Improved circuit board tin spraying process

Abstract

The invention discloses an improved circuit board tin spraying process which comprises the following steps: preparing a circuit board to be subjected to tin spraying or screen printing treatment, ensuring that the surface of the circuit board is clean, removing an oxide layer, performing cleaning pretreatment, operating a tin spraying machine to preheat tin spraying equipment, and adjusting tin spraying energy parameters. The method comprises the following steps: taking a plurality of pre-treated circuit boards as a group, putting the pre-treated circuit boards on a conveying belt of a tin spraying machine, and coating a tin spraying agent on a bonding pad area of the circuit boards by a tin spraying nozzle on the tin spraying machine after the positions of the circuit boards are ensured to be accurate. Under the same material and drying condition, different jet printing energies and different white oil block thicknesses are adopted, and the blistering influence factors after tin spraying of the white oil block plate are mainly as follows: the ink thickness is too large, the energy mode is too high, the jet printing extraction point is adjusted to be 25%, the energy is reduced to be 2 / 2 / 3, and 10 jet-printed plates are all qualified.

Description

Technical Field

[0001] The invention relates to the technical field of circuit board tin spraying, and in particular to an improved circuit board tin spraying process. Background Art

[0002] The names of circuit boards include: ceramic circuit boards, alumina ceramic circuit boards, aluminum nitride ceramic circuit boards, circuit boards, PCB boards, aluminum substrates, high-frequency boards, thick copper boards, impedance boards, PCBs, ultra-thin circuit boards, ultra-thin circuit boards, printed (copper etching technology) circuit boards, etc. Circuit boards make circuits miniaturized and intuitive, and play an important role in the mass production of fixed circuits and the optimization of electrical appliance layouts. Circuit boards can be called printed circuit boards or printed circuit boards. However, during the production process of circuit boards, the tin spraying process of circuit boards is one of the important links in the production of circuit boards. Tin spraying is also called hot air leveling. First, molten tin is applied to the surface of the circuit board, and then the solder is blown flat with heated compressed air. The molten solder is evenly attached to the copper skin and generates copper-tin oxide. The solder pad after tin spraying can effectively protect the copper skin from corrosion and increase the mechanical properties of the copper skin. However, when tin is sprayed on the surface of the circuit board in practice, the edge of the white oil block of the large white oil block is prone to bubbling and oil loss when the printed board is sprayed with tin, resulting in a lower qualified rate of the product after tin spraying. Therefore, an improved tin spraying process for circuit boards is provided to solve the above problems. Summary of the invention

[0003] In order to solve the problems in the above background technology, the technical solution adopted by the present invention to solve the technical problems is: an improved circuit board tin spraying process, which includes the following steps:

[0004] Step 1: First, prepare the circuit board to be tinned or silk-screened, ensure the surface of the circuit board is clean, and remove the oxide layer and pre-clean;

[0005] Step 2: Run the tin spraying machine to preheat the tin spraying equipment and adjust the tin spraying energy parameters. Then, extract several pre-treated circuit boards as a group and place them on the conveyor belt of the tin spraying machine. After ensuring that the position of the circuit boards is accurate, the tin spraying agent is applied to the pad area of ​​the circuit board by the tin spraying nozzle on the tin spraying machine.

[0006] Step 3: After the circuit board is coated with tin spray in step 3, the circuit board is sent to a drying room to dry the tin spray at high temperature to form a uniform solder layer;

[0007] Step 4: After drying in step 3, the circuit board enters the cooling area to cool and solidify the solder layer, and the circuit board is inspected by visual inspection system or automatic inspection equipment to check the quality and coverage of the solder layer;

[0008] Step 5: Complete ultrasonic cleaning or chemical cleaning to remove any residue or dirt generated during the tin spraying process, and finally test the quality of the circuit board to ensure that the quality of the solder layer of the circuit board meets the requirements.

[0009] As a preferred technical solution of the present invention, in step 2, the printing energy mode of the inkjet printer is adjusted to 2 / 2 / 3, and the printing sampling is 100% normal, and 10 pre-treated circuit boards are selected and sprayed with tin spray agent. After spraying, they are sent to the drying room for drying, and the drying temperature and time are 60℃ / 60min+70℃ / 60min+80℃ / 60min+90℃ / 30min+110℃ / 45min+130℃ / 45min+155℃ / 120min.

