CN114953643A

CN114953643A - Terminal, shell assembly thereof and bonding method of shell assembly

Info

Publication number: CN114953643A
Application number: CN202210678638.5A
Authority: CN
Inventors: 陈江
Original assignee: Guangdong Oppo Mobile Telecommunications Corp Ltd
Current assignee: Guangdong Oppo Mobile Telecommunications Corp Ltd
Priority date: 2022-06-15
Filing date: 2022-06-15
Publication date: 2022-08-30

Abstract

The application discloses a terminal, a shell assembly of the terminal and a bonding method of the shell assembly. The bonding method comprises the following steps: forming a coating layer on the preset surface of the conductive shell; the glass cover plate is abutted against one side of the conductive shell with the coating layer; pre-bonding the glass cover plate and one side of the conductive shell with the coating layer; and loading a first positive voltage on the conductive shell and loading a first negative voltage on the glass cover plate, so that one side of the glass cover plate with the coating layer is bonded with the conductive shell. This application will electrically conduct one side that the casing has the coating film layer and glass apron and pass through the bonding mode and connect, need not glue and can reach sealing connection's effect, avoided adopting the defect that glue bonding arouses, bonding strength is high, and the gas tightness is good, and outward appearance wholeness, exquisite degree and integrality are good.

Description

Terminal, shell assembly thereof and bonding method of shell assembly

Technical Field

The application relates to the field of structural part connection of terminals, in particular to a terminal, a shell assembly of the terminal and a bonding method of the shell assembly.

Background

The current intelligent watch is connected with a glass watch cover through a conductive shell, and generally adopts hot melt adhesive or pressure sensitive adhesive for contact connection. The hot melt adhesive is glue sensitive to temperature, and can be heated by the temperature for curing, but because the hot melt adhesive has strong fluidity, the risk of glue overflow exists in the dispensing process, and the glue easily fails under the high-temperature or high-humidity condition; in addition, the color and the transmittance of the heat-sensitive adhesive in a liquid state and a cured state are obviously changed, and in order to avoid causing defects in color, material and decorative surface, the periphery of the glass surface cover is generally shielded by ink, so that the influence of the defects of the adhesive on the whole design is prevented. The pressure-sensitive adhesive is an adhesive tape prepared by coating pressure-sensitive adhesive on a strip-shaped substrate. Because the pressure-sensitive adhesive is attached to the base material, the bonding gap is larger in the contact surface area of the glass surface cover and the conductive shell due to the existence of the base material, and the product connectivity is greatly influenced. Meanwhile, the pressure sensitive adhesive may also fail at very low temperatures or very high temperatures.

Disclosure of Invention

In view of the above, the present application provides a terminal, a housing assembly thereof and a method for bonding the housing assembly to solve the above technical problems.

A first aspect of an embodiment of the present application provides a method for bonding a housing assembly, including the steps of:

forming a coating layer on the preset surface of the conductive shell;

the glass cover plate is abutted against one side of the conductive shell with the coating layer;

pre-bonding the glass cover plate and one side of the conductive shell with the coating layer; and

and loading a first positive voltage on the conductive shell and loading a first negative voltage on the glass cover plate, so that one side of the glass cover plate with the coating layer is bonded with the conductive shell.

According to a second aspect of the embodiments of the present application, a housing assembly is provided, which includes a conductive housing and a glass cover plate, wherein the conductive housing and the glass cover plate are bonded and connected by the bonding method of the housing assembly according to the first aspect

A third aspect of embodiments of the present application provides a terminal including the housing assembly of the second aspect.

In this application, at the electrically conductive casing predetermine on the surface and form the coating film layer, will electrically conduct the casing and have one side on coating film layer and carry out the bonding with the glass apron, the potential difference on coating film layer itself is relative the potential difference of electrically conductive casing is bigger some, consequently, under the condition of same bonding voltage, compares electrically conductive casing with the direct bonding of glass apron has one side on coating film layer with bonding reaction between the glass apron is more thorough, and the bonding effect is better, consequently, drawing force and gas tightness are better, just coating film layer itself has decoratively, need not glue to connect and can reach sealing connection's effect, has avoided adopting the defect that glue bonds and arouse, and it is little influenced by the environment, and joint strength is high, and the gas tightness is good, and the outward appearance wholeness at terminal is good, can improve outward appearance exquisite degree and integrality.

Drawings

In order to more clearly illustrate the embodiments of the present application or the technical solutions in the prior art, the drawings used in the description of the embodiments or the prior art will be briefly described below, it is obvious that the drawings in the following description are only some embodiments of the present application, and for those skilled in the art, other drawings can be obtained according to the drawings without creative efforts.

