Method of forming protective film on at least one electronic module

A method of forming a protective film on at least one electronic module is provided. The method includes the following steps. A protective material is disposed on at least one electronic module such that the protective material and the electronic modules are in contact with each other. The electronic modules and the protective material disposed on the electronic modules are disposed in a chamber, and a first ambient pressure is provided in the chamber. The protective material in the chamber is heated to a first temperature to soften the protective material disposed on the electronic modules. After the protective material is softened, a second ambient pressure greater than the first ambient pressure is provided in the chamber, wherein a gas in the chamber directly pressurizes the protective material such that the protective material conformally covers a top of the electronic modules. The protective material conformally covering the top of the electronic modules is heated to a second temperature to solidify the protective material conformally covering the top of the electronic modules to form a protective film conformally covering the top of the electronic modules.

BACKGROUND

Technical Field

The invention relates to a method of forming a protective film on at least one electronic module, and in particular, to a method of forming a protective film on at least one electronic module via a method of pressurizing via a high-pressure gas.

Description of Related Art

Electronic components of different sizes are often disposed on a regular motherboard for an electronic device. A traditional method involves attaching a protective adhesive to the motherboard via a mechanical or manual method to protect the motherboard and the electronic components on the motherboard. However, in the method above, since the protective adhesive does not adhere tightly, residual bubbles are often present between the protective adhesive and the motherboard or between the protective adhesive and the electronic components. Therefore, water vapor coating often occurs, such that the life of the electronic components is reduced or the reliability thereof is compromised.

SUMMARY

The invention provides a method of forming a protective film on at least one electronic module. Via the method of the invention, the electronic modules and/or the protective film conformally covering a top of a circuit board may have good performance and good quality.

An embodiment of the invention provides a method of forming a protective film on at least one electronic module. The method includes the following steps. At least one electronic module and a protective material disposed on the electronic modules are disposed in a chamber, wherein the protective material and the electronic modules are in contact with each other. A first heating process is performed on the protective material in the chamber to soften the protective material disposed on the electronic modules, and a gas decompression process is performed on the chamber. A second heating process is performed on the protective material in the chamber after the protective material is softened, and a boost process is performed on the chamber, wherein in the boost process, a gas in the chamber directly pressurizes the protective material such that the protective material conformally covers a top of the electronic modules. The protective material conformally covering the top of the electronic modules is solidified to form the protective film conformally covering the top of the electronic modules.

In the method of forming the protective film on the at least one electronic module according to an embodiment of the invention, the electronic modules include a circuit board and a plurality of electronic devices. The plurality of electronic devices are disposed on the circuit board. In the step of disposing the electronic modules and the protective material disposed on the electronic modules in the chamber, the protective material is at least in contact with the plurality of electronic devices.

In the method of forming the protective film on the at least one electronic module according to an embodiment of the invention, an area of the electronic modules is greater than or equal to an area of the protective material. In the step of disposing the electronic modules and the protective material disposed on the electronic modules in the chamber, the protective material does not cover a sidewall of the electronic modules.

In the method of forming the protective film on the at least one electronic module according to an embodiment of the invention, the first heating process involves heating the protective material to a first temperature. The first temperature is greater than or equal to a softening point of the protective material, and the first temperature is less than a solidifying point of the protective material. The second heating process involves heating the protective material to a second temperature, and the second temperature is greater than the solidifying point of the protective material.

In the method of forming the protective film on the at least one electronic module according to an embodiment of the invention, the first temperature is greater than 50° C.

In the method of forming the protective film on the at least one electronic module according to an embodiment of the invention, the gas decompression process involves reducing a gas pressure in the chamber to a first ambient pressure, wherein the first ambient pressure is less than a gas pressure outside the chamber. The boost process involves increasing the gas pressure in the chamber to a second ambient pressure, wherein the second ambient pressure is higher than the gas pressure outside the chamber.

In the method of forming the protective film on the at least one electronic module according to an embodiment of the invention, the first heating process and the gas decompression process are performed at the same time.

In the method of forming the protective film on the at least one electronic module according to an embodiment of the invention, the second heating process and the boost process are performed at the same time.

In the method of forming the protective film on the at least one electronic module according to an embodiment of the invention, the chamber, a boost unit, a pumping unit, and a heating unit form a device. The boost unit and the pumping unit are linked to the chamber. The heating unit is thermally coupled to the chamber.

In the method of forming the protective film on the at least one electronic module according to an embodiment of the invention, the at least one electronic module is a plurality of electronic modules, and at least two of the plurality of electronic modules are overlapped with each other in the chamber.

