Technical Library | 2023-01-17 17:27:13.0
Reflow profile has significant impact on solder joint performance because it influences wetting and microstructure of the solder joint. The degree of wetting, the microstructure (in particular the intermetallic layer), and the inherent strength of the solder all factor into the reliability of the solder joint. This paper presents experimental results on the effect of reflow profile on both 63%Sn 37%Pb (SnPb) and 96.5%Sn 3.0%Ag 0.5%Cu (SAC 305) solder joint shear force. Specifically, the effect of the reflow peak temperature and time above solder liquidus temperature are studied. Nine reflow profiles for SAC 305 and nine reflow profiles for SnPb have been developed with three levels of peak temperature (230 o C, 240 o C, and 250 o C for SAC 305; and 195 o C, 205 o C, and 215 o C for SnPb) and three levels of time above solder liquidus temperature (30 sec., 60 sec., and 90 sec.). The shear force data of four different sizes of chip resistors (1206, 0805, 0603, and 0402) are compared across the different profiles. The shear force of the resistors is measured at time 0 (right after assembly). The fracture surfaces have been studied using a scanning electron microscopy (SEM) with energy dispersive spectroscopy (EDS)
Technical Library | 2024-02-02 07:48:31.0
Maximizing Efficiency: The High-Speed SMT Line With Laser Depanelizer In today's rapidly evolving electronics manufacturing landscape, optimizing efficiency, cost-effectiveness, and precision remains paramount. Businesses engaged in producing industrial control boards, computer motherboards, mobile phone motherboards, and mining machine boards face ongoing challenges in streamlining production processes. The integration of expensive equipment strains budgets, making the creation of an efficient, cost-effective high-speed SMT line a daunting task. However, a solution exists that seamlessly combines these elements into a singular, high-performance, and cost-effective SMT line. Let's delve into the specifics. A Comprehensive High-Speed SMT Line Our innovative solution amalgamates two pivotal components: a cutting-edge SMT (Surface Mount Technology) production line and a laser cutting line equipped with a depanelizer. The SMT Production Line The high-speed SMT line comprises several essential components, each fulfilling a unique role in the manufacturing process: 1. PCB Loader: This initial stage involves loading boards onto the production line with utmost care. Our Board Loader prioritizes safety, incorporating various safety light curtains and sensors to promptly halt operations and issue alerts in case of any anomalies. 2. Laser Marking Machine: Every PCB receives a unique two-dimensional code or barcode, facilitating comprehensive traceability. Despite the high-temperature laser process potentially leading to dust accumulation on PCB surfaces, our dedicated PCB Surface Cleaner swiftly addresses this issue. 3. SMT Solder Paste Printer: This stage involves applying solder paste to the boards, a fundamental step in the manufacturing process. 4. SPI (Solder Paste Inspection): Meticulous inspections are conducted at this stage. Boards passing inspection proceed through the NG (No Good) Buffer Conveyor to the module mounters. Conversely, "No Good" results prompt storage of PCBs in the NG Buffer Conveyor, capable of accommodating up to 25 PCBs. Operators can retrieve these NG boards for rework after utilizing our specialized PCB Mis Cleaner to remove solder paste. 5. Module Mounters: These machines excel in attaching small and delicate components, necessitating precision and expertise in the module mounting process. 6. Standard Pick And Place Machines: The selection of these machines is contingent upon your specific BOM (Bill of Materials) list. 7. Pre-Reflow AOI (Automated Optical Inspection): Boards undergo examination for component quality at this stage. Detected issues prompt the Sorting Conveyor to segregate boards for rework. 8. Reflow Oven: Boards undergo reflow soldering, with our Lyra series reflow ovens recommended for their outstanding features, including nitrogen capability, flux recycling, and water cooling function, ensuring impeccable soldering results. 9. Post-Reflow AOI: This stage focuses on examining soldering quality. Detected defects prompt the Sorting Conveyor to segregate boards for further inspection or rework. Any identified defects are efficiently addressed with the BGA rework station, maintaining the highest quality standards. 10. Laser Depanelizer: Boards advance to the laser depanelizer, where precision laser cutting, often employing green light for optimal results, ensures smoke-free, highly accurate separation of boards. 11. PCB Placement Machine: Cut boards are subsequently managed by the PCB Placement Machine, arranging them as required. With this, all high-speed SMT line processes are concluded. Efficiency And Output This production line demonstrates exceptional productivity when manufacturing motherboards with approximately 3000 electronic components, boasting the potential to assemble up to 180 boards within a single hour. Such efficiency not only enhances output but also ensures cost-effectiveness and precision in your manufacturing processes. At I.C.T, we specialize in crafting customized SMT production line solutions tailored to your product and specific requirements. Our equipment complies with European safety standards and holds CE certificates. For inquiries or to explore our exemplary post-sales support, do not hesitate to contact us. The I.C.T team is here to elevate your electronics manufacturing to new heights of efficiency and cost-effectiveness.