Fig. 1 is a schematic flow chart illustrating a bonding method of a housing assembly according to an embodiment of the present disclosure.

Fig. 2 is a schematic structural diagram of a bonding process of a housing assembly according to an embodiment of the present application.

Fig. 3 is a schematic diagram illustrating a structure and circuit connection of a bonding tool according to an embodiment of the present application.

Fig. 4 is an enlarged view of IV of fig. 2 prior to bonding in an embodiment of the present application.

Fig. 5 is an enlarged view of IV shown in fig. 2 after bonding in an embodiment of the present application.

Fig. 6 is a schematic structural diagram of a conductive housing and a glass cover plate after being completely bonded in an embodiment of the present application.

Detailed Description

In order to make the objects, technical solutions and advantages of the embodiments of the present application clearer, the technical solutions of the embodiments of the present application are clearly and completely described below with reference to the drawings of the embodiments of the present application. It is to be understood that the described embodiments are merely exemplary of some, and not all, of the present application. All other embodiments, which can be derived by a person skilled in the art from the embodiments given herein without making any creative effort, shall fall within the protection scope of the present application.

Unless defined otherwise, technical or scientific terms used herein shall have the ordinary meaning as understood by one of ordinary skill in the art to which this application belongs. The use of the terms "a," "an," or "the" and similar referents in the context of this application are not to be construed as limiting in number, but rather as indicating the presence of at least one. The word "comprising" or "comprises", and the like, means that the element or item preceding the word covers the element or item listed after the word and its equivalents, but does not exclude other elements or items. The terms "connected" or "coupled," and the like, are not restricted to physical or mechanical connections, but may include electrical connections, whether direct or indirect.

Reference herein to "an embodiment" means that a particular feature, structure, or characteristic described in connection with the embodiment can be included in at least one embodiment of the application. The appearances of the phrase in various places in the specification are not necessarily all referring to the same embodiment, nor are separate or alternative embodiments mutually exclusive of other embodiments. It is explicitly and implicitly understood by one skilled in the art that the embodiments described herein can be combined with other embodiments.

Referring to fig. 1 to 3, fig. 1 is a schematic flow chart illustrating a bonding method of a housing assembly according to an embodiment of the present application. Fig. 2 is a schematic structural diagram of a terminal bonding process in an embodiment of the present application. Fig. 3 is a schematic diagram illustrating a structure and circuit connection of a bonding tool according to an embodiment of the present application. In which the bonding method of the housing assembly shown in fig. 1 is applied to the housing assembly 2 shown in fig. 2. In this embodiment, the terminal is a smart watch. In other embodiments, the terminal may be, but is not limited to, other electronic products, such as a cell phone, tablet, and the like. The shell assembly 2 comprises a conductive shell 21 and a glass cover plate 22, a coating layer 20 is formed on the preset surface of the conductive shell 21, and the glass cover plate 22 is connected with one side of the conductive shell 21 with the coating layer 20. Wherein the bonding method comprises:

11: forming a coating layer 20 on a preset surface of a conductive shell 21;

12: a glass cover plate 22 is abutted against one side of the conductive shell 21 with the coating layer 20;

13: pre-bonding the glass cover plate 22 and one side of the conductive shell 21 with the coating layer 20;

14: and loading a first positive voltage on the conductive shell 21 and loading a first negative voltage on the glass cover plate 22, so that the glass cover plate 22 is bonded with one side of the conductive shell 21 with the coating layer 20.

In the present application, a plating layer 20 is formed on a predetermined surface of a conductive case 21, one side of the conductive case 21 having the plating layer 20 is bonded to a glass cover plate 22, the potential difference of the coating layer 20 itself is larger than that of the conductive shell 21, and therefore, under the condition of the same bonding voltage, compared with the direct bonding of the conductive shell 21 and the glass cover plate 22, the bonding reaction between the side with the coating layer 20 and the glass cover plate 22 is more thorough, the bonding effect is better, therefore, the drawing force and the air tightness are better, the coating layer 20 has decoration performance, the effect of sealing connection can be achieved without glue connection, the defect caused by glue bonding is avoided, the environment influence is small, the bonding strength is high, the air tightness is good, the appearance integrity of the terminal is good, and the appearance delicacy and integrity can be improved.

In some embodiments, the conductive housing 21 may be, but is not limited to, a metal middle frame of the housing assembly 2, which is made of aluminum alloy, which may be, but is not limited to, 6-series aluminum alloy, or stainless steel, which may be, but is not limited to, 316L stainless steel.

