DISASSEMBLING AND RECYCLING OF IN MOLD
ELECTRONICS 3D PLASTRONICS SYSTEMS
BASED ON POLYCARBONATE SUBSTRATE

Hugo Cauchy-Clerc, Philippe Lombard, Nicolas Duguet, Tony Gerges, Vincent Semet, Bruno Allard, Jean-Yves Charmeau, Michel Cabrera

► To cite this version:

Hugo Cauchy-Clerc, Philippe Lombard, Nicolas Duguet, Tony Gerges, Vincent Semet, et al. DISASSEMBLING AND RECYCLING OF IN MOLD ELECTRONICS 3D PLASTRONICS SYSTEMS BASED ON POLYCARBONATE SUBSTRATE. LOPEC (Large-area, Organic & Printed Electronics Convention) 2025, OE-A (Organic and Printed Electronics Association); Messe München, Feb 2025, München, Germany. hal-04990943v2

HAL Id: hal-04990943

https://hal.science/hal-04990943v2

Submitted on 28 Nov 2025

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INSA

INSTITUT NATIONAL
DES SCIENCES
APPLIQUEES
LYON

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Université Claude Bernard Lyon 1

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DISASSEMBLING AND RECYCLING
OF IN MOLD ELECTRONICS 3D
PLASTRONICS SYSTEMS BASED
ON POLYCARBONATE SUBSTRATE

Hugo CAUCHY-CLERC¹,², Philippe LOMBARD², Nicolas DUGUET³, Tony GERGES², Vincent SEMET², Bruno Allard², Jean-Yves CHARMEAU¹, Michel CABRERA²

(1) Université de Lyon, Université Claude Bernard Lyon 1, INSA Lyon, Ecole Centrale de Lyon, CNRS, Ingénierie des Matériaux Polymères IMP, UMR 5223, F-69622 Villeurbanne Cedex, France

(2) Université de Lyon, Université Claude Bernard Lyon 1, INSA Lyon, Ecole Centrale de Lyon, CNRS, AMPERE, UMR 5005, F-69622 Villeurbanne Cedex, France

(3) Université de Lyon, Université Claude Bernard Lyon 1, Institut de Chimie et Biochimie Moléculaires et Supramoléculaires (ICBMS), UMR 5246, F-69622 Villeurbanne Cedex, France

Projet ANR-22-CE05-0015-03 AMBRE : Antenne Multifonctionnelle Biosourcée pour la récupération d'Energie

hugo.cauchy-clerc@insa-lyon.fr

michel.cabrera@insa-lyon.fr

anr
agence nationale
de la recherche

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Plastronique
Convergence de l'électronique et de la plasturgie
1. 3D PLASTRONICS AT AMPERE AND IMP LABORATORIES

2. IN-MOLD ELECTRONICS

3. CHALLENGE OF ELECTRONICS END-OF-LIFE

4. AIM AND MOTIVATIONS

5. POLYMER DISSOLUTION ROUTE

6. DEPOLYMERIZATION ROUTE

7. CONCLUSION
# 3D PLASTRONICS AT AMPERE AND IMP LABORATORIES

## Positioning and scientific activities → Research and development in Plastronics:

* Electrical engineering: advanced packaging of electronic components and systems

* Materials engineering: polymers and shaping processes

* Global approach: Feasibility – Design/Simulation – Manufacturing (prototyping) – Characterization → Plastronics functionalization of polymers: from sensor to system

## Our objectives :

* New process & Design innovative functions → Understand the physical phenomena involved

* Starting from an idea, designing and producing a functional prototype and obtaining its multi-physical characteristics

* Our resources → Dedicated 3D plastronics platform + Plastics processing platform + Resources and skills of 2 laboratories specializing in electronics and materials

## Academic activities → Training offers through research in connection with industry (theoretical and practical training, projects monitoring, internships, etc.)
# 3D PLASTRONICS - PLAST(IC) + (ELECT)RONICS

<figure><img src="image_10.png" /></figure>

<figure><img src="image_11.png" /></figure>

## 3D Plastronics:

* Enables seamless integration of disparate technologies into a single device

* Combines electronics, mechanics, optics, and other functions for reduced complexity and improved performance

* Simplifies assembly and design processes through standardization and compatibility

<figure><img src="image_12.png" /></figure>

* Polymer substrates can be produced on a scale ranging from small batches to large quantities through various manufacturing methods, including precision machining, additive 3D printing, and conventional injection molding and thermoforming processes

