精密金属皮膜无引线电阻器，在行业中通常被称为MELF电阻（Metal Electrode Leadless Face），因其无引线的圆柱形外观，也常被称作晶圆电阻、柱状电阻或色环贴片电阻。它是一种专为表面贴装技术（SMT） 而设计的电子元件。
它的核心特点是在高性能陶瓷棒上沉积精密的金属薄膜作为电阻体，两端直接形成金属电极，取代了传统直插电阻的引线。这种设计不仅赋予了它一系列卓越的性能，也使其在高可靠性应用中占据一席之
| Item Type | 额定功率 at 70℃ | 工作温度 范围(℃) | 最高额定 工作电压 | 最高短时间 过负载电压 | 电阻值范围 | T.C.R. (PPM/℃) |
| ±0.05%、±0.1%、 ±0.25%、±0.5% | ||||||
| 0204 | 1/4 W | -55~155 | 200V | 400V | 1Ω-100KΩ | ±5、±15、±25 |
| 101K-2MΩ | ±50、±100 | |||||
| 0207 | 1/2 W | -55~155 | 300V | 700V | 1Ω-100KΩ | ±5、±15、±25 |
| 101k-2MΩ | ±50、±100 | |||||
| 0309 | 1W | -55~155 | 400V | 700V | 1Ω-100KΩ | ±15、±25 |
| 101K-2MΩ | ±50、±100 |
| Item Type | 额定功率 at 70℃ | 工作温度 范围(℃) | 最高额定 工作电压 | 最高短时间 过负载电压 | 电阻值范围 | T.C.R. (PPM/℃) |
| ±0.05%、±0.1%、 ±0.25%、±0.5% | ||||||
| 0204SS | 2/5 W | -55~155 | 200V | 400V | 1Ω-100KΩ | ±5、±15、±25 |
| 101K-2MΩ | ±50、±100 | |||||
| 0207SS | 1 W | -55~155 | 350V | 700V | 1Ω-100KΩ | ±5、±15、±25 |
| 101K-2MΩ | ±50、±100 | |||||
| 0309SS 0411 | 2W | -55~155 | 500V | 800V | 1Ω-100KΩ | ±15、±25 |
| 101K-2MΩ | ±50、±100 |
■ 测试步骤和要求/ Environmental Characteristics
| 测试项目/ Item | 测试要求/Requirement | 测试步骤/ Test Method |
| 电阻温度系数试验 Temperature Coefficient | As Spec. | -55℃~+125℃, 25℃ is the reference temperature. |
| 短时间过附载试验 Short Time Overload | ±(0.25%+0.05Ω) | RCWV×2.5 or Max. Overload voltage for 5 seconds. |
| 湿度负载寿命试验(加速) Biased Humidity | ±(0.5%+0.05Ω) | 1,000 hrs. 85℃/ 85%RH, 10% of operating power (<100V). |
| 寿命负载试验 Endurance | ±(1.0%+0.05Ω) | 70±2℃, RCWV or Max. Operating voltage for 1,000 hrs. (with 1.5 hrs. ON and 0.5 hrs. OFF). |
| 耐湿负载试验 Damp Heat with Load | ±(1.5%+0.05Ω) | 40±2℃, 90~95% R.H. RCWV or Max. Operating voltage for 1,000 hrs. (with 1.5 hrs. ON and 0.5 hrs. OFF). |
| 弯曲端子强度试验 Bending Strength | ±(0.5%+0.05Ω) | Bending once for 5 seconds with 2mm. |
| 焊锡性试验 Solder ability | 95% min. coverage | 245±5℃ for 3 seconds. |
| 焊锡耐热性试验 Resistance to Soldering Heat | (±0.1%+0.05Ω) | 260±5°C for 10 seconds. |
| 溫度循環 Temp. cycle | ≦±(0.5%+0.05Ω) | -55℃(30 min.) > Room Temp.(3min.) > +155℃(30 min.) > Room Temp. (3min.) / (5 cycle). |
| 绝缘耐压试验 Voltage Proof | No breakdown or flashover | 0204:AC 300V, 0207、0309:AC 500V for 1 minute. |
| 绝缘电阻试验 Insulation Resistance | >1,000MΩ | DC 500V Megger. |
＊RCWV (Rated Continuous Working Voltage)
＊RCWV(Rated continuous working voltage)=√(P*R) or Max. Operating voltage whichever is lower
＊工作电压RCWV =(电阻额定功率×公称电阻值)开根号或法定最高使用电压。
＊Overload Voltage=2.5*√(P×R) or Max. Overload voltage listed above, whichever is lower.
＊短时间过负荷电压=(电阻额定功率×公称电阻值)开根号×2.5 倍或法定最高短时间过负荷电压。
＊测试标准参考/Reference Standards: IEC 60115-1；JIS-C 5201-1
＊储存环境条件/ Storage Temperature: 25±3°C; Humidity < 80% RH
Unit: mm
| Type | ∮A | ∮B | ∮C | W | T | Emboss Plastic Tape (EA) |
| 0102 | 178.5±1.5 | 60.0+1.0 | 13.0±0.2 | 9.0±0.5 | 12.5±0.5 | 3,000(7.0”) |
| 0204 | 178.5±1.5 | 60.0+1.0 | 13.0±0.2 | 9.0±0.5 | 12.5±0.5 | 3,000(7.0”) |
| 0207 | 178.5±1.5 | 60.0+1.0 | 13.0±0.5 | 13.0±0.5 | 15.5±0.5 | 2,000(7.0”) |
| 0309 | 330±1.5 | 100.0+1.0 | 13.0±0.5 | 17.0±0.5 | 19.0±0.5 | 2,500(13.0”) |
Unit: mm
| Type | A | B | W | E | F | P0 | P1 | P2 | ΦD0 | T |
| 0102 | 1.30±0.10 | 2.40±0.10 | 8.00±0.10 | 1.75±0.1 | 3.50±0.05 | 4.00±0.10 | 4.00±0.10 | 2.00±0.05 | 1.50±0.10 | 1.45±0.10 |
| 0204 | 1.60±0.10 | 3.70±0.10 | 8.0±0.10 | 1.75±0.1 | 3.50±0.05 | 4.00±0.10 | 4.00±0.10 | 2.00±0.05 | 1.50+0.10 | 1.45±0.10 |
| 0207 | 2.40±0.10 | 6.30±0.10 | 12.0±0.10 | 1.75±0.1 | 5.50±0.05 | 4.00±0.10 | 4.00±0.10 | 2.00±0.05 | 1.50+0.10 | 2.50±0.10 |
| 0309 | 3.30±0.10 | 9.00±0.10 | 16.00±0.3 | 1.75±0.1 | 7.50±0.10 | 4.00±0.10 | 8.00±0.10 | 2.00±0.05 | 1.50+0.10 | 3.30±0.10 |