In some embodiments, the material of the glass cover plate 22 may be, but is not limited to, a lithium aluminum silicon system glass, which has high hardness and good wear resistance. It is understood that in other embodiments, glass of other materials may be used for the glass cover plate 22.

Wherein, in some embodiments, the thickness of the coating layer 20 is less than or equal to 1 μm. When the thickness of the film coating layer 20 is less than or equal to 1 μm, the glass cover plate 22 and the conductive shell 21 can achieve a better state in terms of combination degree, air tightness and decoration.

Wherein, in some embodiments, the plating layer 20 is a metal with relatively low reactivity and relatively large potential difference, and includes but is not limited to one of a nickel plating layer, a silver plating layer, a gold plating layer, a zinc plating layer, a copper plating layer, and a nobelium plating layer. Wherein the nickel plating layer comprises one of a pearl nickel plating layer, a sand nickel plating layer and a black nickel plating layer. The silver plating layer comprises one of a surface silver plating layer and a thick silver plating layer. The zinc coating comprises one of a color zinc coating, a black zinc coating and a blue zinc coating. The copper plating layer comprises one of a green drum copper plating layer, a white tin copper plating layer, an alkali copper plating layer, a coke copper plating layer and an acid copper plating layer. The chromium plating layer comprises one of a white chromium plating layer, a hard chromium plating layer and a black chromium plating layer. In this embodiment, the plating layer 20 is a gold plating layer, a chromium plating layer, or a copper plating layer.

In some embodiments, the coating process of the coating layer 20 includes, but is not limited to, magnetron sputtering, evaporation plating, vacuum plating, physical vapor deposition, chemical vapor deposition, and the like.

Therefore, since the potential difference of the plated layer 20 itself is larger than that of the conductive housing 21, under the same bonding voltage, compared with the direct bonding between the conductive housing 21 and the glass cover plate 22, the bonding reaction between the side having the plated layer 20 and the glass cover plate 22 is more thorough, not only the bonding time can be shortened, but also the bonding effect is not deteriorated due to the shortened bonding time, but also better, and further, since the bonding effect between the side having the plated layer 20 and the glass cover plate 22 is better, the pulling force between the side having the plated layer 20 and the glass cover plate 22 is stronger, the airtightness is better, and the plated layer 20 itself has a color, and can be decorative.

Wherein, in some embodiments, pre-bonding the glass cover plate 22 and the conductive housing 21 specifically includes:

applying a first pressure to the glass cover plate 22;

heating the glass cover plate 22 and the conductive housing 21;

vacuumizing the space between the glass cover plate 22 and the conductive shell 21; and

and maintaining the pressure when the vacuum degree between the glass cover plate 22 and the conductive shell 21 reaches a preset threshold value.

Thus, in the present application, as the conductive housing 21 and the glass cover plate 22 are heated and the temperature rises, the movement of air between the conductive housing 21 and the glass cover plate 22 is accelerated to escape, and the pressure on the glass cover plate 22 is applied and vacuum is applied, so that the air between the glass cover plate 22 and the conductive housing 21 is accelerated to escape and sufficiently contact.

In one embodiment, the glass cover plate 22 is a cover of a smart watch, the size of the glass cover plate 22 is about 3 cm long and 2 cm wide, the first pressure applied to the glass cover plate 22 is 30-60N, and the converted pressure per unit area is 0.05～0.1Mpa/m ² . For example, when the first pressure is 30N, the pressure per unit area is 0.05MPa/m ² . When the first pressure is 45N, the converted pressure per unit area is 0.075MPa/m ² . When the first pressure is 50N, the converted pressure per unit area is 0.083MPa/m ² . When the first pressure is 60N, the converted pressure per unit area is 0.1MPa/m ² . It is understood that in other embodiments, the area of the glass cover plate 22 and the magnitude of the first pressure applied to the glass cover plate 22 can be adjusted according to actual needs.

