A method for measuring a plastic package gap by laser drilling

Abstract

The application discloses a kind of methods for measuring plastic sealing gap by laser drilling, comprising the following steps: first, select several pre-punching positions on the whole fingerprint product after packaging;Subsequently, select appropriate laser parameters, and small holes are successively burned in pre-punching position, to ensure that only plastic sealing material is burned through, just Die can be exposed, and Die surface is not affected;Subsequently, the height difference between the bottom of the small hole and the surface is measured, which is the required plastic sealing gap.The method for measuring plastic sealing gap by laser drilling provided by the application, when laser drilling is carried out on the surface of product plastic sealing body, the hole is directly drilled to the surface of Die, and then the depth of the hole is measured to obtain the plastic sealing gap.The accuracy of laser drilling is the same as that of Cross-section method.Compared with Cross-section method, it is more efficient and lower in cost, suitable for rapid testing of plastic sealing gap, and has high practicability.

Description

Technical Field

[0001] This invention belongs to the field of encapsulation technology, specifically relating to a method for measuring encapsulation gaps by laser drilling. Background Technology

[0002] LGA fingerprint products have high requirements for molding gaps, typically requiring a tolerance range within ±20μm; otherwise, product performance will fail. During the product packaging process, the main factors affecting molding gaps are substrate thickness, die thickness, molding powder application amount, molding mold flatness, and grinding thinning thickness. To ensure the molding gap is within the standard range after molding, it is necessary to confirm the product's molding gap during the first molding or the first strip grinding process, and determine parameters based on the gap data from the first mold or the first strip, ensuring that the gaps of subsequent products meet the standards. Traditional gap measurement uses cross-section measurement technology, requiring the product to be cut into individual pieces, sent to a laboratory for cross-section measurement, and then analyzed by SEM to measure the distance from the die surface to the molding surface. This method takes approximately 3 days, cannot monitor anomalies immediately and make corresponding adjustments, is not suitable for mass production, and has a high production loading rate. Summary of the Invention

[0003] To address the technical problems existing in the prior art, the present invention aims to provide a method for measuring the gap of plastic seals by laser drilling.

[0004] To achieve the above objectives and technical effects, the technical solution adopted by this invention is as follows:

[0005] A method for measuring the gap of a plastic seal by laser drilling includes the following steps:

[0006] First, select several pre-drilled holes on the entire packaged fingerprint product;

[0007] Then, select appropriate laser parameters to burn small holes one by one at the pre-drilled positions, ensuring that only the molding compound is burned through, just enough to expose the die, without affecting the die surface;

[0008] Then, the height difference between the bottom of the hole and the surface is measured, and this height difference is the required sealing gap.

[0009] Furthermore, the step of selecting several pre-drilled locations on the entire packaged fingerprint product includes:

[0010] Select the pre-drilling position based on the size and shape of the side fingerprint and the planar fingerprint. If the package is rectangular, drill 3 holes per chip. If the package is square, drill 5 holes per chip. During debugging, ensure that all holes are positioned above the chip.

[0011] Furthermore, the laser parameters include:

[0012] The wavelength is 492-577nm;

[0013] The laser current is 31.7A;

[0014] The frequency is 30kHz;

[0015] The moving speed is 260 mm / s.

[0016] Furthermore, the laser parameters include:

[0017] Green light, with a wavelength of 532nm;

[0018] The laser current is 15-50A;

[0019] The frequency ranges from 30 to 500 kHz.

[0020] The moving speed is 100-1000 mm / s.

[0021] Furthermore, a high-powered microscope was used to focus and measure the height difference between the bottom of the aperture and the surface.

[0022] Furthermore, it also includes steps for adjusting the sealing gap:

[0023] If the gap between the plastic seals is small, increase the amount of powder applied; if the gap between the plastic seals is large, reduce the amount of powder applied.

[0024] The formula for calculating the amount of powder applied is: Powder application amount = (molding volume - die volume) × molding material density / 1000.

[0025] Furthermore, it also includes steps for adjusting the sealing gap:

[0026] The gap between the plastic seals is kept within the standard range by adjusting the amount of grinding.

