Method and apparatus for jetting, manufacturing and attaching uniform solder balls

Patent · Thu Dec 31 23:00:00 EST 1998

OSTI ID:872069

Yost, Frederick G ^[1]; Frear, Darrel R ^[2]; Schmale, David T ^[2]

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1. Cedar Crest, NM
2. Albuquerque, NM

An apparatus and process for jetting molten solder in the form of balls directly onto all the metallized interconnects lands for a ball grid array package in one step with no solder paste required. Molten solder is jetted out of a grid of holes using a piston attached to a piezoelectric crystal. When voltage is applied to the crystal it expands forcing the piston to extrude a desired volume of solder through holes in the aperture plate. When the voltage is decreased the piston reverses motion creating an instability in the molten solder at the aperture plate surface and thereby forming spherical solder balls that fall onto a metallized substrate. The molten solder balls land on the substrate and form a metallurgical bond with the metallized lands. The size of the solder balls is determined by a combination of the size of the holes in the aperture plate, the duration of the piston pulse, and the displacement of the piston. The layout of the balls is dictated by the location of the hooks in the grid. Changes in ball size and layout can be easily accomplished by changing the grid plate. This invention also allows simple preparation of uniform balls for subsequent supply to BGA users.

• Research Organization: AT & T CORP
• DOE Contract Number: AC04-76DP00789
• Assignee: Sandia Corporation (Albuquerque, NM)
• Patent Number(s): US 5855323
• OSTI ID: 872069
• Country of Publication: United States
• Language: English

Related Subjects

/239/219/222/
accomplished
allows
aperture
aperture plate
apparatus
applied
array
attached
attaching
ball
ball grid
balls
bga
bond
changes
changing
combination
creating
crystal
decreased
desired
determined
dictated
directly
displacement
duration
easily
expands
extrude
fall
forcing
form
forming
grid
grid array
holes
hooks
instability
interconnects
jetted
jetting
land
lands
layout
location
manufacturing
metallized
metallurgical
metallurgical bond
method
molten
molten solder
motion
package
paste
piezoelectric
piezoelectric crystal
piston
piston attached
plate
plate surface
preparation
process
pulse
required
reverses
simple
size
solder
spherical
step
subsequent
substrate
supply
surface
uniform
users
voltage
volume