CN110248496B - PCB (printed circuit board) mounting process and mounting adhesive applied to same - Google Patents
PCB (printed circuit board) mounting process and mounting adhesive applied to same Download PDFInfo
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- CN110248496B CN110248496B CN201910472018.4A CN201910472018A CN110248496B CN 110248496 B CN110248496 B CN 110248496B CN 201910472018 A CN201910472018 A CN 201910472018A CN 110248496 B CN110248496 B CN 110248496B
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- H—ELECTRICITY
- H05—ELECTRIC TECHNIQUES NOT OTHERWISE PROVIDED FOR
- H05K—PRINTED CIRCUITS; CASINGS OR CONSTRUCTIONAL DETAILS OF ELECTRIC APPARATUS; MANUFACTURE OF ASSEMBLAGES OF ELECTRICAL COMPONENTS
- H05K3/00—Apparatus or processes for manufacturing printed circuits
- H05K3/30—Assembling printed circuits with electric components, e.g. with resistor
- H05K3/32—Assembling printed circuits with electric components, e.g. with resistor electrically connecting electric components or wires to printed circuits
- H05K3/34—Assembling printed circuits with electric components, e.g. with resistor electrically connecting electric components or wires to printed circuits by soldering
- H05K3/341—Surface mounted components
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- H—ELECTRICITY
- H05—ELECTRIC TECHNIQUES NOT OTHERWISE PROVIDED FOR
- H05K—PRINTED CIRCUITS; CASINGS OR CONSTRUCTIONAL DETAILS OF ELECTRIC APPARATUS; MANUFACTURE OF ASSEMBLAGES OF ELECTRICAL COMPONENTS
- H05K3/00—Apparatus or processes for manufacturing printed circuits
- H05K3/30—Assembling printed circuits with electric components, e.g. with resistor
- H05K3/32—Assembling printed circuits with electric components, e.g. with resistor electrically connecting electric components or wires to printed circuits
- H05K3/34—Assembling printed circuits with electric components, e.g. with resistor electrically connecting electric components or wires to printed circuits by soldering
- H05K3/3494—Heating methods for reflowing of solder
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- Engineering & Computer Science (AREA)
- Manufacturing & Machinery (AREA)
- Microelectronics & Electronic Packaging (AREA)
- Adhesives Or Adhesive Processes (AREA)
- Electric Connection Of Electric Components To Printed Circuits (AREA)
Abstract
The invention discloses a PCB (printed circuit board) mounting process and a mounting adhesive applied to the same, belongs to the field of PCBs, and solves the problem that an additive influences the curing degree of epoxy resin in the prior art. The mounting process comprises the following steps: s1: printing solder paste on the surface A of the PCB; s2: dispensing a piece of adhesive on the surface A of the PCB, pasting the component on the surface A, and enabling the surface A to face upwards to enter a reflow oven for reflow soldering; s3: printing solder paste on the surface B of the PCB, pasting components on the surface B, and enabling the surface B to face upwards to enter a reflow furnace for reflow soldering; the reflow furnace is internally provided with illumination equipment which is arranged in front of the reflow soldering area in the reflow furnace and positioned at two sides of the conveying belt; the detention time of the A surface of the PCB in the heating area is 2-4 min. Before the components in the PCB board obtained by the invention enter the reflow soldering region, the surface mount adhesive can reach sufficient curing degree.
Description
Technical Field
The invention relates to the field of PCBs (printed circuit boards), in particular to a PCB (printed circuit board) mounting process and a mounting adhesive applied to the mounting process.
Background
The PCB is also called as a circuit board or a printed circuit board, and a wiring method is replaced by a printing method; the PCB board miniaturizes, concentrates and simplifies complicated wiring and circuits of electronic parts. The PCB board comprises a single-sided board with parts concentrated on one side, a double-sided board with parts distributed on two sides, and a multilayer board capable of increasing wiring area.
