173-104LAF-301 NTC Thermistor Equivalent & Substitute Parts

Part Overview

The 173-104LAF-301 is an NTC thermistor manufactured by Honeywell Sensing and Productivity Solutions, rated at 100kΩ resistance at 25°C with a B25/85 value of 4250K. This surface-mount component in 0805 (2012 Metric) package is designed for temperature sensing applications across the -60°C to 125°C operating range. The part is currently listed as obsolete, making identification of equivalent substitute components essential for ongoing production and maintenance requirements. Substitute parts must maintain identical electrical characteristics and mechanical compatibility to ensure direct replacement without circuit redesign.

Substiute Parts

173-104LAF-301

Honeywell Sensing and Productivity SolutionsIn Stock: 1190173-104LAF-301 Datasheet

Current PartRFQ

NHQM104B425T5

Amphenol ThermometricsIn Stock: 872NHQM104B425T5 Datasheet

SimilarRFQ

Key Parameters

Substitute Part Grouping Explanation

Substitution of the 173-104LAF-301 is determined by strict equivalence across the following critical parameters:

Electrical Equivalence Criteria:

• Resistance value at 25°C: 100kΩ (exact match required)
• Resistance tolerance: ±5% (matching tolerance band)
• B25/85 thermal coefficient: 4250K (exact match required)

Mechanical Equivalence Criteria:

• Package type: 0805 (2012 Metric) surface-mount form factor
• Mounting compatibility: Surface-mount technology (SMT)

Compliance Criteria:

• RoHS compliance status
• Moisture sensitivity level: 1 (Unlimited)

The substitute part NHQM104B425T5 meets all electrical and mechanical equivalence requirements. Substitution is valid only when all parameters listed above are matched. Operating temperature range differences do not preclude substitution when the application operates within the overlapping temperature window (-40°C to 125°C).

Parameter Comparison

Engineering Selection Recommendations

The NHQM104B425T5 from Amphenol Thermometrics is a direct electrical and mechanical equivalent to the obsolete 173-104LAF-301. Selection of this substitute is based on the following engineering factors:

Compliance and Certification: Both components maintain RoHS compliance and identical moisture sensitivity ratings, ensuring regulatory and environmental compatibility with existing designs.

Product Status: The substitute part carries active product status, ensuring continued availability and supply chain reliability compared to the obsolete main part.

Thermal Operating Range: The substitute operates across -40°C to 125°C. Applications requiring operation below -40°C must verify that the main part's extended lower temperature limit (-60°C) is necessary for the specific use case. For applications within the -40°C to 125°C window, the substitute provides full functional equivalence.

Packaging and Mounting: Identical 0805 (2012 Metric) surface-mount package ensures direct PCB compatibility without layout modifications or rework procedures.

Electrical Performance: Matching resistance value, tolerance, and B25/85 thermal coefficient guarantee equivalent temperature sensing performance and circuit behavior.

Frequently Asked Questions (FAQ)

Q: Can NHQM104B425T5 be used as a direct replacement for 173-104LAF-301 in existing designs?

A: Yes, for applications operating within the -40°C to 125°C temperature range. The substitute provides identical electrical characteristics (100kΩ at 25°C, ±5% tolerance, 4250K B25/85 value) and mechanical compatibility (0805 surface-mount package). If your application requires operation below -40°C, verify that the extended lower temperature capability of the original part is essential before substituting.

Q: Are there any soldering or assembly differences between these components?

A: No. Both components use identical 0805 (2012 Metric) surface-mount packaging and are compatible with standard SMT assembly processes. No changes to reflow profiles, solder paste specifications, or pick-and-place programming are required.

Q: What is the significance of the B25/85 value in thermistor selection?

A: The B25/85 value (4250K for both parts) defines the thermistor's thermal sensitivity between 25°C and 85°C. This parameter directly determines the component's temperature coefficient and is critical for accurate temperature measurement. Matching B25/85 values ensure equivalent thermal response in the application circuit.

Q: Does the substitute part's ±5% B value tolerance affect circuit performance?

A: The substitute specifies ±5% B value tolerance, while the main part does not specify this parameter. This additional specification on the substitute provides tighter control of thermal characteristics. For applications where B value tolerance is critical, the substitute's specified tolerance is advantageous.

Q: Is the packaging format (Tape & Reel) of the substitute compatible with my assembly process?

A: Tape & Reel (TR) packaging is the standard format for high-volume SMT assembly. If your process uses bulk or tube packaging, contact your supplier to confirm packaging format availability. The component itself is identical regardless of packaging format.

Q: What compliance certifications apply to both parts?

A: Both the 173-104LAF-301 and NHQM104B425T5 are RoHS compliant and carry MSL 1 (Unlimited) moisture sensitivity ratings. Both are classified under ECCN EAR99 and HTSUS 8533.40.8070 for export and tariff purposes.