It should be noted that, because the difference between the thermal expansion coefficients of the glass cover plate 22 and the conductive housing 21 is large, the direct bonding has a crack risk, and the place where the glass cover plate 22 and the conductive housing 21 are not flat needs to be accommodated by elastic-plastic deformation, so the pressure applied to the glass cover plate 22 and the first pressure applied to the glass cover plate 22 cannot be too large, because the first pressure too large will cause the gap between the glass cover plate 22 and the conductive housing 21 to be too small and air cannot escape, which may affect the bonding effect, or even cause the bonding failure due to the presence of air between the two. Of course, the first pressure applied to the glass cover plate 22 cannot be too low, and the pre-bonding effect cannot be achieved even if the first pressure is too low. In summary, the first pressure applied to the glass cover plate 22 should not be too large or too small, since too large or too small would affect the pre-bonding effect. In addition, in the pre-bonding process, not only pressure needs to be applied to the glass cover plate 22, but also air between the bonded interfaces of the glass cover plate 22 and the conductive shell 21 with the plating layer 20 needs to be forced to escape by a heated and vacuumized manner to reach a vacuum state, so that points on the bonded interfaces of the glass cover plate 22 and the conductive shell 21 are in full contact.

It should be noted that the pre-bonding process involves three processes, namely, pressing, heating and vacuum pumping, and the three processes can be performed simultaneously or in different time periods. In short, the parameter condition of the pressure holding can be satisfied during the pressure holding. Of course, in other embodiments, the pre-bonding may involve only two processes, namely, pressing and vacuuming, and the heating process is omitted. The heating process is added in the pre-bonding process, on one hand, the heating can increase the accelerated escape of air, and promote the elastic deformation between the glass cover plate 22 and the side of the conductive shell 21 with the coating layer 20 to increase and make the adhesion more tight, so that the pre-bonding effect is better, and on the other hand, the secondary problems caused by the rapid temperature rise for achieving the bonding temperature in the subsequent bonding process can be avoided.

Wherein, in some embodiments, heating the glass cover plate 22 and the conductive housing 21 comprises:

the conductive housing 21 and the glass cover plate 22 are heated by means of electrical heating, wherein,

the output voltage of the electrical heating is gradually increased so that the temperatures of the glass cover plate 22 and the conductive housing 21 are gradually increased.

Referring to fig. 3, the bonding method of the housing assembly of the present application is assisted by a bonding jig 5. The bonding jig 5 comprises a heating module 3. Wherein, the heating of the conductive shell 21 and the glass cover plate 22 by electric heating is as follows: placing the glass cover plate 22 and the conductive housing 21 in a heating module 3, wherein the heating module 3 includes a first power source 31, a first heating plate 32 and a second heating plate 33, a positive electrode of the first power source 31 is connected to the first heating plate 32, the first heating plate 32 is disposed on a side of the conductive housing 21 away from the glass cover plate 22, a negative electrode of the first power source 31 is connected to the second heating plate 33, the second heating plate 33 is disposed on a side of the glass cover plate 22 away from the conductive housing 21, and the first heating plate 32 and the second heating plate 33 are electrically connected; the resistance values of the first heating plate 32 and the second heating plate 33 are greater than a preset resistance threshold value.

The output voltage of the electric heater is gradually increased as follows: the output voltage of the first power supply 31 is controlled to be increased. Accordingly, the temperature of the first heating plate 32 and the second heating plate 33 can be increased by increasing the output voltage of the first power source 31, thereby adjusting the heating temperature of the conductive housing 21 and the glass cover 22.

In some embodiments, the output voltage of the first power source 31 is increased as the pre-bonding process advances to heat the glass cover plate 22 and the conductive housing 21, and the pressure applied to the glass cover plate 22 is adjusted. That is, during the pre-bonding process, the pressure applied to the glass cover plate 22 is increased as the pre-bonding temperature is increased. For example, as the pre-bonding process advances, the bonding temperature is increased from 0 ℃ to about 150 ℃, and the pressure applied to the glass cover plate 22 is increased as the pre-bonding temperature is increased, specifically, when the temperature is increased to 50 ℃, the pressure is increased by 0 to 0.4Mpa, when the temperature is increased to 100 ℃, the pressure is increased by 0 to 0.4Mpa, when the temperature is increased to 150 ℃, the pressure is increased by 0 to 0.4Mpa, and the like. Alternatively, in other embodiments, the pressure applied to the glass cover plate 22 may be a gradual increase in the pressure applied to the glass cover plate 22 as the temperature increases. Therefore, the pre-bonding temperature is gradually increased along with the recommendation of the pre-bonding process, so that a series of secondary temperature pedicles caused by too fast temperature change can be avoided, and in addition, in the process of increasing the pre-bonding temperature, the temperature increase speed at a lower temperature is slower than that at a higher temperature, for example, the time is 10-15 minutes when the temperature is increased from 0 ℃ to 50 ℃, the time is 8-12 minutes when the temperature is increased from 50 ℃ to 100 ℃, and the time is 5-10 minutes when the temperature is increased from 100 ℃ to 150 ℃.

