Bussco Bus Bar Product Materials

Conductor

Copper alloy 110 is the conductor material typically used in bus bar designs. It has lower resistivity than brass and aluminum, which are also used. The tables below list some relevant physical and electrical properties of the most commonly used conductor materials in bus bar fabrication.

Table 2 - Relevant physical properties of conductor materials used in bus bar construction

Metal	Density @ 20° C (lb/in³)	CTE @ 20°C (x10^-6m/m•°C)	Thermal Conductivity @ 20°C (W/m•K)	Specification
Copper 110	.323	17	388	ASTM B-152 QQ-C-576
Copper 101	.323	17	383 - 391	ASTM B-152 QQ-C-576
Brass 260	.308	19.9	120	ASTM B-152 QQ-B-613
Aluminum 6061-T651	.098	23.6	154	ASTM-B236

Table 3 - Relevant electrical properties of conductor materials used in bus bar construction

Metal	Resistivity (ρ) @ 20°C Ω ° sqmil/ft	Conductivity % IACS @ 20°C	Thermal Coefficient of Resistivity (α) @20°C (10^-2/°C)
Copper 110	8.1	101	.393
Copper 101	8.1	101	.393
Brass Alloy 260	29.06	28	.098
Aluminum 6061-T651	13.35	62	.423

Insulation

A variety of materials can be used for insulation between conductors and for the outer covers. If the bus bar is to be edge-filled, a rigid material is recommended for top and bottom insulators. If the outer insulation is sealed by pinch bonding, we recommend the use of a flexible dielectric film. The table below shows some relevant specifications for the materials typically used. The data presented in the table is for the base material without adhesive.

Table 4 - Insulation material general specifications

Material	Thickness Range (inches)	Dielectric Constant @23°C, 50%RH, 60Hz	Dielectric Strength @23°C, 50%RH, 60Hz (volts/mil)	Maximum Continuous Use Temperature (°C)	CTE 30 to 100°C (x10^-6m/m•°C)	UL Rating	CTI (volts)
Epoxy Glass (FR4/G-10)	.010-.125	4.3	1250	140	12-16	94V-0	388
Mylar⁽¹⁾	.003 .005 .010	3.3	7,500	120	17	94VTM-2	400-600
Kapton⁽¹⁾	.001 .002 .003 .005	3.9 ⁽³⁾	6000 5000 4500 3000	200	17	94V-0	100-175
Nomex⁽¹⁾	.002-.030	1.6-3.7	430-840	220	16	94V-0	175-250
Mylar/Tedlar^(1,2)	.005	8.5	2860	105	NA	94HB	n/a

¹ Mylar®, Nomex® and Tedlar® are registered trademarks of Dupont.
²Mylar (.003") bonded to Telar (.002")
³Measured @ 23°C, 50%RH, 1kHz

Plating

The plating material used is dependent on environmental requirements as well as electrical requirements. If required, products can be processed with RoHS compliant plating.

Table 5 - Plating materials

Metal	Conductivity % IACS @ 20°C	Thermal Coefficient of Resistivity (α) @ 20°C (10^-2/°C)	Specification
Tin	13.6	.42	ASTM B545, MIL-T-10727
Nickel	11.8	.48	AMS 2403, AMS-QQ-N-290, QQ-N-290
Silver	105.8	.38	ASTM B700
Solder Alloy 60/40	10.0	.40	AMS-P-81728, MIL-P-81728

Potting

There are a variety of different electrical grade epoxy resins that can be used to edge fill bus bars. These materials are specifically chosen by the bus bar manufacturer to meet the physical, electrical and environmental requirements of the application and the limitations imposed during the manufacture of the bus bar. Each manufacturer may standardize on a potting compound that is suited to its own processing capabilities, therefore not all manufacturers use the same material.