When the double-sided PCB is manufactured, solder pastes are required to be printed on the surface A and the surface B of the PCB in sequence and are sent into a reflow oven; place the PCB board on the conveyer belt, the PCB board experiences heating-up area, reflow soldering district, cooling space in proper order in the reflow furnace, if the printing and the reflow soldering of tin cream are carried out earlier to A face, then B face when carrying out reflow soldering, the tin cream of A face and B face can be softened, and the viscosity of tin cream can reduce gradually, the great components and parts of volume on the B face that this moment is down, because the effect of gravity just drops very easily. In order to avoid dropping of components with larger volume, a piece of surface mount adhesive is added at the position of the surface A where the components with larger volume are to be welded, and the piece of surface mount adhesive is adhered to the shell of the component on the PCB of the component; the surface mount adhesive can be solidified at high temperature, and when the solder paste is melted, the surface mount adhesive can realize the fixation of components, so that the fixation of the A-surface and B-surface elements is ensured.
Most of the existing adhesive patches comprise epoxy resin, imidazole curing agents and transition metal inorganic salt additives, and the epoxy resin is cured under the heating condition, so that the effects of adhering and fixing components are achieved; the transition metal inorganic salt additive in the adhesive is mainly used for improving the storage property of the adhesive. When the imidazole curing agent and the transition metal inorganic salt additive are mixed, the complex formed by the transition metal ions and the imidazole can weaken the activity of the transition metal ions, thereby playing the effect of improving the storage property of the patch adhesive; and after the PCB adhered with the surface mount adhesive enters the reflow furnace, the complex can influence the active temperature of the curing agent, the temperature at which the complex starts to react cannot be determined, namely the temperature at which the epoxy resin starts to cure cannot be determined, so that the curing degree before the surface mount adhesive enters the reflow soldering region cannot be ensured.
Disclosure of Invention
The invention aims to overcome the defects in the prior art, and the first object of the invention is to provide a PCB mounting process, which can ensure that the surface mount adhesive can reach a sufficient curing degree before components in the obtained PCB enter a reflow soldering area under the condition of not using additives.
The second purpose of the invention is to provide a surface mount adhesive applied to the surface mount technology, which achieves the effect of improving the curing speed.
In order to achieve the first object, the invention provides the following technical scheme:
The technical purpose of the invention is realized by the following technical scheme: a PCB board mounting process comprises the following steps:
S1: printing solder paste on the surface A of the PCB;
S2: dispensing a piece of adhesive on the surface A of the PCB, pasting the component on the surface A, and enabling the surface A to face upwards to enter a reflow oven for reflow soldering;
S3: printing solder paste on the surface B of the PCB, pasting components on the surface B, and enabling the surface B to face upwards to enter a reflow furnace for reflow soldering;
The reflow furnace is internally provided with illumination equipment which is arranged in front of the reflow soldering area in the reflow furnace and positioned at two sides of the conveying belt; the detention time of the A surface of the PCB in the heating area is 2-4 min;
The patch adhesive comprises epoxy resin and a curing agent, wherein the curing agent is a mixture of a visible light curing agent and a first curing agent or a visible light curing agent.
By adopting the technical scheme, after the surface A of the PCB enters the reflow oven, the surface A is irradiated by the illumination equipment, and the light-cured curing agent initiates the polymerization reaction and the crosslinking reaction of the low molecules of the epoxy resin, so that the curing of the epoxy resin is realized. The photocuring curing agent has high curing speed and long storage period, and does not need to add other auxiliary agents; the photocuring curing agent has low requirement on temperature, mainly plays a role in light, and can be cured only by being irradiated by the light for a period of time. Before the PCB enters a reflow soldering area of a reflow furnace, curing the epoxy resin by utilizing illumination, and before the solder paste is melted, bonding components with large volume by utilizing a surface mount adhesive; the detention time of the A surface of the PCB in the temperature rising area is 2-4min, and most of curing and even complete curing of the surface mount adhesive is guaranteed before the surface mount adhesive enters the reflow soldering area. The use of cooperation first curing agent, first curing agent and photocuring are solidified epoxy simultaneously for the solidification rate improves the solidification degree of paster gluey before getting into reflow soldering district.
More preferably: the detention time of the A surface of the PCB in the heating area is 2-2.6 min.
By adopting the technical scheme, experiments 1 show that the curing time of the adhesive is appropriate and the curing degree is good within 2-2.6 min; meanwhile, the retention time of the PCB in the heating area is shortened, so that the heat preservation time can be shortened, and the manufacturing cost is saved.
