Thick Film Chip Resistors RK73B

Product catalog summary

Product Overview

The RK73B series consists of thick film flat chip resistors designed for general purpose applications. These resistors feature a black coating and are constructed with a metal glaze thick film resistive layer, providing excellent heat and weather resistance. The electrodes have a triple-layer structure ensuring high stability and reliability. The products support various automatic mounting methods including taping and are compatible with both flow and reflow soldering processes. Lead-free terminations comply with EU RoHS regulations, except for Pb-glass contained in electrodes and resistive elements. The series is AEC-Q200 qualified except for types 1F and 1H.

Construction and Materials

Coating color: Black
Resistive film: Metal glaze thick film
Electrodes: Triple-layer structure (Ni plating and solder plating)
Substrate: Ceramic (Alumina)

Reference Standards

IEC 60115-8
JIS C 5201-8
EIAJ RC-2134C

Dimensions and Types

The series includes multiple size codes from 1F (01005) to W3A (2512), with dimensions ranging from 0.4 mm × 0.2 mm up to 6.3 mm × 3.1 mm. Thickness and other dimensional parameters vary accordingly. Weight per 1000 pieces ranges from 0.04 g (1F) to 37.1 g (W3A).

Type Designation and Ratings

Type codes indicate size and power rating, with power ratings from 0.03 W (1F) up to 1 W (W3A). Terminal surface materials include Sn (standard lead-free), Au (gold plated available for some types), and Sn/Pb (limited availability). Various taping options are available for automated assembly.

Electrical Characteristics

Resistance range: from 10 Ω up to 22 MΩ depending on type
Resistance tolerance: ±2% (G) or ±5% (J)
Temperature coefficient of resistance (T.C.R.): typically ±200 to ±400 ppm/K depending on type and resistance value
Maximum working voltage and overload voltage vary by type and resistance; consult manufacturer for specific values

Derating Curve

For ambient temperatures above 70°C, power rating must be derated according to the provided curve. Different derating applies depending on resistor type.

Performance and Reliability Tests

Test Item	Performance Requirement (ΔR ± % + 0.1Ω)	Test Method
Resistance	Within specified tolerance at 25°C	Measurement at 25°C
Temperature Coefficient of Resistance (T.C.R.)	Within specified T.C.R.	Measured between +25°C/-55°C and +25°C/+125°C
Overload (Short Time)	ΔR ≤ 2% for 1F, ≤ 0.5% others	Applied 2.5× rated voltage for 5 seconds (2× for 2B)
Resistance to Soldering Heat	ΔR ≤ 1% for 10Ω ≤ R ≤ 1MΩ, ≤ 3% otherwise	260°C ±5°C for 10 ±1 seconds
Rapid Change of Temperature	ΔR ≤ 1% for 1F, ≤ 0.5% others	100 cycles between -55°C (30 min) and +125°C (30 min)
Moisture Resistance	ΔR ≤ 2% for 1J, 2A, 2B; ≤ 3% others	40°C ±2°C, 90-95% RH, 1000 hours with 1.5h ON/0.5h OFF cycle
Endurance at 70°C	ΔR ≤ 2% for 1J, 2A, 2B; ≤ 3% others	70°C ±2°C, 1000 hours with 1.5h ON/0.5h OFF cycle
High Temperature Exposure	ΔR ≤ 1% for 1F; ≤ 0.5% others	+125°C for 1000 hours (1F, 1H), +155°C for 1000 hours (others)

Operating Conditions

Rated ambient temperature: +70°C
Operating temperature range: -55°C to +125°C for 1F and 1H; -55°C to +155°C for other types
Rated voltage is the lower of (Power rating × Resistance) or maximum working voltage

Precautions for Use

The alumina substrate has a different thermal expansion coefficient than mounting boards, which may cause solder joint cracks under repeated thermal cycling or load ON/OFF cycles, especially for larger types W2H and W3A.
Design considerations should include pad size, solder volume, and heat dissipation to minimize crack risk.
Type 1F is sensitive to static electricity during assembly and may be damaged by electrostatic discharge.
Consult manufacturer before use in critical applications such as automotive, medical, or aerospace equipment due to potential risk of serious damage or loss of life.

Additional Notes

Gold plated electrodes are available for types 1E, 1J, and 2A (10Ω to 1MΩ) upon consultation.
Lead-free plating is standard; contact manufacturer for environmental substance control beyond EU RoHS.
Taping details are provided in Appendix C of the full catalog.
Specifications are subject to change without notice; confirm details before ordering or use.