[0027] Compared with the prior art, the beneficial effects of the present invention are as follows:

[0028] This invention discloses a method for measuring the plastic seal gap by laser drilling, comprising the following steps: laser drilling is performed on the surface of the product plastic seal, the hole reaches the die surface, and then the depth of the hole is measured to obtain the plastic seal gap. The accuracy of laser drilling is the same as that of the cross-section method. Compared with the cross-section method, it is more efficient and less expensive, suitable for rapid testing of plastic seal gap, and has high practicality. Attached Figure Description

[0029] Figure 1 This is a schematic diagram of the single-hole position of the side fingerprint product according to Embodiment 1 of the present invention;

[0030] Figure 2 This is a schematic diagram of the entire perforation position of the side fingerprint product according to Embodiment 1 of the present invention;

[0031] Figure 3 This is a schematic diagram of the single-hole position of the planar fingerprint product according to Embodiment 2 of the present invention;

[0032] Figure 4 This is a schematic diagram of the entire perforation position of the planar fingerprint product according to Embodiment 2 of the present invention;

[0033] Figure 5 This is a schematic diagram of the drilling process in this invention;

[0034] Figure 6 This is a picture of the actual product with holes punched in it. Detailed Implementation

[0035] The present invention will now be described in detail so that its advantages and features can be more easily understood by those skilled in the art, thereby providing a clearer and more explicit definition of the scope of protection of the present invention.

[0036] The following provides a brief overview of one or more aspects to offer a basic understanding of them. This overview is not an exhaustive summary of all conceived aspects, nor is it intended to identify key or decisive elements of all aspects, nor to define the scope of any or all aspects. Its sole purpose is to present some concepts of one or more aspects in a simplified form to prepare for the more detailed descriptions that follow.

[0037] like Figure 1-6 As shown, a method for measuring the over-molding thickness (OMT) of a molding compound by laser drilling is used to measure the distance from the chip surface to the surface of the molding compound after packaging. The method includes the following steps:

[0038] Select locations evenly across the entire packaged product to facilitate subsequent laser drilling.

[0039] Select a suitable laser device, preferably one that emits green light with a wavelength of 492-577nm, suitable for marking non-metallic materials. Utilize the principle of light interference, set the current (15-50A), frequency (30-500KHz), and moving speed (100-1000mm / s) to burn a small hole at the predetermined position. The size of the hole is defined according to the wafer size in the design drawings, generally with a diameter of 0.7-1mm, ensuring that only the molding compound is burned through without affecting the die surface, leaving no molding compound residue on the die surface.

[0040] Subsequently, a high-powered microscope was used to focus and measure the height difference between the bottom of the hole and the surface. This height difference is the required sealing gap (OMT).

[0041] It should be noted that when laser drilling is performed on the surface of the product's plastic seal, by adjusting the laser energy, frequency, and movement speed to just expose the die, the depth of the hole at this point is the sealing gap. Figure 5 As shown.

[0042] To ensure the holes are drilled precisely on the die, depending on the size and shape of the side-mounted and planar fingerprint sensors, if the package is rectangular, three holes are drilled per sensor (e.g., ...). Figure 1-2 As shown), if the package is square, then each chip should have 5 holes (e.g., Figure 3-4 As shown in the diagram, during debugging, it is necessary to ensure that all points are positioned above the chip to ensure the accuracy and stability of the gap data. If the gap is small, increase the amount of powder applied; if the gap is large, decrease the amount of powder applied (the gap size is defined according to the design drawings, generally 55-120μm). The amount of powder applied = (molding volume - die volume) × molding compound density / 1000, or the gap can be kept within the standard range by increasing or decreasing the amount of grinding.

[0043] Example 1

[0044] like Figure 1-2 and Figure 5-6 As shown, a method for measuring the over-molding thickness (OMT) of a molding compound by laser drilling is used to measure the distance from the chip surface to the surface of the molding compound after packaging. The method includes the following steps:

[0045] Select locations evenly across the entire packaged product to facilitate subsequent laser drilling.

[0046] Select a suitable laser device, preferably a green laser with a wavelength of 532nm. Utilize the principle of light interference, set the laser current to 31.7A, frequency to 30kHz, and moving speed to 260mm / s to burn a small hole at the predetermined position. The diameter of the small hole is set to 0.7mm to ensure that only the molding compound is burned through without affecting the die surface, leaving no molding compound residue on the die surface.

[0047] Subsequently, a high-powered microscope was used to focus and measure the height difference between the bottom of the hole and the surface. This height difference is the required sealing gap (OMT).

[0048] It should be noted that when laser drilling is performed on the surface of the product's plastic seal, by adjusting the laser energy, frequency, and movement speed to just expose the die, the depth of the hole at this point is the sealing gap. Figure 5 As shown.

