Finger Pitch minimization method

Abstract

The invention relates to the technical field of chip packaging, in particular to a method for minimizing Finger Pitch. Comprising the following steps: S1, defining a Finger as a landing point of a metal ball; s2, parameters of WB equipment are adjusted, so that the bonding surface of the metal ball and the Finger is in a shape that the middle is in contact and the edge is suspended; and S3, bonding of all Fab is completed on the adjacent Fingers in sequence. Compared with the prior art, the size of the metal ball in the finger area is changed, and the finger width is allowed to be smaller, so that more space is provided for the finger pitch minimization limit.

Description

Technical Field

[0001] The invention relates to the technical field of chip packaging, in particular to a method for minimizing Finger Pitch. Background Art

[0002] During the wire bonding process of chip packaging, the bonding wire passes through the capillary, and then the end of the bonding wire is melted by EFO to obtain a free air ball (FAB). After the FAB contacts the pad, pressure, temperature and ultrasonic energy are applied to the ball for a period of time to complete the bonding. In order to avoid the capillary from squeezing the upper wire, it is now necessary to ensure that the finger spacing is above 70μm.

[0003] The Fab balls on the Finger are currently Figure 3 to Figure 4 As shown, the Fab ball occupies or exceeds the Finger width, and is easily short-circuited with the adjacent Fab ball or Finger.

[0004] Chinese patent publication number CN209133500U discloses a chip with staggered pads, which prevents short circuits between gold balls and adjacent fingers or gold balls on adjacent fingers by staggering the placement of gold balls. In fact, the size of the finger area where the gold balls fall is not changed. In the case of extreme finger pitch, the finger width has a fixed lower limit to ensure that the gold balls do not exceed the fingers. Summary of the invention

[0005] The present invention provides a method for minimizing Finger Pitch in order to overcome the deficiencies of the prior art.

[0006] To achieve the above purpose, a method for minimizing Finger Pitch is designed, which includes the following steps: S1, define Finger as the landing point of the metal ball; S2, adjust the parameters of the WB device so that the bonding surface between the metal ball and the finger is in contact in the middle and the edge is suspended; S3, complete the bonding of all Fabs on adjacent fingers in sequence.

[0007] In the step S2, the diameter of the metal ball is 25-30 μm, the fixed search speed before reaching the contact point is 3-8 mm / s, the initialization force at the moment of contact is 10-20 g, the force that lasts briefly during contact is 20-30 g, the amplitude control parameter that lasts briefly during contact is 30-50 mw, the short duration of contact is 2-4 ms, the amplitude control parameter that lasts for a long time during contact is 5-20 mw, the force that lasts for a long time during contact is 5-10 g, the long duration of contact is 10-12 ms, and the peak start time of the amplitude control parameter is 3-5 ms.

[0008] In the step S2, the metal ball is in the shape of a water drop.

[0009] Compared with the prior art, the present invention changes the size of the metal ball in the finger area, allowing the finger width to be smaller, thereby leaving more room for minimizing the limit of the finger pitch. BRIEF DESCRIPTION OF THE DRAWINGS

[0010] Figure 1 It is the front view of the present invention.

[0011] Figure 2 It is a top view of the present invention.

[0012] Figure 3 It is the front view of the prior art before the present invention improves.

[0013] Figure 4 It is a top view of the prior art before the improvement of the present invention. DETAILED DESCRIPTION

[0014] The present invention will be further described below with reference to the accompanying drawings.

[0015] like Figure 1 to Figure 2 As shown, the method for minimizing Finger Pitch in this embodiment includes the following steps: S1, define Finger 2 as the landing point of metal ball 1; S2, adjust the parameters of the WB equipment so that the bonding surface between metal ball 1 and Finger 2 presents a water drop shape with the middle contact and the edge suspended; S3, complete the bonding of all Fabs on adjacent Finger in sequence.

[0016] In step S2, after contact, the action is first briefly continued, and then continued for a longer time. Specifically, the diameter of the metal ball 1 is 25-30μm, the fixed search speed Search Speed ​​before reaching the contact point is 3~8mm / s, the initial force Initial force at the moment of contact is 10~20g, the contact force for a short time during contact is 20~30g, the amplitude control parameter Contact Power for a short time during contact is 30~50mw, the short time during contact is 2~4ms, the amplitude control parameter Bond Power for a long time during contact is 5~20mw, the force for a long time during contact is 5~10g, the long time during contact is 10~12ms, and the amplitude control parameter Peak start time / parameter acceleration control parameter BQM Time is 3~5ms.

[0017] In this embodiment, the metal ball 1 is in the shape of a water drop.

[0018] In the present invention, a water drop-shaped metal ball 1 is planted on the Finger to minimize the landing point on the Finger, thereby minimizing the Finger pitch. The Finger pitch is minimized, thereby ensuring that the Finger can be arranged at the same horizontal line as the corresponding Pad, reducing the difficulty of WB operation. More Finger can be arranged in a limited area to achieve more functions. In the present invention, the water drop-shaped metal ball 1 avoids interference between adjacent Finger, and the Finger pitch can even approach 0, breaking through the existing Finger process level of the PCB industry, and solving the bottleneck of WB process capability in advance for the future development of the PCB industry on Finger.

Claims

1. A method for minimizing Finger Pitch, characterized by: The steps include: S1, define Finger (2) as the landing point of the metal ball (1); S2, adjusting the parameters of the WB device so that the interface between the metal ball (1) and the finger (2) presents a water drop shape with the middle in contact and the edge suspended; S3, complete the bonding of all Fabs on adjacent fingers in sequence.

2. A method for minimizing Finger Pitch according to claim 1, characterized in that: In the step S2, the diameter of the metal ball (1) is 25-30 μm, the fixed search speed before reaching the contact point is 3-8 mm / s, the initialization force at the moment of contact is 10-20 g, the force during the short-term contact period is 20-30 g, the amplitude control parameter during the short-term contact period is 30-50 mw, the short-term contact period is 2-4 ms, the amplitude control parameter during the long-term contact period is 5-20 mw, the force during the long-term contact period is 5-10 g, the long-term contact period is 10-12 ms, and the amplitude control parameter peak start time is 3-5 ms.

3. The method for minimizing Finger Pitch according to claim 1, characterized in that: In the step S2, the metal ball (1) is in the shape of a water drop.

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