Preparation process of CCGA tin column

Abstract

The invention discloses a CCGA tin column preparation process which comprises the following steps: straightening a prepared finished tin wire and then fixing the tin wire, placing the straightened tin wire in a containing groove, pouring molten paraffin into the containing groove, stopping pouring after the tin wire is submerged by the paraffin, taking out a cooled and solidified paraffin body, cutting the paraffin body into short sections by adopting a blade, and the obtained short section is heated, and the tin column is taken out after the short section is melted. By the adoption of the tin column preparation process, the precision and the qualified rate of the CCGA tin column can be improved, the end face of the prepared CCGA tin column is almost perpendicular to the axis of the CCGA tin column, and the production cost of the CCGA tin column can be greatly reduced.

Description

Technical Field

[0001] The invention belongs to the technical field of microelectronic components, and in particular relates to a CCGA tin column preparation process. Background Art

[0002] With the increase in the total number and density of packaged I / O ports, CBGA and CCGA packaging forms are increasingly used in aerospace and other scientific and technological fields. Due to the difference in CTE between ceramic substrates and PCB boards, thermal cycle reliability issues have become a bottleneck restricting the development of high-density CBGA packaging. The CCGA structure can effectively alleviate the thermal mismatch effect by increasing the spacing between the ceramic substrate and the PCB board, thereby showing higher thermal reliability.

[0003] With the development of high-precision technologies such as aerospace, high-end products of military microelectronic components are packaged with CCGA / LGA. CCGA is another form of CBGA with a size larger than 32*32mm. The difference is that solder columns are used instead of solder balls. The solder columns are connected by eutectic solder or directly cast on the bottom of the ceramic. Traditional ceramic quad flat package (CQFP) or ceramic pin grid array package (CPGA) is no longer suitable for today's high I / O technology FPGA devices. Ceramic column grid array package (CCGA) with a higher number of pins can achieve high-density packaging of high-performance FPGA devices within a reliable level, thus meeting the requirements of space satellites. CCGA package uses solder column (high lead tin column Pb90Sn10, Pb80Sn20, etc., referred to as CCGA tin column) array to replace CBGA solder ball (high lead tin ball Pb90Sn10) array. Its main advantages are: excellent fatigue resistance and heat dissipation, high temperature resistance, high pressure resistance and good moisture resistance. Summary of the invention

[0005] The present invention aims to provide a CCGA tin column preparation process, which is at least used to solve the problem that the end surface of the existing CCGA tin column always has an inclination, and to improve the qualified rate of the produced CCGA tin columns.

[0006] In order to achieve the above object, the present invention adopts the following technical solution.

[0007] A CCGA tin column preparation process, characterized in that the steps include: Step 1, straightening the prepared finished tin wire; Step 2, placing and fixing the straightened tin wire in the receiving groove; Step 3, pouring melted paraffin wax into the containing tank, and stopping pouring after the paraffin wax submerges the tin wire; Step 4, taking out the paraffin body after cooling and solidification, the paraffin body is the general name of the paraffin and its built-in tin wire; Step 5, cutting the paraffin body into short sections using a blade; Step 6, heat the obtained short section, and remove the tin column after the short section is melted.

[0008] As a preferred embodiment, in step 3, the temperature of the melted paraffin is not higher than 150°C.

[0009] As a preferred solution, in step 6, the temperature of the short section after heating is not higher than 100°C.

[0010] As a preferred embodiment, in step 5, the paraffin body is cut into short sections in an atmosphere with a temperature of 0-20°C.

[0011] In order to further improve the qualified rate of CCGA tin pillars produced, in step 1 and step 2, the straightness of the tin wire after being stretched is not less than 0.01mm.

[0012] As a preferred embodiment, in step 5, the blade for cutting the paraffin body is perpendicular to the axis of the straightened tin wire.

[0013] In order to further improve the qualified rate of CCGA tin pillars produced and facilitate operation, the receiving groove should have at least one flat surface with a roughness of IT6~IT9.

