Knowledge of connector materials

Knowledge of connector materials

1. Common materials for connector insulators

Usually, materials such as PBT.NYLON.ABS.PC.LCP are shown in Appendix 1, but in principle, materials with good flame resistance are used.

a. PBT material:

Generally, PBT materials with 20-30% glass fiber are commonly used, which have crack resistance, impact resistance, good electrical resistance, good wear resistance, low friction coefficient, good lubrication effect, good oil resistance, and good chemical resistance. It has good dielectric strength under high temperature and humidity. Its shrinkage rate is between 0.6% -3.0%, and its temperature resistance is around 230 ℃. Good formability and flame resistance. It is a commonly used adhesive in connector products.

b. NYLON66. NYLON6T. PC.LCP Material:

Its shrinkage rate is 1.0% -0.3% with high PBT, commonly used NYLON66 with temperature resistance of 260 ℃ -280 ℃, NYLON6T with temperature resistance of 280 ℃ -300 ℃, and LCP with temperature resistance of 290 ℃ -320 ℃. But its water absorption is relatively high, and it is generally used for products with low temperature resistance and high temperature PITCH resistance (such as SMD.HOUSING.PLCC and other products)

C. ABS material:

Good impact toughness, oil resistance, wear resistance, easy forming, good hardness, good rigidity, and temperature resistance of 100 ℃ are generally used as auxiliary products in connectors.

2. Common injection molding defects and their causes

Common forming defects are as follows: black spots or black liquid on the plastic part, surface roughness, overflow, incomplete plastic forming, bubbles or charring, shrinkage, seam lines, or plastic part compression in the mold. There are three main reasons: factors related to injection molding machines The factors of molds and adhesives.

3. Composition and performance of connectors

Connector material: The plug is made of metal connector material, mainly made of brass, but with extremely high insertion and extraction times, and can have a long lifespan using games such as phosphorus bronze and beryllium copper. The following is an introduction to the types and properties of copper in the current industry

1. Brass copper and zinc alloys, the co color varies depending on the zinc content.

a. Brass - contains 25-35% zinc, most suitable for room temperature processing.

b. Brass - contains 35% to 45% tin, most suitable for room temperature processing, and is one of the copper plates and rods sold in the market.

2. The color of bronze copper and tin alloys varies depending on the content of tin.

Except for brass, copper alloys are generally referred to as bronze.

Phosphorus bronze - Bronze with phosphorus added, resistant to friction, but with excessive phosphorus, making it difficult to cast. Its composition is 8-12% tin and 0.5-1.5% phosphorus

Select contact materials

Contactors can be made of any one of several alloys, depending on the type of contactor, insertion frequency, electrical conditions of the connector, and environmental conditions. Some commonly used materials and their applications are as follows:

Brass - Although brass is a material with good conductivity, it is prone to deformation and rapid fatigue after repeated bending. It is usually used as a fixed contactor in inexpensive connectors or as other metal parts in connectors. Brass contactors should not be used in situations that require good elasticity. Of course, due to its low cost, brass can still be used as a contactor in many places.

Phosphor bronze - Phosphor bronze has a higher hardness than brass and can maintain elasticity for a long time. It is usually used as a contact material for working temperatures below 3000 ℃. For most connectors with low insertion and extraction frequencies or normal bending contact, phosphorus bronze can ensure good reliability.

Beryllium bronze - Beryllium bronze has better mechanical properties than brass or phosphorus bronze. Beryllium bronze parts can be shaped and hardened after annealing, and can actually maintain their shape permanently, making them the most resistant material to mechanical fatigue. In applications with frequent plugging and high reliability, it is recommended to use beryllium bronze material.

4. Local electroplating of copper sheet

Joint surface processing (electroplating): To prevent corrosion and oxidation, ensure smooth contact surfaces, and ensure the mechanical properties of raw materials, electroplating processing is generally used, which has various electroplating characteristics

(1) 30 thick gold plating μ″， Ni thickness measurement of gold-plated area 50-80 μ″。

(2) Gold plating thickness 3 μ″， Ni thickness measurement of gold-plated area 30-50 μ″。

(3) Other:

Size: Acceptance order material number size

Appearance: a. No electroplating surface: No oil stains, the material strip is flat, not deformed, bent or stretched.

b. Electroplated surface: glossy and smooth, with fine particles and no pollution or deformation.

c. Baking: Frozen -55 ± 3 ℃ * 30 ′ Room temperature 10 ′ -15 ′ → 105 ± 2 ℃ * 30 ′ → Room temperature 10 ′ -15 ′.

d. Heat resistance: 85 ± 2 ℃ * 2hr.

