| Business | Phone |
| Fujitsu Compound Semiconductor 151 N Michigan Ave, Chicago 60601 | (312) 932-0050 |
| Broadcom Corp 1825 N Paulina St, Chicago 60622 | (708) 445-8051 |
| H I 7832 S Cregier Ave, Chicago 60649 | (773) 221-1078 |
| Kelburn Engineering 6545 N Olmsted Ave, Chicago 60631 | (773) 775-8383 |