Automotive Electronics
Retronix offers a range of services to improve the reliability of automotive electronics. Unlike many computing and telecommunication electronics, automotive electronics are subject to movement, vibration and temperature extremes that can expose any weakness in the soldering joints of a PCB. Often these issues are undetectable until the electronics are subject to such stresses, and will easily pass any post manufacturing tests.
LCC/QFN Type Devices
These type of devices are soldered directly to the PCB with the expectation to achieve a low profile connection. 
However this can create problems –
The solder connection between IC and PCB is very thin, and susceptible to fracture when subject to vibration CTE (Coefficient of Thermal Expansion) issues can occur when the IC gets warm during operation and the PCB does not. The two expand at different rates and this can crack the solder joints.
Potential Failure Points –
| Typical solder joint cracking due to fatigue failure during thermal cycling. Major difference in CTE (Co-efficient of Thermal Expansion) & vibration between ceramic LCC body and PEC substrate.Solder is a fairly weak alloy which can not withstand cyclic stresses easily. Cycles to failure will be low and reliability in service poor as a result. | Cross-section of fatigue failure showing crack travelling through bulk of solder. Note very low solder thickness under component. |
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The Retronix solution –
| Laser reball (laser attaches spheres without a reflow cycle) high melting point spheres eg 90% lead, copper cored onto the LCC pads - | |
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| This process raises the standoff height of the LCC as the new spheres do not collapse under reflow during assembly. | Cross section of LCC. The dark areas are the HMP spheres. Note the difference in stand off height. |
- Mitigates CTE issues by allowing heat to escape from under the component.
- Stronger connection using HMP sphere (more flexible metal than thin eutectic solder joint)
- Allows cleaning under the IC, avoiding flux residues being trapped.
- Solder spheres avoid outgassing and eliminate voids.
Other Application Include :
Legacy Product Manufacturing –
Legacy Product build will involve ICs which are old, and possible lying around becoming oxidised. This will probably lead to soldering issues, depending on how they have been stored. Oxidisation (often invisible) will have formed on the IC terminations and act as a barrier in the soldering process. The post manufacturing solder joints will appear normal, but are weak and will be subject to early life failure when subject to vibration/heat.
The best way to ensure no issues occur is to retin the terminations, refreshing the alloy and removing any oxidisation present.
Retronix utilise a fully automatic process to do this, ensuring consistent results across the batch of ICs in terms of dip length, dip time, temperature etc.
3D Modelling –
We utilise techniques unique to Retronix to achieve far more reliable 3D modelling, applications include NPI, Site Quality and Warranty Returns.
Processes include :
- Instantly creating a column of solder spheres to achieve a standoff height
- Laser reballing of a BGA without any thermal stress
- Removing ICs using bottom heat to avoid a reflow cycle
Electronic Component/PCB Rework Services:
Retronix have for years been the European/UK go to company in the Automotive Industry for :
- Capacity issues – eg misloads, when an automotive manufacturer has too many PCBs needing work to do them all internally.
- Complicated reworks – eg remove a misplaced BGA, refurbish it, place it back down and X-Ray it to ensure compliance.
We are happy to carry out free of charge samples to assist you to prove the process and the benefits to your company.
Get in touch with us via the Contact Form or email us at sales@retronix.com For more information on CTE issues affecting – Harsh Environment and High Reliability industries – click here
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