In the forming process of the protective film using the protective material of the invention, the protective material conformally covers the top of the electronic modules by a method of pressurizing via a high-pressure gas. Therefore, the electronic modules and/or the protective film conformally covering the circuit board are not readily damaged, and the electronic modules and/or conformally covering the circuit board have good performance and good quality.

DESCRIPTION OF THE EMBODIMENTS

Hereinafter, exemplary embodiments of the invention are described in detail, and examples of the exemplary embodiments are conveyed via the figures. Wherever possible, the same reference numerals are used in the figures and the descriptions to refer to the same or similar portions.

FIG. 1is a schematic showing a device for forming a protective film on at least one electronic module according to one embodiment of the disclosure.

First, referring toFIG. 1, an apparatus100that may be used to form a protective film310(shown inFIG. 4D) on one or a plurality of electronic modules200(shown inFIG. 4D) is schematically provided. The apparatus100includes a chamber110, a boost unit120, a pumping unit130, and a heating unit140.

The chamber110may have a corresponding door (not shown), the hatch may be opened to link the space in the chamber110with the space outside the chamber110, and the hatch may be closed to form a closed space in the chamber110. The hatch is an element common to the chamber110, and therefore is not specifically shown inFIG. 1.

The boost unit120may include, for instance, a high-pressure gas source121, a pipeline122, and a valve123. The high-pressure gas source121may include, for instance, a high-pressure gas steel cylinder or a booster pump. The pipeline122is linked between the high-pressure gas source121and the chamber110. The valve123is located on the pipeline122. If the valve123is open, then the gas of the high-pressure gas source121may enter the chamber110via the pipeline122. Via the boost unit120, the gas pressure in the chamber110may be greater than the gas pressure outside the chamber110. The gas pressure outside the chamber110is generally 1 atm.

The pumping unit130may include, for instance, a pump131, a pipeline132, and a valve133. The pipeline132is linked between the pump131and the chamber110. The valve133is located on the pipeline132. If the valve133and the pump131are open, then the gas in the chamber110may be sucked out of the chamber110via the pipeline132and the pump131. Via the pumping unit130, the gas pressure in the chamber110may be less than the gas pressure outside the chamber110.

The heating unit140may include, for instance, a heating resistor144and an electric fan145. The heating resistor144may heat an object in the chamber110via a method of thermal radiation. Alternatively, when the chamber110contains a gas, the object in the chamber110may be heated via a gas convection method or by circulating the gas in the chamber110via an electric fan145. Via the heating unit140, the temperature in the chamber110may be greater than the temperature outside the chamber110.

In the present embodiment, the apparatus100not only includes the chamber110, the boost unit120, the pumping unit130, and the heating unit140, but may also include an escape unit150and/or a cooling unit160.

The escape unit150may include a pipeline152and a valve153. The pipeline152is linked between the space outside the chamber110and the space in the chamber110. The valve153is located on the pipeline152. When the gas pressure in the chamber110is higher than the gas pressure outside the chamber110, the gas in the chamber110may directly be discharged out of the chamber110via the open valve153and pipeline152via the escape unit150. In other embodiments, if the apparatus100does not have the escape unit150, then the gas in the chamber110may also be discharged via the pumping unit130.

The cooling unit160may include a pipeline162containing a coolant. The coolant is, for instance, water, or water or refrigerant including antifreeze, but the invention is not limited thereto. In the embodiment shown inFIG. 1, a portion of the cooling unit160may be located in the chamber110, and the object in the chamber110may be cooled via a method of gas convection or gas circulation via thermal radiation when the chamber110contains a gas. In other embodiments, if the apparatus100does not have the cooling unit160, then cooling to room temperature may also be achieved in a natural state. Via the cooling unit160, the temperature in the chamber110may be less than the temperature outside the chamber110. Alternatively, when the temperature in the chamber110is greater than the temperature outside the chamber110, the temperature in the chamber110may be rapidly reduced close to the temperature outside the chamber110. Alternatively, the temperature in the chamber110may be further less than the temperature outside the chamber110.

FIG. 2is a schematic showing a method of forming a protective film on electronic modules via a device according to one embodiment of the disclosure.FIG. 3is a flowchart showing a method of forming a protective film on at least one electronic module according to one embodiment of the disclosure.FIG. 4AtoFIG. 4Cshow cross sections of the steps of a method of forming a protective film on electronic modules according to one embodiment of the disclosure. Moreover, for clarity,FIG. 2omits a portion of the elements in the apparatus100(such as the boost unit120, the pumping unit130, and the heating unit140), or a portion of the elements in the electronic modules200(such as the plurality of electronic components220).

