CN110881249A - FQC back-pass surface treatment method for double-sided circuit board - Google Patents

Abstract

The invention discloses a FQC back-end surface treatment method for a double-sided circuit board, which comprises the following steps: FQC, oil removal, secondary water washing, micro etching, secondary water washing, acid washing, DI water washing, OSP treatment, DI water washing, drying and discharging; in the OSP treatment, the PCB is placed in the soaking box, the upper cover of the soaking box is covered, liquid is fed from the front end of the soaking box, liquid is discharged from the rear end of the soaking box, the film forming liquid forms directional flow in the soaking box, the flow rate of the film forming liquid is 6-11 m/min.

Description

FQC back-pass surface treatment method for double-sided circuit board

Technical Field

The invention relates to the technical field of PCB (printed circuit board) processing, in particular to a FQC (field quality control) back-end surface treatment method for a double-sided circuit board.

Background

With the development of light weight, thinness, shortness, miniaturization and multi-functionalization of electronic products, printed circuit boards are developing towards high precision, thinness, multilayering and small hole, especially SMT is rapidly developing, so that high-density sheets (such as printed boards of IC cards, mobile phones, notebook computers, tuners and the like) for SMT are continuously developing, and the hot air leveling process is more and more not suitable for the requirements. Meanwhile, the Sn-Pb solder used by the hot air leveling process does not meet the requirement of environmental protection, and with the formal implementation of RoHS instruction of European Union of 7/1/2006, the industry is in urgent need to find a lead-free alternative way for PCB surface treatment, which is the most common way for Organic Solder Protection (OSP), Electroless Nickel Immersion (ENIG), silver immersion and tin immersion.

OSP is a process for surface treatment of Printed Circuit Board (PCB) copper foil that meets RoHS directive requirements. Briefly, OSP chemically grows an organic film on a clean bare copper surface. The film has the advantages of oxidation resistance, thermal shock resistance and moisture resistance, and is used for protecting the copper surface from continuously rusting (oxidation, vulcanization or the like) in a normal environment; however, at subsequent high soldering temperatures, the protective film must be readily removed by the flux so that the exposed clean copper surface can be immediately bonded to the molten solder in a very short time to form a strong solder joint.

The double-sided PCB is an important PCB in circuit boards, is provided with a double-sided circuit board metal base PCB, a Hi-Tg heavy copper foil circuit board, a flat meandering double-sided circuit board, a high-frequency PCB, a mixed dielectric base high-frequency double-sided circuit board and the like on the market, and is suitable for wide high and new technology industries such as telecommunication, power supply, computers, industrial control, digital products, scientific and educational instruments, medical appliances, automobiles, aerospace defense and the like.

The difference between the double-sided PCB and the single-sided PCB is that the circuit of the single-sided PCB is only arranged on one side of the PCB, while the circuit of the double-sided PCB can be arranged on two sides of the PCB, and the circuit of the double-sided PCB is connected by a via hole in the middle.

The parameter of the double-sided PCB is different from the parameter of the single-sided PCB in the manufacturing process of the double-sided PCB, and besides, a copper deposition process is added, namely, a process for conducting double-sided circuits is added.

The double-sided PCB adopts double-sided wiring, so the requirements on the OSP treatment on the surface are higher, and the OSP treatment in the prior art is formed by deposition, so the problem of uneven thickness of liquid crystal exists.

Disclosure of Invention

The invention aims to provide a back-process surface treatment method for FQC of a double-sided circuit board with uniform film thickness, which aims to solve the problems in the background technology.

In order to achieve the purpose, the invention provides the following technical scheme:

a back-end surface treatment method of a double-sided circuit board FQC,

the method comprises the following steps:

S1、FQC

in the working procedure, visual final inspection is carried out on the tested good PCBs, and the cleanliness of the PCB surfaces is confirmed;

s2 oil removal

Soaking the PCB with qualified cleanliness in degreasing liquid to perform a degreasing process;

s3 DI Water washing

Washing the degreased PCB with DI water;

s4 microetching

Placing the washed PCB in a microetching tank for microetching, wherein the purpose of microetching is to form a rough copper surface on the PCB so as to facilitate film formation;

s5, secondary washing with water

Carrying out secondary washing on the PCB subjected to the microetching by using purified water;

s6 acid washing

Pickling the washed PCB;

s7 DI Water washing

Washing the pickled PCB with DI water;

s8, OSP processing

Placing the PCB in a soaking box, covering an upper cover of the soaking box, feeding liquid from the front end of the soaking box, discharging liquid from the rear end of the soaking box, and allowing the film-forming liquid to form directional flow in the soaking box, wherein the flow rate of the film-forming liquid is 6-11 m/min;

s9 DI Water washing

DI water is adopted for washing, so that the conductivity is less than 500 us/cm;

s10, drying and discharging

And sequentially performing drying and discharging procedures, wherein in the discharging procedure, the PCB is subjected to vacuum packaging.

As a further scheme of the invention: the soaking box in the step S8 is a sealing structure and comprises a box body and an upper cover, the upper cover is arranged at the top of the box body, and a sealing strip is arranged between the upper cover and the box body; the front end of the box body is provided with a plurality of liquid inlets, the rear end of the box body is provided with a plurality of liquid outlets, the plurality of liquid inlets are connected with a liquid inlet collecting pipe through pipelines, the plurality of liquid outlets are connected with a liquid outlet collecting pipe through pipelines, and the liquid inlet collecting pipe and the liquid outlet collecting pipe are both connected with a film forming liquid tank through pipelines; a circulating pump is arranged on a pipeline between the liquid inlet collecting pipe and the film forming liquid tank; the liquid inlet collecting pipe is used for separating the film forming liquid in the film forming liquid tank into a plurality of liquid inlets through the circulating pump, then the liquid inlet collecting pipe enters the box body from the plurality of liquid inlets, the liquid outlet collecting pipe is discharged from the plurality of liquid outlets and collected, the liquid is recycled to the film forming liquid tank, and the film forming liquid flows in the box body when circulating.

