BC857BW/MIF Equivalent & Substitute Parts

Part Overview

The BC857BW/MIF is a PNP bipolar junction transistor manufactured by Nexperia USA Inc., designed for small-signal switching and amplification applications. This component operates at a maximum collector current of 100 mA with a collector-emitter breakdown voltage of 45 V, housed in a surface-mount SOT-323 package. The BC857BW/MIF is classified as obsolete, necessitating identification of active equivalent and substitute parts for new designs and ongoing production requirements. Equivalent parts maintain identical electrical and mechanical specifications, while substitute parts provide functional compatibility within defined parameter tolerances.

Key Parameters

Parameter	Value	Unit
Transistor Type	PNP	—
Current - Collector (Ic) Max	100	mA
Voltage - Collector Emitter Breakdown (Max)	45	V
Vce Saturation (Max) @ Ib, Ic	600 mV @ 5 mA, 100 mA	—
Current - Collector Cutoff (Max)	15	nA
DC Current Gain (hFE) Min @ Ic, Vce	220 @ 2 mA, 5 V	—
Power - Max	200	mW
Frequency - Transition	100	MHz
Operating Temperature (TJ)	150	°C
Mounting Type	Surface Mount	—
Package / Case	SC-70, SOT-323	—
RoHS Status	ROHS3 Compliant	—
Moisture Sensitivity Level (MSL)	1 (Unlimited)	—

Substitute Part Grouping Explanation

Substitution of the BC857BW/MIF is determined by strict adherence to the following electrical and mechanical parameters:

Primary Substitution Criteria:

Transistor Type: PNP
Current - Collector (Ic) Max: 100 mA
Voltage - Collector Emitter Breakdown (Max): 45 V
DC Current Gain (hFE) Min @ Ic, Vce: 220 @ 2 mA, 5 V
Mounting Type: Surface Mount
Package / Case: SC-70, SOT-323

Substitution Categories:

Direct Equivalents maintain all electrical parameters and differ only in packaging format or product status. BC857BW,115 and BC857BW,135 are direct equivalents from Nexperia USA Inc., both active products with identical electrical specifications to the obsolete BC857BW/MIF.

Parametric Equivalents maintain core electrical performance within acceptable tolerances. BC860BW,115 and BC860BW,135 are parametric equivalents with Vce saturation specifications of 650 mV (versus 600 mV for the main part), representing a 50 mV variance within acceptable switching application tolerances. Both are active Nexperia products with AEC-Q101 automotive qualification.

Similar Alternatives provide functional compatibility with minor parameter deviations. MSB1218A-RT1G (onsemi) operates at reduced maximum power (150 mW versus 200 mW) and exhibits different Vce saturation (500 mV @ 10 mA, 100 mA) and collector cutoff current (100 µA versus 15 nA) specifications. This part is suitable for applications where the reduced power rating and parameter variations are acceptable.

Cross-Manufacturer Equivalents include BC857BW from Diotec Semiconductor, which maintains identical electrical specifications and SOT-323 packaging while offering significantly higher inventory availability.

Parameter Comparison

Part Number	Manufacturer	Product Status	Ic Max (mA)	Vce Breakdown (V)	Vce Sat (mV)	hFE Min @ Ic, Vce	Power Max (mW)	Frequency (MHz)	Package	Compliance
BC857BW/MIF	Nexperia USA Inc.	Obsolete	100	45	600 @ 5mA, 100mA	220 @ 2mA, 5V	200	100	SOT-323	ROHS3
BC857BW,115	Nexperia USA Inc.	Active	100	45	600 @ 5mA, 100mA	220 @ 2mA, 5V	200	100	SOT-323	ROHS3, AEC-Q101
BC857BW,135	Nexperia USA Inc.	Active	100	45	600 @ 5mA, 100mA	220 @ 2mA, 5V	200	100	SOT-323	ROHS3, AEC-Q101
BC860BW,115	Nexperia USA Inc.	Active	100	45	650 @ 5mA, 100mA	220 @ 2mA, 5V	200	100	SOT-323	ROHS3, AEC-Q101
BC860BW,135	Nexperia USA Inc.	Active	100	45	650 @ 5mA, 100mA	220 @ 2mA, 5V	200	100	SOT-323	ROHS3, AEC-Q101
MSB1218A-RT1G	onsemi	Active	100	45	500 @ 10mA, 100mA	210 @ 2mA, 10V	150	—	SOT-323	ROHS3
BC857BW	Diotec Semiconductor	Active	100	45	650 @ 5mA, 100mA	220 @ 2mA, 5V	200	100	SOT-323	Not applicable

Engineering Selection Recommendations

For Direct Replacement (Preferred): BC857BW,115 and BC857BW,135 are recommended as primary replacements for the obsolete BC857BW/MIF. Both parts are manufactured by Nexperia USA Inc. and maintain identical electrical specifications. BC857BW,115 is supplied in Cut Tape and Digi-Reel packaging, while BC857BW,135 is supplied in Tape & Reel format. Both are active products with AEC-Q101 automotive qualification and ROHS3 compliance, ensuring long-term availability and regulatory alignment.