[0010] As a preferred technical solution of the present invention, or in step 2, the printing energy mode of the inkjet printer is adjusted to 2 / 2 / 3, and the printing sampling is 25% of the normal value, and 10 pre-treated circuit boards are selected and sprayed with tin spray agent, and after spraying, they are sent to the drying room for drying, and the drying temperature and time are 60℃ / 60min+70℃ / 60min+80℃ / 60min+90℃ / 30min+110℃ / 45min+130℃ / 45min+155℃ / 120min.

[0011] As a preferred technical solution of the present invention, or in step 2, the printing energy mode of the inkjet printer is adjusted to 4 / 2 / 3, and the printing sampling is 100% normal, and 76 pre-treated circuit boards are selected and sprayed with tin spray agent, and sent to the drying room for drying after spraying, and the drying temperature and time are 60℃ / 60min+70℃ / 60min+80℃ / 60min+90℃ / 30min+110℃ / 45min+130℃ / 45min+155℃ / 120min; after the circuit boards are sprayed with tin spray agent, dried and cooled, the normal number of circuit boards sprayed with tin is detected to be 2, and the yield rate is 2.6%.

[0012] As a preferred technical solution of the present invention, after the circuit board tin spraying agent is sprayed, dried and cooled, the normal number of circuit boards sprayed with tin is detected to be 5, and the yield rate is 50%.

[0013] As a preferred technical solution of the present invention, after the circuit board tin spraying agent is sprayed, dried and cooled, the normal number of circuit boards sprayed with tin is detected to be 10, and the yield rate is 100%.

[0014] As a preferred technical solution of the present invention, the test board parameters of the circuit board processed by silk screen printing are that the parameters of solder mask and characters are all made normally, the number of test boards extracted is 96 pieces, and the test result yield is 100%.

[0015] As a preferred technical solution of the present invention, the circuit board test board model is CP6F32471A4.

[0016] As a preferred technical solution of the present invention, the thickness of the normal 100% white oil block for printing is 19um-25um.

[0017] As a preferred technical solution of the present invention, the thickness of the white oil block for printing is 15um-21um according to 25% of the normal white oil block.

[0018] The present invention has the following advantages: when spraying tin on a circuit board, the present invention uses different printing energies and different white oil block thicknesses under the same material and drying conditions, and it is concluded that the main influencing factors of blistering of the white oil block board after spraying tin are that the ink thickness is too thick and the energy mode is too high. The printing sampling point is adjusted to 25%, the energy is lowered to 2 / 2 / 3, and 10 printed boards are all qualified. On this optimal basis, 96 boards are continuously manufactured according to the silk screen printing process, and all are qualified after spraying tin. BRIEF DESCRIPTION OF THE DRAWINGS

[0019] Figure 1 This is a schematic diagram of the operating principle of the circuit board tin spraying according to the preferred embodiment of the present invention;

[0020] Figure 2 It is a schematic diagram of the thickness of the white oil block with a printing point of 100% in a preferred embodiment of the present invention;

[0021] Figure 3 It is a schematic diagram of the thickness of the white oil block when the inkjet printing sampling point is adjusted to 25% in the preferred embodiment of the present invention. DETAILED DESCRIPTION

[0022] The technical solutions in the embodiments of the present invention are described clearly and completely below. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention. Many specific details are explained in the following description to facilitate a full understanding of the present invention. However, the present invention can also be implemented in other ways different from those described herein. Therefore, the scope of protection of the present invention is not limited by the specific embodiments disclosed below.

[0023] In order to more clearly understand the above-mentioned objects, features and advantages of the present invention, the present invention is further described in detail below with reference to the accompanying drawings and specific embodiments.

[0024] Embodiment 1

[0025] Please refer to Figure 1-Figure 3 The present invention provides an improved circuit board tin-spraying process, comprising the following steps:

[0026] Step 1: First, prepare the circuit board to be tinned, ensure the surface of the circuit board is clean, remove the oxide layer, and perform pre-cleaning treatment. The model of the circuit board is CP6F32471A4;

[0027] Step 2: Prepare the tin spraying equipment, run the tin spraying machine to preheat the tin spraying equipment, and adjust the tin spraying energy parameters. Then, extract several pre-treated circuit boards as a group, put them on the conveyor belt of the tin spraying machine, and ensure that the position of the circuit board is accurate. Then, the tin spraying agent is applied to the pad area of ​​the circuit board by the tin spraying nozzle on the tin spraying machine.

[0028] Step 3: tin spray coating. After the circuit board is tin-sprayed in step 3, the circuit board is sent to a drying room to dry the tin spray agent at high temperature to form a uniform solder layer.