Alternatively, in one embodiment, the reaching of the predetermined threshold vacuum between the glass cover plate 22 and the conductive shell 21 includes:

the space between the glass cover plate 22 and the conductive housing 21 is evacuated by an evacuation device.

Wherein, in some embodiments, the predetermined threshold value of the vacuum level is less than-95 KPa. In other embodiments, the preset threshold of the vacuum degree may be adjusted according to actual needs, and is not limited herein.

Thus, it is possible to ensure that the air between the glass cover plate 22 and the conductive housing 21 completely escapes.

Optionally, in one embodiment, the maintaining pressure includes:

applying a first preset pressure to the glass cover plate 22, heating the glass cover plate 22 and the conductive shell 21 to a first preset temperature and keeping the pressure for a first preset time when the temperature reaches a vacuum condition;

applying a second preset pressure to the glass cover plate 22, heating the glass cover plate 22 and the conductive shell 21 to a second preset temperature, and maintaining the pressure for a second preset time when the temperature is raised to the second preset temperature and the vacuum condition is reached, wherein the second preset temperature is higher than the first preset temperature;

and applying a third preset pressure to the glass cover plate 22, heating the glass cover plate 22 and the conductive shell 21 to a third preset temperature, and keeping the pressure for a third preset time when the vacuum condition is reached, wherein the third preset temperature is higher than the second preset temperature.

In one embodiment, the first predetermined pressure is 0.08-0.12 MPa/m ³ The first preset temperature is 40-60 ℃, and the first preset time is 40-60 seconds.

In one embodiment, the second preset pressure is equal to the first preset pressure or greater than the first preset pressure. In this embodiment, the second preset pressure is equal to the first preset pressure. The second preset temperature is 90-110 ℃, and the second preset time period can be equal to the first preset time period or not equal to the first preset time period. In this embodiment, the second preset duration is equal to the first preset duration.

In one embodiment, the third preset pressure is equal to the first preset pressure, or greater than the second preset pressure. In this embodiment, the third predetermined pressure is greater than the second predetermined pressure and is 0.15 to 0.35 Mpa. The third preset duration is equal to or longer than the second preset duration, in this embodiment, the third preset duration is longer than the second preset duration, and the third preset duration is 100-140S.

Thus, by gradually increasing the pre-bonding temperature and gradually increasing the pre-bonding pressure, the air between the conductive shell 21 and the glass cover plate 22 has enough time to escape until the two are completely attached.

In some embodiments, referring to fig. 3 again, the bonding jig 5 further includes a bonding module 4, wherein the bonding module 4 includes a second power source 41, a first electrode 42 and a second electrode 43, and the first electrode 42 is connected between the conductive housing 21 and the positive electrode of the second power source 41. Alternatively, in one embodiment, the first electrode 42 is disposed on a side of the first heating plate 32 facing the second heating plate 33 and is insulated from the first heating plate 32, and the second electrode 43 is disposed on a side of the second heating plate 33 facing the first heating plate 32 and is insulated from the second heating plate 33, wherein the output voltage of the first power source 31 is less than the output voltage of the second power source 41. Optionally, in one embodiment, the bonding jig 5 further includes a positioning block 6, and the positioning block 6 is disposed on a side of the first heating plate 32 facing the second heating plate 33. The positioning block 6 is used for positioning the conductive shell 21. It is understood that the positioning block 6 may be replaced by a positioning groove, which is not limited herein. Alternatively, in one embodiment, a positioning cavity is provided on a side of the second heating plate 33 facing the first heating plate 32. The glass cover plate 22 is disposed in the positioning cavity for positioning. Thus, the positioning of the glass cover plate 22 is facilitated. Therefore, applying a first positive voltage to the conductive housing 21 and a first negative voltage to the glass cover 22 to bond the glass cover 22 and the side of the conductive housing 21 having the plating layer 20 includes: the conductive shell 21 and the glass cover plate 22 are placed in a bonding module 4, wherein the first electrode 42 is connected between the conductive shell 21 and the positive electrode of the second power source 41, the second electrode 43 is connected between the glass cover plate 22 and the negative electrode of the second power source 41, and the output voltage of the second power source 41 is controlled, so that the side of the glass cover plate 22 with the film coating layer 20 is bonded with the conductive shell 21.

