PLCC 20-Position Socket A-CCS20-Z-SM Equivalent & Substitute Parts

Part Overview

The A-CCS20-Z-SM is a 20-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 equivalent substitute parts necessary for ongoing production and maintenance applications. The socket accommodates 4 x 5 position PLCC packages with 0.050" (1.27mm) mating pitch and solder termination.

Key Parameters

Parameter	Value
Type	PLCC Socket
Number of Positions	20 (4 x 5)
Pitch - Mating	0.050" (1.27mm)
Mounting Type	Surface Mount
Contact Finish - Mating	Tin
Housing Material	Polybutylene Terephthalate (PBT), Glass Filled
Operating Temperature Range	-55°C ~ 105°C
Current Rating	1 A
Contact Resistance	30mOhm
Flammability Rating	UL94 V-0
RoHS Status	RoHS non-compliant

Substitute Part Grouping Explanation

Substitution validity for PLCC 20-position sockets is determined by the following critical parameters: 20-position (4 x 5) configuration, 0.050" (1.27mm) mating pitch, surface mount mounting type, tin contact finish on mating surfaces, solder termination, closed frame design, and UL94 V-0 flammability rating. All three substitute parts meet these core electrical and mechanical requirements.

The substitute parts are grouped as follows:

Primary Substitute (MFR Recommended): 540-44-020-17-400000 (Mill-Max Manufacturing Corp., Series 540) — Active product status with ROHS3 compliance and improved contact resistance (20mOhm).

Secondary Substitutes: 8420-21B1-RK-TP (3M, Series 8400) and 940-44-020-17-400000 (Mill-Max Manufacturing Corp., Series 940) — Both active products with ROHS3 compliance and extended operating temperature ranges.

Parameter Comparison

Parameter	A-CCS20-Z-SM (Main)	540-44-020-17-400000	8420-21B1-RK-TP	940-44-020-17-400000
Manufacturer	Assmann WSW Components	Mill-Max Manufacturing Corp.	3M	Mill-Max Manufacturing Corp.
Product Status	Obsolete	Active	Active	Active
Type	PLCC	PLCC	PLCC	PLCC
Number of Positions	20 (4 x 5)	20 (4 x 5)	20 (4 x 5)	20 (4 x 5)
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 Finish Thickness - Mating	150.0µin (3.81µm)	150.0µin (3.81µm)	160.0µin (4.06µm)	150.0µin (3.81µm)
Mounting Type	Surface Mount	Surface Mount	Surface Mount	Surface Mount
Features	Closed Frame	Closed Frame	Closed Frame	Closed Frame
Termination	Solder	Solder	Solder	Solder
Pitch - Post	0.050" (1.27mm)	0.100" (2.54mm)	0.100" (2.54mm)	0.050" (1.27mm)
Contact Finish - Post	Tin	Tin	Tin	Tin
Housing Material	Polybutylene Terephthalate (PBT), Glass Filled	Polyphenylene Sulfide (PPS)	Polybutylene Terephthalate (PBT), Glass Filled	Polycyclohexylenedimethylene Terephthalate (PCT), Polyester
Operating Temperature Range	-55°C ~ 105°C	-55°C ~ 125°C	-40°C ~ 105°C	-55°C ~ 125°C
Current Rating	1 A	Not specified	1 A	1 A
Contact Resistance	30mOhm	20mOhm	Not specified	30mOhm
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)

Engineering Selection Recommendations

For RoHS3 Compliant Applications: All three substitute parts (540-44-020-17-400000, 8420-21B1-RK-TP, and 940-44-020-17-400000) are ROHS3 compliant, whereas the original A-CCS20-Z-SM is RoHS non-compliant. Selection among these three depends on specific PCB layout and thermal requirements.

For Standard Temperature Range (-55°C to 105°C): The 8420-21B1-RK-TP (3M) maintains the original operating temperature range and is suitable for direct replacement in applications with standard thermal profiles.

For Extended Temperature Range (-55°C to 125°C): The 540-44-020-17-400000 and 940-44-020-17-400000 both support extended upper temperature limits, providing thermal margin for demanding applications.

For Optimized Contact Performance: The 540-44-020-17-400000 offers reduced contact resistance (20mOhm versus 30mOhm), improving signal integrity and reducing power dissipation in high-current or high-frequency applications.

For PCB Layout Compatibility: The 940-44-020-17-400000 maintains the original 0.050" (1.27mm) post pitch, ensuring direct footprint compatibility. The 540-44-020-17-400000 and 8420-21B1-RK-TP use 0.100" (2.54mm) post pitch and require PCB redesign.

Frequently Asked Questions (FAQ)

Q: Can I use 540-44-020-17-400000 as a direct drop-in replacement for A-CCS20-Z-SM?

A: Electrically and mechanically, yes. The 20-position PLCC configuration, 0.050" mating pitch, tin contact finish, and solder termination are identical. However, the post pitch differs (0.100" versus 0.050"), requiring PCB footprint modification.

Q: What is the primary advantage of 940-44-020-17-400000 over other substitutes?

A: The 940-44-020-17-400000 maintains the original 0.050" (1.27mm) post pitch, enabling direct PCB footprint compatibility without layout redesign. It also supports extended operating temperature (-55°C to 125°C) and is ROHS3 compliant.

Q: Are all substitute parts suitable for high-reliability applications?

A: All substitute parts carry UL94 V-0 flammability certification and MSL 1 (unlimited moisture sensitivity), meeting standard reliability requirements. The 540-44-020-17-400000 and 940-44-020-17-400000 offer extended temperature ranges, providing additional margin for demanding environments.

Q: Does the housing material difference affect electrical performance?

A: Housing material differences (PBT, PPS, PCT) do not affect electrical performance for this socket application. Material selection impacts thermal stability and mechanical durability. PPS (540-44-020-17-400000) offers superior thermal performance; PBT and PCT provide standard performance.

Q: Why is the original A-CCS20-Z-SM obsolete?

A: The original part is classified as obsolete by the manufacturer. All three substitute parts are active products with current manufacturing support and improved compliance certifications (ROHS3).

Q: Can I mix substitute parts in the same assembly?

A: Yes, all substitute parts are electrically and mechanically equivalent for the 20-position PLCC socket function. However, using a single part number per assembly simplifies procurement, inventory management, and traceability.

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