2.0 Processing

General Process
Transfer tape processing closely follows the steps used in the well established multilayer thick film process with the multiple dielectric printing per layer being replaced by a tape lamination step. A flow chart for preparing the transfer tape process is shown below.

1.0 Materials Description

Transfer Tape Dielectric
The transfer tape dielectric is a cast film consisting of inorganic materials in a flexible organic matrix. The inorganics are a mixture of vitreous and crystalline phases based on proven dielectric formulations. They are designed to be fired on alumina substrates at a peak temperature of 8500 C. The organic binder provides strength and flexibility for handling and machining in the green state, thermoplastic character to allow tape bonding to the substrate and complete thermal decomposition so that full densification can be achieved. The transfer tape is provided on a polyester carrier film for increased ease of handling and film protection. The carrier is silicone coated to facilitate tape removal.

Conductors
Gold, Palladium/Silver, and silver based conductor systems are available for use with transfer tape. Special via fills, and buried layer conductors have been developed for each of the metalization types to meet the demanding compatibility and conductive requirements. The flexibility in processing and the less stringent compatibility needs allow a wide variety of thick film conductors to be used for metalizing the top layer.

2.0 Processing

General Process
Transfer tape processing closely follows the steps used in the well established multilayer thick film process with the multiple dielectric printing per layer being replaced by a tape lamination step. A flow chart for preparing the transfer tape process is shown on the next page:

Index