As a further scheme of the invention: the inside of box body is equipped with anchor clamps, and anchor clamps are located the middle level of box body, are fixed in on the inner wall of box body. The clamp is used for clamping the PCB and is arranged on the middle layer to keep the PCB positioned on the middle layer of the box body.

As a further scheme of the invention: the liquid inlets on the box body are divided into two rows which are transversely arranged, and the two rows of liquid inlets are respectively positioned above and below the clamp. Convection currents can be formed above and below the PCB respectively, and the double-sided PCB processing is suitable.

As a further scheme of the invention: the liquid outlets on the box body are divided into two rows which are transversely arranged, and the two rows of liquid outlets are respectively positioned above and below the clamp. Convection currents can be formed above and below the PCB respectively, and the double-sided PCB processing is suitable.

As a further scheme of the invention: in step S8, the film thickness is detected.

As a further scheme of the invention: the membrane is thick detects the frequency and is tested twice for every shift, when thick >0.35um, reduces the liquid medicine acidity to reach the thick purpose of reduction membrane, when thick <0.2um, promote liquid medicine PH value, in order to reach the thick purpose of improvement membrane, and then control the membrane thickness at 0.2-0.35 um.

As a further scheme of the invention: the detection method of the film forming thickness comprises the following steps:

firstly, processing a single-side bare copper plate with the size of 40 multiplied by 50mm and a production plate together;

secondly, placing the treated single-side bare copper plate in a clean beaker;

taking 50ml of 5% hydrochloric acid solution by using a pipette, putting the hydrochloric acid solution into a beaker, slightly shaking the beaker, and taking out the plate after three minutes;

fourthly, using 5% hydrochloric acid solution to be zero, and measuring the absorbance at 269.1nm on a spectrophotometer of 751G;

fifthly, the absorbance A of the liquid in the beaker in the third step at 170nm on a spectrophotometer 751G;

sixthly, calculating to obtain the film thickness h, h is 0.7 xA (um).

Compared with the prior art, the invention has the beneficial effects that: according to the invention, the film is formed inside the soaking box with a fixed volume, and the surface of the circuit board is contacted with the film forming solution flowing at a constant speed, so that the circuit board is deposited in the flowing film forming solution to form a film, the uneven thickness of a film caused by the crystallization of the film forming solution and other factors is avoided, and a more smooth and uniform OSP film can be formed;

the flowing of the film forming liquid is limited by the soaking box, thereby effectively avoiding fluctuation and oscillation and avoiding influencing the flatness of the formed film.

Detailed Description

The present application is described in further detail below, and it should be noted that the following detailed description is provided for illustrative purposes only, and is not intended to limit the scope of the present application, which is defined by the appended claims.

Example one

A back-end surface treatment method for FQC of a double-sided circuit board comprises the following steps:

S1、FQC

in the working procedure, visual final inspection is carried out on the tested good PCB, the cleanliness of the PCB surface is confirmed, meanwhile, 10-20 sets of PCB surface are extracted for each batch to carry out a copper chloride test, when the cleanliness of the PCB surface does not meet the requirement, the working procedure of the PCB is improved, and when the cleanliness of the PCB surface meets the requirement, the PCB enters an oil removing working procedure;

s2 oil removal

The PCB with qualified cleanliness is soaked in degreasing liquid to carry out a degreasing process, and the quality of a degreasing effect directly influences the film forming quality. If the degreasing is poor, the film thickness is not uniform. In one aspect, the concentration can be controlled within a process range by analyzing the solution. On the other hand, whether the oil removal effect is good or not is often checked, and if the oil removal effect is not good, the oil removal liquid should be replaced in time.

S3 DI Water washing

Washing the degreased PCB with DI water;

s4 microetching

And placing the washed PCB in a microetching groove for microetching, wherein the purpose of microetching is to form a rough copper surface on the PCB so as to facilitate film formation. The thickness of the microetching directly affects the film forming rate, and therefore, it is very important to maintain the stability of the microetching thickness for forming a stable film thickness, and the microetching rate of the microetching bath is controlled to be between 1 to 2 um. Before each production, the microetching rate can be measured, and the microetching time can be determined according to the microetching rate.

S5, secondary washing with water

Carrying out secondary washing on the PCB subjected to the microetching by using purified water;

s6 acid washing

Pickling the washed PCB;

s7 DI Water washing

Washing the pickled PCB with DI water;

s8, OSP processing

Placing the PCB in a soaking box, covering an upper cover of the soaking box, feeding liquid from the front end of the soaking box, discharging liquid from the rear end of the soaking box, and allowing the film-forming liquid to form directional flow in the soaking box, wherein the flow rate of the film-forming liquid is 6 m/min;

s9 DI Water washing

DI water is adopted for washing, so that the conductivity is less than 500 us/cm;

s10, drying and discharging

And sequentially performing drying and discharging procedures, wherein in the discharging procedure, the PCB is subjected to vacuum packaging.

Wherein in the detecting and discharging process, the humidity of the inspection workshop and the packaging workshop is controlled at 50%. In S1-S10, workers in contact with the PCB all wear finger-stall work. In addition, DI water was used for washing in the washing steps S1-S10 to prevent the deposition solution from being contaminated.