Please refer to fig. 4 to 6 together, wherein fig. 4 is an enlarged view of IV shown in fig. 2 before bonding in an embodiment of the present application. Fig. 5 is an enlarged view of IV shown in fig. 2 after bonding in an embodiment of the present application. Fig. 6 is a schematic structural diagram of a conductive housing and a glass cover plate after being completely bonded in an embodiment of the present application. The bonding is anodic by connecting the positive terminal of the second power source 41 to the conductive housing 21 and the negative terminal of the second power source 41 to the glass cover 22. The glass cover plate 22 behaves like an electrolyte at high temperatures (below the softening point of glass), while the resistivity of the conductive housing 21 decreases to 0.1flm due to intrinsic excitation when the temperature is raised to 300-400 ℃. Conductive ions such as Na ions in the glass cover plate 22 drift to the glass surface of the negative electrode when an applied electric field is applied, leaving a negative charge on the glass surface adjacent to the conductive housing 21. Due to the drift of Na ions (directional flow of charged particles), there is a current flow through the circuit, and a space charge region or depletion layer 23 of very thin width of about a few millimeters is formed next to the glass surface of the conductive shell 21. Since the depletion layer is negatively charged and the conductive shell 21 is positively charged, a large electrostatic attraction force (about 10MV/cm) exists between the conductive shell 21 and the glass cover plate 22, so that the conductive shell and the glass cover plate are in close contact, and a physicochemical reaction occurs at a bonding surface to form a firmly-bonded covalent bond, thereby completing bonding.

In one embodiment, the step of bonding the side of the glass cover plate 22 having the coating layer 20 to the conductive housing 21 by applying a first positive voltage to the conductive housing 21 and applying a first negative voltage to the glass cover plate 22 comprises:

loading a first positive voltage on the conductive shell 21 and a first negative voltage on the glass cover plate 22 at a bonding temperature of 200-300 ℃, a vacuum degree of less than-95 KPa and a bonding pressure of 0.3-0.8 Mpa so as to enable the bonding voltage difference between the conductive shell 21 and the glass cover plate 22 to be in a range of 500-1000V, and bonding one side of the glass cover plate 22 with the coating layer 20 with the conductive shell 21.

The parameters related to bonding include at least bonding temperature, bonding voltage, bonding pressure, and the like. The bonding temperature has a great influence on the bonding process, and if the temperature is too low, the conductivity of the glass cover plate 22 is poor, and the glass cover plate 22 cannot be softened, the influence of the fluctuation of the glass cover plate 22 on the bonding cannot be overcome; excessive temperatures in turn can cause thermal mismatch between the glass cover plate 22 and the conductive housing 21, increasing bonding stress. Therefore, in this embodiment, the bonding temperature is selected to be 200-300 ℃. The bonding voltage has a great influence on the bonding quality, and the excessively low voltage causes the electric attraction between the glass cover plate 22 and the conductive shell 21 to be weakened, so that the bonding cannot be effectively completed, and even if the bonding reaction occurs, the good bonding strength cannot be realized; an excessively high voltage sometimes causes the glass cover plate 22 to break down, making bonding impossible. Therefore, a direct current voltage of about 200V to 1000V is generally used for anodic bonding of the glass cover plate 22. In this embodiment, the bonding voltage is 500-1000V. The bonding pressure is a condition for promoting better bonding reaction, and at the too low bonding pressure, the softened glass cover plate 22 cannot be tightly attached to the conductive shell 21, so the bonding quality is low; at too high a bonding pressure, the glass cover plate 22 is susceptible to chipping. Therefore, in this example, the bonding pressure was 0.3MPa to 0.8 MPa.

Thus, the glass cover plate 22 and the conductive housing 21 gradually change from point contact to surface contact as the bonding process advances until all bonding is completed.

In one embodiment, bonding at a bonding voltage of 500V to 1000V includes:

the bonding voltage is gradually increased as the bonding process advances.

In one embodiment, the bonding includes a first stage, a second stage and a third stage, the applying a first positive voltage to the conductive shell 21 and a first negative voltage to the glass cover 22 to make the bonding voltage difference between the conductive shell 21 and the glass cover 22 range from 500V to 1000V, including:

the bonding voltage is gradually increased as the bonding process advances, wherein,

in the first stage of the bonding process, the bonding voltage difference between the conductive shell 21 and the glass cover plate 22 ranges from 500V to 700V;

in the second stage of the bonding process, the bonding voltage difference between the conductive shell 21 and the glass cover plate 22 ranges from 600V to 800V;

in the third stage of the bonding process, the bonding voltage difference between the conductive shell 21 and the glass cover plate 22 ranges from 800V to 100V. Wherein the third stage continues until bonding is complete.

