EA041850B1 - METHOD FOR MANUFACTURING MICROASSEMBLY OF UNPACKAGED ELECTRONIC COMPONENTS ON FLEXIBLE ORGANIC SUBSTRATES - Google Patents

Description

The proposed technical solution relates to microassembly, in particular, to the technology of mounting a frameless electronic component base on flexible substrates.

There is a known method of mounting electronic components with ball leads, presented in the patent of the Russian Federation RU 2331993 C2, in which the mounting is carried out by the flip-chip method, including installing the component on the mounting surface of the substrate and melting the solder balls. However, the known method has significant disadvantages:

the method is not suitable for installation on low-temperature organic substrates, including polyethylene naphthalate (PEN), since the basic process is high-temperature heat treatment to create solder joints of a component with current-carrying layers;

the method leads to an increase in the thickness of the product by the length of the layer of melted ball leads and solder;

the method requires high-precision alignment of the multilayer-switched electronic component during mounting to achieve the required electrical contact.

Also known is a method for manufacturing a microelectronic assembly on a plastic base (RF patent RU 2597210 C1), according to which a multi-chip module is manufactured by pouring unpackaged electronic components with an organosilicon polymer to form a planar structure in the form of crystals of unpackaged electronic components integrated into the substrate for their subsequent switching. The disadvantage of this method is also the need for high-temperature treatment of the organosilicon polymer at the stage of hardening (up to 250°C), which significantly limits the range of compatible materials, increases the rigidity of the entire structure and places high demands on the technology for ensuring the flatness of the polymer surface during its application and after heat treatment, taking into account further use as a basis for the implementation of metal current wiring.

The closest technical solution (prototype) is a method of embedding a component into a base and forming an electrical contact with the component, described in RF patent RU 2297736 C2, which is a method for manufacturing a microassembly of unpackaged electronic components on flexible organic substrates, including the creation of a multilayer switching and the formation of an electrical contact between multilayer switching and pins of electronic components. In the proposed method, a microrelief is actually formed in the substrate in the form of cavities into which components are placed, and then the free volume of the cavity is filled with resin to fix unpackaged components inside the substrate. After that, switching is applied to the surface of the resulting pseudoplanar structure.

The disadvantage of this method is the need to implement the operation of forming cavities in the substrate and ensuring the flatness of the surface when filling the resulting cavities with resin. In addition, the heterogeneity of the substrate obtained in this way reduces the mechanical strength of the product as a whole, including in terms of flexibility, and also limits the possibility of using ultrathin substrates to create a product, since the fixation of a packageless electronic component in the substrate is carried out due to the adhesion of its end face to the filler (resin ), as well as a filler with a substrate along the boundary of the formed cavity.

The objective of the claimed invention is to create a method that makes it possible to manufacture ultra-thin hybrid assemblies based on thinned crystals of packaged electronic components on flexible organic substrates to enable their further conformal integration into functional products.

The technical result obtained in solving this problem consists in simplifying the manufacturing technology of microassembly of unpackaged components on flexible substrates, while achieving flexibility of the resulting product and reducing its thickness.

The specified technical result is achieved due to the fact that in the method for manufacturing a microassembly of packageless electronic components on flexible organic substrates, including the creation of a multilayer switching and the formation of electrical contacts between the multilayer switching and the terminals of electronic components, the electronic component is placed on the surface of the substrate, followed by pseudo-planarization of the surface by sequential drop-jet deposition of layers of dielectric material around the perimeter of the component, and the formation of an electrical contact of the terminals of the electronic component with multilayer switching is carried out simultaneously with the creation of the lower switching layer after pseudo-planarization of the substrate surface.

This method is based on the use of inkjet printing technology for the formation of multilayer switching on flexible substrates with electronic component crystals placed on them, pre-thinned to a thickness of less than 100 microns. In this case, the formation of switching and electrical connection of the component is performed simultaneously in a single cycle of the inkjet printing process. The choice of substrate material is not essential for the process; it can be carried out both with a rigid base (for example, FR4 textolite) and using an ultra-thin flexible organic substrate (for example, PEN film 30 microns thick). The possibility of using organic polymers as a substrate material is ensured by the fact that in the proposed method, with

- 1 041850 only low-temperature processes (up to 150°C) change.

