BACKGROUND OF THE INVENTION

1. Field of the Invention

The present invention relates to a die-bonding method and a die-bonding structure and, more particularly, to a method and a structure using a beam generator to generate at least one energy for die-bonding.

2. Description of the Related Art

One of the buzzwords in light-emitting diode (LED) and liquid crystal display (LCD) marketing recently is “local dimming” Ostensibly, local dimming can dim the area of the screen that needs it, while keeping the bright parts of the screen bright. This technology can really increase the contrast ratio and 3D color gamut to make a better image. As a result, it stands to reason that local dimming is possible with LCD TVs, such that LCD TVs to bear favorable technical comparison with organic light-emitting diode (OLED) TVs in delivering high-definition resolution.

However, the necessity of local dimming resides in a significant number of LEDs mounted on the backlight module, which differ from the approaches for conventional edge-lit TVs and direct-lit TVs. To that end, a huge circuit board is thus required for mounting of LEDs while, statistically, doing so may lead to the issue of low die-bonding yield of LEDs. A countermeasure to the issue is to provide a multi-layer circuit board. Whereas, current circuit boards oftentimes have the warpage problem after reflow soldering as the circuit boards are made by the material including Flame Retardant (FR-4) or bismaleimide-triazine (BT) resin with copper conductors formed thereon.

SUMMARY OF THE INVENTION

An objective of the present invention is to provide a die-bonding method and a die-bonding structure resolving the PCB warpage issue in conventional reflow process and ensuring higher bonding strength between semiconductor elements and target substrate to be bonded.

To achieve the foregoing objective, the die-bonding method, comprising steps of:

(a) providing a target substrate having a circuit structure formed thereon and multiple semiconductor elements; the circuit structure has multiple electrical contacts formed thereon and a glass plate formed therein, and each semiconductor element includes a pair of electrodes;

(b) arranging the multiple semiconductor elements on the target substrate with the pair of electrodes of each semiconductor element aligned with two corresponding electrical contacts of the target substrate; and

(c) applying at least one energy beam to join and electrically connect the at least one pair of electrodes of every at least one of the multiple semiconductor elements and the corresponding electrical contacts aligned therewith in a heating cycle by heat carried by the at least one energy beam in the heating cycle.

Preferable, the step (a) further comprises:

determining a bonding type associated with at least one location where at least one bonding material is to be applied and quantity of the at least one bonding material, wherein when the at least one bonding material includes one bonding material and the bonding material is pre-formed on the electrical contacts of the circuit structure of the target substrate, the bonding type is defined to be one, when the at least one bonding material includes one bonding material and the bonding material is pre-formed on the pairs of electrodes of the semiconductor elements, the bonding type is defined to be two, when the at least one bonding material includes one bonding material and the bonding material is applied to the electrical contacts of the circuit structure of the target substrate before the electrical contacts are aligned with corresponding electrodes at step (b), the bonding type is defined to be three, and when the at least one bonding material includes two bonding materials and one of the two bonding materials is pre-formed on the pairs of electrodes of the semiconductor elements and the other bonding material is applied to the electrical contacts before the electrical contacts are aligned with corresponding electrodes at step (b), the bonding type is defined to be four;

when the bonding type is one, pre-forming the bonding material on each electrical contact of the target substrate;

when the bonding type is two, per-forming the bonding material on each of the pair of electrodes of each semiconductor element;

when the bonding type is three, applying the bonding material to the electrical contacts of the circuit structure of the target substrate; and

when the bonding type is four and the at least one bonding material includes a first bonding material and a second material, per-forming the first bonding material on each of the pair of electrodes of each semiconductor element, and applying the second bonding material on each electrical contact of the target substrate.

Preferably, when the bonding type is one, the bonding material is solder paste with a melting point in a range of 140° C. to 300° C. that contains one of a group of metals including tin, titanium, indium, and silver, an alloy selected from a combination of the group of metals, or stacked layers with each layer formed of a metal material selected from the group of metals.

Preferably, when the bonding type is two, the bonding material is solder paste with a melting point in a range of 140° C. to 300° C. that contains one of a group of metals including tin, titanium, indium, and silver, an alloy selected from a combination of the group of metals, or stacked layers with each layer formed of a metal material selected from the group of metals.

Preferably, when the bonding type is three, the first bonding material is a bonding material containing insulating adhesive or adhesive containing flux, or adhesive containing metal particles selected from one of a group of metals including tin, titanium, indium, and silver.

Preferably, when the bonding type is four, the first bonding material is a metal layer of tin or tin-silver, and the second bonding material is flux or insulating adhesive, such as epoxy or silicone.

According to the foregoing die-bonding method, the method employs the approach of generating at least one energy beam and applying the at least one energy beam to heat and electrically connect the pairs of electrodes of the multiple semiconductor elements and the respective electrical contacts of the circuit structure of the target substrate, and various ways of applying bonding materials to the semiconductor elements and the circuit structure, thus significantly reducing the warpage issue of PCB in conventional reflow process by virtue of a dot-scattering heating pattern that is uniformly distributed over the target substrate by heat carried by the at least one energy, and increasing the bonding strength between the semiconductor elements and the circuit structure of the target substrate with a variety ways and materials of the bonding materials.

To achieve the foregoing objective, the die-bonding structure includes a target substrate, multiple semiconductor elements, and a beam generator.

The target substrate has a support base and a circuit structure.

The circuit structure is formed on one side of the supporting base and has a glass plate, a transparent conductive layer, a metal layer, a bonding-reinforced circuit layer, and multiple electrical contacts.

The glass plate is formed on the supporting base.

The transparent conductive layer is formed on the glass plate.

The metal layer is formed on the transparent conductive layer.

The bonding-reinforced circuit layer is formed on the metal layer.

The multiple electrical contacts are formed on the bonding-reinforced circuit layer.

The multiple semiconductor elements are attached to a carrier plate and are spaced apart from each other by gaps. Each semiconductor element has a pair of electrodes aligned with two corresponding electrical contacts of the circuit structure of the target substrate.

The beam generator generates at least one energy beam for joining and electrically connecting the at least one pair of electrodes of every at least one of the multiple semiconductor elements and the corresponding electrical contacts aligned therewith in a heating cycle by heat carried by the at least one energy beam in the heating cycle.

In view of the foregoing die-bonding structure, the beam generator that generates at least one energy beam and applies the at least one energy beam to heat and electrically connect the multiple semiconductor elements and the circuit structure of the target substrate addresses a solution to the warpage issue of PCB involved with a dot-scattering heating pattern uniformly distributed over the target substrate by heat carried by the at least one energy, and the circuit structure and the bonding materials delivering higher bonding strength between the semiconductor elements and the circuit structure of the target substrate because the bonding strength between the circuit structure of the target substrate and the semiconductor elements can be enhanced as a result of the circuit designs tailored to the drawbacks of the conventional COG (chip on glass) circuit, a multitude of bonding materials, and a variety of ways of applying the bonding materials.

Other objectives, advantages and novel features of the invention will become more apparent from the following detailed description when taken in conjunction with the accompanying drawings.