Technical Library | 2007-08-16 13:34:31.0
While experienced inspectors may be able to determine the aesthetic differences between a lead-free PCB assembly and a tin-lead version, one cannot rely on the "experienced eye". "Less wetting out to the pad edges" (Figure A) and "graininess and lack of shininess of the solder joint" (Figure B) are typical comments about some lead-free solder joints. However, in cases where a Nitrogen atmosphere was present during the reflow of the solder joint (Figure C), there will be little visual differences between the lead free alloys and their tin-lead counterparts.
Technical Library | 2013-01-24 19:16:35.0
The electronics industry has mainly adopted the higher melting point Sn3Ag0.5Cu solder alloys for lead-free reflow soldering applications. For applications where temperature sensitive components and boards are used this has created a need to develop low melting point lead-free alloy solder pastes. Tin-bismuth and tin-bismuth-silver containing alloys were used to address the temperature issue with development done on Sn58Bi, Sn57.6Bi0.4Ag, Sn57Bi1Ag lead-free solder alloy pastes. Investigations included paste printing studies, reflow and wetting analysis on different substrates and board surface finishes and head-in-pillow paste performance in addition to paste-in-hole reflow tests. Voiding was also investigated on tin-bismuth and tin-bismuth-silver versus Sn3Ag0.5Cu soldered QFN/MLF/BTC components. Mechanical bond strength testing was also done comparing Sn58Bi, Sn37Pb and Sn3Ag0.5Cu soldered components. The results of the work are reported.
Technical Library | 2022-10-31 17:25:37.0
Mixed formulation solder alloys refer to specific combinations of Sn-37Pb and SAC305 (96.5Sn–3.0Ag–0.5Cu). They present a solution for the interim period before Pb-free electronic assemblies are universally accepted. In this work, the surfaces of mixed formulation solder alloys have been studied by in situ and real-time Auger electron spectroscopy as a function of temperature as the alloys are raised above the melting point. With increasing temperature, there is a growing fraction of low-level, bulk contaminants that segregate to the alloy surfaces. In particular, the amount of surface C is nearly _50–60 at. % C at the melting point. The segregating impurities inhibit solderability by providing a blocking layer to reaction between the alloy and substrate. A similar phenomenon has been observed over a wide range of (SAC and non-SAC) alloys synthesized by a variety of techniques. That solder alloy surfaces at melting have a radically different composition from the bulk uncovers a key variable that helps to explain the wide variability in contact angles reported in previous studies of wetting and adhesion. VC 2011 American Vacuum Society. [DOI: 10.1116/1.3584821]
Technical Library | 2021-01-13 21:34:29.0
Package-on-Package (PoP) is a popular technology for fabricating chipsets of accelerated processing units. However, the coefficient of thermal expansion mismatch between Si chips and polymer substrates induces thermal warpage during the reflow process. As such, the reflow temperature and reliability of solder joints are critical aspects of PoP. Although Sne58Bi is a good candidate for low-temperature processes, its brittleness causes other reliability issues. In this study, an in-situ observation was performed on composite solders (CSs) made of ...