The soaking box in the S8 is a sealing structure and comprises a box body and an upper cover, wherein the upper cover is arranged at the top of the box body, and a sealing strip is arranged between the upper cover and the box body; the front end of the box body is provided with a plurality of liquid inlets, the rear end of the box body is provided with a plurality of liquid outlets, the plurality of liquid inlets are connected with a liquid inlet collecting pipe through pipelines, the plurality of liquid outlets are connected with a liquid outlet collecting pipe through pipelines, and the liquid inlet collecting pipe and the liquid outlet collecting pipe are both connected with a film forming liquid tank through pipelines; a circulating pump is arranged on a pipeline between the liquid inlet collecting pipe and the film forming liquid tank; the liquid inlet collecting pipe is used for separating the film forming liquid in the film forming liquid tank into a plurality of liquid inlets through the circulating pump, then the liquid inlet collecting pipe enters the box body from the plurality of liquid inlets, the liquid outlet collecting pipe is discharged from the plurality of liquid outlets and collected, the liquid is recycled to the film forming liquid tank, and the film forming liquid flows in the box body when circulating.

Preferably, the inside of box body is equipped with anchor clamps, and anchor clamps are located the middle level of box body, are fixed in on the inner wall of box body. The clamp is used for clamping the PCB and is arranged on the middle layer to keep the PCB positioned on the middle layer of the box body.

Preferably, the liquid inlets on the box body are divided into two rows which are transversely arranged, and the two rows of liquid inlets are respectively positioned above and below the clamp. Convection currents can be formed above and below the PCB respectively, and the double-sided PCB processing is suitable.

Preferably, the liquid outlets on the box body are divided into two rows which are transversely arranged, and the two rows of liquid outlets are respectively positioned above and below the clamp. Convection currents can be formed above and below the PCB respectively, and the double-sided PCB processing is suitable.

Preferably, flow regulating valves are arranged on pipelines between the liquid inlet and the liquid inlet collecting pipe and pipelines between the liquid outlet and the liquid outlet collecting pipe.

Detecting the film thickness in S8, wherein the film thickness detection frequency is twice per shift, when the film thickness is greater than 0.35um, the acidity of the liquid medicine is reduced to achieve the purpose of reducing the film thickness, when the film thickness is less than 0.2um, the PH value of the liquid medicine is increased to achieve the purpose of increasing the film thickness, and further the film thickness is controlled to be 0.2-0.35 um;

the detection method of the film forming thickness comprises the following steps:

firstly, processing a single-side bare copper plate with the size of 40 multiplied by 50mm and a production plate together;

secondly, placing the treated single-side bare copper plate in a clean beaker;

taking 50ml of 5% hydrochloric acid solution by using a pipette, putting the hydrochloric acid solution into a beaker, slightly shaking the beaker, and taking out the plate after three minutes;

fourthly, using 5% hydrochloric acid solution to be zero, and measuring the absorbance at 269.1nm on a spectrophotometer of 751G;

fifthly, the absorbance A of the liquid in the beaker in the third step at 170nm on a spectrophotometer 751G;

sixthly, calculating to obtain the film thickness h, h is 0.7 xA (um).

Taking a single-side bare copper plate with the area larger than 400 x 500mm, dividing the single-side bare copper plate into 100 small pieces with the size of 40 x 50mm, randomly taking ten of the small pieces (respectively numbered 1-10), and detecting the film forming thickness, wherein the detection results are as follows:

example two

A back-end surface treatment method for FQC of a double-sided circuit board comprises the following steps:

S1、FQC

in the working procedure, visual final inspection is carried out on the tested good PCB, the cleanliness of the PCB surface is confirmed, meanwhile, 10-20 sets of PCB surface are extracted for each batch to carry out a copper chloride test, when the cleanliness of the PCB surface does not meet the requirement, the working procedure of the PCB is improved, and when the cleanliness of the PCB surface meets the requirement, the PCB enters an oil removing working procedure;

s2 oil removal

The PCB with qualified cleanliness is soaked in degreasing liquid to carry out a degreasing process, and the quality of a degreasing effect directly influences the film forming quality. If the degreasing is poor, the film thickness is not uniform. In one aspect, the concentration can be controlled within a process range by analyzing the solution. On the other hand, whether the oil removal effect is good or not is often checked, and if the oil removal effect is not good, the oil removal liquid should be replaced in time.

S3 DI Water washing

Washing the degreased PCB with DI water;

s4 microetching

And placing the washed PCB in a microetching groove for microetching, wherein the purpose of microetching is to form a rough copper surface on the PCB so as to facilitate film formation. The thickness of the microetching directly affects the film forming rate, and therefore, it is very important to maintain the stability of the microetching thickness for forming a stable film thickness, and the microetching rate of the microetching bath is controlled to be between 1 to 2 um. Before each production, the microetching rate can be measured, and the microetching time can be determined according to the microetching rate.

S5, secondary washing with water

Carrying out secondary washing on the PCB subjected to the microetching by using purified water;

s6 acid washing

Pickling the washed PCB;

s7 DI Water washing

Washing the pickled PCB with DI water;

s8, OSP processing

Placing the PCB in a soaking box, covering an upper cover of the soaking box, feeding liquid from the front end of the soaking box, discharging liquid from the rear end of the soaking box, and allowing a film forming liquid to form directional flow in the soaking box, wherein the flow rate of the film forming liquid is 6.5 m/min;

s9 DI Water washing

DI water is adopted for washing, so that the conductivity is less than 500 us/cm;

s10, drying and discharging

And sequentially performing drying and discharging procedures, wherein in the discharging procedure, the PCB is subjected to vacuum packaging.

Wherein in the detecting and discharging process, the humidity of the inspection workshop and the packaging workshop is controlled at 50%. In S1-S10, workers in contact with the PCB all wear finger-stall work. In addition, DI water was used for washing in the washing steps S1-S10 to prevent the deposition solution from being contaminated.