[0014] As a preferred solution, the accommodating groove is a trapezoidal groove, an arc groove, a rectangular groove or a U-shaped groove.

[0015] As a preferred solution, the receiving groove is made of a stainless steel groove, and the inner wall of the receiving groove has a self-lubricating coating.

[0016] As a preferred solution, the straightened tin wire is embedded in the middle of the paraffin body.

[0017] Beneficial effects: The tin column preparation process of the present invention can not only improve the accuracy and qualified rate of CCGA tin columns, the end face of the prepared CCGA tin column is almost perpendicular to its axis, but also can greatly reduce the production cost of CCGA tin columns; the present invention creates a new method for preparing high-precision tin columns with an extremely simple process, which is suitable for large-scale industrial production. BRIEF DESCRIPTION OF THE DRAWINGS

[0018] Figure 1 is a schematic cross-sectional view of the tin column preparation process in Example 1; Figure 2 is a schematic diagram of the tin column prepared in Example 1; Figure 3 is a schematic cross-sectional view of the tin column preparation process in Example 2; Figure 4 is a schematic cross-sectional view of the tin column preparation process in Example 3; Figure 5 is a schematic cross-sectional view of the tin column preparation process in Example 4; In the figure, 1 represents a receiving tank shell, 2 represents paraffin, 3 represents a tin column, and the inner cavity of the receiving tank shell is the receiving tank. DETAILED DESCRIPTION

[0019] The technical solution of the present invention is further described in conjunction with the accompanying drawings, but the following embodiments are only used to help understand the principle and core idea of ​​the present invention, and are not intended to limit the scope of protection of the present invention. It should be pointed out that for ordinary technicians in this technical field, without departing from the principle of the present invention, improvements made to the present invention also fall within the scope of protection of the claims of the present invention. Example 1

[0020] A CCGA tin column preparation process, the steps comprising: Step 1, straighten and fix the prepared finished tin wire (diameter 0.5 mm), and the straightness of the straightened tin wire is not less than 0.01 mm; the tin wire is fixed on the fixture after being straightened, and the segments between the fixing points are always in a straight state; Step 2, place the straightened tin wire in a receiving groove, the inner wall of which has a self-lubricating coating, the wall thickness of which is 5 mm, the receiving groove is an arc groove made of stainless steel, the end of which is sealed with a detachable cover, the bottom of which is a plane with a surface roughness of IT8, and the cross section of which is as follows: Figure 1 As shown; Step 3, pour the melted paraffin into the containing tank, the temperature of the melted paraffin is controlled to be about 110°C, and the pouring is stopped after the paraffin submerges the tin wire. At this time, the straightened tin wire is built into the middle of the paraffin body; when pouring the melted paraffin, pour it from the side of the tin wire, and do not let the fluid paraffin fall directly on the tin wire; Step 4, taking out the paraffin body after cooling and solidification, removing the cover at the end of the arc groove and pushing out the paraffin body; Step 5, transfer the paraffin body to a workshop at 15°C, check and adjust the blade for cutting the paraffin body (the blade wall thickness is not more than 1mm, the same below) so that it is perpendicular to the axis of the straightened tin wire, and cut the paraffin body into short sections (paraffin short sections, the same below). The standard length of the short section is 2.5mm, and the cross section of the short section is as follows: Figure 1 As shown; Step 6, heating the obtained short section to a maximum of 90° C., and using tweezers or other tools to remove the tin column after the short section is melted.