<figure><img src="image_13.png" /></figure>

* There are many plastronic processes → The choice is influenced by factors such as: geometry complexity, polymer material, quantity, cost, and performance requirements
# IN-MOLD ELECTRONICS (IME)

## 4 major steps :

<figure><img src="image_14.png" /><figcaption>Electronic components
implementation</figcaption></figure>

<figure><img src="image_15.png" /><figcaption>3D thermoforming</figcaption></figure>

<figure><img src="image_16.png" /><figcaption>Overmolding</figcaption></figure>

<figure><img src="image_17.png" /></figure>

## IME examples in Human Machine Interfaces :

<figure><img src="image_18.png" /><figcaption>Technology demonstrator by Tactotek</figcaption></figure>

<figure><img src="image_19.png" /><figcaption>Mercedes Benz concept car</figcaption></figure>
# IN-MOLD ELECTRONICS (IME)

## 4 major steps :

### Screen printing

<figure><img src="image_20.png" /></figure>

### Electronic components implementation

<figure><img src="image_21.png" /></figure>

### 3D thermoforming

<figure><img src="image_22.png" /></figure>

### Overmolding

<figure><img src="image_23.png" /></figure>

<figure><img src="image_24.png" /></figure>

## IME versus conventional electronic Printed Circuit Board (PCB):

* IME is based on conductive silver ink (ρ (Ag) ~ at best 20-40 μΩ.cm for commercial inks)

* PCB is based on copper (ρ (Cu) ~ at best 1,72 μΩ.cm for bulk copper)

<figure><img src="image_25.png" /></figure>

## Limiting points of IME Process:

* Ink: high resistivity tracks → Increases with 3D thermoforming stretching : Limitation of aspect ratio

* Connection to SMDs performed with conductive silver paste reinforced with non-electrically conductive glue

* High resistivity & cost (compared to solder paste used in conventional PCB)

* Bond strength may be weak → Structural adhesive/encapsulating may be required

* Long drying (ink & glue) process (> for example 20' curing à 120°C for each screen-printed layer)
# CHALLENGE OF ELECTRONICS END OF LIFE

<figure><img src="image_26.png" /></figure>

Current recycling process for Waste from Electrical and Electronic Equipment (WEEE)

In 2022 : **60M tons of**
WEEE generated
worldwide.

In the EU [4] :
**14M tons generated**
**5M tons collected**

➤ Only ~**40%** of WEEE generated by weight

## We can do better !

Our team has already demonstrated the feasibility of **dismantling of PLA-based IME devices** [2].

We also found previous works on easy ways to depolymerize polycarbonate parts [3].

The two methods proposed here can be thought of larger approaches, allowing the **full recycling of an IME**
**plastronic device**.
# AIM AND MOTIVATIONS

Propose a novel way to separate electronic components and inks from the polymer in PC IME devices

Propose a novel way of **recycling the polymer** part of the device

More precisely:

* Allow an easy, industry-compatible way to **separate** the different materials

* Propose a way to limit **manufacturing waste** of IME devices

* Propose a way to **value the products** of this process

Main challenge: As companies making IME devices may not be equipped for heavy chemistry, the proposed process must not be too requiring in this department
OVERVIEW OF THE PROPOSED PROCESS

<figure><img src="image_27.png" /></figure>

Two processes are proposed :

➤ **Dissolution** of the polymer part for **recycling** into new devices

➤ **Depolymerization** of the polymer for **upcycling** into new material
# POLYCARBONATE

* Derived from petrochemicals, but **recycled PC** can be found

* **Excellent optical properties** (transmission between 85 and 90% over the entire visible spectrum)

* Good mechanical properties (Young's modulus ~2 GPa)

* **Highly impact resistant** (Charpy ~30kJ/m²)

* **Good temperature resistance** (HDT 137°C for the Covestro 2405)

* **Good dielectric properties** ($r$ = 2.9, $tan$ = 0.01 at 1MHz)

Very common material :

<figure><img src="image_28.png" /></figure>

<figure><img src="image_29.png" /></figure>

<figure><img src="image_30.png" /></figure>

Chemically, polycarbonate is **mostly BPA molecules** chained together by a carbonate functional group
# DEVICE DISASSEMBLY- OPTIONAL GRINDING STEP

**Goal : accelerate (and improve ?) the process**

The plastronic device is first ground into small fragments. This is done in several grinding steps, from very coarse chunks to tiny particles. This allows us to hand pick some SMD components before starting the chemical process.