Detecting the film thickness in S8, wherein the film thickness detection frequency is twice per shift, when the film thickness is greater than 0.35um, the acidity of the liquid medicine is reduced to achieve the purpose of reducing the film thickness, when the film thickness is less than 0.2um, the PH value of the liquid medicine is increased to achieve the purpose of increasing the film thickness, and further the film thickness is controlled to be 0.2-0.35 um;

the detection method of the film forming thickness comprises the following steps:

firstly, processing a single-side bare copper plate with the size of 40 multiplied by 50mm and a production plate together;

secondly, placing the treated single-side bare copper plate in a clean beaker;

taking 50ml of 5% hydrochloric acid solution by using a pipette, putting the hydrochloric acid solution into a beaker, slightly shaking the beaker, and taking out the plate after three minutes;

fourthly, using 5% hydrochloric acid solution to be zero, and measuring the absorbance at 269.1nm on a spectrophotometer of 751G;

fifthly, the absorbance A of the liquid in the beaker in the third step at 170nm on a spectrophotometer 751G;

sixthly, calculating to obtain the film thickness h, h is 0.7 xA (um).

Taking a single-side bare copper plate with the area larger than 400 x 500mm, dividing the single-side bare copper plate into 100 small pieces with the size of 40 x 50mm, randomly taking ten of the small pieces (respectively numbered 1-10), and detecting the film forming thickness, wherein the detection results are as follows:

EXAMPLE III

A back-end surface treatment method for FQC of a double-sided circuit board comprises the following steps:

S1、FQC

in the working procedure, visual final inspection is carried out on the tested good PCB, the cleanliness of the PCB surface is confirmed, meanwhile, 10-20 sets of PCB surface are extracted for each batch to carry out a copper chloride test, when the cleanliness of the PCB surface does not meet the requirement, the working procedure of the PCB is improved, and when the cleanliness of the PCB surface meets the requirement, the PCB enters an oil removing working procedure;

s2 oil removal

The PCB with qualified cleanliness is soaked in degreasing liquid to carry out a degreasing process, and the quality of a degreasing effect directly influences the film forming quality. If the degreasing is poor, the film thickness is not uniform. In one aspect, the concentration can be controlled within a process range by analyzing the solution. On the other hand, whether the oil removal effect is good or not is often checked, and if the oil removal effect is not good, the oil removal liquid should be replaced in time.

S3 DI Water washing

Washing the degreased PCB with DI water;

s4 microetching

And placing the washed PCB in a microetching groove for microetching, wherein the purpose of microetching is to form a rough copper surface on the PCB so as to facilitate film formation. The thickness of the microetching directly affects the film forming rate, and therefore, it is very important to maintain the stability of the microetching thickness for forming a stable film thickness, and the microetching rate of the microetching bath is controlled to be between 1 to 2 um. Before each production, the microetching rate can be measured, and the microetching time can be determined according to the microetching rate.

S5, secondary washing with water

Carrying out secondary washing on the PCB subjected to the microetching by using purified water;

s6 acid washing

Pickling the washed PCB;

s7 DI Water washing

Washing the pickled PCB with DI water;

s8, OSP processing

Placing the PCB in a soaking box, covering an upper cover of the soaking box, feeding liquid from the front end of the soaking box, discharging liquid from the rear end of the soaking box, and allowing a film forming liquid to form directional flow in the soaking box, wherein the flow rate of the film forming liquid is 7 m/min;

s9 DI Water washing

DI water is adopted for washing, so that the conductivity is less than 500 us/cm;

s10, drying and discharging

And sequentially performing drying and discharging procedures, wherein in the discharging procedure, the PCB is subjected to vacuum packaging.

Wherein in the detecting and discharging process, the humidity of the inspection workshop and the packaging workshop is controlled at 50%. In S1-S10, workers in contact with the PCB all wear finger-stall work. In addition, DI water was used for washing in the washing steps S1-S10 to prevent the deposition solution from being contaminated.

Detecting the film thickness in S8, wherein the film thickness detection frequency is twice per shift, when the film thickness is greater than 0.35um, the acidity of the liquid medicine is reduced to achieve the purpose of reducing the film thickness, when the film thickness is less than 0.2um, the PH value of the liquid medicine is increased to achieve the purpose of increasing the film thickness, and further the film thickness is controlled to be 0.2-0.35 um;

the detection method of the film forming thickness comprises the following steps:

firstly, processing a single-side bare copper plate with the size of 40 multiplied by 50mm and a production plate together;

secondly, placing the treated single-side bare copper plate in a clean beaker;

taking 50ml of 5% hydrochloric acid solution by using a pipette, putting the hydrochloric acid solution into a beaker, slightly shaking the beaker, and taking out the plate after three minutes;

fourthly, using 5% hydrochloric acid solution to be zero, and measuring the absorbance at 269.1nm on a spectrophotometer of 751G;

fifthly, the absorbance A of the liquid in the beaker in the third step at 170nm on a spectrophotometer 751G;

sixthly, calculating to obtain the film thickness h, h is 0.7 xA (um).

Taking a single-side bare copper plate with the area larger than 400 x 500mm, dividing the single-side bare copper plate into 100 small pieces with the size of 40 x 50mm, randomly taking ten of the small pieces (respectively numbered 1-10), and detecting the film forming thickness, wherein the detection results are as follows:

example four

A back-end surface treatment method for FQC of a double-sided circuit board comprises the following steps:

S1、FQC

in the working procedure, visual final inspection is carried out on the tested good PCB, the cleanliness of the PCB surface is confirmed, meanwhile, 10-20 sets of PCB surface are extracted for each batch to carry out a copper chloride test, when the cleanliness of the PCB surface does not meet the requirement, the working procedure of the PCB is improved, and when the cleanliness of the PCB surface meets the requirement, the PCB enters an oil removing working procedure;

s2 oil removal

The PCB with qualified cleanliness is soaked in degreasing liquid to carry out a degreasing process, and the quality of a degreasing effect directly influences the film forming quality. If the degreasing is poor, the film thickness is not uniform. In one aspect, the concentration can be controlled within a process range by analyzing the solution. On the other hand, whether the oil removal effect is good or not is often checked, and if the oil removal effect is not good, the oil removal liquid should be replaced in time.