Referring toFIG. 2, in the present embodiment, the electronic modules200and the protective material300disposed on the electronic modules200may be disposed in the chamber110to form the protective film310on the electronic modules200via the apparatus100. As shown inFIG. 2, a separator400may be disposed in the chamber100, the plurality of electronic modules200may be disposed in the chamber110, and at least two of the plurality of electronic modules200may be overlapped with each other in the chamber110via the separator400and not be in contact in the vertical direction (i.e., the gravity direction).

Refer to all ofFIG. 1toFIG. 3andFIG. 4A. First, in step S1, the electronic modules200and the protective material300disposed on the electronic modules200are disposed in the chamber110, wherein the protective material300and the electronic modules200are in contact with each other.

In the present embodiment, the electronic modules200include a circuit board210and a plurality of electronic components220. The electronic components220are disposed on the circuit board210. The size or function between the plurality of electronic components220may be the same or different, and the invention is not limited in this regard. The electronic components220may be electrically connected to the circuit board210. For instance, the electronic modules200may include a motherboard, and the plurality of electronic components220may include an active device (such as a chip) an/or a passive component (such as a capacitor or an inductor) disposed on the circuit board210.

In the present embodiment, the protective material300naturally covers the top of the electronic modules200via gravity (“top” refers to being in a particular state of gravity). Of course, after the protective material300naturally covers the top of the electronic modules200via gravity, the protective material300and the electronic modules200are adhered to each other only via a Van der Waals force or an electrostatic force. Therefore, if needed, the protective material300may be removed from the electronic modules200without applying a large peel force.

In the present embodiment, the electronic components220are disposed on the circuit board210. Therefore, after the protective material300is disposed on the electronic modules200, the protective material300is at least in contact with a portion of the electronic components220. Moreover, in the present embodiment, the protective material300not only is in contact with a portion of the electronic components220, but may also be in contact with a portion of the circuit board210, and the invention is not limited in this regard.

When viewed from the top, the area of the electronic modules200is greater than or equal to the area of the protective material300. In other words, after the protective material300is disposed on the electronic modules200, the protective material300does not need to cover a sidewall210aor a bottom210bof the circuit board210.

In the present embodiment, the material of the protective material300is a thermosetting polymer, and the invention is not limited in this regard. The thermosetting polymer may include, for instance, a bulk molding compound (BMC), a diallyl phthalate (DAP) resin, a urea formaldehyde (UF) resin, or a phenolic resin, but the invention is not limited in this regard.

In the present embodiment, the protective material300may be first disposed on the electronic modules200outside the chamber110, and then the electronic modules200and the protective material300disposed on the electronic modules200are disposed in the chamber110together, but the invention is not limited thereto. In other embodiments, the electronic modules200may also first be disposed in the chamber110, and then the protective material300is disposed on the corresponding electronic modules200disposed in the chamber110.

Moreover, after one or a plurality of electronic modules200for which the top is covered by the protective material300is disposed in the chamber110of the apparatus100, a closed space may be formed in the chamber110. At this point, the gas pressure in the chamber110is substantially equal to the ambient pressure outside the chamber110, but the invention is not limited thereto. For instance, if the apparatus100has a purge gas pipeline linked to the chamber110, then after a closed space is formed in the chamber110, the pressure in the chamber110may be slightly greater than the ambient pressure outside the chamber110.

In the present embodiment, the protective material300directly covers the top of the electronic modules200, and the protective material300is a flexible film layer at room temperature. Therefore, some gas gaps10may be present between the protective material300and the electronic modules200.

Refer to all ofFIG. 1toFIG. 3andFIG. 4B. In step S2, a first heating process is performed on the protective material300in the chamber110to soften the protective material300disposed on the electronic modules200, and a gas decompression process is performed on the chamber110.

In the present embodiment, the first heating process may be performed via the heating unit140of the apparatus100. The first heating process involves heating the protective material300covering the top of the electronic modules200to a first temperature. The first temperature is greater than or equal to the softening point of the protective material300, and the first temperature is less than the solidifying point of the protective material300. Therefore, the protective material300covering the top of the electronic modules200is softened, but is not solidified.

In the present embodiment, the timing of the first heating process and the timing of the gas decompression process need to be at least partially overlapped. In some embodiments, when the first heating process is performed, the gas decompression process may be performed at the same time via the pumping unit130of the apparatus100. The gas decompression process involves reducing the gas pressure in the chamber110to a first ambient pressure, wherein the first ambient pressure is less than the gas pressure outside the chamber110. Since the protective material300and the electronic modules200are adhered to each other via only a Van der Waals force or an electrostatic force, the gas decompression process may gradually discharge the gas in the gas gaps20between the protective material300and the electronic modules200. Moreover, the protective material300covering the electronic modules200is softened by heating. As a result, the protective material300may be better adhered on the electronic modules200.

