ultra-micro screws as small as M0.3. They are widely used in electronic products, precision instruments, medical equipment, aerospace and high-end manual manufacturing industries.

Although micro screws are small in size, they have extremely high requirements for materials, processing accuracy, thread strength, surface treatment, etc. Their design and manufacturing represent a model of high-end machining technology.

2. Structural characteristics and professional data of micro screws

1. Size range and specifications

The common metric thread diameters of micro screws include:

M0.6 / M0.8 / M1.0 / M1.2 / M1.4 / M1.6 / M1.7 / M2.0

Thread Pitch: fine thread design, common M1.0 thread pitch is 0.25mm

Screw length (L): usually 1mm to 10mm, some products can be customized to 0.5mm

2. Material selection

Micro screws have strict requirements on materials, both high strength and high processing performance:

Material Features Professional parameters

Stainless steel (SUS304/SUS316) Corrosion-resistant, non-magnetic Tensile strength ≥ 520 MPa, Rockwell hardness HV180~220

Titanium alloy (Ti6Al4V) Lightweight, high strength, medical safety Density 4.5 g/cm³, tensile strength ≥ 950 MPa

Brass (C3604) Good conductivity and machinability Conductivity is about 23% IACS, hardness HV 80-100

Carbon steel (SCM435) High strength, suitable for mechanical parts Tensile strength ≥ 1000 MPa, can reach HV320 after heat treatment

3. Head type and drive method

Common head types include:

Cheese Head

Pan Head

Flat Head

Cylindrical

Common drive slots:

Phillips

Hex

Torx

Slotted

Professional parameters such as cross slot size (e.g. PH000, suitable for M1.0 screws), drive hole depth is about 0.3mm~0.6mm, to ensure no slipping and no damage to the head.

4. Tolerance control

Micro screws have extremely strict processing accuracy:

Dimensional tolerance: ±0.01mm ~ ±0.02mm

Coaxiality: less than 0.03mm

Surface roughness (Ra): usually between 0.4~1.6μm

Thread accuracy: in line with ISO 68-1, JIS B0205 and other standards

5. Surface treatment process

In order to improve rust prevention, aesthetics or conductivity, the following processes are often used:

Nickel plating (high brightness, corrosion resistance)

Black oxidation (commonly used in industrial equipment)

Gold plating (used to connect conductive parts)

Dacromet (environmentally friendly corrosion-resistant treatment)

III. Application scenarios

1. Consumer electronics

Smartphones, tablets: used to fix screens, camera modules, motherboards, metal middle frames and other precision structures

Example: iPhone motherboard uses about 30 M1.2 screws, only 1.5mm long

2. Medical devices

Applied to insulin pumps, implantable devices, surgical robots, biocompatible and non-magnetic

Mostly use SUS316L or titanium alloy micro screws to meet FDA or ISO 10993 standards

3. Aerospace and military industry

M0.8~M1.6 high-strength screws are widely used in micro inertial navigation equipment and satellite communication modules

Required to be shock-resistant, high-temperature resistant, and not release gas in high vacuum (low gas release materials)

4. Optical instruments

Used for high-precision adjustment of component connections in microscopes, optical sights, and laser modules

Extremely high precision requirements, no displacement error and thermal expansion control must be ensured

5. Watches and jewelry manufacturing

An average of 50,100 M0.6M1.0 screws are used in micro mechanical watches

In addition to the connection function, some screws are also used to adjust the tension of the watch movement mechanism

IV. Care and maintenance

Although micro screws have a long service life, due to their tiny structure, improper maintenance may cause equipment damage or fastening failure. The following are general maintenance strategies:

1. Install torque control

Use a professional micro torque screwdriver or electric screwdriver

Typical torque values are as follows (depending on the material and diameter):

The recommended torque for M1.0 screws is 0.02~0.04 N·m

The recommended torque for M1.6 screws is 0.06~0.1 N·m

Do not apply excessive force manually to avoid "slipping" or "cracking"

2. Cleaning management

Use alcohol or electronic cleaning fluid to clean and dry

Keep the screws free of oil and dust, especially in clean room assembly conditions (such as medical and aerospace)

3. Storage conditions

It is recommended to place in a dry antistatic box with an ambient humidity of 40~60%

Use vacuum packaging or deoxygenated packaging for long-term storage

High-precision screws should be managed in batches to prevent mixing

4. Replacement cycle

For frequently disassembled parts (such as mobile phones and cameras), it is recommended to replace micro screws every 500 times

If the following conditions occur, they should be replaced immediately:

Screw head wear, drive slot slippage

Thread damage, deformation

Surface oxidation, rust