S3 DI Water washing

Washing the degreased PCB with DI water;

s4 microetching

And placing the washed PCB in a microetching groove for microetching, wherein the purpose of microetching is to form a rough copper surface on the PCB so as to facilitate film formation. The thickness of the microetching directly affects the film forming rate, and therefore, it is very important to maintain the stability of the microetching thickness for forming a stable film thickness, and the microetching rate of the microetching bath is controlled to be between 1 to 2 um. Before each production, the microetching rate can be measured, and the microetching time can be determined according to the microetching rate.

S5, secondary washing with water

Carrying out secondary washing on the PCB subjected to the microetching by using purified water;

s6 acid washing

Pickling the washed PCB;

s7 DI Water washing

Washing the pickled PCB with DI water;

s8, OSP processing

Placing the PCB in a soaking box, covering an upper cover of the soaking box, feeding liquid from the front end of the soaking box, discharging liquid from the rear end of the soaking box, and allowing a film forming liquid to form directional flow in the soaking box, wherein the flow rate of the film forming liquid is 7.5 m/min;

s9 DI Water washing

DI water is adopted for washing, so that the conductivity is less than 500 us/cm;

s10, drying and discharging

And sequentially performing drying and discharging procedures, wherein in the discharging procedure, the PCB is subjected to vacuum packaging.

Wherein in the detecting and discharging process, the humidity of the inspection workshop and the packaging workshop is controlled at 50%. In S1-S10, workers in contact with the PCB all wear finger-stall work. In addition, DI water was used for washing in the washing steps S1-S10 to prevent the deposition solution from being contaminated.

Detecting the film thickness in S8, wherein the film thickness detection frequency is twice per shift, when the film thickness is greater than 0.35um, the acidity of the liquid medicine is reduced to achieve the purpose of reducing the film thickness, when the film thickness is less than 0.2um, the PH value of the liquid medicine is increased to achieve the purpose of increasing the film thickness, and further the film thickness is controlled to be 0.2-0.35 um;

the detection method of the film forming thickness comprises the following steps:

firstly, processing a single-side bare copper plate with the size of 40 multiplied by 50mm and a production plate together;

secondly, placing the treated single-side bare copper plate in a clean beaker;

taking 50ml of 5% hydrochloric acid solution by using a pipette, putting the hydrochloric acid solution into a beaker, slightly shaking the beaker, and taking out the plate after three minutes;

fourthly, using 5% hydrochloric acid solution to be zero, and measuring the absorbance at 269.1nm on a spectrophotometer of 751G;

fifthly, the absorbance A of the liquid in the beaker in the third step at 170nm on a spectrophotometer 751G;

sixthly, calculating to obtain the film thickness h, h is 0.7 xA (um).

Taking a single-side bare copper plate with the area larger than 400 x 500mm, dividing the single-side bare copper plate into 100 small pieces with the size of 40 x 50mm, randomly taking ten of the small pieces (respectively numbered 1-10), and detecting the film forming thickness, wherein the detection results are as follows:

EXAMPLE five

A back-end surface treatment method for FQC of a double-sided circuit board comprises the following steps:

S1、FQC

in the working procedure, visual final inspection is carried out on the tested good PCB, the cleanliness of the PCB surface is confirmed, meanwhile, 10-20 sets of PCB surface are extracted for each batch to carry out a copper chloride test, when the cleanliness of the PCB surface does not meet the requirement, the working procedure of the PCB is improved, and when the cleanliness of the PCB surface meets the requirement, the PCB enters an oil removing working procedure;

s2 oil removal

The PCB with qualified cleanliness is soaked in degreasing liquid to carry out a degreasing process, and the quality of a degreasing effect directly influences the film forming quality. If the degreasing is poor, the film thickness is not uniform. In one aspect, the concentration can be controlled within a process range by analyzing the solution. On the other hand, whether the oil removal effect is good or not is often checked, and if the oil removal effect is not good, the oil removal liquid should be replaced in time.

S3 DI Water washing

Washing the degreased PCB with DI water;

s4 microetching

And placing the washed PCB in a microetching groove for microetching, wherein the purpose of microetching is to form a rough copper surface on the PCB so as to facilitate film formation. The thickness of the microetching directly affects the film forming rate, and therefore, it is very important to maintain the stability of the microetching thickness for forming a stable film thickness, and the microetching rate of the microetching bath is controlled to be between 1 to 2 um. Before each production, the microetching rate can be measured, and the microetching time can be determined according to the microetching rate.

S5, secondary washing with water

Carrying out secondary washing on the PCB subjected to the microetching by using purified water;

s6 acid washing

Pickling the washed PCB;

s7 DI Water washing

Washing the pickled PCB with DI water;

s8, OSP processing

Placing the PCB in a soaking box, covering an upper cover of the soaking box, feeding liquid from the front end of the soaking box, discharging liquid from the rear end of the soaking box, and allowing a film forming liquid to form directional flow in the soaking box, wherein the flow rate of the film forming liquid is 8 m/min;

s9 DI Water washing

DI water is adopted for washing, so that the conductivity is less than 500 us/cm;

s10, drying and discharging

And sequentially performing drying and discharging procedures, wherein in the discharging procedure, the PCB is subjected to vacuum packaging.

Wherein in the detecting and discharging process, the humidity of the inspection workshop and the packaging workshop is controlled at 50%. In S1-S10, workers in contact with the PCB all wear finger-stall work. In addition, DI water was used for washing in the washing steps S1-S10 to prevent the deposition solution from being contaminated.

