Low‐stress over‐molding of media‐tight electronics using thermoplastic foam injection molding

Ott, Constantin; Drummer, Dietmar

doi:10.1002/pen.25672

Cited by 4 publications

(2 citation statements)

References 14 publications

(18 reference statements)

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“…The mechanical forces may be considered separately as shear loads acting in-plane and pressure loads acting normally upon the component surfaces. To bypass the high stresses inherent to the injection molding process, Ott and Drummer [6] proposed using thermoplastic foam injection molding. That way, they could encapsulate epoxy-based printed circuit boards (PCBs) with cavity pressures of approx.…”

Section: Introductionmentioning

confidence: 99%

Parameter Study on Force Curves of Assembled Electronic Components on Foils during Injection Overmolding Using Simulation

et al. 2023

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The integration of assembled foils in injection-molded parts is a challenging step. Such assembled foils typically comprise a plastic foil on which a circuit board is printed and electronic components are mounted. Those components can detach during overmolding when high pressures and shear stresses prevail due to the injected viscous thermoplastic melt. Hence, the molding settings significantly impact such parts’ successful, damage-free manufacturing. In this paper, a virtual parameter study was performed using injection molding software in which 1206-sized components were overmolded in a plate mold using polycarbonate (PC). In addition, experimental injection molding tests of that design and shear and peel tests were made. The simulated forces increased with decreasing mold thickness and melt temperature and increasing injection speed. The calculated tangential forces in the initial stage of overmolding ranged from 1.3 N to 7.3 N, depending on the setting used. However, the experimental at room temperature-obtained shear forces at break were at least 22 N. Yet, detached components were present in most of the experimentally overmolded foils. Hence, the shear tests performed at room temperature can only provide limited information. In addition, there might be a peel-like load case during overmolding where the flexible foil might bend during overmolding.

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Section: Introductionmentioning

confidence: 99%

Parameter Study on Force Curves of Assembled Electronic Components on Foils during Injection Overmolding Using Simulation

et al. 2023

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“…To reduce the prevailing forces on the components, Ott and Drummer proposed using thermoplastic foam injection molding. Through this technology, they could encapsulate epoxy-based printed circuit boards (PCBs) with significantly lower cavity pressures (about 1 MPa) compared to traditional injection molding [ 6 ].…”

Section: Introductionmentioning

confidence: 99%

Process Optimization of Injection Overmolding Structural Electronics with Regard to Film Distortion

et al. 2022

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The integration of structural electronics in injection-molded parts is a challenging step. The films—comprising of laminated stacks with electronics—are exposed to shear stresses and elevated temperatures by the molten thermoplastic. Hence, molding settings have a significant impact on the successful, damage-free manufacturing of such parts. In this paper, test films with polycarbonate (PC) sheets as outer and two different thermoplastic polyurethanes (TPUs) as middle layers incorporating conductive tracks on a flexible printed circuit board (flexPCB) are manufactured and overmolded with PC. Parameter studies investigating the influence of the melt temperature, mold temperature, injection speed and used TPU layer were performed. The molded parts were inspected visually and compared with a numerical simulation using injection molding software. A shear distortion factor for the TPU layer was derived based on the simulations that linked the shear stresses with the injection time and the softening (melting) of the TPU. The distortion of the films was found to reduce with higher melt temperature, lower mold temperature and faster injection speed. Films using the TPU with the higher melting temperature yielded significantly better results. Moreover, distortion on the films reduced with the increasing distance to the gate and a larger cavity thickness was found to be beneficial. All those relations could be correlated with the shear distortion factor.

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In-situ leakage behavior of polymer-metal hybrids under mechanical load

Ott

Drummer

2022

International Polymer Processing

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Tightness against media is a frequent requirement for technical components. Despite various standardized test procedures, failure regularly occurs during use. Often, no clear cause for failure can be determined afterwards. In this article, a new test setup is presented and applied, which allows an in-situ measurement during a mechanical load. A flow meter with a measuring range of 0.02 mL/min to 5 mL/min is used for this purpose. This makes it possible to determine leakage rates with time resolution and thus to identify the moment of failure or the causal failure load. This new method was applied directly to different aluminum inserts with a polyamide 66 (PA66) overmold. It was shown that no increase in leakage occurs until a maximum force is reached, even with multiple loads. This maximum force depends only on the pretreatment of the inserts and can be determined in a simple pull-out test independently of the test setup used here and can therefore be used for the design of assemblies. In the test, a maximum force of 100 N was achieved for untreated inserts, 140 N for adhesion promoter-coated parts and 600 N for etched inserts with a contact area of 48 mm2. With this results, a new link between adhesion and tightness can be shown, which of course is only valid for initial tight parts.

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Low‐stress over‐molding of media‐tight electronics using thermoplastic foam injection molding

Cited by 4 publications

References 14 publications

Parameter Study on Force Curves of Assembled Electronic Components on Foils during Injection Overmolding Using Simulation

Parameter Study on Force Curves of Assembled Electronic Components on Foils during Injection Overmolding Using Simulation

Process Optimization of Injection Overmolding Structural Electronics with Regard to Film Distortion

In-situ leakage behavior of polymer-metal hybrids under mechanical load

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