Thus, as the electric charge between the glass cover plate 22 and the conductive housing 21 decreases as the bonding reaction proceeds, the electric potential difference between the glass cover plate 22 and the conductive housing 21 decreases, and the increase in voltage increases the electric charge between the glass cover plate 22 and the conductive housing 21, and further increases the electric potential difference between the glass cover plate 22 and the conductive housing 21, thereby promoting the continuous progress of the bonding process.

In a specific embodiment, in the early stage of bonding, a pressure of 0.4-0.6 Mpa is applied to the glass cover plate 22, the vacuum degree is kept to be less than-95 KPa, the temperature is 180-220 ℃, the bonding voltage is adjusted to 500-700V, and the bonding duration is 400-550 s; in the middle bonding stage, applying pressure of 0.4-0.6 Mpa to the glass cover plate 22, keeping the vacuum degree less than-95 KPa, raising the bonding temperature to 240-260 ℃, adjusting the bonding voltage to 600-800V, and keeping the bonding duration of 340-380 s; and in the later stage of bonding, applying pressure of 0.4-0.6 Mpa to the glass cover plate 22, keeping the vacuum degree less than-95 KPa, raising the bonding temperature to 270-290 ℃, adjusting the bonding voltage to 800-1000V, and continuing the bonding process until the bonding current is stable and unchanged or the attenuation speed of the bonding current approaches zero, namely, the bonding is finished.

Optionally, in one embodiment, the method further includes:

detecting a change in current in a conductive path formed between the second power source 41, the first electrode 42, the second electrode 43, the conductive housing 21, and the glass cover 22;

when the current change is smaller than a preset threshold value, it is determined that the glass cover plate 22 and the conductive shell 21 are bonded, and the glass cover plate 22 and the conductive shell 21 are connected through a depletion layer 23.

Optionally, in one embodiment, before forming the plated layer 20 on the predetermined surface of the conductive shell 21, the bonding method further includes the steps of:

providing a surface-treated conductive housing 21;

and forming a coating layer 20 on the preset surface of the conductive shell 21.

Wherein, the surface treatment of the conductive shell 21 includes, but is not limited to, magnetic grinding, mechanical polishing, etc. of the preset surface of the conductive shell 21, so that the surface roughness Ra of the conductive shell 21 does not exceed 0.02 μm, and the flatness of the conductive shell 21 does not exceed 0.03 mm.

The surface treatment of the conductive shell 21 and the surface treatment of the glass cover plate 22 further include cleaning, and the cleaning includes but is not limited to surface cleaning of the conductive shell 21 and the glass cover plate 22 with a weakly alkaline cleaning agent to remove surface impurities.

In some embodiments, the forming of the plated layer 20 on the predetermined surface of the conductive housing 21 includes:

providing a metal blank, which may be, but is not limited to, aluminum alloy, 316L stainless steel, etc.;

machining the metal blank to obtain a conductive shell 21 with a preset shape;

cleaning the conductive shell 21 for the first time to remove impurities generated by a machining process;

roughly polishing the conductive shell 21;

performing fine polishing on the roughly polished conductive shell 21;

carrying out secondary cleaning on the conductive shell 21 subjected to the fine polishing to remove impurities generated by the polishing process;

and performing surface coating on the conductive shell 21 subjected to the second cleaning to obtain a coated layer.

The cleaning agent used for cleaning is sodium carbonate, a surfactant, sodium hydroxide and the like, and the pH value of the cleaning agent is 7-9.

Wherein, rough polishing can be carried out to metal surface and smooth, eliminates showing the defect, and the polishing solution composition: silicon carbide, silicon dioxide, a surfactant, a pH stabilizer, a complexing agent and the like.

Wherein, the fine polishing is to realize the specular highlight effect on the surface of the aluminum alloy, and the polishing solution comprises alumina, an oxidant, a dispersant, a complexing agent, a pH value regulator and the like.

Wherein, the process flow of the coating layer is as follows: degreasing, alkaline etching, activation, zinc replacement, activation, electroplating (such as nickel, zinc, copper and the like), chrome plating or passivation and drying.

In summary, when the bonding of the conductive housing 21 and the glass cover plate 22 is completed, a bonding effect test is performed. The test result shows that the drawing force between the conductive shell 21 and the glass cover plate 2 is more than or equal to 28Mpa, and the combination requirement between the conductive shell and the glass cover plate is met; moreover, the glass cover plate 22 and the conductive shell 21 pass the 10ATM air tightness test after being bonded, and the air tightness is good.

Referring to fig. 6, the housing assembly 2 includes a conductive housing 21 and a glass cover 22, and the conductive housing 21 and the glass cover 22 are bonded and connected by the above-mentioned bonding method of the housing assembly.

