Adhesive interconnections

Adhesive interconnections

We have worked for a long time with adhesive interconnections. We have the knowhow and equipment to manufacture and optimize adhesive bonding processes for several applications. We can also help you to select the most suitable adhesive materials.

Electrically conductive adhesives

We work with many adhesive types such as thermal, optical and non-conductive adhesives. One type of adhesives is nevertheless very close to our hearts: Electrically conductive adhesives, ECAs, ACAs, ACPs, ACFs, ICAs, ICPs, epoxy glues, silver glues –  however you want to call them.

Electrically and thermally conductive adhesives are very useful and versatile materials. They can also perform very reliably even in harsh environments, but for this a right material must be chosen and the attachment process must be optimized. Various kinds of electrically conductive adhesives are commercially available. However, depending on their composition, intended use and their sensitivity to bonding parameters, they are not as straightforward to use as solders. When selecting an adhesive material, several things affect the requirements for suitable adhesive. These include for example materials (component, substrate, conductive traces), particle in the adhesive (material, size, concentration) and use environment for the final product.

We have worked with ECAs for more than 15 years, especially in demanding applications. 

We can therefore help you to select the best ECA for your  application and to obtain the best and the most reliable bonding profile. For new applications we strongly recommend experimental testing of several adhesives, since even relative similar materials can have very different stability and reliability in use.  

 

Not familiar with electrically conductive adhesives (ECA)?

ECAs are polymeric materials that contain conductive particles. Conductive particles provide electrical conductivity for the adhesive material. ECAs are widely used in electronics, including commercial, industrial, medical, aerospace and automotive applications. Their benefits include, for example, environmental friendliness, fine-pitch capability, good thermal cycling performance and lower processing temperatures, which enable the use of temperature-sensitive and low-cost substrate materials.

Based on the concentration of conductive particles, ECAs are divided to isotropic conductive adhesives (ICA) and anisotropic conductive adhesives (ACA). ICAs conduct in all directions because they have a high concentration of conductive particles and, therefore, they are used as an alternative for solders. ACAs, on the other hand, have much lower particle count and they only conduct in z-axis after attachment. Therefore, they are ideal for fine pitch flip chip and flex-on-board applications.

Today, ACAs are widely used in commercial and industrial applications, such as smart cards, mobile phones, digital cameras and laptops. Benefits of using ACAs include the capability of using materials that are not applicable for soldering or otherwise cannot withstand typical soldering temperatures. In addition, underfilling process required with solder bump or ICA flip chip attachments can be avoided and fine pitch interconnections achieved.

A wide variety of ICA materials is commercially available. ICAs are used both for thermal and electrical conductivity. The most common material used in ICAs is silver filled epoxy, but numerous other options are also available. To ensure the reliability of an ICA interconnection, it is critical to choose a suitable and optimized material. ICAs are often used in applications in which soldering is difficult. This may be because of the structure and materials of the connected surfaces. Additionally, ICAs are commonly used with temperature sensitive materials due to their low curing temperatures. Especially, in new flexible and low temperature structures ICAs offer lots of benefits.

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Available attachment methods with adhesives

Flex and stretch attachments

We can attach various flex and stretch structures including flex-on-board, flex-to-flex, stretch-on-board and stretch-on-flex.

Flip chip 

We can attach flip chip attachments both on rigid substrates (chip-on-board, chip-on-glass) and flexible substrates (chip-on-flex). We have years of experience in small pitch as well as large area and high I/O flip chip attachments on different substrate types. We can for example attach demanding sensor components.

Pick and place

We offer attachments of surface mount components for prototyping and test structures even with small components.

 

Optimization of bonding processes

Adhesives are very useful and versatile materials. They can also perform very reliably even in harsh environments, but for this a right material must be selected and the attachment process must be optimized. We can optimize your process parameter for example with principles of design of experiments (DOE).

Understanding challenging environments and how to consider them in electronics

Products can be exposed to various environmental stresses during assembly, shipment, storage and operation. Depending on their service conditions, products are subjected to different stress factors and failure mechanisms that will eventually cause failures. Furthermore, environmental aging may cause deterioration of e.g. material properties, which will no longer function as planned.

One of our main expertise areas is understanding demanding environments, what kind of stresses are present and how to consider them regarding your product. We can therefore help you with interconnection technology, and component and material selection for demanding applications. We have also widely worked with protective materials in electronics including optical adhesives, conductive adhesives, conformal coatings, underfills, glob tops and overmolds and can provide services with these materials. We have years of experience in performing various kinds of environmental testing and we can assist you in the selection of the most relevant test methods. We also provide standard and tailored reliability testing including failure analysis.

 

To learn more about our expertise areas and services we can offer, please contact:

Laura Frisk, Mobile: +358 50 597 9667

Sanna Lahokallio, Mobile: +358 40 775 7497

email. firstname.lastname@trelic.fi