[0021] The tin column prepared in this embodiment is as follows Figure 2As shown, the end face is straight when observed with the naked eye. With the help of instruments, it is measured that the height difference of one end face (the size difference between different parts of the same end face of the tin column relative to the reference surface) is about 0.002mm, and accordingly, the angle between the end face of the tin column and its axis is about 0.23° (angle θ=arc tan0.002 / 0.5≈0.23°, the calculation method of angle θ is the same below); the height difference of the other end face is about 0.003mm, and accordingly, the angle between the end face of the tin column and its axis is about 0.34°. Example 2

[0022] A CCGA tin column preparation process, the steps comprising: Step 1, straighten and fix the prepared finished tin wire (diameter 0.4 mm), and the straightness of the straightened tin wire is not less than 0.01 mm; Step 2, place the straightened tin wire in the receiving groove, the inner wall of the receiving groove has a self-lubricating coating, the wall thickness of the receiving groove is 6mm, the receiving groove is a trapezoidal groove made of stainless steel material, the end of the trapezoidal groove is sealed with a detachable cover, the bottom surface of the trapezoidal groove is a plane with a surface roughness of IT7 grade, and the cross section of the trapezoidal groove is as follows Figure 3 As shown; Step 3, pouring melted paraffin into the containing tank, the temperature of the melted paraffin is controlled to be about 100°C, and the pouring is stopped after the paraffin submerges the tin wire, at which time the straightened tin wire is built into the middle of the paraffin body; Step 4, taking out the paraffin body after cooling and solidification, removing the cover at the end of the arc groove and pushing out the paraffin body; Step 5, transfer the paraffin body to the operating room at 10℃, check and adjust the blade for cutting the paraffin body so that it is perpendicular to the axis of the straightened tin wire, and cut the paraffin body into short sections (paraffin short sections). The standard length of the short section is 2.2mm, and the cross section of the short section is as follows: Figure 3 shown.

[0023] Step 6, heat the obtained short section to 80-85°C, and use tweezers or other tools to remove the tin column after the short section is melted.

[0024] The tin column prepared in this embodiment has a straight end face when observed with the naked eye. The height difference of one end face (the size difference between different parts of the same end face of the tin column relative to the reference surface) is measured by an instrument to be approximately 0.001 mm, and accordingly, the angle between the end face of the tin column and its axis is approximately 0.14°; the height difference of the other end face is approximately 0.002 mm, and accordingly, the angle between the end face of the tin column and its axis is approximately 0.29°. Example 3

[0025] A CCGA tin column preparation process, the steps comprising: Step 1, straighten and fix the prepared finished tin wire (diameter 0.3mm), and the straightness of the straightened tin wire is not less than 0.01mm; Step 2, place the straightened tin wire in a receiving groove, the inner wall of the receiving groove has a self-lubricating coating, the wall thickness of the receiving groove is 4mm, the receiving groove is a rectangular groove made of stainless steel material, the end of the rectangular groove is sealed with a detachable cover, the bottom surface of the rectangular groove is a plane with a surface roughness of IT6 grade, and the cross section of the rectangular groove is as follows Figure 4 As shown; Step 3, pouring melted paraffin into the containing tank, the temperature of the melted paraffin is controlled to be about 95°C, and the pouring is stopped after the paraffin submerges the tin wire, at which time the straightened tin wire is built into the middle of the paraffin body; Step 4, taking out the cooled and solidified paraffin body, removing the cover at the end of the rectangular groove and pushing out the paraffin body; Step 5, transfer the paraffin body to the operating room at 5℃, check and adjust the blade for cutting the paraffin body so that it is perpendicular to the axis of the straightened tin wire, and cut the paraffin body into short sections (paraffin short sections). The standard length of the short section is 1.5mm, and the cross section of the short section is as follows: Figure 4 shown.

[0026] Step 6, heating the obtained short section to 70° C., and taking out the tin column using tweezers or other tools after the short section is melted.

