Technical Library | 2023-01-17 18:07:31.0
To achieve higher levels of consistency in PCB output, process engineers are able to maintain tighter controls and reduce process-related defects by using closed-loop process controls. At every stage of assembly, from screen printing through placement to reflow, closed-loop systems help control the variable factors that can have adverse effects on the process.
Technical Library | 2008-10-15 20:16:12.0
Solder paste dispensing is usually considered a slow process. Due to the speed advantages, screen printing is used to apply solder paste whenever possible. However, screen printing is not always an option. Leveraging the high speed of piezo drive technology opens the door to a broad range of solder paste dispensing applications. The ability to dispense dots under 300-μm diameter, even as small as 125 μm, enables BGA rework, small geometry deposits for miniaturized passive components, electrical connections in recessed cavities, and RF shield attach for handheld devices.
Technical Library | 2019-05-30 10:59:13.0
In the current economic environment, the ability to reuse ball grid array(BGA) components that have failed due to solder defects may be an efficient way for electronics manufacturers to reduce costs. Cost may not be the only driving factor in the decision to engage in this recycling practice. The increasing demands placed upon the complexity of microprocessors and integrated circuits (ICs) has decreased the availability of some components, and increased their lead time. Because of this, reballing may provide a means to meet schedule, reduce rework turn-around time, and give a manufacturer a decisive advantage over other companies in an ever increasingly competitive market. This article will discuss the process of reballing BGA components (Figure 1), examining preparation (the preform method, the screen method), and cleaning and bake-out.
Technical Library | 2009-05-14 13:57:43.0
Is screen printing technology able to keep pace with rising quality demands and increasingly complex board layouts? Or, is new jet printing technology ready to fill the gap? A comparison study between the two methods reveals some interesting differences. Screen printers offer some possibilities for optimizing solder paste deposits, but optimization is far easier and quicker with the jet printer. At the same time, the ability to print individualized deposits on every single pcb pad may be the ultimate answer to the growing quality challenge.
Technical Library | 2014-12-11 18:00:09.0
The growth of portable and wireless products is driving the miniaturization of packages resulting in the development of many types of thin form factor packages and cost effective assembly processes. Wire bonded packages using conventional copper lead frame have been used in industry for quite some time. However, the demand for consumer electronics is driving the need for flip chip interconnects as these packages shorten the signals, reduce inductance and improve functionality as compared to the wire bonded packages. The flip chip packages have solder bumps as interconnects instead of wire bonds and typically use an interposer or organic substrate instead of a metal lead frame (...) The paper provides a general overview of typical defects and failure modes seen in package assembly and reviews the efforts needed to understand new failure modes during package assembly. The root cause evaluations and lessons learned as the factory transitioned to thin form factor packages are shared
Technical Library | 2018-05-23 12:12:43.0
Driven by miniaturization, cost reduction and tighter requirements for electrical and thermal performance, the use of lead-frame based bottom-termination components (LF-BTC) as small-outline no-leads (SON), quad-flat no leads (QFN) packages etc., is increasing. However, a major distractor for the use of such packages in high-reliability applications has been the lack of a visible solder (toe) fillet on the edge surface of the pins: because the post-package assembly singulation process typically leaves bare copper leadframe at the singulation edge, which is not protected against oxidation and thus does not easily solder-wet, a solder fillet (toe fillet) does not generally develop.
Technical Library | 2016-08-04 14:33:23.0
Solder paste screen printing is known to be one of the most difficult processes to quality assure in Printed Board Assembly (PBA) manufacturing. An important process step in solder paste screen printing is the under stencil cleaning process and one of the key materials in this process is the cleaning paper1. This, often neglected, material affects the cleaning process and thereby also the print quality. It is therefore important to perform tests of different cleaning papers before one could be chosen. This article describes how cleaning papers can be tested and it also tells how big differences it can be between different materials.
Technical Library | 2010-05-12 16:21:05.0
Numerous studies have shown that greater than 60% of end of line defects in SMT assembly can be traced to solder paste and the printing process. Reflowing adds another 15% or so. In light of this fact, it is surprising that no simplified procedure for solder paste evaluation has been documented. This paper is about such a procedure.
Technical Library | 2009-09-09 15:08:19.0
Stencil printing equipment has traditionally been used in the surface mount assembly industry for solder paste printing. In recent years the flexibility of the tool has been exploited for a wide range of materials and processes to aid semiconductor packaging and assembly. One such application has been the deposition of adhesive coatings onto the backside of silicon wafers.
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.