In order to achieve the second object, the invention provides the following technical scheme: a patch adhesive applied to the mounting process comprises the following components in parts by weight:
An epoxy resin;
A thermosetting phenolic resin;
4-20 parts of a curing agent;
15-20 parts of a thixotropic agent;
3-15 parts of an auxiliary agent;
The total weight of the epoxy resin and the thermosetting phenolic resin is 100-150 parts;
The thixotropic agent is organic bentonite or fumed silica;
The auxiliary agent comprises a silane coupling agent and 1-2 parts of pigment.
By adopting the technical scheme, a composite resin system formed by mixing epoxy resin and phenolic resin is adopted, the epoxy resin is matched with a visible light curing agent, and the curing of the epoxy resin is realized under the irradiation of a reflow oven illumination device; the thermosetting phenolic resin can be thermally cured at the temperature of 130-200 ℃, no curing agent is required to be added, the thermosetting phenolic resin can be cured once the temperature reaches 130-200 ℃ after the PCB enters a reflow furnace, and at the moment, the illumination equipment irradiates the surface mount adhesive, so that the epoxy resin and the thermosetting phenolic resin are simultaneously cured, the curing speed is improved, and the curing degree of the surface mount adhesive before entering a reflow soldering region is improved. The use of the silane coupling agent can reduce the water absorption of the cured epoxy resin and phenolic resin.
More preferably: the epoxy resin accounts for 70-82% of the total weight of the epoxy resin and the thermosetting phenolic resin.
By adopting the technical scheme, a composite resin system with epoxy resin as a main component and phenolic resin as an auxiliary component is adopted, a mounting process is matched, the temperature can reach 180-183 ℃ before a reflow furnace enters a reflow soldering region, thermosetting phenolic resin can be cured at the temperature of 130-200 ℃, and no curing agent is required to be added; the thermosetting phenolic resin may be partially or fully cured while the epoxy completes a partial light cure before entering the reflow soldering area.
Because the components on the PCB are not suitable to be heated for too long time in the reflow oven, and the curing of the epoxy resin is established on the basis of illuminating for a certain time period, the time of a reflow soldering area and a cooling area in the reflow oven is not suitable to be shortened, and the quality of solder paste reflow soldering is easily influenced. Therefore, to a certain extent, the time of the epoxy resin photocuring can directly influence the time of the whole reflow soldering step, so that the time of the PCB at high temperature is prolonged; in order to reduce the light curing time of the epoxy resin, on one hand, the dosage of the epoxy resin is reduced, and on the other hand, the thermosetting phenolic resin is added, so that the epoxy resin and the thermosetting phenolic resin are cured simultaneously in a heating area and a preheating area, and the curing degree of the surface mount adhesive before entering a reflow soldering area is improved.
The epoxy resin has good bonding strength and chemical resistance, good cohesion and excellent mechanical property; the phenolic resin has certain brittleness, but has excellent heat resistance. After the two resins are combined, the adhesive has good mechanical property and adhesion property after being cured on the premise of shortening the time of a heating area and a preheating area as much as possible, a reticular cross-linked structure is vertically generated after the adhesive is cured, and the water resistance of the adhesive is improved. When the content of the epoxy resin is 70% -82%, the curing degree of the patch adhesive in the same time is higher.
More preferably: the first curing agent consists of dicyandiamide and imidazole, the visible light curing agent accounts for 75-80% of the total weight of the curing agent, and the weight part ratio of dicyandiamide to imidazole is (1.8-2.2): 1.
By adopting the technical scheme, the curing agent comprises 75-80% of visible light curing agent as a main curing agent, and dicyanodiamine and imidazole as secondary curing agents to form a compound curing agent. The dicyandiamide curing agent enables the cured resin to have high curing strength but high curing temperature, and the imidazole curing agent is used, so that the cured resin has low curing strength but high curing speed; on the other hand, the curing agent of azole and its derivatives can be used as an auxiliary agent of dicyanodiamine to lower the curing temperature. The curing effect of imidazole and dicyanodiamine can realize curing at the temperature of 130-170 ℃, so that the curing degree of the surface mount adhesive before entering the reflow soldering area is further improved; the content of imidazole and dicyanodiamide is low, and the influence on the storage is small.
