Description of Technical Skills
Wire additions & trace repair
Ever-shrinking geometries and increasingly complex boards mean that trace repair and wire additions require greater precision and more sophisticated tools than ever before. Although most developers understand how to make a modification, repairs of components with fine or variable pitch require years of experience to perform correctly. And the complexities of modern PCBs, including smaller, more sensitive components and package-on-package memory, require more sophisticated, expensive tools.
- We modify complex prototypes to improve or alter a board’s function, giving developers a chance to determine if their modifications are working before moving to the next stage of prototype development or manufacturing.
- We also make repairs that few in the industry are willing to attempt. We’ll perform trace modification in the most inaccessible areas, including under BGAs or other sensitive components.
- We repair and restore pad sites for any component, including fine-pitch and variable-pitch BGAs, QFNs, and package-on-package stacks. Our technicians routinely rework the most intricate PCB designs, saving even heavily damaged boards.
Variable Volumes, a Suite of Solutions
Sometimes our customers need to perform the same repair on dozens, or even hundreds, of boards. Or we may be presented with a set of identical PCBs, each with a different problem, each requiring a different solution. Either way, we’ll analyze the entire board to find mechanical and thermal faults, then present the most effective solutions for fixing them.
Usually, we can offer several solutions based on the desired result. We may recommend a more complex repair that ensures device reliability in challenging conditions, or a short-term repair that prolongs the useful life of the device — whatever meets your needs. And once the repair is complete, we’ll inspect each component and provide documentation to ensure repeatability in future projects.
We rework the most intricate devices, leading the industry in complex repairs, component salvage and prototype assembly. To tackle the kind of extremely difficult projects we receive, we develop temperature profiles that ensure our clients’ expensive — sometimes irreplaceable — boards are handled with the utmost care.
Almost any cook can follow a recipe, but only a highly trained chef can take a random pile of ingredients and turn them into something that works. In the same way, assembling a board requires a precise recipe, but once the recipe has been formulated it can be applied with generally anticipated results. Complex, high-quality rework, however, requires the kind of creativity and experience found only in a master chef.
Our technicians train for a year to learn the basics of thermal profiling, and constantly update and improve their skills. It’s not simply a matter of understanding how much heat to apply and how long to apply it: an experienced technician understands the art of balancing a wide range of physical limitations to arrive at the best possible result for each client and each project, carefully handling particular components while accounting for the cohesiveness of the rest of the board. The thickness of the board, the component, the size of the spheres, the pitch — all exert their influence.
Our nine VJ Electronix Rework Stations use forced nitrogen — at temperatures up to 350°C — to prevent oxidation while precisely manipulating even the most sensitive components. Nitrogen provides a number of advantages, especially for fine-pitch devices, prototypes, and complex or expensive rework. Nitrogen’s forgiving nature makes rework less prone to defects, improving overall device quality. By incorporating nitrogen into all rework we improve solder quality, increase the wetted surface, improve the solder process and improve the appearance of the solder joint, making it easier to inspect and repair.
Inaccuracies in the thermal profile create faults in finished devices which may go unnoticed … until the device fails. Intermetallic formation must be precisely calibrated; too much can be worse than too little. Flux must be outgassed precisely to avoid void formation. Unseen or overlooked faults can create defective products, unhappy customers and public relations disasters — all for the want of an accurate thermal profile.
- We define a number of variables to ensure the right results: the height off the heater, thermocouple location, nozzle type, device orientation on the rework station, the best way to avoid warping, and many more. Placement of the thermocouples is critical; a slight error can provide false readings that destroy the board. We do whatever we can to ensure the most precise, dependable rework possible.
- When reworking devices, we also keep manufacturability in mind. When developing prototypes or eliminating defects, we document each step of the process to make sure that when you’re ready to go back to manufacture, you have information that will increase device life, decrease failure rates and improve profitability.
An accurate thermal profile is also a critical component in PCB assembly. We use a Juki Cube.460 selective soldering system to provide superior flexibility and reliability in all of our assembly operations, and employ nitrogen to ensure joint quality.
For complex or expensive devices, partial samples can be created and tested to ensure that when the first complete device is baked, components aren’t wasted on a test PCB. If needed, changes can be made to the thermal profile and additional tests run until assembly is ready to begin. Each stage of the process, from preheat to soak to reflow to cooling, is carefully monitored and each device is inspected to ensure that expectations match reality.
Coating & Underfill
As circuits become smaller and their presence more ubiquitous, PCBs are being assaulted by every conceivable environmental stress. From dropping a cell phone to launching sensitive equipment into the depths of the oceans or the radiation of space, developing a PCB can be as much about manufacturing as about anticipating the life it will lead. We know how to safeguard your boards from the rigors of the real world, extending their useful life and ensuring they perform as you intend.
Underfilling can dramatically extend the useful life of a device, protecting solder joints from extreme temperature changes, vibration, chemical exposure and other environmental stresses, while ensuring that devices work efficiently and experience the longest possible useful life.
- We perform capillary underfill for devices that require the most stable adhesion. Underfill is placed alongside the component and heated, allowing capillary action (sometimes referred to as “wicking”) to pull the material into even the tightest interstitial spaces. We also routinely perform side and corner underfill to enhance a board’s stability.
- Several underfill materials are available. Our technicians know how to choose the right material for your project, addressing component requirements and expected environmental stresses to choose an underfill with the right thermal properties and chemistry to produce the best result for the device. We also work with OEM field application engineers to determine the right underfill or conformal coating for each PCB.
- Both reworkable and non-reworkable underfill materials are available, allowing for future rework and prototype testing.
- Once applied, underfills are cured using an oven or our 400-watt UV curing system.
The most perfectly performed rework and assembly can be quickly ruined by environmental exposure. Our technicians understand how to choose the right coating chemistry for your device and make sure the coating is applied precisely.
Environmental stresses can make some coatings ineffective. In the same way that we choose an underfill based on variations in temperature, moisture levels, vibration resistance, and other expected considerations, our technicians understand how to balance moisture, temperature variation, chemical exposure and other factors to choose the right conformal coating for your boards.
Coatings are applied using precise methods, creating a breach-free coat of exactly the right thickness. Coatings can then be cured using UV light or one of our five ovens.