Detecting the film thickness in S8, wherein the film thickness detection frequency is twice per shift, when the film thickness is greater than 0.35um, the acidity of the liquid medicine is reduced to achieve the purpose of reducing the film thickness, when the film thickness is less than 0.2um, the PH value of the liquid medicine is increased to achieve the purpose of increasing the film thickness, and further the film thickness is controlled to be 0.2-0.35 um;

the detection method of the film forming thickness comprises the following steps:

firstly, processing a single-side bare copper plate with the size of 40 multiplied by 50mm and a production plate together;

secondly, placing the treated single-side bare copper plate in a clean beaker;

taking 50ml of 5% hydrochloric acid solution by using a pipette, putting the hydrochloric acid solution into a beaker, slightly shaking the beaker, and taking out the plate after three minutes;

fourthly, using 5% hydrochloric acid solution to be zero, and measuring the absorbance at 269.1nm on a spectrophotometer of 751G;

fifthly, the absorbance A of the liquid in the beaker in the third step at 170nm on a spectrophotometer 751G;

sixthly, calculating to obtain the film thickness h, h is 0.7 xA (um).

Taking a single-side bare copper plate with the area larger than 400 x 500mm, dividing the single-side bare copper plate into 100 small pieces with the size of 40 x 50mm, randomly taking ten of the small pieces (respectively numbered 1-10), and detecting the film forming thickness, wherein the detection results are as follows:

EXAMPLE six

A back-end surface treatment method for FQC of a double-sided circuit board comprises the following steps:

S1、FQC

in the working procedure, visual final inspection is carried out on the tested good PCB, the cleanliness of the PCB surface is confirmed, meanwhile, 10-20 sets of PCB surface are extracted for each batch to carry out a copper chloride test, when the cleanliness of the PCB surface does not meet the requirement, the working procedure of the PCB is improved, and when the cleanliness of the PCB surface meets the requirement, the PCB enters an oil removing working procedure;

s2 oil removal

The PCB with qualified cleanliness is soaked in degreasing liquid to carry out a degreasing process, and the quality of a degreasing effect directly influences the film forming quality. If the degreasing is poor, the film thickness is not uniform. In one aspect, the concentration can be controlled within a process range by analyzing the solution. On the other hand, whether the oil removal effect is good or not is often checked, and if the oil removal effect is not good, the oil removal liquid should be replaced in time.

S3 DI Water washing

Washing the degreased PCB with DI water;

s4 microetching

And placing the washed PCB in a microetching groove for microetching, wherein the purpose of microetching is to form a rough copper surface on the PCB so as to facilitate film formation. The thickness of the microetching directly affects the film forming rate, and therefore, it is very important to maintain the stability of the microetching thickness for forming a stable film thickness, and the microetching rate of the microetching bath is controlled to be between 1 to 2 um. Before each production, the microetching rate can be measured, and the microetching time can be determined according to the microetching rate.

S5, secondary washing with water

Carrying out secondary washing on the PCB subjected to the microetching by using purified water;

s6 acid washing

Pickling the washed PCB;

s7 DI Water washing

Washing the pickled PCB with DI water;

s8, OSP processing

Placing the PCB in a soaking box, covering an upper cover of the soaking box, feeding liquid from the front end of the soaking box, discharging liquid from the rear end of the soaking box, and allowing the film-forming liquid to form directional flow in the soaking box, wherein the flow rate of the film-forming liquid is 9 m/min;

s9 DI Water washing

DI water is adopted for washing, so that the conductivity is less than 500 us/cm;

s10, drying and discharging

And sequentially performing drying and discharging procedures, wherein in the discharging procedure, the PCB is subjected to vacuum packaging.

Wherein in the detecting and discharging process, the humidity of the inspection workshop and the packaging workshop is controlled at 50%. In S1-S10, workers in contact with the PCB all wear finger-stall work. In addition, DI water was used for washing in the washing steps S1-S10 to prevent the deposition solution from being contaminated.

Detecting the film thickness in S8, wherein the film thickness detection frequency is twice per shift, when the film thickness is greater than 0.35um, the acidity of the liquid medicine is reduced to achieve the purpose of reducing the film thickness, when the film thickness is less than 0.2um, the PH value of the liquid medicine is increased to achieve the purpose of increasing the film thickness, and further the film thickness is controlled to be 0.2-0.35 um;

the detection method of the film forming thickness comprises the following steps:

firstly, processing a single-side bare copper plate with the size of 40 multiplied by 50mm and a production plate together;

secondly, placing the treated single-side bare copper plate in a clean beaker;

taking 50ml of 5% hydrochloric acid solution by using a pipette, putting the hydrochloric acid solution into a beaker, slightly shaking the beaker, and taking out the plate after three minutes;

fourthly, using 5% hydrochloric acid solution to be zero, and measuring the absorbance at 269.1nm on a spectrophotometer of 751G;

fifthly, the absorbance A of the liquid in the beaker in the third step at 170nm on a spectrophotometer 751G;

sixthly, calculating to obtain the film thickness h, h is 0.7 xA (um).

Taking a single-side bare copper plate with the area larger than 400 x 500mm, dividing the single-side bare copper plate into 100 small pieces with the size of 40 x 50mm, randomly taking ten of the small pieces (respectively numbered 1-10), and detecting the film forming thickness, wherein the detection results are as follows:

EXAMPLE seven

A back-end surface treatment method for FQC of a double-sided circuit board comprises the following steps:

S1、FQC

in the working procedure, visual final inspection is carried out on the tested good PCB, the cleanliness of the PCB surface is confirmed, meanwhile, 10-20 sets of PCB surface are extracted for each batch to carry out a copper chloride test, when the cleanliness of the PCB surface does not meet the requirement, the working procedure of the PCB is improved, and when the cleanliness of the PCB surface meets the requirement, the PCB enters an oil removing working procedure;

s2 oil removal

The PCB with qualified cleanliness is soaked in degreasing liquid to carry out a degreasing process, and the quality of a degreasing effect directly influences the film forming quality. If the degreasing is poor, the film thickness is not uniform. In one aspect, the concentration can be controlled within a process range by analyzing the solution. On the other hand, whether the oil removal effect is good or not is often checked, and if the oil removal effect is not good, the oil removal liquid should be replaced in time.

