Technical Library: jot 1/2 meter conveyor (Page 1 of 1)

Higher Defluxing Temperature and Low Standoff Component Cleaning - A Connection?

Technical Library | 2020-11-04 17:49:45.0

OEMs and CMs designing and building electronic assemblies for high reliability applications are typically faced with a decision to clean or not to clean the assembly. If ionic residues remain on the substrate surface, potential failure mechanisms, including dendritic growth by electrochemical migration reaction and leakage current, may result. These failures have been well documented. If a decision to clean substrates is made, there are numerous cleaning process options available. For defluxing applications, the most common systems are spray-in-air, employing either batch or inline cleaning equipment and an engineered aqueous based cleaning agent. Regardless of the type of cleaning process adopted, effective cleaning of post solder residue requires chemical, thermal and mechanical energies. The chemical energy is derived from the engineered cleaning agent; the thermal energy from the increased temperature of the cleaning agent, and the mechanical energy from the pump system employed within the cleaning equipment. The pump system, which includes spray pressure, spray bar configuration and nozzle selection, is optimized for the specific process to create an efficient cleaning system. As board density has increased and component standoff heights have decreased, cleaning processes are steadily challenged. Over time, cleaning agent formulations have advanced to match new solder paste developments, spray system configurations have improved, and wash temperatures (thermal energy) have been limited to a maximum of 160ºF. In most cases, this is due to thermal limitations of the materials used to build the polymer-based cleaning equipment. Building equipment out of stainless steel is an option, but one that may be cost prohibitive. Given the maximum allowable wash temperature, difficult cleaning applications are met by increasing the wash exposure time; including reducing the conveyor speed of inline cleaners or extending wash time in batch cleaners. Although this yields effective cleaning results, process productivity may be compromised. However, high temperature resistant polymer materials, capable of withstanding a 180°F wash temperature, are now available and can be used in cleaning equipment builds. For this study, the authors explored the potential for increasing cleaning process efficiency as a result of an increase in thermal energy due to the use of higher wash temperature. The cleaning equipment selected was an inline cleaner built with high temperature resistant polymer material. For the analysis, standard substrates were used. These were populated with numerous low standoff chip cap components and soldered with both no-clean tin-lead and lead-free solder pastes. Two aqueous based cleaning agents were selected, and multiple wash temperatures and wash exposure times were evaluated. Cleanliness assessments were made through visual analysis of under-component inspection, as well as localized extraction and Ion Chromatography in accordance with current IPC standards.

ZESTRON Americas

Through-Hole Soldering Defects And The Solutions

Technical Library | 2020-03-01 23:06:45.0

For though hole soldering, no matter it's wave soldering or selective soldering, the process is same formed by fluxing,preheating,soldering. How these 3 process will change the soldering result? When you face the soldering defects, what could be the reasons caused these and how to debug them? With below information you may get some hints.

1 CLICK SMT TECHNOLOGY CO., Limited

Wave Solder Parameter Chart

Technical Library | 2006-05-13 13:07:53.0

This Excel Spreadsheet calculates the Wave Solder Contact Time automatically with given main Solder Wave width and Conveyor Speed. There is one chart where conveyor speed is expressed in meters/min and in another where it is expressed in feet/minute.

Jabil Circuit, Inc.

Design Rules For Selective Soldering Assemblies

Technical Library | 2018-02-14 22:58:54.0

This document describes general guidelines and attention points for PCB design regarding selective soldering. The guidelines can be applied for Select Wave and/or Multi Wave soldering process in both leaded and leadfree alloy. When a PCB is designed according to these guidelines, a stable and solid solder-process can be guaranteed.

Vitronics Soltec

Lead-Free Reliability - Building It Right The First Time

Technical Library | 2008-07-01 18:59:09.0

As lead-free and RoHS compliancy fast approaches, it is more important than ever to build it right the first time. Lead-free assembly and RoHS will bring about numerous changes and the number of variables with which to contend is increasing, creating increased risk of defects and reduced product reliability. However, understanding what the variables are and their impact on the assembly can great increase product reliability.

Kester

Reduce Pollution of Process Gasses in an Air Reflow Oven

Technical Library | 2019-07-02 23:02:05.0

The introduction of lead-free solders resulted in a selection of different chemistries for solder pastes. The higher melting points of lead-free alloys required thermal heat resistant rosin systems and activators that are active at elevated temperatures. As a result, more frequent maintenance of the filtration systems is required and machine downtime is increased.Last year a different method of cleaning reflow ovens was introduced. Instead of cooling down the process gasses to condensate the residues, a catalyst was used to maintain the clean oven. Catalytic thermal oxidation of residues in the nitrogen atmosphere resulted in cleaner heating zones. The residues were transformed into carbon dioxide. This remaining small amount of char was collected in the catalyst. In air ovens the catalyst was not seen as a beneficial option because the air extracted out of the oven was immediately exhausted into the environment. When a catalyst is used in an air environment there is not only the carbon dioxide residues, but also water. When a catalyst is used in an air reflow oven the question is where the water is going to. Will it condensate in the process part of the oven or is the gas temperature high enough to keep it out of the process area? A major benefit of using a catalyst to clean the air before it is exhausted into the environment is that the air pollution is reduced dramatically. This will make environmental engineers happy and result in less pollution of our nature. Apart from this, the exhaust tubes remain clean which reduces the maintenance of air ovens.This paper will give more detailed information of catalyst systems during development and performance in production lines.

Vitronics Soltec

PCB Surface Finishes & Cost Effective Pb Free Assembly Materials

Technical Library | 2014-03-27 14:32:24.0

The surface finish you select will have a large influence on quality, reliability and cost. It is a complex decision that impacts many areas of the business. Select a finish that optimal for the business (and not just one function). Know that there are engineering tricks to improve on weak areas of each finish. Stay current in this field because new developments continue to be made.

Cookson Electronics

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