[0049] To ensure the holes are properly aligned with the die, based on the size and shape of the side and planar fingerprint sensors, and given the rectangular packaging in this embodiment, three holes are drilled for each sensor (e.g., ...). Figure 1-2 As shown in the diagram, during debugging, it is necessary to ensure that all points are positioned above the chip to ensure the accuracy and stability of the gap data. If the gap is small, increase the amount of powder applied; if the gap is large, decrease the amount of powder applied (the gap size is defined according to the design drawings, generally 55μm). The amount of powder applied = (molding volume - die volume) × molding compound density / 1000. Alternatively, the gap can be kept within the standard range by increasing or decreasing the amount of grinding.

[0050] Example 2

[0051] like Figure 3-6 As shown, a method for measuring the over-molding thickness (OMT) of a molding compound by laser drilling is used to measure the distance from the chip surface to the surface of the molding compound after packaging. The method includes the following steps:

[0052] Select locations evenly across the entire packaged product to facilitate subsequent laser drilling.

[0053] Select a suitable laser device, preferably a green laser with a wavelength of 532nm. Utilize the principle of light interference, set the laser current to 31.7A, frequency to 30kHz, and moving speed to 260mm / s to burn a small hole at the predetermined position. The diameter of the small hole is set to 0.7mm to ensure that only the molding compound is burned through without affecting the die surface, leaving no molding compound residue on the die surface.

[0054] Subsequently, a high-powered microscope was used to focus and measure the height difference between the bottom of the hole and the surface. This height difference is the required sealing gap (OMT).

[0055] It should be noted that when laser drilling is performed on the surface of the product's plastic seal, by adjusting the laser energy, frequency, and movement speed to just expose the die, the depth of the hole at this point is the sealing gap. Figure 5 As shown.

[0056] To ensure the holes are drilled onto the die, based on the size and shape of the side fingerprint and the planar fingerprint, and since the package in this embodiment is square, five holes are drilled for each chip (e.g., ...). Figure 3-4 As shown in the diagram, during debugging, it is necessary to ensure that all points are positioned above the chip to ensure the accuracy and stability of the gap data. If the gap is small, increase the amount of powder applied; if the gap is large, decrease the amount of powder applied (the gap size is defined according to the design drawings, generally 55μm). The amount of powder applied = (molding volume - die volume) × molding compound density / 1000. Alternatively, the gap can be kept within the standard range by increasing or decreasing the amount of grinding.

[0057] Same as Example 1.

[0058] Any parts or structures not specifically described in this invention can be made using existing technologies or products, and will not be elaborated upon here.

[0059] The above description is merely an embodiment of the present invention and does not limit the patent scope of the present invention. Any equivalent structural or procedural transformations made based on the content of the present invention specification, or direct or indirect applications in other related technical fields, are similarly included within the patent protection scope of the present invention.

Claims

1. A method for measuring the gap of a plastic seal by laser drilling, characterized in that, Includes the following steps: First, select several pre-drilled holes on the entire packaged fingerprint product; Then, select appropriate laser parameters to burn small holes one by one at the pre-drilled positions, ensuring that only the molding compound is burned through, just enough to expose the die, without affecting the die surface; Subsequently, the height difference between the bottom of the small hole and the surface is measured, and this height difference is the required sealing gap; The steps involved in selecting several pre-drilled locations on the entire packaged fingerprint product include: Select the pre-drilling position according to the size and shape of the side fingerprint and the planar fingerprint. If the package is rectangular, drill 3 holes per chip. If the package is square, drill 5 holes per chip. During debugging, ensure that all holes are on top of the chip. The laser parameters include: Green light, with a wavelength of 532nm; The laser current is 15-50A; The frequency ranges from 30 to 500 kHz. The moving speed is 100-1000 mm / s; The height difference between the bottom of the small hole and the surface was measured using a high-magnification microscope.

2. The method for measuring the gap of a plastic seal by laser drilling according to claim 1, characterized in that, It also includes steps for adjusting the sealing gap: If the gap between the plastic seals is small, increase the amount of powder applied; if the gap between the plastic seals is large, reduce the amount of powder applied. The formula for calculating the amount of powder applied is: Powder application amount = (molding volume - die volume) × molding material density / 1000.

3. The method for measuring the gap of a plastic seal by laser drilling according to claim 1, characterized in that, It also includes steps for adjusting the sealing gap: The gap between the plastic seals is kept within the standard range by adjusting the amount of grinding.

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