DSM presents reflow best practices during 2019 Auto EPCON

The Society of Plastics Engineers (SPE) hosted its fourteenth annual Auto EPCON conference in Troy, Michigan, in May 2019. Paula Kruger, application engineer for DSM Engineering Materials, presented best practices for reflow of electronic components during the conference.

The theme of this year’s conference was “Pushing the Boundaries.” With the evolution of electric and autonomous vehicles, the automotive plastics industry is expanding into new applications.

Kruger’s presentation focused on electronic components—the reflow process and key material properties for success. As the integration of electronics into automotive continues, compact design becomes more important, and to ensure safe and reliable operating during the vehicle’s lifetime, several requirements must be met.

The example application discussed was an electronic control unit (ECU) for electric power steering. For this specific application, ForTii T11, PPA-GF30 FR(40) was utilized in components such as lead frames and connectors. It is 30% glass reinforced, PA4T, electro-friendly, halogen free, red phosphorous free, and certified V-0 at 0.2mm.

Kruger spoke about the aspects of selecting the proper materials; industry standards that must be met; reflow soldering process; and thermal, mechanical and electrical properties.

At the beginning of the session, Kruger pointed out that the design of the ECU is very compact, and electronics are being squeezed into the smallest packaging space possible. “When working with compact designs, components like lead frames and connectors suitable to the reflow soldering process are needed,” said Kruger.  

Reflow soldering process

Kruger also explained the reflow soldering process and why there are concerns about deformation, fast moisture evaporation for materials that absorb moisture and thermal degradation of the components.

“The European Union started banning lead in electronics in 2006 and since then lead-free solder paste is used—it melts at higher temperatures than lead containing paste, which means one must put the board through a higher temperature process to have this solder to reflow,” explained Kruger.

Materials properties and selection

As the bar is raised for lead-free soldering, only a few materials can handle this process, and PPA is one of them. However, there are some concerns about moisture and blistering. Blistering leads to irregular wall thickness that can cause potential mechanical and electrical performance issues.

ForTii has a high HDT compared to others, which means less risk of deformation when exposed to high heat for a short time. Regarding the mechanical properties, there is a good balance between tensile stress and strain, which is essential for design flexibility.

Furthermore, the high RTIs indicate good resistance to thermal degradation, and the higher CTI [low PLC] is desired for thin walls.

She also emphasized the importance of considering weldline strength and CLTE during the design process. “Typically, PA-based materials will present weldline strength in the rage of 40-50% of the strength of the original material,” said Kruger. “In the case of ForTii T11, the CLTE is important too, especially when connectors need to be exposed to testing and temperatures range from -40° to 150° C. Since this is such a wide temperature range there can be a lot of contraction and expansion.” 

Takeaways for design success

Kruger wrapped up her session with a list of key takeaways:

  • Thinnovation: UL V0 rating is at the smallest wall thickness in design.
  • Moisture and blistering: Most manufacturers look for a MSL1 or 2 approved materials. 
  • Materials properties for design:

            o   A high deflection temperature that is above temperature in reflow process.
            o   Mechanical strength and weldline strength (it doesn’t help to have a really strong
                 material when the weldline’s strength is very low).
            o   Long-term heat resistance for USCAR Class 4 in this application.    
            o   Comparative tracking index (CTI): A small PLC of zero will allow for shorter
                 distance between terminals.
            o   Coefficient of linear thermal expansion (CLTE): a good balance between parallel
                 and normal directions is important for performance of the part.  

To search for PPA materials, visit plasticsfinder.com, or contact us for questions or technical inquiries. 

Candace Roulo

Global Manager of Messaging and Content Development

Published on

22 May 2019


  • Blog
  • ForTii
  • Electronic & Electrical
  • System Design
  • Connectors

ForTii: The best in class stiffness

Popular blogs


Candace Roulo

Global Manager of Messaging and Content Development

Candace Roulo is Global Manager of Messaging and Content Development for Envalior. Based in Troy, Michigan, she specializes in writing blogs and articles about advanced materials solutions. Prior to joining Envalior, Candace served in editorial roles at SME and Penton Media. Candace earned her bachelor’s degree in communication, specializing in public relations, at Michigan State University’s College of Communication Arts and Sciences.

Subscribe to our monthly newsletter

Leave your e-mail address below to start receiving the latest news about plastics, new products and events delivered to your inbox. 

I agree with Envalior's Terms and Conditions and acknowledge that Envalior will process my personal data for the purposes described in our Privacy Policy.