Copper Bonding Wire

Copper wire has become one of the preferred materials for wire bonding interconnects in many semiconductor and microelectronic applications. Copper is used for fine wire ball bonding in sizes up to 0.003 inch (75 microns). Copper wire has the ability of being used at smaller diameters providing the same performance as gold without the high material cost.

Copper wire up to 0.010 inch (250 microns) can be successfully wedge bonded with the proper set-up parameters. Large diameter copper wire can and does replace aluminum wire where high current carrying capacity is needed or where there are problems with complex geometry. The annealing and process steps used by Coining enhance the ability to use large diameter copper wire to wedge bond to silicon without damage occurring to the die.

Copper wire does pose some challenges in that it is harder than both gold and aluminum, so bonding parameters must be kept under tight control. The formation of oxides is inherent with this material, so storage and shelf life are issues that must be considered. Coining uses special packaging in order to protect its copper wire and achieve a longer shelf life.


Properties of Wire Materials

Property	Cu	Au	Al	Ag
Electric Conductivity (%IACS)	103.1	73.4	64.5	108.4
Electric Resistivity (µÙcm)	1.7	2.3	2.66	1.6
Thermal Conductivity (W/m K)	398.0	317.9	243.0	428.0
Thermal Expansion Coeff. (µm/m K)	16.5	14.2	23.6	19.0
Young's Modulus (GPa@300K)	130	88	75	100

Copper Wire

	Hard Wire		Annealed Wire
Diameter	Elongation	Tensile Strength	Elongation	Tensile Strength
(inches(microns))	(%)	(g)	(%)	(g)
0.0007 (18)	0.5 – 4	10 – 20	6 – 20	5 – 12
0.001 (25)	0.5 – 4	20 – 30	10 – 25	10 – 20
0.00125 (32)	0.5 – 4	35 – 45	10 – 25	15 – 25
0.0015 (38)	0.5 – 4	45 – 75	10 – 25	25 – 35
0.002 (50)	0.5 – 4	80 – 120	10 – 25	45 – 55
0.003 (75)	0.5 – 4	200 – 270	10 – 30	95 – 115
0.004 (100)	0.5 – 4	350 – 450	10 – 30	175 – 225
0.005 (125)	0.5 – 4	600 – 700	10 – 30	260 – 310
0.010 (250)	0.5 – 4	2200 – 2600	10 – 30	1040 – 1240

Note: Other specific requirements can be achieved upon request.