Technical Library | 2014-03-06 19:04:07.0
Over the last few years, there has been an increase in the rate of Head-in-Pillow component soldering defects which interrupts the merger of the BGA/CSP component solder spheres with the molten solder paste during reflow. The issue has occurred across a broad segment of industries including consumer, telecom and military. There are many reasons for this issue such as warpage issues of the component or board, ball co-planarity issues for BGA/CSP components and non-wetting of the component based on contamination or excessive oxidation of the component coating. The issue has been found to occur not only on lead-free soldered assemblies where the increased soldering temperatures may give rise to increase component/board warpage but also on tin-lead soldered assemblies.
Technical Library | 2013-12-27 10:39:21.0
The head-in-pillow defect has become a relatively common failure mode in the industry since the implementation of Pb-free technologies, generating much concern. A head-in-pillow defect is the incomplete wetting of the entire solder joint of a Ball-Grid Array (BGA), Chip-Scale Package (CSP), or even a Package-On-Package (PoP) and is characterized as a process anomaly, where the solder paste and BGA ball both reflow but do not coalesce. When looking at a cross-section, it actually looks like a head has pressed into a soft pillow. There are two main sources of head-in-pillow defects: poor wetting and PWB or package warpage. Poor wetting can result from a variety of sources, such as solder ball oxidation, an inappropriate thermal reflow profile or poor fluxing action. This paper addresses the three sources or contributing issues (supply, process & material) of the head-in-pillow defects. It will thoroughly review these three issues and how they relate to result in head-in pillow defects. In addition, a head-in-pillow elimination plan will be presented with real life examples will be to illustrate these head-in-pillow solutions.
Technical Library | 2015-02-12 13:32:52.0
Market forces, particularly legislation against the use of lead in electronics, have driven electronics manufacturers towards lead-free solders for PCB assembly and rework. This approach creates challenges because of the relatively high temperatures needed for lead-free soldering. Additionally, lead-free solder alloys typically do not wet or wick as easily as Sn63Pb37 leaded types. As PCBs often include both BGAs and simpler discrete devices, a lead-free rework capability should include a suitable soldering station and a BGA rework station. This article shows how such equipment can be adapted to overcome the lead-free issues and provide a successful reworking facility.
Technical Library | 2020-11-24 23:01:04.0
The miniaturization trend is driving industry to adopting low standoff components or components in cavity. The cost reduction pressure is pushing telecommunication industry to combine assembly of components and electromagnetic shield in one single reflow process. As a result, the flux outgassing/drying is getting very difficult for devices due to poor venting channel. This resulted in insufficiently dried/burnt-off flux residue. For a properly formulated flux, the remaining flux activity posed no issue in a dried flux residue for no-clean process. However, when venting channel is blocked, not only solvents remain, but also activators could not be burnt off. The presence of solvents allows mobility of active ingredients and the associated corrosion, thus poses a major threat to the reliability. In this work, a new halogen-free no-clean SnAgCu solder paste, 33-76-1, has been developed. This solder paste exhibited SIR value above the IPC spec 100 MΩ without any dendrite formation, even with a wet flux residue on the comb pattern. The wet flux residue was caused by covering the comb pattern with 10 mm × 10 mm glass slide during reflow and SIR testing in order to mimic the poorly vented low standoff components. The paste 33-76-1 also showed very good SMT assembly performance, including voiding of QFN and HIP resistance. The wetting ability of paste 33-76-1 was very good under nitrogen. For air reflow, 33-76-1 still matched paste C which is widely accepted by industry for air reflow process. The above good performance on both non-corrosivity with wet flux residue and robust SMT process can only be accomplished through a breakthrough in flux technology.
