Tecniche per l'assemblaggio BGAPubblicato il 29/06/2020
Le linee guida per l'ispezione BGA sono determinate in base alle linee guida per l'assemblaggio dei circuiti stampati finiti in IPC-A-610, nonché ad altri criteri che sono stati definiti tra l'utente e l'installatore. In pratica, questi criteri di ispezione sono soddisfatti nella pratica con una varietà di tecniche di ispezione BGA. Queste tecniche includono l'ispezione visiva e l'ispezione a raggi X.
There are a variety of techniques that make up optical inspection techniques for BGA inspection. These techniques include endoscopy and visual inspection. Endoscopy uses an optical gradient prism to align the transverse viewing area with the plane of the plate. This allows the inspector to see “below” the BGA package. This ad may be within a few lines of the page.
Endoscopy and visual inspection
This observation allows the inspector to see how the ball gets wet on both the PCB pads and the device pads. The corners are also a good indicator of whether a good reflow profile has been created. The inspector looks for a uniformly collapsed ball without stretching or “wasting” the spreading sweat fillet. Furthermore, the shape of the solder ball is seen in relation to the uniformity in the outer row of the solder balls. Furthermore, the surface of the ball is inspected with this instrument.
All signs of flaking, depressions, excess flow residue, and the like are visible and are part of the inspection route. A visual microscope is often used in visual inspection, in which the printed circuit board is tilted at an angle so that the same type of evaluation can be seen as the endoscope. There are often components along the way that limit the usefulness of this special technique.
BGA X-ray inspection
BGA X-ray inspection is the second category of BGA assembly inspection. X-ray inspection can be performed using an automatic X-ray inspection, which essentially takes an image when the dash is scanned, and then compares those images to the acceptable image library for a call or manual inspection, meaning that the operator must “drive” the device being tested under the x-ray source.
There are many different conditions that the X-ray system tries to recognize as part of BGA X-ray images for inspection. As part of the IPC-A-610 BGA inspection criteria, the BA must be aligned with other components and other grounded parts of the circuit board assembly. This is to ensure that minimum electrical clearances are not violated. Similarly, the distance between the solder balls must be confirmed using the same criteria. Also, the BGA X-ray test should confirm that there are no solder bridges or connections to unusual areas of the device. It is also used to determine voids in reflux joints to ensure that they are not more than 30% or less of the inspectable area of the part.
In addition to these IPC criteria that radiography should use as part of accepting/rejecting calls, there are other uses of radiography during BGA inspection. The x-ray image also determines the sphericity of the “roundness” of the solder balls when viewed from the z-axis plane. Also, the actual size of the solder balls can be measured and compared as a pass/fail criterion for BGA inspection.
An electronic assembly service is a company that deals with the manufacture of electronic assemblies, such as the spherical grid die or BGA. Why do manufacturers have to outsource these services?
The biggest advantage of outsourcing assemblies is that they save a lot of resources. You don’t have to build or lease additional assembly space, and you don’t need assembly personnel. The installation of a production plant, the purchase of appropriate equipment, and the use of well-trained and experienced personnel to manage the plant require a lot of capital. The fact that you can focus on the core function of your business means that you are more productive. This also saves time.
With good electronic assembly services, your assembly is contracted. This means that your electronic products are manufactured to your specifications. You can even determine things like the materials to use. If you have many product variants, it is better to outsource the service as you do not have to change your machine settings every time you want a product variant.
An electronic assembly service tends to attract and retain top talent. If you do the assembly yourself, you are unlikely to attract talent to make sure you have a highly reliable application that can withstand the abuse, potential attacks, and harsh environments. By outsourcing the service, you don’t have to worry about training your employees and constantly updating them with the latest technology.
The professionalism offered by electronic assemblies means that you get valuable advice on how to make your products more efficient and effective. The electronic assembly service will have learned from your successes and mistakes, as well as from the mistakes and successes of others. When you outsource, you get different products from the same company, which means you have no compatibility issues and save money.
Lead-free solder balls are primarily used in applications with chip packages, chip dump wafer protrusions, and ball-grid dies as LBGA, CBGA, and PBGA components. Products available in this category cover all types of alloy options, including lead-free, eutectic, low lead, and low silver content, and even custom options for various applications with specific requirements. However, given the current trend in the industry to introduce lead-free solder pastes and products, solder balls of this particular type are the most in-demand. Due to the small size of the solder balls and the fact that a single device or PCB can hold thousands of these beads, you definitely want to make sure that the product on offer is of high quality. Let’s examine the quality factors of lead-free solder balls you should consider when choosing the most suitable alternative for your PCB assembly.
Ball diameter and tolerance
Design consistency is paramount if you want to enjoy the predictable performance and ease of use of your lead-free solder balls. It is important that the product you selected has a uniform diameter, a narrow diameter, and tolerance to spheroids. This factor becomes even more important if the desired size of the solder ball is less than average since in such cases you must verify the diameter and tolerance of sphericity with greater precision (a measure of how round or around the sphere).
Alloy casting technology for production.
The process and technology for melting solder alloys are also an important factor to consider. Accurate levels of metal must be maintained in the lead-free solder bumps, and proper process optimization must be maintained to avoid segregation of the alloy, which eventually leads to multiple peaks. Your manufacturer must also be able to ensure consistent production and repeatability of quality parameters from batch to batch. Deviations significantly affect your own SMT for the BGA assembly line.
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