Technical Library | 2023-01-17 17:12:33.0
Reflowed indium metal has for decades been the standard for solder thermal interface materials (solder TIMs or sTIMs) in most high-performance computing (HPC) TIM1 applications. The IEEE Heterogeneous Integration Thermal roadmap states that new thermal interface materials solutions must provide a path to the successful application of increased total-package die areas up to 100cm2. While GPU architectures are relatively isothermal during usage, CPU hotspots in complex heterogeneously-integrated modules will need to be able to handle heat flux hotspots up to 1000W/cm2 within the next two years. Indium and its alloys are used as reflowed solder thermal interface materials in both CPU and GPU "die to lid/heat spreader" (TIM1) applications. Their high bulk thermal conductivity and proven long-term reliability suit them well for extreme thermomechanical stresses. Voiding is the most important failure mode and has been studied by x-ray. The effects of surface pretreatment, pressure during reflow, solder flux type/fluxless processing, and preform design parameters, such as alloy type, are also examined. The paper includes data on both vacuum and pressure (autoclave) reflow of sTIMs, which is becoming necessary to meet upcoming requirements for ultralow voiding in some instances.
Technical Library | 1999-08-27 09:29:49.0
Contract packaging houses have to contend with a large mix of die types and products. Flexibility and quick turnaround of package types is a must in this industry. Traditional methods of die encapsulation, (i.e., use of transfer-molding techniques), are only cost effective when producing a large number of components. Liquid encapsulants now provide similar levels of reliability1, and are cost effective...
Technical Library | 2019-07-29 10:35:47.0
ACI Technologies can assist its users with process development and experimentation through the use of the conformal coating capabilities in the Demonstration Factory. Four types of coating processes are available at ACI Technologies: dip coating, manual spray coating, programmable spray coating, and manual brush application. (Manual brush application will not be discussed in this article.)
Technical Library | 2019-05-21 17:31:39.0
In the field of electronics manufacturing, the end use of the product will always dictate the processes, procedures, and methods, not only for building the product, but also for testing, cleaning, and protecting the assembly in order to assure the level of quality required for proper operation. The need to protect an electronic assembly from its end use environment may stem from anyone of a number of hazardous (or potentially hazardous) conditions. Choosing the type of protective material is dependent upon matching that material’s characteristics with the conditions to be overcome. Naturally, the use of a protective (conformal) coating will require some method of verification to ensure the desired level and type of protection is achieved.
Technical Library | 2019-05-23 10:38:07.0
Solvent and co-solvent cleaning involves the use of engineered solvents in a vapor phase system. The solvents classically used were Class 1 Ozone Depleting Substances, but new types of solvents have been developed that are less environmentally harmful. In some cases, isopropyl alcohol is used with a co-solvent. In these types of cleaning systems, a cloud of boiling vapor solvent is maintained between a boil sump and a cooling coil. When the items to be cleaned are immersed in the vapor cloud, the solvent condenses on the assemblies and acts to dissolve the residues. These processes usually involve a final rinse step outside of the vapor cloud to ensure that all dissolved residues are washed off the assemblies (Figure 1).
Technical Library | 2018-04-27 12:59:29.0
Hot Air and IR are the two main types of rework stations used by OEMs and PCB contract manufacturers today. Both have advantages and disadvantages and choosing the right one for your application requires a careful consideration of a number of factors, including your budget, your working requirements and the capabilities of your staff. In this article, we outline some of the differences between hot air and IR BGA rework stations.
Technical Library | 2019-05-31 14:15:01.0
ACI Technologies (ACI) is working on a project where one of the challenges is removing a large quantity of heat from audio amplifier circuits. This challenge is further complicated in that the heat generating circuits are located in a rack mounted box that needs to be shielded from electro-magnetic interference (EMI). Mechanically, this means that there cannot be open passages into the rack mounted box. We will first review the basic types of cooling available as commercial off-the-shelf (COTS) systems for the electronics industry, then discuss the pros and cons of each for different applications, and finally reveal the criteria and solution for the ACI project.
Technical Library | 2019-08-08 10:23:51.0
High mix production is the mainstay of many electronics assembly plants. Lot sizes and board complexities vary and the boards are often mixed technology, comprising a blend of both surface mount and through-hole technology. Modularizing a production line enables a clear distinction between one type of assembly process and another. This article assumes a modern factory where a job can be routed to the selective soldering machine module, the hand assembly bench, or a combination of both. The decision rules of routing a circuit board through hand assembly versus automated selective soldering are discussed. Hand assembly soldering operations require no explanation.
Technical Library | 2019-06-04 10:19:46.0
Interconnection technology relies very heavily on the ability of the conductors on a printed wiring assembly to maintain reliable signal integrity. Harsh environmental factors can precipitate a loss of conductivity due to oxidation and corrosion. Connections are typically soldered or inserted using pressure fitted connectors to obtain enough surface contact to meet the electrical conductivity requirements. In pressure contacts, surface integrity is especially critical where the abrasive effects of retraction and insertion can wear off the metallic finish from the contact area. This can expose the underlying copper or nickel and lead to increased resistance at the contact points. These types of conductors are frequently found in card edge connectors where the terminations are plated with a layer of nickel and gold (frequently referred to as gold fingers). A hard gold is typically used containing very small amounts of nickel and cobalt to increase the wear resistance.
Technical Library | 2019-06-06 13:40:47.0
Legacy electronics assemblies, such as through-hole (Figure 1) and connectorized component packages, are robust and prevalent throughout industry. However, each of these assembly methods have reached their limits in terms of weight, volume, reliability, and most importantly cost. With cost reduction of assemblies now the primary focus area throughout the electronics industry, there is more of a need than ever to implement the latest advancements in surface mount technology (SMT) into electronics assembly designs. Although SMT has been utilized in the electronics industry for many years, implementation of the technology is still in the ever-evolving process of reducing component footprint size, component spacing, and component I/O pitch. Implementation of the most up-to-date SMT processes provides optimal weight, volume, and cost savings, for any type of assembly.