For Parametric Substitution: BC860BW,115 and BC860BW,135 are suitable where the 50 mV increase in Vce saturation (650 mV versus 600 mV) is acceptable for the application. Both parts are active Nexperia products with AEC-Q101 qualification and ROHS3 compliance. These parts are appropriate for switching applications where saturation voltage tolerance permits the variance.

For Alternative Sourcing: BC857BW from Diotec Semiconductor provides an active cross-manufacturer equivalent with identical electrical specifications and significantly higher inventory availability (245,400 pieces). This part is suitable for applications requiring high-volume sourcing and extended supply chain security.

For Cost-Optimized Applications: MSB1218A-RT1G (onsemi) is suitable for applications where reduced power dissipation (150 mW versus 200 mW) is acceptable and where the lower Vce saturation (500 mV) provides design margin. This part exhibits lower collector cutoff current (100 µA versus 15 nA), which may impact leakage-sensitive applications. Selection requires confirmation that application requirements accommodate these parameter variations.

Frequently Asked Questions (FAQ)

Q: Can BC857BW,115 and BC857BW,135 be used interchangeably with BC857BW/MIF?

A: Yes. Both parts are direct electrical equivalents manufactured by Nexperia USA Inc. with identical specifications for collector current, breakdown voltage, saturation voltage, current gain, power rating, and transition frequency. The primary difference is packaging format: BC857BW,115 is supplied in Cut Tape and Digi-Reel, while BC857BW,135 is supplied in Tape & Reel. Selection depends on assembly line requirements and inventory management practices.

Q: What is the significance of the Vce saturation difference between BC857BW and BC860BW variants?

A: BC860BW parts exhibit 650 mV Vce saturation compared to 600 mV for BC857BW parts, a 50 mV variance. This difference is acceptable in most switching applications where saturation voltage tolerance is ±100 mV or greater. For precision applications with tight saturation voltage specifications, BC857BW variants are preferred. For general-purpose switching, BC860BW variants provide equivalent functionality.

Q: Is the MSB1218A-RT1G suitable as a direct replacement?

A: MSB1218A-RT1G is a functional alternative with compatible package and core electrical ratings. However, it differs in maximum power rating (150 mW versus 200 mW), Vce saturation (500 mV @ 10 mA, 100 mA versus 600 mV @ 5 mA, 100 mA), and collector cutoff current (100 µA versus 15 nA). Selection requires confirmation that the application tolerates these parameter variations. This part is suitable for low-power switching applications where the reduced power rating and lower saturation voltage provide design margin.

Q: What is the difference between Cut Tape, Digi-Reel, and Tape & Reel packaging?

A: Cut Tape (CT) and Digi-Reel packaging are used for lower-volume orders and manual assembly processes, with components supplied on tape that can be cut to length. Tape & Reel (TR) packaging supplies components on continuous tape wound on reels, optimized for high-speed automated assembly equipment. Electrical specifications are identical; packaging selection depends on assembly process requirements and order volume.

Q: Are all substitute parts ROHS3 compliant?

A: BC857BW,115, BC857BW,135, BC860BW,115, BC860BW,135, and MSB1218A-RT1G are all ROHS3 compliant. BC857BW from Diotec Semiconductor lists RoHS status as "Not applicable." Confirm RoHS compliance requirements with your procurement and regulatory teams before final part selection.

Q: Do all substitute parts have AEC-Q101 automotive qualification?

A: BC857BW,115, BC857BW,135, BC860BW,115, and BC860BW,135 are all AEC-Q101 qualified. MSB1218A-RT1G and BC857BW from Diotec Semiconductor do not list AEC-Q101 qualification. For automotive applications, Nexperia-manufactured parts with AEC-Q101 qualification are required.

Q: What is the Moisture Sensitivity Level (MSL) for these parts?

A: BC857BW,115, BC857BW,135, BC860BW,115, BC860BW,135, and MSB1218A-RT1G all have MSL 1 (Unlimited), indicating no moisture sensitivity restrictions. BC857BW from Diotec Semiconductor lists MSL as "Not Applicable." MSL 1 parts require no special moisture control during storage, handling, or assembly.

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