Processing LTCC Circuits

Low Temperature Cofired Ceramic (LTCC) technology is utilized at Barry Industries, Inc. to produce a wide variety of circuits for applications ranging from hermetic packages for microwave semiconductors to highly integrated System on Package (SoP) modules.  SoP modules typically feature integration of many passive RF components and hermetic or near hermetic cavities for semiconductor devices on a single robust ceramic carrier.  These guidelines delineate the current standard capabilities at Barry Industries, Inc.  Advanced process development and device design is constantly improving capabilities, and therefore, if designs outside of these guidelines are required, please consult the factory.

 
Barry LTCC Design Pic
 While the processing of each LTCC circuit has a unique flow, it is comprised of a number of common processes.  Manufacturing planning for an LTCC circuit therefore involves selection and ordering of these operations in such a way as to optimize the results.


Punch

Holes for vias and openings for cavities are formed using an automated punch system.

 

Via Fill

Via holes are filled with either thick film silver or gold paste using a vision assisted screen printer – Inspection is accomplished using an optical measurement system.
Barry LTCC Design Pic

 

Thick Film Printing

Conductor, resistor and dielectric layers are then printed on the individual tape sheets.

 

Lamination

The completed sheets are then collated, stacked and laminated using an isostatic press.
Barry LTCC Design Pic


Sintering

After lamination the green ceramic assemblies are sintered at 850 degrees Celcius.


Singulation

Circuits are typically fabricated in an array on as large a ceramic plate size as practical.  While there are many methods of singulating the circuits, the most common method employed at Barry Industries, Inc. is to cut the ceramic using a diamond blade in a dicing saw.  This results in a precise tolerance circuit that exhibits excellent surface quality on the cut edges.  Alternative methods are available when minimizing manufacturing cost is essential.

 


Layout Standardization

Barry Industries, Inc. has an experienced staff dedicated to translating customer's requirements to hardware.  The following information is representative of internally used standards and is provided as a tool to facilitate discussion. 



Nomenclature

Each feature is assigned a unique designator as follows:

LX [B,T]  NMR – where x is the layer number starting at the base and B or T designate bottom or top respectively, N is a circuitry code (C=conductor, R=resistor, D=dielectric), M is a reference for the particular layer indicating the instance (such as 1 for first conductor), and R is the revision level

Example L4 T C1A – first conductor printed on the top of layer 4 (indicated in figure)

 


File Formats

The preferred formats for supplied artwork are AutoCAD DXF, AutoCAD DWG and Solidworks.  While other formats may be used, it is advisable to consult the factory to confirm compatibility.