Due to growth of requirement to manufacture smaller PCB assemblies the all markets, such as automotive, aerospace, medical and even consumer electronics markets are forced to use micro SMT components, such as 0402 and 0201 due to their small size and low cost. There is also a benefit of limited power dissipation when using 0201 components. Manufacturing and rework are 2 inseparable processes in order to achieve higher yields and ROI within business as the post-assembly quality inspection pass rates are lower when using micro 0201 components on PCBAs. Manual 0201 rework on populated assemblies involve tools micro tweezers, various inspection microscopes and specialised soldering irons however they do become more and more impractical due to growing margins of operator errors. Another big challenge when reworking 0201 components is adjacent component clearance and sensitivity as the component, which requires replacement usually needs to be removed, site cleaned, de-oxidised and prepared to accept new SMT component. Automated rework tools do help to accurately place component and reflow it in place with minimal impact of neighboring components. Most critical challenge to such equipment manufacturers is safe de-soldering, vacuum pickup of component, site preparation, pick and place of new component and sufficient reflow to achieve as close as possible solder-ability to manufacturing standards.

Manual 0201 Rework of SMT Components

0201 Rework Lab at TFix in South London-4-2

During manual rework of 0201 components operators can use semi-automated pick and place machinery, which employs high-powered microscopes to aid in alignment of tiny components. Such equipment usually consists of vacuum pickup solution and axis rotation to correctly position part on prepared PCB site. Fully automated rework systems manage to recognize preprogrammed pad location on circuit assembly and place component with highest precision on required pads, which further increases the success of 0201 rework reducing the chance of human error. 0201 also has very poor self-aligning properties during solder reflow further requiring increased accuracy during placement.

It is suggested to follow correct manufacturers suggested reflow profile to solder component in place as most of 0201 components are sensitive to thermal shock and can be easily damaged if using incorrect soldering procedures. The 0201 ceramic capacitors are especially prone to sudden temperature increases and can easily become faulty, so suggested profile ramp up rate is only 2C per second during rework of such components. It also important to use non-forced cooling to allow gradual solder joint relaxation in case of any thermal mismatch within soldering joints. Cleaning with solvents such as IPA or other solutions should be avoided until component is fully cooled due to risk of cracking these ceramic 0201 capacitors.

As demand for smaller printed circuit board assemblies increases the 0201 components will only become more popular solution within PCBA due to their size and performance ration. Due to this technological advancement assembly and rework industry has to become more adaptive by developing new strategies, procedures and tools to keep up with demand. As always most important factors in achieving successful 0201 rework procedures is sufficient operator training and correct tools. Most important investment should be a quality 2D or 3D inspection systems to correctly verify the validity of successful rework.

0201 Rework Workflow

1. Identification

Faulty component has to be identified by either test engineer and marked accordingly and replacement option provided.

2. De-soldering

Using assigned procedures component is removed by either operator or automated machinery. Site also cleaned and prepared.

3. New Component

Using either solder paste or hoof method solder is applied to dressed site and new component reflowed into place.

4. Inspection

If no functional tests are available various 2D and 3D microscopes are used to verify the validity of the 0201 rework process.

Manual 0201 Rework Options

0201 Rework Lab at TFix in South London-2-2

Micro tweezers – convenient way to allow operator to simply pickup component of the PCB by simultaneously desoldering both sides of component, however limitations are imposed by space allowance of adjacent components. The soldering tweezers have to be placed in direct contact with solder joints to allow sufficient heat transfer.

Hot air flow – targeted forced hot air convection method allows operator to melt solder joints of the component and remove it using tweezers. Great care needs to be taken to secure or shield adjacent components to minimize the risk of damage. Lowest possible air flow is suggested to prevent movement of neighboring components.

Site cleaning during 0201 rework can be a challenge if using non-automated systems as standard methods, such as de-soldering wick cannot be used due to physical space limitations. A simple technique of using hoofed soldering iron is a current industry standard to remove old solder and dress the PCB pads with new solder of 0201 rework-able component location.