Specializing in LTCC & Thickfilm Products
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ZERO SHRINK TECHNOLOGY
This page is devoted entirely to LTCC zero shrink materials and processes.
Sea Ceramics is actively developing Zero Shrink Technology for use in product designed for LTCC. Recent breakthroughs in conductor materials, ceramic particle size control and composite tape casting now positions this technology for use in new POC / POD products. Sea Ceramics is presently working with both the Heralock and ZST zero shrink material systems. We have provided the following technical information for your review:
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Heralock HL2000 Design Guide
"The following documentation has been prepared by Heraeus, Incorporated, Circuit Materials Division, as a guide for both the LTCC foundry and the circuit designer to aid in the application and processing of Heraeus LTCC materials. In addition, many LTCC foundries have developed their own set of design guidelines that outline the specific capabilities of that foundry. Where conflicts arise between guidelines published by a specific foundry and guidelines published by Heraeus, the foundry guidelines should be used."
Heraeus LTCC materials set consists of Heralock
This Heraeus LTCC materials set consists of HeralockÒ HL2000, as well as a family of conductors in silver, gold, and mixed metal which have been specifically formulated to match the HL2000 tape. This family of materials has been developed to address todays and emerging market demands for LTCC module design and production. The near zero shrink capability of HL2000 allows for increased ease of use, process simplification, and lower overall cost. HL2000 offers a combination of competitively priced LTCC tape and high performance conductors, which together offer excellent electrical and mechanical performance."
Microwave Module Design with Heralock HL2000
Abstract - The free-sintered LTCC manufacturing process is a cost-effective approach for building complex electronic modules, especially when good RF performance is needed. The x-y shrinkage and the shrinkage variation that occurs during the firing of standard LTCC is a limitation of this technology for large format manufacturing processes and can cause problems with precision microwave structures. Although several techniques for controlling the x-y shrinkage with constrained sintering have been developed, these additional processes tend to complicate the manufacturing process. HeraLock 2000 LTCC tape (patent pending) is formulated to yield the benefits of constrained sintering techniques with a free-sintered process. While standard LTCC has x-y shrinkage similar to the shrinkage in the z-axis, free sintered HeraLock 2000 densifies primarily in the z-axis, leaving near-zero shrinkage in the x and y directions. The HeraLock 2000 tape is lead-free and cadmium-free with fired properties appropriate for microwave devices requiring low-loss at frequencies up to at least 6 GHz as well as automotive and general-purpose packaging applications. The effect of various firing profile variations on the shrinkage of HL2000 is discussed. Mobile residual glass affects LTCC tapes to varying degrees; these effects will be discussed in the context of conductor and post-fired resistor performance. An overview of microwave material testing with the HL2000 material set will also be shown. The benefits of the HeraLock 2000 material system for existing applications as well as for entirely new module designs will be described. The self-constrained tape has unique advantages for building cavity structures and integrating passive components. New fiber optic packaging structures are also enabled.
Key words: LTCC, constrained sintering, RF materials, cavity structures, microwave, embedded passives
Heralock 2000 Self Constrained LTCC Tape
Abstract - A limitation of low-temperature co-fired ceramic (LTCC) technology involves the x-y shrinkage of LTCC structures upon firing and the control or tolerance of that shrinkage. This problem affects component design, materials utilization, lot-to-lot tolerance of fired components and surface circuit feature location. This paper discusses a novel method to prevent the x-y shrinkage of LTCC structures with the implementation of a new LTCC tape formulation. The HeraLock 2000 tape is in most ways indistinguishable from a standard LTCC tape formulation. A modified form of CT2000 tape, HeraLock 2000 is a lead-free and cadmium-free formulation with properties appropriate for general-purpose packaging, automotive modules and RF applications requiring low-loss at frequencies up to at least 6 GHz. The main advantage of HeraLock 2000 tape is its unique shrinkage properties during firing. Most free-sintered tapes have shrinkage in the x and y directions similar to the shrinkage in the z-axis. In contrast, free sintered HeraLock 2000 densifies by shrinking primarily in the z-axis, leaving near-zero shrinkage in the x and y directions. In an example significant for large-format manufacturing, the x-y shrinkage on six-inch square parts (152 mm x 152 mm) fired with the standard profile was 0.114% +/- 0.014%.In its green state, HeraLock 2000 is handled similarly to conventional tapes. The only change in processing relative to CT2000 is a somewhat longer firing profile. The HeraLock tape is compatible with standard design guidelines with respect to conductors or via holes. The HeraLock formulation resists camber or show-through from co-fired conductors and is compatible with 100% coverage ground-planes on surface or buried metal layers. The paper concludes by discussing the advantages of HeraLock HL2000 for the manufacturing LTCC modules. For example, cavity structures cut into the green HeraLock tape show no x-y shrinkage or distortion after firing. Large area boards can be fabricated with minimal solder pad alignment problems a common disadvantage of LTCC. These large area boards permit the fabrication of circuits in high volume at low cost. A further benefit compared to sacrificial layer constrained sintered processes is the ability to use co-fired solderable top conductors.
Key words: LTCC, constrained sintering, RF materials, cavity structures, microwave, opto-electronic
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Multilayer Ceramic Integrated Circuit