S3 DI Water washing

Washing the degreased PCB with DI water;

s4 microetching

And placing the washed PCB in a microetching groove for microetching, wherein the purpose of microetching is to form a rough copper surface on the PCB so as to facilitate film formation. The thickness of the microetching directly affects the film forming rate, and therefore, it is very important to maintain the stability of the microetching thickness for forming a stable film thickness, and the microetching rate of the microetching bath is controlled to be between 1 to 2 um. Before each production, the microetching rate can be measured, and the microetching time can be determined according to the microetching rate.

S5, secondary washing with water

Carrying out secondary washing on the PCB subjected to the microetching by using purified water;

s6 acid washing

Pickling the washed PCB;

s7 DI Water washing

Washing the pickled PCB with DI water;

s8, OSP processing

Placing the PCB in a soaking box, covering an upper cover of the soaking box, feeding liquid from the front end of the soaking box, discharging liquid from the rear end of the soaking box, and allowing a film forming liquid to form directional flow in the soaking box, wherein the flow rate of the film forming liquid is 10 m/min;

s9 DI Water washing

DI water is adopted for washing, so that the conductivity is less than 500 us/cm;

s10, drying and discharging

And sequentially performing drying and discharging procedures, wherein in the discharging procedure, the PCB is subjected to vacuum packaging.

Wherein in the detecting and discharging process, the humidity of the inspection workshop and the packaging workshop is controlled at 50%. In S1-S10, workers in contact with the PCB all wear finger-stall work. In addition, DI water was used for washing in the washing steps S1-S10 to prevent the deposition solution from being contaminated.

Detecting the film thickness in S8, wherein the film thickness detection frequency is twice per shift, when the film thickness is greater than 0.35um, the acidity of the liquid medicine is reduced to achieve the purpose of reducing the film thickness, when the film thickness is less than 0.2um, the PH value of the liquid medicine is increased to achieve the purpose of increasing the film thickness, and further the film thickness is controlled to be 0.2-0.35 um;

the detection method of the film forming thickness comprises the following steps:

firstly, processing a single-side bare copper plate with the size of 40 multiplied by 50mm and a production plate together;

secondly, placing the treated single-side bare copper plate in a clean beaker;

taking 50ml of 5% hydrochloric acid solution by using a pipette, putting the hydrochloric acid solution into a beaker, slightly shaking the beaker, and taking out the plate after three minutes;

fourthly, using 5% hydrochloric acid solution to be zero, and measuring the absorbance at 269.1nm on a spectrophotometer of 751G;

fifthly, the absorbance A of the liquid in the beaker in the third step at 170nm on a spectrophotometer 751G;

sixthly, calculating to obtain the film thickness h, h is 0.7 xA (um).

Taking a single-side bare copper plate with the area larger than 400 x 500mm, dividing the single-side bare copper plate into 100 small pieces with the size of 40 x 50mm, randomly taking ten of the small pieces (respectively numbered 1-10), and detecting the film forming thickness, wherein the detection results are as follows:

example eight

A back-end surface treatment method for FQC of a double-sided circuit board comprises the following steps:

S1、FQC

in the working procedure, visual final inspection is carried out on the tested good PCB, the cleanliness of the PCB surface is confirmed, meanwhile, 10-20 sets of PCB surface are extracted for each batch to carry out a copper chloride test, when the cleanliness of the PCB surface does not meet the requirement, the working procedure of the PCB is improved, and when the cleanliness of the PCB surface meets the requirement, the PCB enters an oil removing working procedure;

s2 oil removal

The PCB with qualified cleanliness is soaked in degreasing liquid to carry out a degreasing process, and the quality of a degreasing effect directly influences the film forming quality. If the degreasing is poor, the film thickness is not uniform. In one aspect, the concentration can be controlled within a process range by analyzing the solution. On the other hand, whether the oil removal effect is good or not is often checked, and if the oil removal effect is not good, the oil removal liquid should be replaced in time.

S3 DI Water washing

Washing the degreased PCB with DI water;

s4 microetching

And placing the washed PCB in a microetching groove for microetching, wherein the purpose of microetching is to form a rough copper surface on the PCB so as to facilitate film formation. The thickness of the microetching directly affects the film forming rate, and therefore, it is very important to maintain the stability of the microetching thickness for forming a stable film thickness, and the microetching rate of the microetching bath is controlled to be between 1 to 2 um. Before each production, the microetching rate can be measured, and the microetching time can be determined according to the microetching rate.

S5, secondary washing with water

Carrying out secondary washing on the PCB subjected to the microetching by using purified water;

s6 acid washing

Pickling the washed PCB;

s7 DI Water washing

Washing the pickled PCB with DI water;

s8, OSP processing

Placing the PCB in a soaking box, covering an upper cover of the soaking box, feeding liquid from the front end of the soaking box, discharging liquid from the rear end of the soaking box, and allowing a film forming liquid to form directional flow in the soaking box, wherein the flow rate of the film forming liquid is 11 m/min;

s9 DI Water washing

DI water is adopted for washing, so that the conductivity is less than 500 us/cm;

s10, drying and discharging

And sequentially performing drying and discharging procedures, wherein in the discharging procedure, the PCB is subjected to vacuum packaging.

Wherein in the detecting and discharging process, the humidity of the inspection workshop and the packaging workshop is controlled at 50%. In S1-S10, workers in contact with the PCB all wear finger-stall work. In addition, DI water was used for washing in the washing steps S1-S10 to prevent the deposition solution from being contaminated.

