Reed relay is widely used in Automatic Test Equipment (ATE) for its high speed,low cost and wide availabilities. However,being mechanical relays,they have their share of limitations and this paper will try to address these challenges and explore alternatives such as solid state relays as replacement.

The SMT assembly world,especially within the commercial electronics realm,is dominated by no-clean solder paste technology. A solder paste flux residue that does not require removal is very attractive in a competitive world where every penny of assembly cost counts. One important aspect of the reliability of assembled devices is the nature of the no-clean solder paste flux residue. Most people in this field understand the importance of having a process that renders the solder paste flux residue as benign and inert as possible,thereby ensuring electrical reliability. But,of all the factors that play into the electrical reliability of the solder paste flux residue,is there any impact made by the age of the solder paste and how it was stored? This paper uses J-STD-004B SIR (Surface Insulation Resistance) testing to examine this question. Two commercially available SAC305,Type 4,no-clean solder pastes—one with a ROL0 and the other with a ROL1 J-STD-004B classification—were subjected to two different storage conditions (room temperature and refrigeration) and aged for varying lengths of time. After aging,the solder pastes were printed and reflowed using the same common reflow profile and then submitted to SIR testing to see what,if any,difference could be detected in their SIR performances. The reason for testing both a ROL0 and a ROL1 was to see if differences in chemistry could have an impact on how a solder paste ages relative to SIR performance.

Solder paste has long been viewed as “black magic”. This “black magic” can easily be dispelled through a solder paste evaluation. Unfortunately,solder paste evaluation can be a challenge for electronic assemblers. Interrupting the production schedule to perform an evaluation is usually the first hurdle. Choosing the solder paste properties to test is simple,but testing for these properties can be difficult. Special equipment or materials may be required depending upon the tests that are chosen. Once the testing is complete,how does one make the decision to choose a solder paste? Is the decision based on gut feel or hard data? This paper presents a process for evaluating solder pastes using a variety of methods. These methods are quick to run and are challenging,revealing the strengths and weaknesses of solder pastes. Methods detailed in this paper include: print volume,stencil life,response to pause,open time,tack force over time,wetting,solder balling,graping,voiding,accelerated aging,and others. Hard data is gathered and used in the evaluation process. Also presented in this paper are a set of methods that do not require expensive equipment or materials but still generate useful data. The goal is to help the electronics assembler choose the best solder paste for their process.

The transition from eutectic tin-lead to lead-free soldering in electronic assembly,mandatedby the RoHS legislation, has brought great pressure and challenge to solder material formulationdue to the high soldering temperature and high alloy surface tension. Moreover,the demand for halogen-free materials,which should be transparent toprocess yields,along withtheminiaturization trend in the electronic industry,is triggering arevolution in solder flux and paste formulations.The chemicalandmaterialinteractionsrelatedtosoldering andassemblyprocesses are many and varied. In general, the chemicals have to bestable during handling at mild temperaturesto warrant a process-friendlyshelf-life.Whileatpreheatandsoldering temperatures,thesolderfluxort h e pastehave to provide thermal transfer to the joint area and reactwiththemetallizationontheprintedcircuitboard(PCB) andcomponentleadstoremoveoxideandsurfacecontaminationinordertopreparethesurfaceforgood metallurgicalbonding,prevent re-oxidation with the atmosphere until the solder alloy re-solidifies,and promote wetting to form the joint.Residuescreatedbythefluxcontainmetalsalts,aswellasorganicandinorganic byproducts.A traditional formulation mainly relies on organic-based materials,rosins and carboxylic acidsto promote fluxing.Several attempts to understand the reactivity of organic acids and halogenated species have demonstrated the complexity of the chemical systems involved in fluxing mechanisms. Amine based formulations were mostly found in the old days,in the forms of ammonium orammonium halides. Here,we report a preliminary study aiming at giving some insight into the role of amines in electronic assembly applications. Our work shows that practical tests can be developed to characterize some fundamental properties of the activator packageswhich directly impact the final performance. The studyofinteractions between individual components within the systemis another key aspect of the design work.From that perspective,we intend to demonstrate that the formulator can develop robust formula based on scientific principles and rational studies rather than empirical knowledge and trial-and-error approaches.

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What’s the Future of Interposers for Semiconductor IC Packaging?

In today’s world it is important that a product has sufficient accreditation that it can be enter many different market places. While accreditation can be a costly process,it is prudent to know that your product is fit for purpose before going for accreditation. We propose a novel cost effective system for testing 100% of the LEDs (Light Emitting Diode) on a lighting product. This system will not only monitor the intensity and colour changes of a product while it is running but alert the engineer of early failures allowing the test to terminate,and faults to be examined. We propose this system as a rapid prototype tester. This system also allows unique LED changes to be monitored such as one LED to noticeably change while not changing the macro properties of the lighting unit. While a small change in individual LEDs or a small group of LEDs in a lighting product might not affect the accreditation process,it could have warrantee effects when the product is in the market
place. We will introduce the system,and show the results of five different LED based products being tested simultaneously over the course of three months. Each product consists of twenty LEDs,so we will monitor 100 LEDs simultaneously. The results will show unexpected behaviour of the LEDs,over the period of three months as a case study. We will show how such a system could be adapted for Standards such as IESNA LM-80 [1] and TM-21 [2]. Lastly we will show the advantage of pre-aging LED products to allow for improved lifetime estimation. While not a replacement for standards such as IESNA LM-80 [1] and TM-21 [2],the technique outlined above would allow smaller companies increased confidence in their product when getting a product range accredited. The system allow shorter prototype development times and hence a cost
saving to end-users.

To find defects of solder joint in printed wiring board assembly,quite a few test methods have been developed so far.
Capacitance method and IEEE 1149.1 or boundary scan method are often used to find opens between component leads and
pads on a printed wiring board. These methods,however,can find complete opens or complete shorts only. Latent defects that
can be complete defect after several years have not been found by the conversational method.
We have developed a method to find such latent defects by using 4-wire small resistance measurement technique and have
built in a flying-probe in-circuit tester. It measures the resistance between component leads and pads,and checks the volume
of the solder. Because the volume of the solder is inversely proportional to the resistance in-between,resistance measurement
can be a way to test the solderability.
This technique is industry proven. A lot of manufacturing plants which produce printed board assembly used in automotive
have adapted it. The printed wiring board assembly for automotive must endure vibration. Thus if a board assembly has a
latent defect,it can bring a serious accident. In my presentation,I would like to introduce the importance of SJIT,Solder Joint
Integrity Test,and a technique of SJIT.

This paper proposes an integrated design and test strategy which uses functional design blocks common to both designs and test fixtures,with the aim of saving time and money. Benefits of this strategy include reducing total product lifecycle cost by decreasing product and test development times,improving sustaining engineering processes,and reducing unique component counts across products and test fixtures.
Benefits and drawbacks to such a system are explored for a company that produces low volume,long life products. Benefits analysis is applied to software development and maintenance,schematic design,printed circuit board layout,hardware design,and fixture development for verification,qualification,and functional tests. A brief explanation is provided regarding how existing commercial functional test platforms can be inadequate in a low volume,long life integrated systems production environment. Analyses of process changes and technical hurdles that will need to be overcome while deploying such a system is examined. Finally,a phased approach is suggested that will minimize disruptions to daily operations; minimize any significant,up-front expenditure; and integrate into existing systems.