This grinding is done using a **commercial cutting mill**, using rotating cutting blades and different sieves to ensure an homogenous size of the particles

<figure><img src="image_31.png" /><figcaption>Dysfunctional or end-of-life IME device</figcaption></figure>

<figure><img src="image_32.png" /><figcaption>Coarse fragments of the IME device</figcaption></figure>

<figure><img src="image_33.png" /><figcaption>Smaller fragments ready for chemical dismantling</figcaption></figure>

<figure><img src="image_34.png" /></figure>
First option : polymer dissolution
# POLYMER DISSOLUTION ROUTE - OVERVIEW

## 1st step

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The device is ground into small fragments to be processed

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Polymer fragments are dissolved, leaving SMDs and silver ink (silver flakes + organic binder + solvent)

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The polymer can be reused to make new devices and the solvents can be used for any other chemical process

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Solidified polycarbonate

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Solvent + Antisolvent

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An antisolvent is added to the mix to precipitate the polymer

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After the polymer precipitates, the solvent and antisolvent are removed by evaporation

<figure><img src="image_46.png" /></figure>

Silver and SMDs are simply filtered away and are sent to conventional e-waste processing

<figure><img src="image_47.png" /></figure>
POLYMER DISSOLUTION

Once divided into fragments, the polymer is placed with an
appropriate solvent in a reaction vessel.

It is heated to speed-up the process, until full dissolution of the
polymer.

<figure><img src="image_48.png" /></figure>

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Dissolved polycarbonate, with
SMD components and silver flakes
floating inside

<figure><img src="image_50.png" /></figure>

Different solvents being tested for Polycarbonate dissolution

Several solvents can dissolve polycarbonate, including **tetrahydrofuran, dichloromethane and dimethyl carbonate**
RECOVERY OF THE NON-POLYMER PART

Using **fine paper filters**, all the SMD fragments and most of the silver particles are recovered.

The SMD components and silver particles recovered at this step can then be processed as if they came from **conventional electronic waste**.

<figure><img src="image_51.png" /><figcaption>Dissolved polycarbonate, with SMD components and silver flakes floating inside</figcaption></figure>

<figure><img src="image_52.png" /></figure>

<figure><img src="image_53.png" /><figcaption>Silver flakes recovered after a fine filtration step</figcaption></figure>
RECOVERY OF THE POLYMER

<figure><img src="image_54.png" /></figure>

The anti-solvent is selected to precipitate the polycarbonate into a **solid form**.

It is then separated from the solvent/anti-solvent mix by evaporating those.

<figure><img src="image_55.png" /></figure>

<figure><img src="image_56.png" /></figure>

<figure><img src="image_57.png" /></figure>

Using the rotary evaporator, the two chemicals can be separated during the process due to the difference in evaporation temperature of the chemicals.
POLYMER DISSOLUTION ROUTE - CONCLUSION

The dissolution of the polymer is a simple process, allowing an easy separation of the different parts of the IME device, and directly **yielding solid polymer** without needing an additional synthesis step.

<figure><img src="image_58.png" /></figure>

The recovered polymer is close to the virgin matter after dissolution in terms of physical properties, but **further investigation is ongoing** to ensure exactly how close.
Second option : polymer depolymerization
# DEPOLYMERIZATION ROUTE - OVERVIEW

## 1st step

<figure><img src="image_59.png" /></figure>

The dimethyl carbonate and the bisphenol A can be used to make new polycarbonate

<figure><img src="image_60.png" /></figure>

The device is ground into small fragments to be processed

Polymer fragments react with an alcohol and depolymerize, leaving only SMDs and silver flakes floating

<figure><img src="image_61.png" /></figure>

$$ \begin{array}{l} \text{PC} + \text{Methanol} \\ \rightarrow \text{BPA} + \text{DMC} \end{array} $$

<figure><img src="image_62.png" /></figure>

The solvent and alcohol can be used for a new batch of the reaction

<figure><img src="image_63.png" /></figure>

<figure><img src="image_64.png" /></figure>

Bisphenol A

<figure><img src="image_65.png" /></figure>

<figure><img src="image_66.png" /></figure>

Dimethyl carbonate

<figure><img src="image_67.png" /></figure>

<figure><img src="image_68.png" /></figure>

Water is added to help crystallize the BPA

<figure><img src="image_69.png" /></figure>

After the reaction and filtration, the liquids are separated by evaporation

<figure><img src="image_70.png" /></figure>

Silver and SMDs are simply filtered away and are sent to conventional e-waste processing

<figure><img src="image_71.png" /></figure>

Waste metal treatment

<figure><img src="image_72.png" /></figure>

Monomer in solution

<figure><img src="image_73.png" /></figure>
ALCOHOLYSIS REACTION

Once ground into fragments, the polymer is placed with THF in a reaction vessel, which will soften the polycarbonate. Methanol is then added along with a catalyzer to start the alcoholysis reaction.