Detecting the film thickness in S8, wherein the film thickness detection frequency is twice per shift (6h), when the film thickness is more than 0.35um, the acidity of the liquid medicine is reduced to achieve the purpose of reducing the film thickness, when the film thickness is less than 0.2um, the PH value of the liquid medicine is increased to achieve the purpose of increasing the film thickness, and then the film thickness is controlled to be 0.2-0.35 um;

the detection method of the film forming thickness comprises the following steps:

firstly, processing a single-side bare copper plate with the size of 40 multiplied by 50mm and a production plate together;

secondly, placing the treated single-side bare copper plate in a clean beaker;

taking 50ml of 5% hydrochloric acid solution by using a pipette, putting the hydrochloric acid solution into a beaker, slightly shaking the beaker, and taking out the plate after three minutes;

fourthly, using 5% hydrochloric acid solution to be zero, and measuring the absorbance at 269.1nm on a spectrophotometer of 751G;

fifthly, the absorbance A of the liquid in the beaker in the third step at 170nm on a spectrophotometer 751G;

sixthly, calculating to obtain the film forming thickness h, h is 0.7 xA (um);

taking a single-side bare copper plate with the area larger than 400 x 500mm, dividing the single-side bare copper plate into 100 small pieces with the size of 40 x 50mm, randomly taking ten of the small pieces (respectively numbered 1-10), and detecting the film forming thickness, wherein the detection results are as follows:

although the preferred embodiments of the present patent have been described in detail, the present patent is not limited to the above embodiments, and various changes can be made without departing from the spirit of the present patent within the knowledge of those skilled in the art.

Claims (8)

1. A back-end surface treatment method for FQC of a double-sided circuit board is characterized by comprising the following steps:

S1、FQC

in the working procedure, visual final inspection is carried out on the tested good PCBs, and the cleanliness of the PCB surfaces is confirmed;

s2 oil removal

Soaking the PCB with qualified cleanliness in degreasing liquid to perform a degreasing process;

s3 DI Water washing

Washing the degreased PCB with DI water;

s4 microetching

Placing the washed PCB in a microetching tank for microetching, wherein the purpose of microetching is to form a rough copper surface on the PCB so as to facilitate film formation;

s5, secondary washing with water

Carrying out secondary washing on the PCB subjected to the microetching by using purified water;

s6 acid washing

Pickling the washed PCB;

s7 DI Water washing

Washing the pickled PCB with DI water;

s8, OSP processing

Placing the PCB in a soaking box, covering an upper cover of the soaking box, feeding liquid from the front end of the soaking box, discharging liquid from the rear end of the soaking box, and allowing the film-forming liquid to form directional flow in the soaking box, wherein the flow rate of the film-forming liquid is 6-11 m/min;

s9 DI Water washing

DI water is adopted for washing, so that the conductivity is less than 500 us/cm;

s10, drying and discharging

And sequentially performing drying and discharging procedures, wherein in the discharging procedure, the PCB is subjected to vacuum packaging.

2. The double-sided circuit board FQC back-end surface treatment method according to claim 1, wherein the soaking box in step S8 is a sealed structure, and comprises a box body and an upper cover, the top of the box body is provided with the upper cover, and a sealing strip is arranged between the upper cover and the box body; the front end of the box body is provided with a plurality of liquid inlets, the rear end of the box body is provided with a plurality of liquid outlets, the plurality of liquid inlets are connected with a liquid inlet collecting pipe through pipelines, the plurality of liquid outlets are connected with a liquid outlet collecting pipe through pipelines, and the liquid inlet collecting pipe and the liquid outlet collecting pipe are both connected with a film forming liquid tank through pipelines; a circulating pump is arranged on a pipeline between the liquid inlet collecting pipe and the film forming liquid tank; the liquid inlet collecting pipe is used for separating the film forming liquid in the film forming liquid tank into a plurality of liquid inlets through the circulating pump, then the liquid inlet collecting pipe enters the box body from the plurality of liquid inlets, the liquid outlet collecting pipe is discharged from the plurality of liquid outlets and collected, the liquid is recycled to the film forming liquid tank, and the film forming liquid flows in the box body when circulating.

3. The FQC post-process surface treatment method for the double-sided circuit board according to claim 2, wherein the box body is internally provided with a clamp, and the clamp is arranged at the middle layer of the box body and fixed on the inner wall of the box body.

4. The back-end surface treatment method for the FQC of a double-sided circuit board according to claim 2, wherein the liquid inlets on the box body are divided into two rows which are transversely arranged, and the two rows of liquid inlets are respectively positioned above and below the clamp.

5. The back-end surface treatment method for the FQC of the double-sided circuit board according to claim 2, wherein the liquid outlets on the box body are divided into two rows arranged transversely, and the two rows of liquid outlets are respectively located above and below the clamps.

6. The double-sided circuit board FQC back-end surface treatment method according to claim 1, wherein the film thickness is detected in step S8.

7. The double-sided circuit board FQC back-end surface treatment method according to claim 6, wherein the film thickness detection frequency is twice per shift, when the film thickness is greater than 0.35um, the acidity of the liquid medicine is reduced to achieve the purpose of reducing the film thickness, when the film thickness is less than 0.2um, the PH value of the liquid medicine is increased to achieve the purpose of increasing the film thickness, and further the film thickness is controlled to be 0.2-0.35 um.

8. The FQC back-end surface treatment method of a double-sided circuit board according to claim 6, wherein the detection method of the film thickness comprises the following steps:

firstly, processing a single-side bare copper plate with the size of 40 multiplied by 50mm and a production plate together;

secondly, placing the treated single-side bare copper plate in a clean beaker;

taking 50ml of 5% hydrochloric acid solution by using a pipette, putting the hydrochloric acid solution into a beaker, slightly shaking the beaker, and taking out the plate after three minutes;

fourthly, using 5% hydrochloric acid solution to be zero, and measuring the absorbance at 269.1nm on a spectrophotometer of 751G;

fifthly, the absorbance A of the liquid in the beaker in the third step at 170nm on a spectrophotometer 751G;

sixthly, calculating to obtain the film thickness h, h is 0.7 xA (um).