After placing and fixing the electronic component on the substrate, in order to provide subsequent access to the terminals of the electronic component and its conformal mechanical fastening on the substrate, the surface is pseudoplanarized by leveling the height difference at the interface between the component and the substrate. To do this, layers of dielectric material are applied around the component by the inkjet method with a gradual increase in the perimeter of the printing zone, while due to the overlap with the previous layer, the step at the border of the component and the substrate is gradually smoothed out. All dielectric leveling layers are applied with UV curing after each print pass to achieve maximum layer thickness, and the final layer is applied with backlight after printing is complete. In this case, the surface relief is smoothed due to the increased ink spreading time and a uniform smooth surface is formed, which is required for the formation of multilayer switching.

The resulting pseudoplanar surface is suitable for printing the lower switching layer, and the applied layer also provides electrical connection of the electronic component leads to the switching. The use of conductive ink with a sintering temperature of less than 150°C makes it possible to implement the process on ultrathin organic substrates, since their annealing does not damage the substrate.

Further, within the framework of the unified technology of inkjet printing, it is possible to further sequentially increase the number of conductive and dielectric layers to create multilayer switching. In this case, windows are left in the dielectric layers, areas in which the material is not applied, providing electrical contact between the connecting layers. It is possible to mount the basic components of the circuit on the multilayer switching obtained by the above method.

The present invention is illustrated in Fig. 1 (A, B, C, D, E, E) - the sequence of technological operations of the method for manufacturing a microassembly of unpackaged electronic components on flexible organic substrates.

Microassembly (Fig. 1) contains:

- organic polymer substrate,

- adhesive layer

- unpackaged electronic component,

- terminals of the electronic component,

- pseudo-planar thinning dielectric structure,

- lower layer of multilayer switching,

- dielectric layer (interlayer insulation of multilayer switching),

- the second layer of multilayer switching.

An example of the implementation of the technological process is shown in Fig. 1 and depicts the entire technological process according to the invention. Further, the process depicted in Fig. 1 is considered step by step.

At stage A (Fig. 1A), adhesive 2 is locally applied to the original organic substrate 1, for example, from PEN, in the area of the intended installation of packageless electronic components using any of the known available methods.

The placement and fixation of the unpackaged electronic component 3 is performed at stage B (Fig. 1B). The thinned crystal of the component is installed on the adhesive on the substrate with pins 4 up, after which the adhesive 2 is hardened.

At stage B (Fig. 1B), pseudoplanarization of the surface is performed by local application by the drop-jet method around the perimeter around the component of a set of dielectric layers 5 with a gradual decrease in their number as the distance from the end of the component increases. After each pass, to reduce flow and allow climbing, all but the last layer is cured. The last layer is tanned at the end of the printing process to obtain a smooth pseudo-planar surface.

Further (Fig. 1D) the ink jet printing of the lower layer of the multilayer switching 6 is performed, and simultaneously with the formation of the switching in the process of printing with conductive ink, the contact of the switching with the electrical leads of the component is realized.

After that, sequential deposition of dielectric 7 (Fig. 1D) and conductive 8 (Fig. 1E) layers is carried out, forming a multilayer switching structure. To ensure contact between switching layers, in the process of printing dielectric layers, windows are created that carry out communication between switching levels.

As a result, an ultra-thin microassembly was made based on thinned crystals of unpackaged electronic components on a flexible organic substrate, which has flexibility within the limits of the flexibility of the electronic component.

Claims (1)

CLAIM A method for manufacturing a microassembly of unpackaged electronic components on flexible organic substrates, including the creation of a multilayer switching and the formation of electrical contacts between the multilayer switching and the terminals of electronic components, characterized in that the electronic component is placed on the surface of the substrate with subsequent pseudo-planarization of the surface by successive drop-jet deposition of dielectric layers around the component perimeter material, and the formation of the electrical contact of the terminals of the electronic component with multilayer switching is carried out simultaneously with the creation of the lower switching layer after pseudo-planarization of the substrate surface.