Patent Application
20230122163
This application claims priority of China Patent Application No. 202111210387.X, filed on Oct. 18, 2021, the entirety of which is incorporated by reference herein.
The present disclosure relates to an electronic device, and in particular it relates to an electronic device with bonding pads and method for fabricating the same.
At present, electronic components are soldered on a thin-film transistor (TFT) glass substrate through tin. However, after a reliability test (such as thermal shock), cracks may occur in the glass directly under the electronic components, resulting in bright/dark spots or even the electronic components peeling off the substrate. These abnormal phenomena occur due to the difference in the coefficient of thermal expansion (CTE) between the electronic components and the glass, and the tensile stress occurs after the thermal expansion and contraction process of thermal shock. Eventually, the rupture initiation point occurs at the location of the stress maximum in the structure and extends outward.
In accordance with one embodiment of the present disclosure, a method for fabricating an electronic device is provided. The fabrication method includes the following steps. A substrate is provided. A solder and a flux are formed on the substrate. An electronic component is bonded on the solder. At least a portion of the flux is removed.
In accordance with one embodiment of the present disclosure, an electronic device is provided. The electronic device includes a substrate, an electronic component and a glue. The electronic component including a plurality of bonding pads is on the substrate. The glue is between the bonding pads.
A detailed description is given in the following embodiments with reference to the accompanying drawings.
The disclosure can be more fully understood from the following detailed description when read with the accompanying figures. It is worth noting that, in accordance with standard practice in the industry, various features are not drawn to scale. In fact, the dimensions of the various features may be arbitrarily increased or reduced for clarity of discussion.
Various embodiments or examples are provided in the following description to implement different features of the present disclosure. The elements and arrangement described in the following specific examples are merely provided for introducing the present disclosure and serve as examples without limiting the scope of the present disclosure. For example, when a first component is referred to as “on a second component”, it may directly contact the second component, or there may be other components in between, and the first component and the second component do not come in direct contact with one another.
It should be understood that additional operations may be provided before, during, and/or after the described method. In accordance with some embodiments, some of the stages (or steps) described below may be replaced or omitted.
In this specification, spatial terms may be used, such as “below”, “lower”, “above”, “higher” and similar terms, for briefly describing the relationship between an element relative to another element in the figures. Besides the directions illustrated in the figures, the devices may be used or operated in different directions. When the device is turned to different directions (such as rotated 45 degrees or other directions), the spatially related adjectives used in it will also be interpreted according to the turned position. In addition, in this specification, expressions such as “first material layer disposed above/on/over a second material layer”, may indicate the direct contact of the first material layer and the second material layer, or it may indicate a non-contact state with one or more intermediate layers between the first material layer and the second material layer. In the above situation, the first material layer may not be in direct contact with the second material layer. In some embodiments of the present disclosure, terms concerning attachments, coupling and the like, such as “connected” and “interconnected,” refer to a relationship wherein structures are secured or attached to one another either directly or indirectly through intervening structures, as well as both movable or rigid attachments or relationships, unless expressly described otherwise.
Herein, the terms “about”, “around” and “substantially” typically mean a value is in a range of +/−15% of a stated value, typically a range of +/−10% of the stated value, typically a range of +/−5% of the stated value, typically a range of +/−3% of the stated value, typically a range of +/−2% of the stated value, typically a range of +/−1% of the stated value, or typically a range of +/−0.5% of the stated value. The stated value of the present disclosure is an approximate value. Namely, the meaning of “about”, “around” and “substantially” still exists even if there is no specific description of “about”, “around” and “substantially”.
It should be understood that, although the terms “first”, “second”, “third”, etc. may be used herein to describe various elements, components, regions, layers, portions and/or sections, these elements, components, regions, layers, portions and/or sections should not be limited by these terms. These terms are only used to distinguish one element, component, region, layer, portion or section from another element, component, region, layer, portion or section. Thus, a first element, component, region, layer, portion or section discussed below could be termed a second element, component, region, layer, portion or section without departing from the teachings of the present disclosure.
Unless defined otherwise, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this disclosure belongs. It should be appreciated that, in each case, the term, which is defined in a commonly used dictionary, should be interpreted as having a meaning that conforms to the relative skills of the present disclosure and the background or the context of the present disclosure, and should not be interpreted in an idealized or overly formal manner unless so defined.
Referring to
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In some embodiments, the substrate 10 may include a rigid substrate or a flexible substrate, for example, a glass substrate or a polyimide (PI) substrate, but the present disclosure is not limited thereto. In some embodiments, the first insulating layer 12 and the second insulating layer 14 are insulating materials, and may include silicon oxide, silicon nitride or silicon oxynitride, but the present disclosure is not limited thereto. In some embodiments, the patterned metal layer 16 is a metal material, which may include copper, but the present disclosure is not limited thereto. In some embodiments, the pixel defining layer (PDL) 18 is an organic material or an inorganic material, and may include resin, organic silicon, silicon nitride or silicon oxide, but the present disclosure is not limited thereto. In some embodiments, the metal layer 20 is a metal material, which may include nickel, but the present disclosure is not limited thereto.
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The following will describe in detail how to remove the flux 26.
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In some embodiments, the substrate 10 may include a rigid substrate or a flexible substrate, for example, a glass substrate or a polyimide (PI) substrate, but the present disclosure is not limited thereto. In some embodiments, the first insulating layer 12 and the second insulating layer 14 may include silicon oxide, silicon nitride or silicon oxynitride, but the present disclosure is not limited thereto. In some embodiments, the patterned metal layer 16 may include copper, but the present disclosure is not limited thereto. In some embodiments, the pixel defining layer (PDL) 18 may include resin, organic silicon, silicon nitride or silicon oxide, but the present disclosure is not limited thereto. In some embodiments, the metal layer 20 (including the first bonding structure 22a and the second bonding structure 22b) may include nickel, but the present disclosure is not limited thereto. In some embodiments, the solder 24 may include tin or tin-bismuth alloy, but the present disclosure is not limited thereto.