[0029] Step 4: Drying of the tin spray agent. After drying in step 3, the circuit board enters the cooling area to cool and solidify the solder layer, and inspects the circuit board. The quality and coverage of the solder layer are checked by a visual inspection system or automatic inspection equipment.

[0030] Step 5: Complete ultrasonic cleaning or chemical cleaning to remove any residue or dirt generated during the tin spraying process, and finally test the quality of the circuit board to ensure that the quality of the solder layer of the circuit board meets the requirements.

[0031] In step 2, the printing energy mode of the printer is adjusted to 2 / 2 / 3, and the printing sampling is 100% normal, and 10 pre-treated circuit boards are selected and sprayed with tin spray agent, and then sent to the drying room for drying after spraying, and the drying temperature and time are 60℃ / 60min+70℃ / 60min+80℃ / 60min+90℃ / 30min+110℃ / 45min+130℃ / 45min+155℃ / 120min. After the circuit board tin spray agent spray is dried and cooled, the normal number of circuit boards sprayed with tin is detected to be 5, and the yield rate is 50%.

[0032] Embodiment 2

[0033] Adjust the printing energy mode of the printer to 2 / 2 / 3, and the printing sampling rate is 25% of the normal value. Then select 10 pre-treated circuit boards and spray them with tin spray agent. After spraying, send them to the drying room for drying, and the drying temperature and time are 60℃ / 60min+70℃ / 60min+80℃ / 60min+90℃ / 30min+110℃ / 45min+130℃ / 45min+155℃ / 120min. After the circuit board tin spray agent spray is dried and cooled, the normal number of circuit boards sprayed with tin is 10, and the yield rate is 100%.

[0034] Embodiment 3

[0035] The printing energy mode of the printer was adjusted to 4 / 2 / 3, and the printing sampling rate was 100% normal. 76 pre-treated circuit boards were selected and coated with tin spray. After coating, they were sent to the drying room for drying, and the drying temperature and time were 60℃ / 60min+70℃ / 60min+80℃ / 60min+90℃ / 30min+110℃ / 45min+130℃ / 45min+155℃ / 120min. After the circuit board tin spray was sprayed, dried and cooled, the normal number of circuit boards sprayed with tin was detected to be 2, and the yield rate was 2.6%.

[0036] Embodiment 4

[0037] The test board parameters of the circuit board processed by silk screen are solder mask and character parameters are all produced normally. The number of test boards taken is 96 pieces, and the test results show that the yield rate is 100%.

[0038] Table 1 Test board process and parameter table

[0039]

[0040] In summary, the thickness of the white oil block at the soldering position on the circuit board surface after drying and forming in Example 1 and Example 3 is 19um-25um, and the yield rate is 50% and 2.6% respectively; the thickness of the white oil block at the soldering position on the circuit board surface after drying and forming in Example 2 is 15um-21um, and the yield rate is 100%; it is concluded that the main factors affecting the blistering after tin spraying of the white oil block board are: a. The ink thickness is too thick; b. The energy mode is too high; the printing point is adjusted to 25% (that is, the thickness of the white oil block is thinned), the energy is lowered to 2 / 2 / 3, and all 10 printed circuit boards are completely All of them are qualified; only the energy is lowered to 2 / 2 / 3, and the printing spot is adjusted to 100%, only 5 of the 10 circuit boards are qualified; according to the existing energy of 4 / 2 / 3, the printing spot is adjusted to 100%, only 2 of 76 circuit boards are qualified, and 96 blocks are made according to the silk screen process, and all are qualified after tin spraying. Further, the printing supplier is notified to adjust the existing parameters to the test parameters for batch follow-up, and the existing printing parameters are changed after the batch follow-up is confirmed to be OK (qualified); before the white oil block printing batch is verified to be OK (qualified), the large copper skin with white oil blocks is produced according to the silk screen process.

[0041] The above shows and describes the basic principles and main features of the present invention and the advantages of the present invention. It is obvious to those skilled in the art that the present invention is not limited to the details of the above exemplary embodiments, and the present invention can be implemented in other specific forms without departing from the spirit or basic features of the present invention. Therefore, no matter from which point of view, the embodiments should be regarded as exemplary and non-restrictive. The scope of the present invention is defined by the attached claims rather than the above description, and it is intended that all changes falling within the meaning and scope of the equivalent elements of the claims are included in the present invention. Any figure mark in the claims should not be regarded as limiting the claims involved.

