Technical Library | 1999-05-07 10:47:00.0
White residue remaining after cleaning circuit board assemblies can be caused by a variety of chemicals and reactions. Rosin and water-soluble fluxes, circuit board resins and epoxies, component materials and other contamination all contribute to this complex chemistry. This paper discusses many of the sources of the residues that seem to be an ever-increasing occurrence.
Technical Library | 2015-04-29 03:48:39.0
SPI equipment is routinely used in Printed Circuit Board (PCB) manufacturing to monitor and control one of the most crucial steps affecting the finished quality of circuit board. Solder paste deposition is the key process in board assembly operations using SMT techniques. Our LSM™ system was the industry's first popular method of manually inspecting solder paste; our SE systems revolutionized SMT production by offering an automated method for performing in-process 3D inspection on the assembly line. SPI systems measure the height and volume of the solder pads before the components are applied and the solder melted, and when used properly, can reduce the incidence of solder-related defects to statistically insignificant amounts. Critical to the SPI measurement is the accuracy of the height measurement because that has a direct correlation with solder volume and defects.
Technical Library | 2016-01-12 11:01:25.0
More and more Land Grid Array (LGA) components are being used in electronic devices such as smartphones, tablets and computers. In order to enhance LGA mechanical strength and reliability, capillary flow underfill is used to improve reliability. However, due to the small gap, it is difficult for capillary underfill to flow into the LGA at SMT level. Due to cost considerations, there are usually no pre-heating underfill or cleaning flux residue processes at the SMT assembly line. YINCAE solder joint encapsulant SMT256 has been successfully used with solder paste for LGA assembly. Solder joint encapsulant is used in in-line LGA soldering process with enhanced reliability. It eliminates the underfilling process and provides excellent reworkability. The shear st rength of solder joint is stronger than that of underfilled components. The thermal cycling performance using solder joint encapsulant is much better than that using underfill. Bottom IC of POP has been studied for further understanding of LGA assembly process parameters. All details such as assembly process, drop test and thermal cycling test will be discussed in this paper.
Technical Library | 2015-11-19 18:15:07.0
The move to lead free (Pb-free) electronics by the commercial industry has resulted in an increasing number of ball grid array components (BGAs) which are only available with Pb-free solder balls. The reliability of these devices is not well established when assembled using a standard tin-lead (SnPb) solder paste and reflow profile, known as a backward compatible process. Previous studies in processing mixed alloy solder joints have demonstrated the importance of using a reflow temperature high enough to achieve complete mixing of the SnPb solder paste with the Pb-free solder ball. Research has indicated that complete mixing can occur below the melting point of the Pb-free alloy and is dependent on a number of factors including solder ball composition, solder ball to solder paste ratio, and peak reflow times and temperatures. Increasing the lead content in the system enables full mixing of the solder joint with a reduced peak reflow temperature, however, previous research is conflicting regarding the effect that lead percentage has on solder joint reliability in this mixed alloy solder joint.
Technical Library | 2015-01-08 17:26:59.0
Regardless of the accelerating trend for design and conversion to Pb-free manufacturing, many high reliability electronic equipment producers continue to manufacture and support tin-lead (SnPb) electronic products. Certain high reliability electronic products from the telecommunication, military, and medical sectors manufacture using SnPb solder assembly and remain in compliance with the RoHS Directive (restriction on certain hazardous substances) by invoking the European Union Pb-in-solder exemption. Sustaining SnPb manufacturing has become more challenging because the global component supply chain is converting rapidly to Pb-free offerings and has a decreasing motivation to continue producing SnPb product for the low-volume, high reliability end users. Availability of critical, larger SnPb BGA components is a growing concern
Technical Library | 2015-08-25 13:51:27.0
The stencil printing process is one of the most critical processes in the electronic production. Due to the requirement: "faster and smaller" it is necessary to place components with different paste volume close together without regard to solder paste printing. In our days it is no longer possible to control the solder paste volume only by adjustment of the aperture dimensions. The requirements of solder paste volumes for specific components are realized by different thicknesses of metal sheets in one stencil with so called step stencils. The step-down stencil is required when it is desirable to print fine-pitch devices using a thinner stencil foil, but print other devices using a thicker stencil foil. The paper presents the innovative technology of step-up and step-down stencils in a laser cutting and laser welding process. The step-up/step-down stencil is a special development for the adjustment of solder paste quantity, fulfilling the needs of placement and soldering. This includes the laser cutting and laser welding process as well as the resulting stencil characteristics and the potential of the printing process.