<figure><img src="image_74.png" /></figure>

<figure><img src="image_75.png" /><figcaption>Fig. 1. Mechanism of PC depolymerization by alkali-catalyzed methanolysis. [3]</figcaption></figure>

The silver from the ink and the SMD components fall to the bottom of the reactor, and the polymer chains are broken into smaller valuable molecules, namely **dimethyl carbonate** and **bisphenol A**.
RECOVERY OF THE NON-POLYMER PART

Exactly like in the dissolution route, we are able to recover all the SMD fragments and most of the silver particles from the IME ink using paper filtration.

The SMD components and silver particles recovered at this step can then be processed as if they came from **conventional electronic waste**.

<figure><img src="image_76.png" /></figure>

The liquid part is then further separated by evaporation to isolate valuable products and solvents. In this case, we can recover the solvent and the alcohol to **reuse them in another reaction**.

<figure><img src="image_77.png" /></figure>
RECOVERY OF THE REACTION PRODUCTS

By adding **water** to the resulting mixture, we allow the bisphenol A to crystallize. Using our rotary evaporator once again, we can subsequently remove the water and separate our products.

In the end, we are left with **solid bisphenol A and liquid Dimethyl Carbonate**.

<figure><img src="image_78.png" /><figcaption>Recovered Bisphenol A powder from polycarbonate depolymerization</figcaption></figure>

<figure><img src="image_79.png" /></figure>

Using FTIR analysis, we can confirm that the resulting powder actually is BPA.

The process yield 90% of the starting mass as BPA, and the rest as DMC.
POLYMER DEPOLYMERIZATION ROUTE - CONCLUSION

<figure><img src="image_80.png" /></figure>

Depolymerization of the polymers produces simple molecules which can then be used for further chemistry.

PC depolymerization yields Dimethyl Carbonate, a **common solvent**, and **Bisphenol A**, which is the **main component in the synthesis of polycarbonate**.

Using these two, it is possible to synthesize brand new, **chemically pure virgin polycarbonate**.
CONCLUSION

<figure><img src="image_81.png" /><figcaption>Silver flakes recovered
after a fine filtration step</figcaption></figure>

<figure><img src="image_82.png" /><figcaption>Dissolved polycarbonate,
with SMD components
and silver flakes floating
inside</figcaption></figure>

<figure><img src="image_83.png" /><figcaption>Recovered polycarbonate
after dissolution</figcaption></figure>

<figure><img src="image_84.png" /><figcaption>Recovered Bisphenol A
powder
from
polycarbonate
depolymerization</figcaption></figure>

Dissolving polycarbonate allow to easily separate all elements of the IME device, and to directly recover polycarbonate, albeit with slightly degraded properties.

Depolymerization is a more involved process, and does not directly yield polycarbonate, but the resulting products are pure and can easily be processed into new polycarbonate by polymer makers.

In both processes, the SMD components and the silver flakes are separated, and as such can be processed separately in traditional WEEE treatment facilities.
BIBLIOGRAPHY

[1] Brasse, Y., Moreno, M.L., Blum, S. et al. Recyclable in-mold and printed electronics with polymer separation layers. RSC Sustainability, 2024, 2, 1883. 10.1039/d4su00092g

[2] Goument, C., Gerges, T., Lombard, P. et al. In-Mold Electronics on Poly(Lactic Acid): towards a more sustainable mass production of plastronic devices. Int J Adv Manuf Technol 125, 2643–2660 (2023). 10.1007/s00170-023-10878-4

[3] Chandrakant Sharad Bhogle, Aniruddha Bhalchandra Pandit, Ultrasound assisted methanolysis of polycarbonate at room temperature, Ultrasonics Sonochemistry, Volume 58, 2019, 104667, ISSN 1350-4177, 10.1016/j.ultsonch.2019.104667.

[4] Waste statistics - electrical and electronic equipment, Eurostat, 2024, [link](https://ec.europa.eu/eurostat/data-quality/data-catalogue/electric-and-electronic-equipment-statistics)
Thank you for your attention.
Questions?

hugo.cauchy-clerc@insa-lyon.fr

michel.cabrera@insa-lyon.fr