Ironwood Electronics SG-BGA User Manual - Manual (Page 4)

P a g e | 4
S G B . d o c , R e v . R , V P , 1 1 / 5 / 1 0
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density application consists of an ultra fine pitch matrix (0.05mm x 0.05mm) of gold plated wires (20 micron
diameter), which are also embedded at a 63-degree angle in a soft insulating sheet of silicone rubber. The
insulation resistance between connections with 500V DC is 1000 M

. The elastomer is ideal for high-current
(50mA per filament) applications where a thin, high-density anisotropic connector is required. The gold-plated
brass filaments protrude several microns from the top and bottom surfaces of the silicone sheet. The operating
temperature range for the elastomer is -35

to 100

C.
Solder balls from the IC package come in contact with the top end of elastomer wire. The bottom end of the
elastomer wire contacts the circuit board pad and thereby makes an electrical path for the signal. The number of
wire filaments making contact depends on the solder ball and circuit board pad diameters. Figure 3 shows the
cross-sectional side view of the elastomer with the BGA IC. The GHz socket can be summarized as a
mechanism in which a downward force applied to an IC compresses its solder balls onto an elastomer, which in
turn compresses on the circuit board, thereby making electrical connection.
PCB Requirements
General
• Where IC body size is < 30.5mm: GHz socket requires 4 mounting holes.
• Where IC body size is > 30.5mm: GHz socket requires 8 mounting holes.
• Two alignment holes are employed in all sockets. (See drawing for location details).
• BGA pattern is not symmetrical with mounting holes due to angled wires in elastomer (see drawing for
layout details).
• Please refer to page 2 of the socket drawing for all PCB recommendations.
Thickness
1.6mm minimum. This will change as per customer's application, environment and usage.
Finish
SnPb plating or Immersion Au or Immersion Ag. Other plating may be used but testing may be required.
Ideally pad surface that is flush or higher than the solder mask is recommended.
Note: Our internal tests were successful with 0.001”-0.002” thick solder mask above the pad surface on 0.5mm
to 1.27mm pitch elastomer sockets.
Cleanliness
Isopropyl Alcohol or similar should be used to clean the board surface prior to attaching socket.
Figure 3: Elastomer cross-sectional side view