What should be paid attention to when selecting raw materials for plastic processing of electronic equipment products?

The core of material selection for plastic injection molding of electronic equipment is to give priority to electrical safety, environmental adaptability and structural reliability, and at the same time give consideration to processability and cost, so as to avoid equipment failure or potential safety hazards caused by mismatched material characteristics.

First, give priority to electrical safety requirements: the core bottom line of electronic equipment

When the electronic equipment is in direct contact with the circuit or in a charged environment, the electrical performance of the material is the primary consideration, and the insulation and flame retardancy should be paid special attention to.

Insulation performance is up to standard

Choose materials with volume resistivity ≥ 10Ω cm and dielectric strength ≥15kV/mm, such as PC, PBT, PA66, etc., to avoid leakage or short circuit caused by poor insulation (such as power adapter housing and circuit board bracket).

High-frequency electronic components (such as routers and antenna housings) need to pay extra attention to dielectric loss (tanδ≤0.01) to prevent signal transmission from being disturbed, and low dielectric loss materials such as PPS and LCP can be preferred.

Flame retardant grade compliance

Must meet the flame retardant standards of electronic equipment, such as UL94 V-0 grade (in vertical combustion test, the flame goes out within 10 seconds, and there is no dripping to ignite the cotton wool below), and common materials such as flame retardant ABS, PC/ABS alloy and flame retardant PBT.

High-voltage components (such as inverter housing) need to choose a higher flame retardant grade (such as UL94 5VA grade) to ensure that large-scale combustion will not occur in extreme cases and reduce the fire risk.

Second, adapt to the environmental adaptability of electronic equipment: deal with complex usage scenarios

Electronic equipment may face high and low temperatures, humidity changes, chemical contact and other environments, and materials should have corresponding tolerance.

Temperature resistance matches the use environment.

Internal heating components (such as CPU radiator shell and power module): choose materials with long-term service temperature ≥120℃, such as PPS (long-term temperature resistance above 200℃) and PA66+glass fiber (long-term temperature resistance above 150℃) to avoid high-temperature deformation or performance degradation.

Outdoor equipment (such as surveillance cameras and outdoor routers): It needs to withstand high and low temperature cycles of-40℃~85℃, and weather-resistant PC and ASA can be selected to prevent low-temperature embrittlement or high-temperature aging.

Moisture resistance and chemical resistance

Equipment in humid environment (such as bathroom electronic scale and industrial humidifier control panel): choose materials with water absorption ≤0.5% (such as POM and PP) to avoid the insulation degradation or dimensional deformation after water absorption.

Components that may come into contact with chemical substances (such as printer housings and household appliances panels contacted by cleaning agents): It is necessary to be resistant to alcohol and weak acid and alkali, and PP, HDPE or chemical-resistant PC are preferred to prevent surface corrosion or cracking.

Third, ensure the structural and mechanical reliability: meet the assembly and use requirements.

Plastic parts of electronic equipment often need to undertake the functions of fixing, supporting and assembling, and the mechanical properties of materials need to match the stress scene.

Mechanical strength adaptation stress type

Load-bearing or stress-bearing components (such as laptop shaft bracket and printer gear): Select materials with tensile strength ≥50MPa and bending modulus ≥2000MPa, such as PA66+glass fiber and PBT+glass fiber, to ensure that they will not break or deform under long-term stress.

Easy-to-collide parts (such as mobile phone charger shell and Bluetooth speaker shell): they must have certain toughness, and the notched impact strength is ≥ 15kJ/m (such as ABS, PC/ABS alloy) to prevent falling or collision damage.

Dimensional stability: avoid assembly deviation

Precision assembly parts (such as circuit board card slot and connector housing): Choose materials with linear expansion coefficient ≤ 10× 10/℃ (such as LCP, PPS+glass fiber) to reduce the dimensional deviation caused by temperature change and ensure accurate fit with other parts (clearance is usually required within ±0.05mm).

Fourth, give consideration to processability and additional demand: ensure production and use experience

In addition to the core performance, the processing difficulty and additional characteristics of materials will affect the production efficiency and product experience.

Processing fluidity adapts to product structure

Complex thin-walled parts (such as micro-sensor housing, circuit board micro-bracket, wall thickness ≤1mm): Select materials with melting index (MI)≥10g/10min (such as high-flow ABS and PC) to ensure that the cavity can be filled quickly during injection molding to avoid material shortage or bubbles.

Large or thick-walled parts (such as display back case and server chassis): The material should have moderate fluidity (MI 5-15g/10min) to prevent uneven shrinkage from causing shrinkage marks.

Additional features match usage scenarios.

Appearance parts (such as mobile phone back cover and smart watch dial): Good surface gloss (Ra≤0.02μm) is required, and high-gloss ABS, transparent PC or materials supporting surface spraying and printing can be selected.

Scratch-proof components (such as screen protective cover of tablet computer and central control panel of automobile): choose materials with surface hardness ≥HB (pencil hardness) (such as hardened PC and PMMA), or need surface hardening treatment in the later stage.