More preferably: the second curing agent consists of dicyandiamide, imidazole and 0.5-3 parts of transition metal inorganic salt, the visible light curing agent accounts for 75-80% of the total weight of the curing agent, and the weight parts of dicyandiamide and imidazole are (1.8-2.2): 1.
By adopting the technical scheme, the curing agent comprises 75-80% of visible light curing agent as a main curing agent, and dicyanodiamine and imidazole as secondary curing agents to form a compound curing agent. The dicyandiamide curing agent enables the cured resin to have high curing strength but high curing temperature, and the imidazole curing agent is used, so that the cured resin has low curing strength but high curing speed; on the other hand, imidazole curing agents may act as adjuvants for dicyanodiamines to lower the curing temperature. The curing action of imidazole and dicyanodiamine can realize curing at the temperature of 130-170 ℃, thereby further improving the curing degree of the surface mount adhesive before entering the reflow soldering area. The transition metal inorganic salt and the imidazole form a coordination complex, so that the storage property of the patch adhesive is improved, and meanwhile, the imidazole content is low, the complex formed by the imidazole and the transition metal inorganic salt is low, and the overall influence on the curing of the epoxy resin is small.
More preferably: the transition metal inorganic salt is zinc chloride.
By adopting the technical scheme, experiments 2 show that the zinc ions have greater help on the storage property, and the covalent action of the zinc ions and imidazole is strongest.
More preferably: the assistant also comprises nano titanium dioxide, and the weight part of the silane coupling agent in the assistant is 0.5-4.
By adopting the technical scheme, the density of the titanium dioxide reaches 3.8-4.23g/cm 3Among the inorganic substances, the substances belong to materials with higher density; the nano titanium dioxide has small particle size and is convenient to be used as a filling material of resin, on the other hand, the resin on the outer surface is initiated to start curing by light rays irradiated by illumination equipment, and the inside of the resin is slower; after adding nanometer titanium dioxide, light in case get into the resin and contact with titanium dioxide, because titanium dioxide has fine light shielding performance, and self density is higher, titanium dioxide can reflect partial light, according to light incidence angle and at the difference of titanium dioxide surface contact point, the light of reflection has different reflection angle to reflect light to the inside different positions of resin, increase the area of contact of light and resin for photocuring speed.
More preferably: the auxiliary agent also comprises 1.5-4 parts of phenol.
By adopting the technical scheme, the boiling point of the phenol is 181.9 ℃, when the phenol is in the reflow furnace, before the reflow soldering area is started and when the reflow soldering area is reflowed, the phenol is gradually decomposed and forms a protective atmosphere outside the patch adhesive, so that the contact between the air in the reflow furnace and the patch adhesive is reduced, and the moisture absorption possibility of the patch adhesive at high temperature is reduced; on the other hand, when the phenol starts to evaporate, the phenol resin has already finished the substantial curing, and the influence on the phenol resin is small.
More preferably: the silane coupling agent is one of kh560, kh570 and kh 792.
By adopting the technical scheme, the boiling point of KH550 is 217 ℃, the boiling point of KH560 is 290 ℃, the boiling points of KH570 and KH792 are sequentially increased on the basis of KH560, and the boiling point of KH550 is too low and can be evaporated after entering a reflow soldering area of a reflow oven, so that the application is not suitable.
In conclusion, the invention has the following beneficial effects:
1. According to the invention, the illumination equipment is arranged in front of the reflow soldering area of the reflow furnace, the surface mount adhesive adopts the visible light curing agent and the first curing agent, the requirement of the visible light curing agent on temperature is not high, light mainly plays a role, the curing of the epoxy resin can be realized as long as the surface mount adhesive is irradiated by the light for a period of time, the residence time of the surface A of the PCB in the temperature rising area is 2-4min, the surface mount adhesive is ensured to complete most of curing or even complete curing before entering the reflow soldering area, and meanwhile, the first curing agent also cures the epoxy resin;
2. The invention adopts a composite resin system which takes epoxy resin as a main part and thermosetting phenolic resin as an auxiliary part, and accelerates the curing speed of the resin before entering a reflow soldering region, thereby reducing the time of a PCB in a reflow furnace as much as possible and further reducing irreversible damage to components of the PCB caused by high temperature;
3. In the invention, dicyandiamide and imidazole are adopted to form a compound curing agent, and the curing effect of imidazole and dicyandiamide can realize curing at the temperature of 130-170 ℃, so that the curing degree of the surface mount adhesive before entering a reflow soldering region is further improved;
4. According to the invention, the nano titanium dioxide is adopted, and the high density and the light shielding property of the nano titanium dioxide are utilized to realize the reflection of light rays, so that the light rays are reflected to different positions in the resin, the contact area of the light rays and the resin is enlarged, and the photocuring speed is accelerated.
