A-CCS28-Z-SM PLCC 28-Position Socket Equivalent & Substitute Parts

Part Overview

The A-CCS28-Z-SM is a 28-position PLCC socket manufactured by Assmann WSW Components, designed for surface mount applications with tin-plated phosphor bronze contacts. This component is classified as obsolete, making identification of active equivalent parts essential for ongoing production and design requirements. Substitute parts must maintain electrical and mechanical compatibility while meeting current manufacturing and compliance standards.

Key Parameters

Parameter	Value
Type	PLCC Socket
Number of Positions	28 (4 x 7)
Pitch - Mating	0.050" (1.27mm)
Contact Finish - Mating	Tin
Mounting Type	Surface Mount
Housing Material	Polybutylene Terephthalate (PBT), Glass Filled
Operating Temperature Range	-55°C ~ 105°C
Current Rating	1 A
Material Flammability Rating	UL94 V-0
Moisture Sensitivity Level	1 (Unlimited)

Substitute Part Grouping Explanation

Substitution eligibility for the A-CCS28-Z-SM is determined by strict adherence to the following parameters:

Socket Type & Configuration: PLCC socket with 28 positions in 4 x 7 grid arrangement
Pitch Specification: 0.050" (1.27mm) mating pitch
Contact Finish: Tin plating on mating surface
Mounting Technology: Surface mount termination
Housing Material: PBT glass-filled polymer construction
Electrical Performance: 1 A current rating minimum
Environmental Rating: UL94 V-0 flammability classification
Moisture Sensitivity: MSL 1 classification

All three substitute parts meet these core requirements. Variations in contact material composition, contact finish thickness, operating temperature range, and RoHS compliance status do not preclude substitution when the above parameters are satisfied.

Parameter Comparison

Parameter	A-CCS28-Z-SM (Main)	8428-21B1-RK-TP	8428-21B1-RK-TR	940-44-028-17-400000
Manufacturer	Assmann WSW Components	3M	3M	Mill-Max Manufacturing Corp.
Product Status	Obsolete	Active	Active	Active
Type	PLCC	PLCC	PLCC	PLCC
Number of Positions	28 (4 x 7)	28 (4 x 7)	28 (4 x 7)	28 (4 x 7)
Pitch - Mating	0.050" (1.27mm)	0.050" (1.27mm)	0.050" (1.27mm)	0.050" (1.27mm)
Contact Finish - Mating	Tin	Tin	Tin	Tin
Contact Material - Mating	Phosphor Bronze	Copper Alloy	Copper Alloy	Beryllium Copper
Mounting Type	Surface Mount	Surface Mount	Surface Mount	Surface Mount
Housing Material	PBT, Glass Filled	PBT, Glass Filled	PBT, Glass Filled	PCT, Polyester
Operating Temperature	-55°C ~ 105°C	-40°C ~ 105°C	-40°C ~ 105°C	-55°C ~ 125°C
Current Rating	1 A	1 A	1 A	1 A
Contact Resistance	30mOhm	Not specified	15mOhm	30mOhm
Material Flammability Rating	UL94 V-0	UL94 V-0	UL94 V-0	UL94 V-0
RoHS Status	RoHS non-compliant	ROHS3 Compliant	ROHS3 Compliant	ROHS3 Compliant
Moisture Sensitivity Level	1 (Unlimited)	1 (Unlimited)	1 (Unlimited)	1 (Unlimited)
Packaging	Not specified	Tube	Tape & Reel	Tube

Engineering Selection Recommendations

All three substitute parts are active products with current manufacturing support, addressing the obsolescence status of the A-CCS28-Z-SM. Selection among substitutes should be based on the following factors:

3M 8428-21B1-RK-TP (Tube Packaging): Active product with ROHS3 compliance. Operating temperature range of -40°C to 105°C covers standard industrial applications. Suitable for designs where tube packaging is preferred for manual assembly or lower-volume production runs.

3M 8428-21B1-RK-TR (Tape & Reel Packaging): Active product with ROHS3 compliance and lower contact resistance (15mOhm). Tape & reel packaging is optimized for automated assembly processes. Recommended for high-volume production environments requiring pick-and-place compatibility.

Mill-Max 940-44-028-17-400000: Active product with ROHS3 compliance and extended operating temperature range (-55°C to 125°C). Beryllium copper contact material and PCT housing provide enhanced thermal performance. Suitable for applications requiring wider temperature operating margins or harsh environmental conditions.

Frequently Asked Questions (FAQ)

Q: Can the A-CCS28-Z-SM be directly replaced with any of these substitute parts?

A: Yes. All three substitute parts maintain the critical electrical and mechanical parameters: 28-position PLCC configuration, 0.050" mating pitch, tin contact finish, surface mount termination, 1 A current rating, and UL94 V-0 flammability classification. Physical footprint and electrical performance are compatible.

Q: What is the difference between the two 3M parts (8428-21B1-RK-TP and 8428-21B1-RK-TR)?

A: Both are identical electrically and mechanically. The primary difference is packaging: 8428-21B1-RK-TP is supplied in tube format, while 8428-21B1-RK-TR is supplied in tape & reel format. Tape & reel is standard for automated assembly; tube packaging is used for manual or lower-volume applications.

Q: Why does the Mill-Max part have a higher operating temperature range?

A: The 940-44-028-17-400000 uses beryllium copper contacts and PCT housing material, which provide superior thermal stability compared to phosphor bronze contacts and PBT housing. This enables operation up to 125°C versus 105°C for the 3M parts.

Q: Are there RoHS compliance considerations for substitution?

A: The original A-CCS28-Z-SM is RoHS non-compliant. All three substitute parts are ROHS3 compliant. If your application or market requires RoHS compliance, any of these substitutes is appropriate. If legacy RoHS non-compliant designs must be maintained, the original part should be sourced from inventory.

Q: What is the contact resistance difference between substitutes?

A: The 3M 8428-21B1-RK-TR specifies 15mOhm contact resistance, while both the original A-CCS28-Z-SM and Mill-Max 940-44-028-17-400000 specify 30mOhm. The 3M tape & reel variant offers lower contact resistance, which may provide marginal performance benefits in high-current or noise-sensitive applications. The 3M tube variant does not specify contact resistance.

Q: Which substitute is recommended for new designs?

A: For automated assembly environments, the 3M 8428-21B1-RK-TR (tape & reel) is the standard choice due to packaging compatibility and lower contact resistance. For applications requiring extended temperature performance, the Mill-Max 940-44-028-17-400000 is appropriate. Both are active products with established supply chains.

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