The reason of copper on the chip pins is exposed after soldering, the coating is not plated, If it is the upper and lower surfaces of the parts, the plating is not done well. If it is the side, it is acceptable to have different positions
Why does the needle weld off with only copper and nickel, no tin, lead, gold, etc.? The extra zinc may be the alloying element in the gold needle matrix H62 brass (copper-zinc alloy). when the gold coating on the bottom of nickel is very thin, the X-ray tester may be sensitive to the alloying elements in the base metal
Analysis and discussion on the causes of IC solder joint falling off: Cold solder, IC PIN coating, pin oxidation or pin plating, add flux solder, soldering temperature is not high enough, the soldering was good and the function was normal by manually soldered.
The gold wire bonded printed circuit board pads and component leads and terminal plating must be more than 99.99% pure gold, and cannot be hard gold containing 0.0X% cobalt or nicke, The thickness of such an immersion gold coating is essentially determined by the size of the gold crystal particles, and the maximum thickness is difficult to exceed 0.15 microns.
BGA pad fall off reason is because design wrong, The desoldering temperature control was incorrect.
What reinforcement measures can be taken from a process perspective while a QFN packaged chip fails during environmental testing?use silicone rubber adhesive to reinforce.
Nickel-plated pins are difficult to solder and the tin penetration is poor. Is there any good solution? raising the temperature of the soldering iron to 400 degrees. use a more powerful soldering iron and a thicker soldering iron head. a small-diameter hot air gun with an air outlet of 150C to fix the position.
Flip chip (FC) technology is a packaging method that directly connects the chip to the substrate. It has the advantages of high density, high performance and low cost.Underfill can improve the stress distribution of the solder joints, reduce the strain amplitude of the solder joints, and extend the thermal fatigue life of the solder joints.