Detailed Description
Examples 1 to 12: a patch adhesive, examples 1-6 include components and corresponding masses shown in Table 1, and examples 7-12 include components and corresponding masses shown in Table 2, and is prepared by the following steps:
The method comprises the following steps: mixing epoxy resin, thermosetting phenolic resin, thixotropic agent and auxiliary agent, and stirring at 300r/min for 2h under the environment of 30 +/-1 ℃ and 0.05MPa of vacuum degree to obtain a mixture A;
Step two: adding the visible light curing agent and the first curing agent into the mixture A, and stirring for 1h at 50r/min in a closed environment.
TABLE 1 examples 1-6 compositions and corresponding masses (kg)
TABLE 2 examples 7-12 compositions and corresponding masses (kg)
In the above-described embodiment of the present invention,
The visible light curing agent is obtained by mixing diaryl iodonium salt and dye in a weight ratio of 2: 1.
The transition metal inorganic salts in examples 7 to 9 employed copper chloride; the transition metal inorganic salts in examples 10 to 12 employed zinc chloride.
The particle size of the nano titanium dioxide is 30 +/-5 nm.
Example 13: a PCB board paster technology comprises the following steps:
S1: printing solder paste on the surface A of the PCB;
S2: dispensing a piece of adhesive on the surface A of the PCB, pasting the component on the surface A, and enabling the surface A to face upwards to enter a reflow oven for reflow soldering;
S3: printing solder paste on the surface B of the PCB, pasting components on the surface B, and enabling the surface B to face upwards to enter a reflow furnace for reflow soldering;
The two sides of the inner cavity of the reflow oven are provided with illumination equipment, the illumination equipment is positioned on the two sides of the conveying belt, and the illumination equipment is arranged in front of the reflow soldering area;
The detention time of the A surface of the PCB in the heating area is 2min totally;
The reflow furnace sequentially comprises an elevating temperature zone, a reflow soldering zone and a cooling zone, wherein the initial temperature of the elevating temperature zone is 30 +/-1 ℃, and the final temperature of the elevating temperature zone is 160 +/-1 ℃; the initial temperature of the reflow soldering zone was 179. + -. 1 ℃ and the final temperature was 230. + -. 1 ℃.
the illumination device in this embodiment is an led explosion-proof lamp with an explosion-proof rating of T2.
Example 14: a PCB die attach process, which is different from embodiment 13 in that: the residence time of the A side of the PCB in the heating area is 2.3min in total.
Example 15: a PCB die attach process, which is different from embodiment 13 in that: the residence time of the A side of the PCB in the heating area is 2.6min in total.
Example 16: a PCB die attach process, which is different from embodiment 13 in that: the residence time of the A surface of the PCB in the heating area is 3min in total.
Example 17: a PCB die attach process, which is different from embodiment 13 in that: the residence time of the A surface of the PCB in the heating area is 4min in total.
The patch gels of examples 13-17 used example 3.
Comparative examples 1 to 2: a patch adhesive, differing from example 3 in that the components included and the corresponding masses are as shown in table 3:
TABLE 3 comparative examples 1-2 components and corresponding masses (kg)
Comparative example 3: a PCB mounting process is different from the embodiment 13 in that the detention time of the A surface of the PCB in the temperature rising area is 1min in total.
Comparative example 4: a PCB mounting process is different from the embodiment 13 in that the detention time of the A surface of the PCB in the temperature rising area is 5min in total.