[0027] The tin column prepared in this embodiment has an end face that is straight when observed with the naked eye. The height difference of one end face (the size difference between different parts of the same end face of the tin column relative to the reference surface) is measured by an instrument to be approximately 0.001 mm, and accordingly, the angle between the end face of the tin column and its axis is approximately 0.2°; the height difference of the other end face is approximately 0.001 mm, and accordingly, the angle between the end face of the tin column and its axis is approximately 0.2°. Example 4

[0028] A CCGA tin column preparation process, the steps comprising: Step 1, straighten and fix the prepared finished tin wire (diameter 0.5 mm), and the straightness of the straightened tin wire is not less than 0.01 mm; Step 2, place the straightened tin wire in a receiving groove, the inner wall of which has a self-lubricating coating, the wall thickness of which is 5 mm, the receiving groove is a U-shaped groove made of stainless steel, the end of which is sealed with a detachable cover, the bottom and side surfaces of which are both planes with a surface roughness of IT9, and the cross section of the U-shaped groove is as follows: Figure 5 As shown; Step 3, pouring melted paraffin into the containing tank, the temperature of the melted paraffin is controlled to be 105°C, and the pouring is stopped after the paraffin submerges the tin wire, at which time the straightened tin wire is built into the middle of the paraffin body; Step 4, taking out the cooled and solidified paraffin body, removing the cover at the end of the U-shaped groove and pushing out the paraffin body; Step 5, transfer the paraffin body to the operating room at 18℃, check and adjust the blade for cutting the paraffin body so that it is perpendicular to the axis of the straightened tin wire, and cut the paraffin body into short sections (paraffin short sections). The standard length of the short section is 2.5mm, and the cross section of the short section is as follows: Figure 5 shown.

[0029] Step 6, heating the obtained short section to 68° C., and taking out the tin column using tweezers or other tools after the short section is melted.

[0030] The tin pillar prepared in this embodiment has a straight end face when observed with the naked eye. The height difference of one end face (the size difference between different parts of the same end face of the tin pillar relative to the reference surface) is about 0.0015mm and the height difference of the other end face is about 0.001mm measured by an instrument.

[0031] Pass rate statistics.

[0032] Statistical standards: The tin pillars with obviously tilted end faces observed with the naked eye are unqualified products; the tin pillars with a height difference of more than 0.1m on the same end faces are unqualified products; the tin pillars with obvious defects such as bending and concave on the surface are unqualified products; the tin pillars with a length between L (standard length) ±0.3mm are unqualified products.

[0033] The 200 tin pillars prepared in the above-mentioned embodiments (50 randomly sampled from each embodiment) were counted, and the number of qualified tin pillars was 196, with a high qualified rate.

Claims

1. A CCGA tin column preparation process, characterized in that the steps include: Step 1, straightening the prepared finished tin wire; Step 2, placing and fixing the straightened tin wire in the receiving groove; Step 3, pouring melted paraffin wax into the containing tank, and stopping pouring after the paraffin wax submerges the tin wire; Step 4, taking out the paraffin body after cooling and solidification; Step 5, cutting the paraffin body into short sections using a blade; Step 6, heat the obtained short section, and remove the tin column after the short section is melted.

2. The tin column preparation process according to claim 1, characterized in that: In step 3, the temperature of the melted paraffin is not higher than 150°C.

3. The tin column preparation process according to claim 2, characterized in that: In step 6, the temperature of the short section after heating is not higher than 100°C.

4. The tin column preparation process according to claim 1, characterized in that: In step 5, cutting the paraffin body into short sections is performed in an atmosphere with a temperature of 0-20°C.

5. The tin column preparation process according to claim 1, characterized in that: In step 1 and step 2, the straightness of the tin wire after being stretched is not less than 0.01mm.

6. The tin column preparation process according to claim 5, characterized in that: In step 5, the blade for cutting the paraffin body is perpendicular to the axis of the straightened tin wire.

7. The tin column preparation process according to any one of claims 1 to 6, characterized in that: The receiving groove should have at least one flat surface, and the roughness of the flat surface should be IT6~IT9.

8. The tin column preparation process according to claim 7, characterized in that: The receiving groove adopts a trapezoidal groove, an arc groove, a rectangular groove or a U-shaped groove.

9. The tin column preparation process according to claim 8, characterized in that: The receiving tank is made of stainless steel, and the inner wall of the receiving tank has a self-lubricating coating.

10. The tin column preparation process according to claim 8, characterized in that: The straightened tin wire is embedded in the middle of the paraffin body.

Images