GB 1 Soldernet SB428
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|GB 1 Soldernet SB428
|BGA rework techniques
One of the most difficult aspects of the printed circuit board (PCB) assembly and repair is ball grid array, or BGA, rework. This is so that the BGA may permanently integrate the circuits and be fixed to the PCB. Reaching those pins that resemble balls is now incredibly challenging but possible.
A successful BGA rework involves BGA rework techniques, technical expertise, and creative vision. Although the BGA rework procedure is laid out online, many typical errors require the expertise of a qualified technician.
Inadequate rework station: Most people need more setup to perform an accurate BGA rework. As a minimum, you’ll need the following:
- Manipulating PCBs with an adjustable X-Y table during rework
- Heating system with temperature control for solder paste and PCBs
- The tool with pressure-adjustable suction
- Cameras with a split-beam prism alignment mechanism
- More electronics, software, and components
The cost of gathering all the essential equipment can be pretty steep. Alternatively, you can always hire experts to perform BGA soldering from an expert company.
Imprecise Inspection: Once the connection is made, solder connections are very difficult to perceive. Since the solder joints are located below the BGA package, they are particularly challenging to perceive on BGA components.
To ensure the caliber of connections and prevent any kind of flaws, BGA inspections are performed. A visual inspection conducted alone will not suffice in this situation. For this reason, using the proper BGA inspection option is critical while viewing solder junctions. The following categories are often where inspection methods and tools fit.
Electric: A current is passed through to assess the BGA’s stability. Since an electric inspection could be better at finding problem sources, it’s usually done in conjunction with another type of test.
Optical—While using just the naked eye has always been an option, medical devices like endoscopes may detect many flaws that otherwise may go undetected.
X-Ray- The most sophisticated examination method uses x-ray radiation to provide a detailed image.
These pictures are excellent for spotting variations in solder joint designs.
Ineffective Training: Making microelectronics is an acquired skill, not a natural gift.
Motivated people frequently attempt BGA rewriting without formal instruction after watching a few tutorials! One of the simplest ways to guarantee future problems and flaws is to do this.
You want to avoid dealing with flaws; therefore, spend some time learning about them in a training institute. The easiest method to lower risk and get the results you want with BGA soldering is to leave it to industry professionals.
Lack of Planning: Before you start soldering, you have a lot of choices to make. Your results will depend on the solder paste you select and the stencils and alloys you use. Before beginning, it’s also crucial to evaluate factors like solder ball size, mask damage, and missing or contaminated pads at the PCB site.
Continue reading to learn about three frequent faults that emerge from the mistakes people commonly make before beginning BGA rework.
Common BGA Defects
Misalignment: The connection points will only be accurately aligned if the PCB and BGA’s positions are altered during the reflow process. This frequently occurs during BGA assembly. BGA parts are often so light that they can float on molten solder.
If used excessively, they may be swiftly moved out of position. Correct alignment is crucial because when the right amount of solder is used, they often stay where you put them.
- Bad soldering technique or excessive solder being used
- An excessive convection rate
- Excessive vibration or abrupt speed variations on the reflow oven conveyor
- Element oxidation
- Asymmetrical components’ ability to conduct heat
How to prevent: With more attention to detail, most misalignment reasons can be prevented. Always make sure you are maintaining the proper levels of humidity and temperature. On pick and place machines, try to reduce needless component movement and always position the component correctly. Using a more aggressive flux will enhance the components’ solderability.
Popcorning: Most individuals need to be made aware that plastic parts like BGAs can take in moisture from the environment. Components absorb moisture when heated, which increases internal pressure as the steam tries to escape. Popcorning, a phenomenon caused by moisture trying to escape, can harm components by causing bubble-like effects.
Potential reasons: BGA needed to be properly sealed inside the package by the manufacturer.
How to prevent: Keeping your BGA dry is the easiest way to avoid pop-corning damage. Only place orders for moisture-sensitive parts as needed. As a result, they will be less likely to idle away by time by soaking in moisture. To keep your BGA dry when ordering, seek companies that include a desiccant in the packaging.
If you think your BGA has been harmed by moisture, try baking the moisture out. Before assembling, prebaking can assist to reduce component cracking due to pop-corning. Ensure that the temperature is lower than the BGA’s maximum operating temperature.
Voiding: “Voiding” refers to the space or voids that occasionally exist within a solder junction. This is a solder flaw since the voids may result in joint cracks and mechanical weaknesses. Components for collapsible BGAs frequently exhibit voiding.
- Caused by oxidized solder paste, oxidation
- Minimal temperature
- Preheat temperature must be high enough to evaporate the flux’s solvent.
- Excessive flux
- If you use too much flux, it will release gas after the solder hardens.
- Quality of solder paste: When cooled, the volume of some solder pastes shrinks, resulting in voids and irregular spacing.
- Circuit board design: Some printed circuit boards (PCBs) have layouts and techniques that make them more prone to voiding.
How to prevent: Preheat for a little while to ensure the ideal temperature is reached. As a result, it should be more likely that the solvent will evaporate completely and no residue will form.
Avoid solder paste that shrinks when cooled, such as lead-free types, as we indicated before. Switching solder pastes is another option. Less moisture from the air is likely to be drawn in by the solder pastes, reducing the likelihood of voids. Reduced voiding can also be achieved by selecting a paste with less volatile ingredients. Finally, think about printing your PCB again. A great design choice is a PCB with gas escape pathways to allow for solder paste clearance during reflow.
The best course of action would be to contact the best firm for BGA reworking and soldering, as they have the requisite knowledge and skilled staff available to complete your work.