Characterization experiment:
1. Speed of curing experiment
(1) Effect of different mounting processes on curing speed
Subject: the patch adhesives of examples 13-17 and comparative examples 3-4, 7 sets of experimental samples, examples 13-17 and comparative examples 3-4 all used the formulation of example 16.
the experimental method comprises the steps of using an instrument, namely an L X-A type Shore durometer, and using an environmental condition that the temperature is 22 +/-2 ℃ and the humidity is 50 +/-5 RH%, directly sending the PCB into a reflow furnace without adhering components during experiment, and directly taking out the PCB and standing for 10min for cooling after the PCB passes through a heating area and a preheating area without entering a reflow soldering area.
The shore durometer operation steps are as follows: 1. zero calibration and full scale calibration; 2. placing the sample on a firm plane, holding the hardness tester, stably pressing the pressure foot on the sample by the pressure pin at least 12mm away from the edge of the sample, and vertically pressing the pressure pin into the sample until the pressure foot is completely contacted with the sample, wherein the reading is within 1 s; 3. the hardness values were measured 5 times at different positions at least 6mm apart from the measuring points, and the average value F (HA) of five experimental readings was calculated and recorded.
The experimental results are as follows: the results of the tests on the effect of different mounting processes on curing speed are reported in table 4.
Table 4 actual results of the effect of different mounting processes on curing speed
And (3) data analysis: as can be seen from the above table, examples 13-15 achieved a greater degree of cure, examples 16-17 and comparative example 4 had a higher degree of cure than examples 13-15, and comparative example 3 had a significantly insufficient degree of cure.
When the detention time of the A surface of the PCB in the temperature rising area is 2min in total, the curing degree of the A surface of the PCB reaches the enough using degree, and the longer the detention time of the A surface of the PCB in the temperature rising area and the preheating area is, the higher the curing degree is until the A surface of the PCB is completely cured. Examples 16 to 17 and comparative example 4 showed extremely high degrees of curing, but comparative example 4 had too long a residence time and was liable to damage the components, and the use thereof was not recommended.
(2) Effect of different Patch adhesive formulations on curing speed
Subject: examples 1-12 and comparative examples 1-2, for a total of 14 experimental samples; examples 1-12 and comparative examples 1-2 were used in combination with example 15.
The experimental method comprises the following steps: the same experimental method as in "(1) the effect of different mounting processes on curing speed".
The experimental results are as follows: the effect of different patch formulations on cure speed the results of the experiments are reported in table 5.
TABLE 5 record of the effect of different patch adhesive formulations on curing speed
And (3) data analysis: the hardness value can reflect the curing degree of the patch adhesive, and the higher the hardness value is, the higher the curing degree is. As can be seen from the above tables, all the test samples showed a better degree of curing, and examples 1 to 3, in which a one-component epoxy resin was used as a host resin, showed a lower degree of curing than the other sample samples in the same period of time.
Examples 4, 7, 10, examples 5, 8, 11, and examples 6, 9, 12 three parallel comparative groups, each with the same ratio of epoxy resin to thermosetting phenolic resin and essentially the same comparative example, were analyzed as examples 4, 7, 10. In example 4, the composite curing agent is not adopted, and the curing speed of the thermosetting phenolic resin is slower than that of examples 7 and 10; example 7, which used copper chloride, showed better cure than example 10, which used zinc chloride, probably because zinc chloride had a stronger covalent interaction with imidazole, showed better storage but a slower cure rate, and thus a lower cure was achieved in the same time.
The worst degree of curing is shown in comparative example 1, probably due to the low curing speed and too high curing temperature required for the dicyanodiamine curing agent; the comparative example 2 achieved a better degree of curing, but the adhesion test showed that the adhesion was not good and was not used.
2. Adhesion Strength test of Patch adhesive
Subject: examples 1-12 and comparative examples 1-2, for a total of 14 experimental samples; examples 1 to 12 and comparative examples 1 to 2 were used in combination with example 15.
The experimental method comprises the following steps: and testing by using a universal tensile tester. And replacing the components in the test sample into a rectangular closed plastic frame, and bonding one side edge of the plastic frame on the adhesive tape. During testing, the upper side edge of the plastic frame and the PCB are respectively clamped on the upper clamp and the lower clamp, and testing is started. After the plastic frame and the PCB are mutually separated, the maximum tension value is recorded, and the average value F of three parallel test samples is calculated and recorded max（N）。
The experimental results are as follows: the results of the patch adhesive strength test are reported in table 6.