In some embodiments, the electronic component 27 may include light-emitting diodes (LEDs), such as organic light-emitting diodes (OLEDs), sub-millimeter light-emitting diodes (mini LEDs), micro light-emitting diodes (micro LEDs) or quantum dot LEDs, but the present disclosure is not limited thereto. In some embodiments, the thickness H of the electronic component 27 is about 600 micrometers. In some embodiments, the first bonding pad 30a and the second bonding pad 30b may include copper, but the present disclosure is not limited thereto.
In some embodiments, the Young's modulus of the glue 34 is between about 1 MPa and about 100 MPa. In some embodiments, the glue 34 may include white glue (e.g., based on silicone), optical glue or waterproof glue, but the present disclosure is not limited thereto. In some embodiments, the thickness h of the glue 34 (from the upper surface 18′ of the pixel defining layer (PDL) 18 to the top 34′ of the glue 34) is between about 50 microns and about 600 microns. Here, the height from the upper surface 18′ of the pixel defining layer (PDL) 18 to the upper surface 28′ of the main body 28 of the electronic component 27 is defined as K. In some embodiments, the height K is between about 600 microns and about 640 microns. It is worth noting that the thickness h of the glue 34 does not exceed the height K.
The proportion of cracks in a substrate after thermal shock on an electronic device
The electronic device 40 as shown in
Next, a thermal shock test was performed on the electronic device. The thermal shock test conditions were as follows, with the temperatures ranging from −40° C. to 80° C. for 339 cycles. After the test, the proportion of cracks in the substrate was observed, and the results are shown in Table 1 below.
The proportion of cracks in a substrate after thermal shock on an electronic device
The electronic device as shown in
Next, a thermal shock test was performed on the electronic device. The thermal shock test conditions were as follows, with the temperatures ranging from −40° C. to 80° C. for 339 cycles. After the test, the proportion of cracks in the substrate was observed, and the results are shown in Table 1 below.
The proportion of cracks in a substrate after thermal shock on an electronic device
The electronic device similar to that shown in
Next, a thermal shock test was performed on the electronic device. The thermal shock test conditions were as follows, with the temperatures ranging from −40° C. to 80° C. for 339 cycles. After the test, the proportion of cracks in the substrate was observed, and the results are shown in Table 1 below.
Here, the “proportion” of cracks in the substrate is defined as the sampling of 100 units, and how many of the 100 units have cracks. From the results in Table 1, it can be seen that when the flux in the electronic device was not removed and the glue was not applied, the proportion of cracks in the substrate was as high as 100% (Comparative Example 1). Although Comparative Example 2 applied part of the glue without removing the flux, the proportion of cracks in the substrate was still quite high, only reduced by about 6%. This reduction in crack proportion is not sufficient to improve product reliability. The reason for the poor improvement effect should be due to the presence of the flux which affects the adhesion of the glue to the substrate. In contrast, in the electronic device of the present disclosure, after the flux is removed, the glue is formed on the substrate and surrounds the electronic component and the first bonding pad and the second bonding pad. After the thermal shock test is performed on this structure, the proportion of cracks in the substrate has been greatly reduced, which is enough to prove that after removing the flux, refilling with glue can effectively improve the reliability of electronic products.
In the present disclosure, after the substrate is soldered, the residual flux is cleaned, and white glue is applied, so that the proportion of cracks in the glass substrate is greatly reduced, and the product reliability is effectively improved. After the glass substrate and the electronic component (for example, light-emitting diode (LED)) are soldered, the flux on the substrate is removed with a cleaning solution. After removing the flux, the glue (e.g., white glue, optical glue, waterproof glue, etc.) is applied on the substrate to absorb stress, and the maximum stress between the electronic component and the thin-film transistor (TFT) glass substrate is reduced. Further, the proportion of cracks in glass is reduced after thermal shock, and the purpose of improving product reliability is finally achieved. The proportion of cracks in the glass under the electronic component of the present disclosure is reduced from 100% to 0%.
Although some embodiments of the present disclosure and their advantages have been described in detail, it should be understood that various changes, substitutions and alterations can be made herein without departing from the spirit and scope of the disclosure as defined by the appended claims. The features of the various embodiments can be used in any combination as long as they do not depart from the spirit and scope of the present disclosure. Moreover, the scope of the present application is not intended to be limited to the particular embodiments of the process, machine, manufacture, composition of matter, means, methods and steps described in the specification. As one of ordinary skill in the art will readily appreciate from the present disclosure, processes, machines, manufacture, compositions of matter, means, methods, or steps, presently existing or later to be developed, that perform substantially the same function or achieve substantially the same result as the corresponding embodiments described herein may be utilized according to the present disclosure. Accordingly, the appended claims are intended to include within their scope such processes, machines, manufacture, compositions of matter, means, methods or steps. In addition, each claim constitutes an individual embodiment, and the claimed scope of the present disclosure includes the combinations of the claims and embodiments. The scope of protection of present disclosure is subject to the definition of the scope of the appended claims. Any embodiment or claim of the present disclosure does not need to meet all the purposes, advantages, and features disclosed in the present disclosure.
| Number | Date | Country | Kind |
|---|---|---|---|
| 202111210387.X | Oct 2021 | CN | national |
