Technical Library | 2010-03-04 18:11:53.0
While the electronics manufacturing industry has been occupied with the challenge of RoHS compliance and with it, Pb-free soldering, established trends of increasing functionality and miniaturization have continued. The increasing use of ultra-fine pitch and area-array devices presents challenges in both printing and flux technology. With the decrease in both the size and the pitch of said components, new problems may arise, such as head-in-pillow and graping defects
Technical Library | 1999-05-09 12:51:38.0
This Technical Note outlines, step by step, the easiest ways to remove and replace surface mounted devices, using the lowest possible temperatures. This document discusses the following topics: Removal and replacement of discrete and passive components (capacitors, resistors, SOTs), Removal of two-sided components (SOICs, SOJs, TSOPs), Removal of quad components (PLCCs, QFPs), Replacement of quad components including fine-pitched devices.
Technical Library | 2019-06-03 21:07:34.0
The objective of this White Paper is to provide users of the above products in the electronics industry a clear understanding of the different types of stencil cleaning paper/fabrics that are currently available. Fine pitch applications are more the norm now and so the performance of stencil cleaning rolls is more critical than ever before. This White Paper will give solder paste stencil printing engineers and purchasing professionals an insight into the main products on the market, thereby enabling them to make informed decisions.
Technical Library | 2021-11-16 22:17:27.0
Ultrasonics, coupled with an aqueous detergent process that cleans at below 43ºC, may be best suited for fine-pitch SMT screens and stencils. Aqueous detergents clean more effectively than solvents, with little or no environmental impact. Because of the environmental concerns driving today's technology decisions, the once simple decision of selecting a stencil cleaning process is now clouded with different chemicals, different cleaning machines and various types of solder paste, all with specific environmental, health and safety related issues and regulations.
Technical Library | 2007-05-31 19:05:55.0
This paper discusses solder paste printing and flux dipping assembly processes for 0.4 and 0.5mm pitch lead-free WLCSPs and the corresponding assembly results and thermal cyclic reliability obtained. Variables evaluated include reflow ambient, paste type, and stencil design. Reliability is also compared to results for the same components assembled under identical conditions using SnPb solder.
Technical Library | 2015-02-27 17:06:01.0
The drive towards fine pitch technology also affects the soldering processes. Selective soldering is a reliable soldering process for THT (through hole) connectors and offers a wide process window for designers. THT connectors can be soldered on the top and bottom side of boards, board in board, PCBs to metal shields or housing out of plastic or aluminum are today's state of the art. The materials that are used to make the solder connections require higher temperatures. Due to the introduction of lead-free alloys, the boards need more heat to get the barrels filled with solder. This not only affects the properties of the flux and components, but the operation temperatures of solder machines become higher (...)First the impact of temperature will be discussed for the separate process steps and for machine tooling. In the experimental part measurements are done to verify the accuracy that can be achieved using today's selective soldering machines. Dedicated tooling is designed to achieve special requirements with respect to component position accuracy.
Technical Library | 2014-05-29 13:48:14.0
Electronics packaging based on stress-engineered spring interconnects has the potential to enable integrated IC testing, fine pitch, and compliance not readily available with other technologies. We describe new spring contacts which simultaneously achieve low resistance ( 30 μm) in dense 2-D arrays (180 ~ 180-µm pitch). Mechanical characterization shows that individual springs operate at approximately 150-µN force. Electrical measurements and simulations imply that the interface contact resistance contribution to a single contact resistance is This paper suggests that integrated testing and packaging can be performed with the springs, enabling new capabilities for markets such as multichip modules.
Technical Library | 2013-03-04 16:51:00.0
Chip-scale (or chip-size) packages are rapidly becoming an important element in electronics due to their size, performance, and cost advantages [Hou, 1998]. The Chip Scale Package (CSP) is becoming a key semiconductor package type, particularly for consumer products. Due to their relatively smaller size, new challenges are presented in the rework and repair of CSPs. (...) The specific focus of this paper is the removal process for rework of CSPs and the site scavenging methods required to properly prepare the circuit board for a new component. Process factors such as the heating, fluxing and, atmosphere are discussed.
Technical Library | 2020-05-07 03:46:27.0
The selective soldering process has evolved to become a standard production process within the electronics assembly industry, and now accommodates a wide variety of through-hole component formats in numerous applications. Most through-hole components can be easily soldered with the selective soldering process without difficulty, however some types of challenging components require additional attention to ensure optimum quality control is maintained. Several high thermal mass components can place demands on the selective soldering process, while the use of specialized solder fixtures and/or pallets often places an additional thermal demand on the preheating process. Fine-pitch through-hole components and connectors place a different set of demands on the selective soldering process and typically require special attention to lead projection and traverse speed to minimize bridging between adjacent pins. Dual in-line memory module (DIMM) connectors, compact peripheral component interface (cPCI) connectors, coax connectors and other high thermal mass components as well as fine-pitch microconnectors,can present challenges when soldered into backplanes or multilayer printed circuit board assemblies. Adding to this challenge, compact peripheral component interface connectors can present additional solderability issues due to their beryllium copper termination pins.
Technical Library | 2007-03-28 10:18:33.0
Legislation against the use of lead in electronics has been the driving force behind the use of lead-free solders, surface finishes, and component lead finishes. The major concern in using lead-free solders in the assembly and rework Chip Scale Packages (CSPs) is the relatively high temperatures that the components and the boards experience. Fine-pitch CSPs have very low standoff heights following assembly making inspection and rework of these components more difficult. One other concern pertinent to rework is the temperature of the neighboring components during rework. These issues, coupled with the limitations of rework equipment to handle lead-free reflow temperatures, make the task of reworking lead-free assemblies more challenging.
