Ready to use Microelectronic AuSn Solder Pad Chip Carrier
If you are using AuSn preforms for chip solder bonding let us introduce you to the new technology...
SOLDER PREFORMS NO LONGER REQUIRED
There are many ways to go about assembling and bonding microelectronics to carriers. None is more efficient than the use of thermally conductive, dielectric materials that incorporate AuSn solder platforms. Unfortunately there has not been a AuSn solder pad that could maintain a consistent eutectic melting temperature. Our new Target Technology changes everything!!
CHIP CARRIER SUBMOUNT DESCRIPTION:
The ceramic chip carrier pictured above is (thin film) coated on the bottom with a Ti/Pt/Au ground plane. The carrier top section is patterned Ti/Pt/Au for various contacts and has three AuSn solder pads added for wire and chip bonding. These are processed in an array of approximately 100 chips on a BeO or AlN wafer and then diced, test/inspected and packaged. The chips can be individually serialized for quality tracking. Also, note that nearly any pattern can be achieved through photomask
Undoubtedly, the most important aspect of the overall technology is the AuSn solder pad. If you have materials and processes that can move temperature away from and electrically isolate the chip, you still have to bond wires or mount the chip. If you are moving thousands of chips through your assembly process the AuSn must have a consistent melting temperature. Preforms are no longer required
Starting with the base substrate materials, we can begin to define the various structures available for dielectric and thermal management. In most cases, the standard ceramic materials used in microelectronics will meet the dielectric requirements. Aluminum oxide, aluminum nitride and beryllium oxide are the main high dielectric ceramics used. They each have specific thermal properties that can be utilized for specific thermal requirements.
This chart shows the dielectric strength and thermal conductivity properties of each material.
Historically, assembly has been achieved through the use of preforms made of the required AuSn alloy for Pb free soldering. Preforms mean that additional handling and placement must be achieved. In recent years suppliers have been trying to provide a ready preform attached to the chip carrier by applying stacked layers of Au and then Sn either by plating or thin film deposition. The electroplated Au-Sn layers are frequently plagued by inconsistent melting tremps. Electroplating is difficult due to the many contact points required on a wafer and controlling the coating thickness. Thin film is easier but still has inconsistent melting temperatures and tends to be expensive due to precious metal material loss during the coating process.
We can now provide any size AuSn solder pad that melts at 280 degrees Celsius consistently at any location on the pad. With this “Target Technology®”, we now have a fully reproducible product that can meet your requirements for volume production on a ready to use carrier. There is no need for flux or forming gas. A simple thermal, scrub in solder process is all that is needed. Various AuSn alloys by weight percentage are available at specific melting temperatures. Contact us for further information and a detailed quotation for your programs.
Submount Array on Ceramic Wafer: Laser Diode Chip Carriers: