Technical Library | 2023-01-17 17:19:44.0
A test program was developed to evaluate the effectiveness of vacuum reflow processing on solder joint voiding and subsequent thermal cycling performance. Area array package test vehicles were assembled using conventional reflow processing and a solder paste that generated substantial void content in the solder joints. Half of the population of test vehicles then were re-processed (reflowed) using vacuum reflow. Transmission x-ray inspection showed a significant reduction in solder voiding after vacuum processing. The solder attachment reliability of the conventional and vacuum reflowed test vehicles was characterized and compared using two different accelerated thermal cycling profiles. The thermal cycling results are discussed in terms of the general impact of voiding on solder thermal fatigue reliability, results from the open literature, and the evolving industry standards for solder voiding. Recommendations are made for further work based on other void reduction methods and additional reliability studies.
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 | 2023-12-15 03:06:24.0
The first process in the SMT industry is solder paste printing. After the solder paste printing is completed, electronic components are attached to PCB pads through a SMT machine, and then reflow soldered. A preliminary PCB board is roughly processed. SMT is a combination of multiple devices, and such a line is called an SMT production line. Our common PCBA is processed through this process. In SMT technology, each process is very important, and poor quality can be caused by different process defects. Today, we are discussing the causes and countermeasures of SMT printing collapse.
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 | 2012-10-04 18:52:43.0
First published in the 2012 IPC APEX EXPO technical conference proceedings... Due to the obsolescence of SnPb BGA components, electronics manufacturers that use SnPb solder paste either have to use lead-free BGAs and adjust the reflow process or re-ball t
Technical Library | 2010-04-29 21:40:37.0
The purpose of this paper is to investigate the effects of reflow time, reflow peak temperature, thermal shock and thermal aging on the intermetallic compound (IMC) thickness for Sn3.0Ag0.5Cu (SAC305) soldered joints.
Technical Library | 2019-04-10 22:08:31.0
The stimulating impact of the automotive industry has sharpened focus on immersion tin (i-Sn) more than ever before. Immersion tin with its associated attributes, is well placed to fulfill the requirements of such a demanding application. In an environment dominated by reliability, the automotive market not only has very stringent specifications but also demands thorough qualification protocols. Qualification is ultimately a costly exercise. The good news is that i-Sn is already qualified by many tier one OSATs. The focus of this paper is to generate awareness of the key factors attributed to soldering i-Sn. Immersion tin is not suitable for wire bonding but ultimately suited for multiple soldering applications. The dominant topics of this paper will be IMC formations in relation to reflow cycles and the associated solderability performance. Under contamination free conditions, i-Sn can provide a solderable finish even after multiple reflow cycles. The reflow conditions employed in this paper are typical for lead free soldering environments and the i-Sn thicknesses are approximately 1 μm.
Technical Library | 2006-12-18 14:55:35.0
Many solder users have preconceived notions and worries involving reflow profiling guidelines. Year after year of reading profiling recommendations in industry publications, from a litany of pundits, has made it clear that perfect profiles exist and should be sought after. They feel if the solder supplier gives them a tidy drawing on a piece of paper with times and temperatures that it will magically solve all their reflow problems. This is, unfortunately, an often incorrect assumption.
Technical Library | 2018-11-20 21:33:57.0
There are several industry-accepted methods for determining the reliability of flux residues after assembly. The recommended methods of test sample preparation do not always closely mimic the thermal cycle experienced by an assembly. Therefore, extraction from actual assemblies has become a popular method of process control to assess consistency of post-reflow cleanliness. Every method of post-reflow flux residue characterization will depend on the reflow process followed to prepare the coupon.This investigation will focus on the effect of thermal conditions on the remainder of active ingredients in flux residues after assembly with no-clean solder pastes.
Technical Library | 2020-09-23 21:37:25.0
The need to minimise thermal damage to components and laminates, to reduce warpage-induced defects to BGA packages, and to save energy, is driving the electronics industry towards lower process temperatures. For soldering processes the only way that temperatures can be substantially reduced is by using solders with lower melting points. Because of constraints of toxicity, cost and performance, the number of alloys that can be used for electronics assembly is limited and the best prospects appear to be those based around the eutectic in the Bi-Sn system, which has a melting point of about 139°C. Experience so far indicates that such Bi-Sn alloys do not have the mechanical properties and microstructural stability necessary to deliver the reliability required for the mounting of BGA packages. Options for improving mechanical properties with alloying additions that do not also push the process temperature back over 200°C are limited. An alternative approach that maintains a low process temperature is to form a hybrid joint with a conventional solder ball reflowed with a Bi-Sn alloy paste. During reflow there is mixing of the ball and paste alloys but it has been found that to achieve the best reliability a proportion of the ball alloy has to be retained in the joint, particular in the part of the joint that is subjected to maximum shear stress in service, which is usually the area near the component side. The challenge is then to find a reproducible method for controlling the fraction of the joint thickness that remains as the original solder ball alloy. Empirical evidence indicates that for a particular combination of ball and paste alloys and reflow temperature the extent to which the ball alloy is consumed by mixing with the paste alloy is dependent on the volume of paste deposited on the pad. If this promising method of achieving lower process temperatures is to be implemented in mass production without compromising reliability it would be necessary to have a method of ensuring the optimum proportion of ball alloy left in the joint after reflow can be consistently maintained. In this paper the author explains how the volume of low melting point alloy paste that delivers the optimum proportion of retained ball alloy for a particular reflow temperature can be determined by reference to the phase diagrams of the ball and paste alloys. The example presented is based on the equilibrium phase diagram of the binary Bi-Sn system but the method could be applied to any combination of ball and paste alloys for which at least a partial phase diagram is available or could be easily determined.