[0042] Other parts of the present invention not described in detail belong to the prior art and will not be described in detail here.

[0043] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention, rather than to limit it. Although the present invention has been described in detail with reference to the aforementioned embodiments, those skilled in the art should understand that they can still modify the technical solutions described in the aforementioned embodiments, or replace some or all of the technical features therein with equivalents. However, these modifications or replacements do not cause the essence of the corresponding technical solutions to deviate from the scope of the technical solutions of the embodiments of the present invention.

Claims

1. An improved circuit board tin spraying process, characterized in that: The following steps are involved: Step 1: First, prepare the circuit board to be tinned or silk-screened, ensure the surface of the circuit board is clean, and remove the oxide layer and pre-clean; Step 2: Run the tin spraying machine to preheat the tin spraying equipment and adjust the tin spraying energy parameters. Then, extract several pre-treated circuit boards as a group and place them on the conveyor belt of the tin spraying machine. After ensuring that the position of the circuit boards is accurate, the tin spraying agent is applied to the pad area of ​​the circuit board by the tin spraying nozzle on the tin spraying machine. Step 3: After the circuit board is coated with tin spray in step 3, the circuit board is sent to a drying room to dry the tin spray at high temperature to form a uniform solder layer; Step 4: After drying in step 3, the circuit board enters the cooling area to cool and solidify the solder layer, and the circuit board is inspected by visual inspection system or automatic inspection equipment to check the quality and coverage of the solder layer; Step 5: Complete ultrasonic cleaning or chemical cleaning to remove any residue or dirt generated during the tin spraying process, and finally test the quality of the circuit board to ensure that the quality of the solder layer of the circuit board meets the requirements.

2. The improved circuit board tin spraying process as claimed in claim 1, characterized in that: In step 2, the printing energy mode of the printer is adjusted to 2 / 2 / 3, and the printing sampling rate is 100% normal. Ten pre-treated circuit boards are sprayed with tin spray agent and sent to the drying room for drying after spraying. The drying temperature and time are 60℃ / 60min+70℃ / 60min+80℃ / 60min+90℃ / 30min+110℃ / 45min+130℃ / 45min+155℃ / 120min.

3. The improved circuit board tin spraying process as claimed in claim 1, characterized in that: Or in step 2, adjust the printing energy mode of the printer to 2 / 2 / 3, and the printing sampling rate is 25% of the normal, and select 10 pre-treated circuit boards for spraying with tin spray agent, and then send them to the drying room for drying after spraying, and the drying temperature and time are 60℃ / 60min+70℃ / 60min+80℃ / 60min+90℃ / 30min+110℃ / 45min+130℃ / 45min+155℃ / 120min.

4. The improved circuit board tin spraying process as claimed in claim 1, characterized in that: Or in step 2, adjust the printing energy mode of the inkjet printer to 4 / 2 / 3, and the printing sampling rate is 100% normal, and select 76 pre-treated circuit boards for spraying with tin spray agent, and send them to the drying room for drying after spraying, and the drying temperature and time are 60℃ / 60min+70℃ / 60min+80℃ / 60min+90℃ / 30min+110℃ / 45min+130℃ / 45min+155℃ / 120min; after the circuit boards are sprayed with tin spray agent, dried and cooled, the normal number of circuit boards sprayed with tin is detected to be 2, and the yield rate is 2.6%.

5. The improved circuit board tin-spraying process as claimed in claim 2, characterized in that: After the circuit board tin spraying agent is sprayed, dried and cooled, the normal number of circuit boards sprayed with tin is detected to be 5, and the good rate is 50%.

6. The improved circuit board tin-spraying process as claimed in claim 3, characterized in that: After the circuit board tin spraying agent is sprayed, dried and cooled, the normal number of circuit boards sprayed with tin is detected to be 10 pieces, and the good product rate is 100%.

7. The improved circuit board tin-spraying process as claimed in claim 1, characterized in that: The test board parameters of the circuit board processed by silk screen are solder mask and character parameters are all produced normally. The number of test boards taken is 96 pieces, and the test results show that the yield rate is 100%.

8. The improved circuit board tin-spraying process according to any one of claims 2 to 7, characterized in that: The circuit board test board model is CP6F32471A4.

9. The improved circuit board tin-spraying process as claimed in claim 2, characterized in that: The thickness of the normal 100% white oil block for printing is 19um-25um.

10. The improved circuit board tin spraying process as claimed in claim 3, characterized in that: The thickness of the normal 25% white oil block for printing is 15um-21um.

Images