In general, the first temperature may be adjusted according to the softening point of the protective material300. In some embodiments, the first temperature is not only greater than or equal to the softening point of the protective material300but is greater than 50° C. As a result, if fine water droplets are present in the chamber110, on the electronic modules200, and/or on the protective material300, then the fine water droplets may form water vapor via the first temperature greater than 50° C. under the first ambient pressure, and then may be discharged from the chamber110via the pumping unit130of the apparatus100.

Refer to all ofFIG. 1toFIG. 3andFIG. 4C. In step S3, a second heating process is performed on the protective material300in the chamber110after the protective material300is softened, and a boost process is performed on the chamber110, wherein in the boost process, the gas in the chamber110directly pressurizes the protective material300such that the protective material300conformally covers the top of the electronic modules200.

In the present embodiment, the second heating process may be performed via the heating unit140of the apparatus100. The second heating process involves heating the protective material300covering the top of the electronic modules200to a second temperature. The second temperature is greater than the solidifying point of the protective material300. Therefore, the protective material300covering the top of the electronic modules200is solidified as a result.

In the present embodiment, the timing of the second heating process and the timing of the boost process need to be at least partially overlapped. In some embodiments, when the second heating process is performed, the boost process may be performed at the same time via the boost unit120of the apparatus100. The boost process involves increasing the gas pressure in the chamber110to a second ambient pressure, wherein the second ambient pressure is higher than the gas pressure outside the chamber110. The protective material300covering the top of the electronic modules200is softened via heating, and almost no gas is present between the protective material300and the electronic modules200. Therefore, the boost process may directly pressurize the softened protective material300covering the top of the electronic modules200via the gas in the chamber110such that the softened protective material300covering the top of the electronic modules200conformally covers the top of the electronic modules200. Of course, a completely gas-free state is relatively difficult to achieve in a natural state (even in outer space), and therefore even if small gas gaps that may not be seen by the naked eye or are difficult to be observed are present between the protective material300and the electronic modules200, this is still within the scope of “almost no gas is present between the protective material300and the electronic modules200”.

In some embodiments, via the boost unit120of the apparatus100, the second ambient pressure may be greater than or equal to 0.8 megapascals (MPa), but the invention is not limited thereto.

In comparison to pressurizing using a mold or other similar mechanical pressurization methods, since in the invention, the protective material300conformally covers the top of the electronic modules200by a method of pressurizing via a high-pressure gas, even if the electronic modules200include a plurality of electronic components220of different sizes, the softened protective material300may still conformally cover the top of the electronic components220on the circuit board210. Moreover, since the invention includes a method of pressurizing via a high-pressure gas, the electronic modules200or the protective material300conformally covering the top of the circuit board210is not damaged.

Refer to all ofFIG. 1toFIG. 3andFIG. 4D. In step S4, the protective material300conformally covering the top of the electronic modules200is solidified to form the protective film310conformally covering the top of the electronic modules200.

In the present embodiment, the second heating process involves heating the protective material300covering the top of the electronic modules200to a second temperature greater than the solidifying point of the protective material300. Therefore, the protective material300conformally covering the top of the electronic modules210may be solidified to form the protective film310conformally covering the top of the electronic modules200.

After step S1to step S4, the method of forming the protective film310on the at least one electronic module200of the present embodiment is largely complete.

Of course, to remove the circuit board210for which the top is conformally covered by the protective film310, cooling may be performed via the cooling unit160of the apparatus100, or cooling may be performed via natural cooling. Moreover, after the gas pressure in the chamber110is reduced to substantially the same gas pressure outside the chamber110via the escape unit150of the apparatus100, the circuit board210for which the top is conformally covered by the protective film310is removed.

The protective material300forming the protective film310does not need to cover the sidewall210aor the bottom210bof the circuit board210. Therefore, the insulating protective film310may protect the electronic components220on the circuit board210, and the portion not covered by the protective film310(such as the sidewall210aor the bottom210bof the circuit board210) may still be electrically connected to the other electronic components220.

In the forming process of the protective film using the protective material of the invention, the protective material conformally covers the top of the electronic modules by a method of pressurizing via a high-pressure gas. Therefore, the electronic modules and/or the protective film conformally covering the top of the circuit board is not readily damaged, and the electronic modules and/or the protective film conformally covering the top of the circuit board have good performance and good quality.