Technical Library | 2021-11-03 16:36:36.0
Laser reflow soldering is an important technology in electronic components processing. In this paper, we presented a simple but efficient method to achieve reflow soldering process with gradient energy band created by just two parallel mirrors. The detailed influence of the variety of optical parameters on the soldering process has been analyzed by using the finite element method. And the modulation of the optical parameters on reflow soldering parameters also has been demonstrated. In our experiment, one HR mirror and one-mirror with transmissivity of 10% have been used to create a gradient energy band with an incident laser power of 50W. In summary, both the simulations and the experiments show that the typical reflow soldering profile has been acquired by the optical system. The high quality joints on both the front and rear surface of the capacitor can be acquired by just one surface radiation of the optical system.
Technical Library | 2019-10-18 10:37:25.0
It usually does not make any logic to invest in costly fabrication equipment in case you just desire to spin some prototypes and rather outsource your Printed Circuit Board assembly as well as prototype fabrication to a trustworthy vendor. I would provide a few tips as to what to consider when seeking a contract manufacturer. The two most common procedures associated with Printed Circuit Board Assembly are through-hole technology and surface mount technology. Talking about the difference between through-hole technology and surface mount technology. Through-hole elements have metal leads, & these metal leads are supplied through-plated holes inside the circuit board. On the other hand, SMT elements might or might not have leads, nevertheless most significantly, they are developed to be soldered onto the surface of the circuit boards straight on the same side as the element body. A lot of contract manufacturers would provide a quick quote mechanism over their site for the fabrication of circuit boards as well as assembly of prototypes. This would bank your time when comparing various vendors. Ensure that the quote system facilitates you to fill your details, for instance, board material, thickness, copper thickness, milling, etc. in order that you can avail of a precise quote devoid of any surprises afterward. And this is quite necessary. Typically the cost per board would decline as quality upgrades. This is owing to the fairly high setup price of circuit board fabrication over and above component assembly. A few vendors would employ a system where they unite boards from various consumers. This manner the setup price would be circulated among numerous clients. When you fabricate an item, you clearly don’t desire to have to fabricate a big quantity of boards straight away whilst you improve your design. One restriction with small quantity prototypes though is that the option of materials & material thicknesses would be constrained. In case you are employing a particular material then opportunities are there will not be any other clients employing the same material. Additionally, lead time plays a major role in indecisive prices. A longer lead time facilitates the fabricator more liberty in slotting your fabrication. This is basically reflected in cheaper prices that would view in the quote section. Clearly, if you are in a hurry and desire to be moved to the summit of the pile you would require splurging more dollars. Ensure that your contract fabricator would support the file sort for producing which you offer. The most general format for printed circuit board fabrication is the Gerber format nonetheless a few vendors would moreover embrace board files from general printed circuit board software products. A few suppliers also provide in house printed circuit design. Even in case, you create your board yourself, choosing a vendor with design services might prove resourceful in case there is an issue with your files. In this scenario, your vendor could make swift changes that would neglect pricey delays. If you are looking for an Electronic Manufacturing Services (EMS Assembly) provider, then the web is the best to search.
Technical Library | 2001-05-03 11:23:09.0
In this age of global competition, world class electronics manufacturers understand that increasing profit margins is accomplished not by increasing price or lowering the quality of components and workmanship, but by increasing production yields. Post-solder inspection ensures that your customers receive good product, but by separating the good boards from the bad boards you only measure yield, not improve it. A yield (and profit) improvement strategy consists of making measurements at critical stages, as early as possible in the assembly process, and adjusting the process parameters to achieve optimal performance.
Technical Library | 2024-06-19 15:23:54.0
Each year the semiconductor industry routes a significant volume of devices to recycling sites for no reliability or quality rationale beyond the fact that those devices were stored on a warehouse shelf for two years. This study identifies the key risks attributed to extended storage of devices in uncontrolled indoor environments and the risk mitigation required to permit safe shelf-life extension. Component reliability was evaluated after extended storage to assure component solderability, MSL stability and die surface integrity. Packing materials were evaluated for customer use parameters as well as structural integrity and ESD properties. Results show that current packaging material (mold compound and leadframe) is sufficiently robust to protect the active integrated circuits for many decades and permit standard reflow solder assembly beyond 15 years. Standard packing materials (bags, desiccant, and humidity cards) are robust for a 32 month storage period that can be extended by repacking with fresh materials. Packing materials designed for long term storage are effective for more than five years.
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