The Low Temperature Cofired Ceramic (LTCC)

The present paper reports and discusses the results of a 3D finite element simulation of the injection molding process of a rubber component, including the stages of the mold filling dynamics and material curing, using the "Reactive Molding" module of the Moldflow 6.2 CAE software. A differential scanning calorimeter (DSC) and a capillary rheometer are employed to characterize the rubber material in order to obtain appropriate curing reaction and viscosity models, respectively. The model parameters so obtained are used to simulate the injection molding process for an engineering rubber component with a complex geometry having a thickness distribution that ranges from 1.5 mm to 20 mm. The computations are found in good agreement with the experimental results, indicating that reliable information on material viscosity and curing kinetic play a key role for well-founded predictions.

Direct Digital Manufacturing techniques such as laser ablation are proposed for the fabrication of lower cost, miniaturized, and lightweight integrated assemblies with high performance requirements. This paper investigates the laser ablation of a Ti/Cu/Pt/Au thin film metal stack on fired low temperature cofired ceramic (LTCC) surfaces using a 355 nm Nd:YAG diode pumped laser ablation system. It further investigates laser ablation applications using unfired, or ‘green’, LTCC materials: (1) through one layer of a laminated stack of unfired LTCC tape to a buried thick film conductor ground plane, and (2) in unfired Au thick films. The UV laser power profile and part fixturing were optimized to address defects such as LTCC microcracking, thin film adhesion failures, and redeposition of Cu and Pt. An alternate design approach to minimize ablation time was tested for efficiency in manufacture. Multichip Modules (MCM) were tested for solderability, solder leach resistance, and wire bondability. Scanning electron microscopy (SEM) as well as cross sections and microanalytical techniques were used in this study.

No abstract

Direct digital manufacturing techniques such as laser ablation are proposed for the fabrication of lower cost, miniaturized, and lightweight integrated assemblies with high performance requirements. This paper investigates the laser ablation of a Ti/Cu/Pt/Au thin-film metal stack on fired low temperature cofired ceramic (LTCC) surfaces using a 355-nm Nd:YAG diode-pumped laser ablation system. It further investigates laser ablation applications using unfired, or “green,” LTCC materials in the following ways: (1) through one layer of a laminated stack of unfired LTCC tape to a buried thick-film-conductor ground plane, and (2) in unfired Au thick films. The UV-laser power profile and part fixturing were optimized to address defects such as LTCC microcracking, thin-film adhesion failures, and redeposition of Cu and Pt. An alternate design approach to minimize ablation time was tested for efficiency in manufacture. Multichip modules were tested for solderability, solder leach resistance, and wire bondability. Scanning electron microscopy, as well as cross sections and microanalytical techniques, were used in this study.

Low temperature cofired ceramic (LTCC) technology has proven itself in military/space electronics, wireless communication, microsystems, medical and automotive electronics, and sensors. The use of LTCC for high frequency applications is appealing due to its low losses, design flexibility and packaging and integration capability. The LTCC thick film process is summarized including some unconventional process steps such as feature machining in the unfired state and thin film definition of outer layer conductors. The LTCC thick film process was characterized to optimize process yields by focusing on these factors: 1) Print location, 2) Print thickness, 3) Drying of tapes and panels, 4) Shrinkage upon firing, and 5) Via topography. Statistical methods were used to analyze critical process and product characteristics in the determination towards that optimization goal.

Low Temperature Cofired Ceramic (LTCC) technology can be applied in numerous functions due to a wide variety of benefits, particularly related to flexibility of applications. Controlling the LTCC shrinkage tolerances in the x, y, and z dimensions is critical during manufacturing and avoids an assortment of down-stream issues that will affect yields. All manufacturers of LTCC tape provide a Certificate of Analysis (COA), which contains the results of the manufacturer's shrinkage testing so production variation can be established from lot to lot. Data from this COA is generally used as a starting point in the shrinkage predictions for manufacturing purposes; however, verification of this data must be performed prior to initiating an LTCC build. This paper investigates validation of one manufacturer's COA data and explains how shrinkage differences can occur between the COA data and the data collected during the verification process. The tracking of this data is also presented as a means to ensure proper controls are in place, and the type and style of lamination and cofiring are shown to be significant contributors to these differences. Data will then be presented in association with characterization prior to and after relocation of LTCC fabrication equipment. Additionally, the COA data can be incorporated into shrinkage estimates that will be utilized to set up process parameters, tolerances, and a control plan.

Low temperature cofired ceramic (LTCC) technology has proven to be invaluable in military/space electronics, wireless communication, microsystems, medical and automotive electronics, and sensors. The use of LTCC for high-frequency applications is appealing due to its low losses, design flexibility, and packaging and integration capability. The LTCC thick film process is summarized, including some unconventional process steps such as feature machining in the unfired state and thin film definition of outer layer conductors. The LTCC thick film process was characterized to optimize process yields by focusing on the following factors: (1) print location, (2) print thickness, (3) drying of tapes and panels, (4) shrinkage upon firing, and (5) via topography. Statistical methods were used to analyze critical process and product characteristics to achieve the optimization goal.