Rework and Repair
Introduction
Rework and repair technology is a critical part of the electronic assembly process. Technology issues and solutions have been identified by industry experts comprised of rework and repair equipment manufacturers and engineers who are involved in this area on a daily basis. Sections addressing Component-level, Board-level rework and repair issues, as well as Workforce issues are presented.
Conclusions and Recommendations
Rework and repair continues to be a challenging area in electronics assembly operations due to the increased miniaturization and densification of components and assemblies. Larger ball grid array (BGA) and BGA socket components are increasing the challenges. Designs for many products are not optimal leading to increased rework and repair.
Technology issues have been identified and projected by industry experts comprising of rework equipment suppliers and engineers who are reworking and repairing product on a daily basis. Rework and repair is sometimes considered as an afterthought of the electronics assembly process but understanding the reworkability of components is vital to successful product launch, which will ensure faster times to market and less cost in the long run. The rework equipment manufacturers continue to research materials, methods and equipment to help to improve the manufacturability of electronics products.
There are many key issues in rework and repair including the following:
Proliferation of single piece radio frequency (RF) shields (removal and replacement challenges).
Temperature sensitive component rework (micro electro mechanical systems (MEMS), sensors, light emitting diode (LED) and some BGA components- mainly sensor components)—There is a need for heat-tolerant components/devices by design.
Design for manufacturing (DfM) for assembly and rework—More participation from rework standpoint in DfM.
Increasing density of component on board—can make rework challenging to perform, due to large adjacent components Rework causing adjacent component to reflow or partially reflow (for BGAs, connectors, etc.), different board laminates used, different rework heat sources—Thermal modelling is needed on the design level.
Mirror image rework.
i) Ensure that top-and bottom-side mirror-imaged components fully reflow even if top- and bottom-side components are partially mirrored.
ii) Development of design software to understand the risks associated with mirror-image component rework.
iii) Incorporate into design guideline rules on rework of mirror-images components (what is feasible and what is not).
iv) Improved thermal delivery system of equipment for thermal process management control.
Availability of rework machines that can rework very small components and very large components on the same board.
i) Automation of rework processes (alignment, paste dispense, board registration).
ii) Specialized, hands on BGA/bottom terminated components (BTC) training
It is important to understand that as designs produce assemblies with miniaturized components with tighter component spacings and with the advent of larger components as well, the challenges for rework and repair are increasing and will continue to increase in the future. In order to ensure a successful product launch, rework and repair considerations need to be incorporated in DfM considerations or else there will be increased costs and times associated with product rework and repair from the field.
The rework and repair equipment manufacturers continue to research materials, designs and methods to address the challenges faced in this area. Some of the areas which need to be addressed include the lack of rework specialists in the industry and this lack, rework is typically a very manual process (resulting in more person-to-person variation), combined with an aging workforce where rework knowledge and techniques are being lost, has produced a situation where there is a deficiency of engineers to do rework process development. There is a critical need for development of training programs for BGA/BTC rework (in-class and online) along with the development of more specialized hands on BGA/BTC training.
Board Assembly Acronyms
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