(4) Copper sheet tin plating

a. The salt spray test shall be conducted according to the agreement of both parties.

b. Baking test, as shown in item (1) and item (3), with a tin content of less than 90%.

c. Direct tin exposure accounts for over 90%.

d. Heat resistance: 85 ± 2 ℃ * 2hr.

e. Copper plating with a thickness of 30-500 μ″。

f. Tin lead ratio Sn/Pb90:10 or 95:5

g. Tin plating thickness according to order requirements.

5. Electrical performance

a. Voltage and current ratings: Voltage ratings involve spacing, while current ratings involve contact area and plug breaking area, and should be used according to specifications and standards.

b. Contact resistance: When the connector is correctly connected, a current of DC0.1A is applied between the terminals and the PIN. The contact impedance should be as shown in the attached table, but it is 1KHZ when used in general circuits. The 1mA current test includes the pressure part between the wire and the connector.

c. Insulation impedance: When DC500V is applied between terminals and the grounding point, the insulation resistance value should be as shown in Table 6.

d. As shown in the attached table, there should be no abnormalities in the voltage time test.

6. Mechanical properties

(1)  Insertion force: Combined speed 25mm ± 3mm/min. The insertion force obtained from insertion should comply with the specifications of the insertion.

(2) Pullout force: Pullout speed 25mm ± 3mm/min. The pull-out force should meet the specifications of the insertion and pull-out force.

(3) Durability: After inserting at a speed of (10 under/minute) for 30 under and then pulling out the test, the following requirements should be met.

a: The contact impedance is within two of the initial value.

b: The extraction force should meet the specification value.

(4) Terminal retention force: 5mm ± 3mm/min The pulling force of the terminal from HSG should meet the specified value of the pulling force.

(5) PIN retention force: Push the PIN from BASE at a speed of 5mm ± 3mm/min, which should meet the thrust specification value.

(6) Terminal riveting force: 5mm ± 3mm/min The speed and wire tension of the terminal should meet the riveting specification value

7. Environmental performance

(1) Terminal temperature rise: After applying the maximum rated current of AC to any junction point for thermal balance, its temperature rise should be below 30 ℃.

(2) Vibration resistance: Under the condition of DC0.1A being powered on, the amplitude is 1.5m/m and the frequency is 10Hz-55Hz/Min. However, after X, Y, and Z are tested three times for two hours each time, the following requirements should be met:

a: The contact impedance should be within two of the initial value;

b: Discontinuous conduction time is 1 μ Below sec;

C: The appearance should be normal.

(3) Impact resistance: Test X, Y, and Z three times per axis under DC0.1A power on condition of 50 and g acceleration condition. After the test, the following requirements should be met: a: I discontinuous conduction time is 1 μ SEC. Below, b: The appearance should be normal

(4) Tin resistance: Within 3 ± 1 seconds of immersion in a tin bath at 230 ± 50 ℃, at a distance of 2mm from the self terminal as the reference plane, there should be more than 95% tin adhesion on the immersion surface

(5) High temperature resistance: After being placed in a constant temperature bath at 85 ± 2 ℃ for 96 hours, it should be abnormal, and the contact resistance should be within twice the initial value

(6) Solder heat resistance: Immerse the terminal body in a 1.2mm reference surface tin bath with a temperature of 260 ± 50 ℃ for 5 ± 1 second. The insulation should have no abnormal conditions such as cracks or deformation, and the terminal strength should be within the specifications.

(7) Humidity resistance: 855 temperature ± 2 ℃, constant temperature and humidity bath 96 hours, humidity 90%~95%, after wiping with small droplets, the following requirements should be met within 30 minutes:

a. The initial contact impedance should be less than the second digit;

b. The insulation resistance should be above 10M Ω;

c. The appearance should be free from abnormalities;

d. It should meet the voltage resistance requirements.

(8) Salt water spray test: place the sample in a salt water spray at 355 ± 2 ℃ with a ratio of 5 ± 1%, and turn it on for 16 hours and off for 8 hours. After three cycles, clean it with clean water. The following requirements shall be met: a: the contact impedance shall be less than twice the initial value; c: there shall be no cracks or obvious corrosion on the appearance.

(9) Sulfide gas test: After placing the sample at 400 ± 2 ℃ and a concentration of 50 ± 5ppm of sulfide gas for 24 hours, the contact impedance should be less than twice the initial value.

8. Copper conductor related testing items

(1) Line diameter tolerance:

0.10mm ≤ d ≤ 0.40mm, allowable deviation ±