TABLE 6 recording of the results of the adhesion strength test of the adhesive
And (3) data analysis: as can be seen from the data in the above table, comparative examples 1-2 all exhibited poor adhesive strength, and were not used; the adhesive strength of examples 1 to 12 was much better than that of comparative examples 1 to 2, and the practical requirements could be met.
The present embodiment is only for explaining the present invention, and it is not limited to the present invention, and those skilled in the art can make modifications of the present embodiment without inventive contribution as needed after reading the present specification, but all of them are protected by patent law within the scope of the claims of the present invention.
Claims (7)
1. A PCB board mounting process is characterized by comprising the following steps:
S1: printing solder paste on the surface A of the PCB;
S2: dispensing a piece of adhesive on the surface A of the PCB, pasting the component on the surface A, and enabling the surface A to face upwards to enter a reflow oven for reflow soldering;
S3: printing solder paste on the surface B of the PCB, pasting components on the surface B, and enabling the surface B to face upwards to enter a reflow furnace for reflow soldering;
The reflow furnace is internally provided with illumination equipment which is arranged in front of the reflow soldering area in the reflow furnace and positioned at two sides of the conveying belt; the detention time of the A surface of the PCB in the heating area is 2-4 min;
The patch adhesive comprises the following components in parts by weight:
An epoxy resin;
A thermosetting phenolic resin;
4-20 parts of a curing agent;
15-20 parts of a thixotropic agent;
3-15 parts of an auxiliary agent;
The total weight of the epoxy resin and the thermosetting phenolic resin is 100-150 parts;
The curing agent is a mixture of a visible light curing agent and a first curing agent or a visible light curing agent;
The thixotropic agent is organic bentonite or fumed silica;
The auxiliary agent comprises 0.5-4 parts of silane coupling agent, 1-2 parts of pigment, 1-4 parts of phenol and the balance of nano titanium dioxide.
2. The mounting process of the PCB as claimed in claim 1, wherein the residence time of the A surface of the PCB in the temperature rising zone is 2-2.6 min.
3. A mounting process for a PCB board according to claim 1, wherein the epoxy resin accounts for 70-82% of the total weight of the epoxy resin and the thermosetting phenol resin.
4. The mounting process of the PCB as recited in claim 1, wherein the first curing agent is composed of dicyanodiamine and imidazole, the visible light curing agent accounts for 75-80% of the total weight of the curing agent, and the weight ratio of dicyanodiamine to imidazole is (1.8-2.2): 1.
5. The mounting process of the PCB board according to claim 1, wherein the first curing agent comprises dicyanodiamine, imidazole and 0.5-3 parts of transition metal inorganic salt, the visible light curing agent accounts for 75-80% of the total weight of the curing agent, and the weight part ratio of dicyanodiamine to imidazole is (1.8-2.2): 1.
6. A mounting process for PCB board according to claim 5, wherein said transition metal inorganic salt is zinc chloride.
7. The mounting process of the PCB board according to claim 1, wherein the type of the silane coupling agent is one of kh560, kh570 and kh 792.
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| CN201659071U (en) * | 2010-03-09 | 2010-12-01 | 研祥智能科技股份有限公司 | Glue dispensing head |
| CN102079957B (en) * | 2010-12-09 | 2013-05-01 | 深圳市库泰克电子材料技术有限公司 | Low-temperature rapidly-curable surface mounting adhesive |
| CN106604564A (en) * | 2016-12-01 | 2017-04-26 | 广东威创视讯科技股份有限公司 | Surface mounting method for printed circuit board |
| CN109306255A (en) * | 2018-08-03 | 2019-02-05 | 瑞声科技(新加坡)有限公司 | Adhesive and loudspeaker enclosure |
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2019
- 2019-05-31 CN CN201910472018.4A patent/CN110248496B/en active Active
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| Publication number | Publication date |
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| CN110248496A (en) | 2019-09-17 |
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Denomination of invention: A PCB board mounting process and a mounting adhesive applied to the mounting process Effective date of registration: 20230216 Granted publication date: 20200731 Pledgee: Shenzhen Rural Commercial Bank Co.,Ltd. Nanshan Sub branch Pledgor: ABP ELECTRONICS LTD. Registration number: Y2023980032797 |