Catalog excerpts

角形面実装抵抗器 Flat Chip Resistors THICK FILM GENERAL PURPOSE 角形チップ抵抗器 Flat Chip Resistors 外装色黒 Coating colorBlack 有しています。テーピング等の各種自動実装機に対応します。ラスに含まれる鉛ガラスは欧州RoHSの適用除外です。 AEC-Q200に対応データ取得しています。 1F、 1H除く Small size and light weight. Excellent heat resistance and weather resistance are ensured by the use of metal glaze thick film. High stability and high reliability with the triple-layer structure of electrode. Applicable to various kinds of automatic mounters for taping, etc. Suitable for both flow and reflow solderings. Products with lead free termination meet EU-RoHS requirements. EU-RoHS regulation is not intended for Pb-glass contained in electrode, resistor element and glass. AEC-Q200 qualified (Exemption 1F, 1H). 寸法が異なります。 d” “ 寸法0.4　 mm −0.1 0.2 ※1 RK73B 2H and RK73B 3A are also still available (different d” “ dimensions=0.4　 mm) −0.1 ■品名構成　Type Designation 　例　Example ■負荷軽減曲線　Derating Curve 定格電力 Power Rating 端子表面材質 Terminal Surface Material 二次加工 Taping 公称抵抗値 Nominal Resistance 抵抗値許容差 Resistance Tolerance TX4mm width 　　1mm pitch plastic 　　embossed TA1mm pitch press paper TBL TC TCM ・・ 2mm pitch press paper TPL・TP 2mm pitch punch paper TD4mm pitch punch paper TE4mm pitch plastic embossed BKBulk ※2 金めっき電極品は、1E、1J、2A 10Ω〜1MΩ で対応しております。　仕様が異なりますので弊社までご相談ください。 ※3 1F、1H、W2H、W3Aは端子表面材質Tのみを対応致します。 ※2 roducts with gold plated electrodes are also available with 1E, 1J and 2A types P 　 10Ω〜1MΩso please consult with us. , ※3 ith type 1F, 1H, W2H, W3A only T is available as the terminal surface material. W 端子表面材質は鉛フリーめっき品が標準となります。環境負荷物質含有についてEU-RoHS以外の物質に対するご要求がある場合にはお問合せください。テーピングの詳細については巻末のAPPENDIX Cを参照してください。 The terminal surface material lead free is standard. Contact us when you have control request for environmental hazardous material other than the substance specified by EU-RoHS. For further information on taping, please refer to APPENDIX C on the back pages. 周囲温度70℃以上で使用される場合は、上図に示す負荷軽減曲線に従って、定格電力を軽減して御使用ください。 For resistors operated at an ambient temperature of 70℃ or above, a power rating shall be derated in accordance with the above derating curve. ■参考規格　Reference Standards 　IEC 60115-8 　JIS C 5201-8 　EIAJ RC-2134C 本カタログに掲載の仕様は予告なく変更する場合があります。ご注文およびご使用前に納入仕様書で内容をご確認ください。車載機器、医療機器、航空機器など人命に関わったり、あるいは甚大な損害を引き起こす可能性のある機器へのご使用を検討される場合には、必ず事前にご相談ください。 Specifications given herein may be changed at any time without prior notice. Please confirm technical specifications before you order and/or use. Contact our sales representatives before you use our products for applications including automotives, medical equipment and aerospace equipment. Malfunction or failure of the products in such applications may cause loss of human life or serious damage.

Open the catalog to page 1

抵抗温度定格電力係数 Power T.C.R. Rating −6 ×10 /K 定格周囲温度 Rated Ambient Temperature :70℃ 使用温度範囲 Operating Temperature Range :−55℃〜125℃ 1F・1H−55℃〜155℃ , 1E・1J・2A・2B・2E・W2H・W3A 定格電圧は √ 定格電力×公称抵抗値による算出値、又は表中の最高使用電圧のいずれか小さい値が定格電圧となります。 Rated voltage √ or Max. working voltage, whichever is lower. Power Rating×Resistance value ※4　内の最高使用電圧、最高過負荷電圧については、お問い合わせください。 ※4 Please consult with us about the Max. working voltage and the Max. overload voltage with ( ). ■性能　Performance 試験項目 Test Items 試験方法 Test Methods 規定の許容差内 Within specified tolerance 規定値内 Within specified T.C.R. 過負荷短時間 Overload Short time はんだ耐熱性...

Open the catalog to page 2

All KOA catalogs and technical brochures

Archived catalogs

KOA Passive Components Selection Guide
8 Pages

*Prices are pre-tax. They exclude delivery charges and customs duties and do not include additional charges for installation or activation options. Prices are indicative only and may vary by country, with changes to the cost of raw materials and exchange rates.

Brand list