In an embodiment of the present application, a terminal is further provided, and the terminal includes the housing assembly 2.

It should be noted that, for simplicity of description, the above-mentioned method embodiments are described as a series of acts or combination of acts, but those skilled in the art will recognize that the present application is not limited by the order of acts described, as some steps may occur in other orders or concurrently depending on the application. Further, those skilled in the art should also appreciate that the embodiments described in the specification are preferred embodiments and that the acts and modules referred to are not necessarily required in this application.

In the foregoing embodiments, the descriptions of the respective embodiments have respective emphasis, and for parts that are not described in detail in a certain embodiment, reference may be made to related descriptions of other embodiments.

The above embodiments are only used for illustrating the technical solutions of the present application, and not for limiting the same; although the present application has been described in detail with reference to the foregoing embodiments, it should be understood by those of ordinary skill in the art that: the technical solutions described in the foregoing embodiments may still be modified, or some technical features may be equivalently replaced; and the modifications or the substitutions do not make the essence of the corresponding technical solutions depart from the scope of the technical solutions of the embodiments of the present application.

Claims

1. A method of bonding a housing assembly, comprising:

forming a coating layer on the preset surface of the conductive shell;

2. The bonding method of claim 1, wherein the plating layer comprises one of a nickel plating layer, a silver plating layer, a gold plating layer, a zinc plating layer, a copper plating layer, a nobelium plating layer.

3. The bonding method according to claim 1, wherein the thickness of the plating layer is 1 μm or less.

4. The bonding method of claim 1, wherein pre-bonding the glass cover plate to the conductive housing comprises:

applying a first pressure to the glass cover plate;

heating the glass cover plate and the conductive shell;

vacuumizing the space between the glass cover plate and the conductive shell; and

and maintaining the pressure when the vacuum degree between the glass cover plate and the conductive shell reaches a preset threshold value.

5. The bonding method of claim 4, wherein heating the glass cover plate and the conductive housing comprises:

heating the conductive shell and the glass cover plate by electric heating, wherein,

gradually increasing the output voltage of the electrical heating causes the temperature of the glass cover plate and the conductive housing to gradually increase.

6. The bonding method of claim 4, wherein the holding pressure comprises:

applying a first preset pressure to the glass cover plate, heating the glass cover plate and the conductive shell to a first preset temperature and keeping the pressure for a first preset time when the glass cover plate and the conductive shell reach a vacuum condition;

applying a second preset pressure to the glass cover plate, heating the glass cover plate and the conductive shell to a second preset temperature, and keeping the pressure for a second preset time when the glass cover plate and the conductive shell reach a vacuum condition, wherein the second preset temperature is higher than the first preset temperature; and

and applying a third preset pressure on the glass cover plate, maintaining the pressure for a third preset time when the glass cover plate and the conductive shell are heated to a third preset temperature and reach a vacuum condition, wherein the third preset temperature is higher than the second preset temperature.

7. The bonding method of claim 1, wherein applying a first positive voltage to the conductive housing and a first negative voltage to the glass cover plate to bond the side of the glass cover plate having the coating to the conductive housing comprises:

loading a first positive voltage on the conductive shell and a first negative voltage on the glass cover plate at the bonding temperature of 200-300 ℃, the vacuum degree of less than-95 KPa and the bonding pressure of 0.3-0.8 Mpa so as to enable the bonding voltage difference between the conductive shell and the glass cover plate to be 500-1000V, and bonding one side of the glass cover plate with the film coating layer with the conductive shell.

8. The bonding method according to claim 7, wherein the bonding comprises a first stage, a second stage and a third stage, the loading of the conductive shell with a first positive voltage and the loading of the glass cover with a first negative voltage such that a bonding voltage difference between the conductive shell and the glass cover is in a range of 500V to 1000V comprises:

gradually increasing the bonding voltage along with the advance of the bonding process, wherein in the first stage of the bonding process, the bonding voltage difference between the conductive shell and the glass cover plate ranges from 500V to 700V; in the second stage of the bonding process, the bonding voltage difference between the conductive shell and the glass cover plate ranges from 600V to 800V; in the third stage of the bonding process, the bonding voltage difference between the conductive shell and the glass cover plate ranges from 800V to 100V.

9. A housing assembly comprising a conductive housing and a glass cover plate, wherein the conductive housing and the glass cover plate are bonded together by the bonding method of the housing assembly as claimed in any one of claims 1 to 8.

10. A terminal comprising the housing assembly of claim 9.