Technical Library | 2021-01-03 19:24:52.0
Reflow soldering is the primary method for interconnecting surface mount technology (SMT) applications. Successful implementation of this process depends on whether a low defect rate can be achieved. In general, defects often can be attributed to causes rooted in all three aspects, including materials, processes, and designs. Troubleshooting of reflow soldering requires identification and elimination of root causes. Where correcting these causes may be beyond the reach of manufacturers, further optimizing the other relevant factors becomes the next best option in order to minimize the defect rate.
Technical Library | 1999-05-09 13:07:16.0
This paper will give the reader a general understanding of EOS and ESD phenomena. It specifically addresses hand soldering's role in EOS and ESD and how to protect against and test for potential problems. It discusses how Metcal Systems address EOS and ESD concerns and how they differ from conventional soldering systems.
Technical Library | 2015-04-23 18:48:18.0
Smart phones are complex, costly devices and therefore need to be reworked correctly the first time. In order to meet the ever-growing demand for performance, the complexity of mobile devices has increased immensely, with more than a 70% greater number of packages now found inside of them than just a few years ago. For instance, 1080P HD camera and video capabilities are now available on most high end smart phones or tablet computers, making their production more elaborate and expensive. The printed circuit boards for these devices are no longer considered disposable goods, and their bill of materials start from $150.00, with higher end smart phones going up to $238.00, and tablets well over $300.00.
Technical Library | 2014-10-23 18:10:10.0
The functional reliability of electronic circuits determines the overall reliability of the product in which the final products are used. Market forces including more functionality in smaller components, no-clean lead-free solder technologies, competitive forces and automated assembly create process challenges. Cleanliness under the bottom terminations must be maintained in harsh environments. Residues under components can attract moisture and lead to leakage currents and the potential for electrochemical migration (...) The purpose of this research study is to evaluate innovative spray and soak methods for removing low residue flux residues and thoroughly rinsing under Bottom Termination and Leadless Components
Technical Library | 2019-10-21 09:58:50.0
An ACI Technologies customer inquired regarding printed circuit board(PCB) failures that were becoming increasingly prevalent after the SMT (surface mount technology) manufacturing process. The failures were detected by electrical testing, but were undetermined as to the location and specific devices causing the failures. The failures were suspected to be caused predominately in the BGA (ball grid array) devices located on specific sites on this 16 layer construction. Information that was provided on the nature of the failures (i.e., opens or shorts) included high resistance shorts that were occurring in those specified areas. The surface finish was a eutectic HASL (hot air solder leveling) and the solder paste used was a water soluble Sn/Pb(tin/lead).
Technical Library | 2019-06-11 09:36:13.0
An experiment was recently performed ACI Technologies for a customer that was interested in comparing the wetting of lead-free solders with varying temperature profiles and atmospheric conditions. In order to deliver an objective measurement of solder wetting (in addition to subjective inspection analysis), a simple wetting indicator pattern was added to the solder stencil in an area on the test vehicle that had exposed and unused copper.
Technical Library | ACI Technologies, Inc.
Tin (Sn) metal displays the characteristic of growing “tin whiskers” from pure tin coatings (most actively on relatively thin, electrodeposited or immersion tin coatings), usually months or years from the initial deposition of the tin. Tin whiskers are electrically conductive, filamentary, single crystals of white (beta phase) tin. These filaments of single crystal tin are usually one to five microns in diameter, and a few microns up to several tens of millimeters long, that grow spontaneously from the tin coatings. Alloying additions of several percent (by weight) of lead (Pb) prevents these electrically conductive tin whiskers from growing. Pb alloyed into the Sn was discovered to prevent the occurrence of tin whiskers in electronic assemblies in the 1950s as the Bell Laboratories solution to the problem of tin whiskers. The alloying of the tin with lead has thus quietly averted incalculable losses from short circuits in electronic equipment for the last 60 years.
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 | 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.
Technical Library | 2019-09-27 09:14:41.0
One of the most critical factors in preventing corrosion from occurring in electronics is maintaining the state of cleanliness. This is not an easy feat to achieve. Corrosion is defined as the deterioration of a material or its properties due to a reaction of that material with its chemical environment.  So, to prevent corrosion from occurring, either the material or the chemical environment must be adjusted. Adjusting the material usually means application of a protective coating or replacing a more reactive material with a less reactive material. Adjusting the chemical environment usually means removing ionic species through cleaning, and removing moisture, usually with a conformal coating or hermetic package. Ionic species and moisture are problematic because they form an electrolyte which is able to conduct ions and electricity. Any metal that comes into contact with the electrolyte can begin to corrode.