Technical Library | 2020-09-23 21:37:25.0
The need to minimise thermal damage to components and laminates, to reduce warpage-induced defects to BGA packages, and to save energy, is driving the electronics industry towards lower process temperatures. For soldering processes the only way that temperatures can be substantially reduced is by using solders with lower melting points. Because of constraints of toxicity, cost and performance, the number of alloys that can be used for electronics assembly is limited and the best prospects appear to be those based around the eutectic in the Bi-Sn system, which has a melting point of about 139°C. Experience so far indicates that such Bi-Sn alloys do not have the mechanical properties and microstructural stability necessary to deliver the reliability required for the mounting of BGA packages. Options for improving mechanical properties with alloying additions that do not also push the process temperature back over 200°C are limited. An alternative approach that maintains a low process temperature is to form a hybrid joint with a conventional solder ball reflowed with a Bi-Sn alloy paste. During reflow there is mixing of the ball and paste alloys but it has been found that to achieve the best reliability a proportion of the ball alloy has to be retained in the joint, particular in the part of the joint that is subjected to maximum shear stress in service, which is usually the area near the component side. The challenge is then to find a reproducible method for controlling the fraction of the joint thickness that remains as the original solder ball alloy. Empirical evidence indicates that for a particular combination of ball and paste alloys and reflow temperature the extent to which the ball alloy is consumed by mixing with the paste alloy is dependent on the volume of paste deposited on the pad. If this promising method of achieving lower process temperatures is to be implemented in mass production without compromising reliability it would be necessary to have a method of ensuring the optimum proportion of ball alloy left in the joint after reflow can be consistently maintained. In this paper the author explains how the volume of low melting point alloy paste that delivers the optimum proportion of retained ball alloy for a particular reflow temperature can be determined by reference to the phase diagrams of the ball and paste alloys. The example presented is based on the equilibrium phase diagram of the binary Bi-Sn system but the method could be applied to any combination of ball and paste alloys for which at least a partial phase diagram is available or could be easily determined.
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170 oC) Phenolic cured (Dicy Free) system with inorganic filler High Td (decomposition temp. > 340 oC by TGA) Lead free process compatible (260 oC IR reflow 6x + 288 oC solder flow 3x, no delamination) Low Coefficient of Thermal Expansion ( 60 min. T
New Equipment | Assembly Services
Edge Plating does not have a set definition per IPC. However, the industry generally accepts this as being copper plating that continues from the top and bottom surfaces and along one or more perimeter edges. Edge Plating can be used for a variety of
New Equipment | Solder Materials
Kapp Golden Flux™ PASTE has been designed specifically for soldering Aluminum to Aluminum and Copper. Kapp Golden Flux™ PASTE stays where you put it. It is designed for use on Aluminum-to-Aluminum or Aluminum-to-Copper sheets and tabs where fluxing a
New Equipment | Solder Materials
Kapp Golden Flux™ PASTE has been designed specifically for soldering Aluminum to Aluminum and Copper. Kapp Golden Flux™ PASTE stays where you put it. It is designed for use on Aluminum-to-Aluminum or Aluminum-to-Copper sheets and tabs where fluxing a
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Technical Library | 2020-09-02 22:14:36.0
The demand for miniaturization and higher density electronic products has continued steadily for years, and this trend is expected to continue, according to various semiconductor technology and applications roadmaps. The printed circuit board (PCB) must support this trend as the central interconnection of the system. There are several options for fine line circuitry. A typical fine line circuit PCB product using copper foil technology, such as the modified semi-additive process (mSAP), uses a thin base copper layer made by pre-etching. The ultrathin copper foil process (SAP with ultrathin copper foil) is facing a technology limit for the miniaturization due to copper roughness and thickness control. The SAP process using sputtered copper is a solution, but the sputtering process is expensive and has issues with via plating. SAP using electroless copper deposition is another solution, but the process involved is challenged to achieve adequate adhesion and insulation between fine-pitch circuitries. A novel catalyst system--liquid metal ink (LMI)--has been developed that avoids these concerns and promotes a very controlled copper thickness over the substrate, targeting next generation high density interconnect (HDI) to wafer-level packaging substrates and enabling 5-micron level feature sizes. This novel catalyst has a unique feature, high density, and atomic-level deposition. Whereas conventional tin-palladium catalyst systems provide sporadic coverage over the substrate surface, the deposited catalyst covers the entire substrate surface. As a result, the catalyst enables improved uniformity of the copper deposition starting from the initial stage while providing higher adhesion and higher insulation resistance compared to the traditional catalysts used in SAP processes. This article discusses this new catalyst process, which both proposes a typical SAP process using the new catalyst and demonstrates the reliability improvements through a comparison between a new SAP PCB process and a conventional SAP PCB process.
Parts & Supplies | Assembly Accessories
HS50 (HS60) Communication Unit Change-over Table 00330037-07 SIEMENS Valve Plunger SP12 00351498-03 SIEMENS 80S15 X Motor BB58.82.11-SN3-S SIEMENS 00119032 SIEMENS Camera 00315224-06 SIEMENS RV6 Camera 00346264 00384286-01 SPK Vacuum Pump Acous
Used SMT Equipment | In-Circuit Testers
The Aeroflex/IFR/Marconi 2968 TETRA Radio Test Set Version 3.2, is designed to provide faster, more comprehensive and easier to use tests for the routine terminal maintenance and repair operations normally undertaken by the emergency services and man
