BGA welding joint mixed process type fracture

The welding temperature of a BGA with a metal shell is 220 ° C and the welding time is 18s. Figure 2-59 shows the welding temperature curve. As a general rule of thumb, it is suspected that the temperature is a little low and there may be quality problems.

Analysis

(1) Dyeing. A total of four BGA were dyed. After the BGA was pulled apart, it could be seen that most of the solder joints were pulled apart from the joint of PCB padand substrate, and some were pulled apart from the side of pad, but there were holes.

(2) Slice

The solder joint does not crack, but there is a certain interface cavity.

(2) What is not pulled away from the BGA side is all pulled away from the PCB side, and 80% is pulled away from the substrate under the pad, and the point pulled away from the PCB pad only accounts for about 20%, and there is a significant feature, there is a small hole in the pulling interface.

This is in sharp contrast to the common BGA side solder joint cracking!

Make clear

This case has typical significance:

(1) Welding at 220℃ is acceptable. In theory, the deformation of BGA will be smaller if the temperature is lower.

(2) Low temperature for a short time is also feasible under certain conditions.

We can draw PCB well, why can't we draw IC well

In the view of non-industry insiders, circuit manufacturing and IC manufacturing are basically the same thing, and the difference is not big, and other industry friends chat, we do not know the difference between component manufacturing and PCB manufacturing.But in the eyes of industry insiders, these are fundamentally two industries, and the two industries think somewhat "completely different". 

IC design and manufacturing: is a large number of microelectronic components (transistors, resistors, capacitors, etc.) formed integrated circuit on a plastic base, made into a chip. IC chip consists of wafer chip and package chip, and the corresponding IC chip production line is composed of wafer production line and package production line.

PCB design and manufacture: It is a large number of packaged chips, capacitors and resistors and other discrete components, connected together through PCB, to form a macro circuit with complex and complete functions.

The relationship between the two is wafer design - Wafer manufacturing - Chip packaging - PCB design - board level packaging - system level software code final test.

That is to say, we are now mobile phone computer leading companies are to do board level packaging, most can draw six or even eight layers of circuit boards, and a variety of impedance antenna, radio frequency signal line play. However, there are some difficulties to go further, can do chip sealing test is mainly to buy equipment and test procedures, earn processing costs, and independent design of the machine is not many.

When it comes to wafer manufacturing and design, the domestic wafer manufacturing is still at the middle and low level, and there are only a few large factories capable of designing.

Why is IC design so hard?

In fact, after careful analysis of this problem, it is found that IC design is not difficult, but complex. The complexity is high to the degree that quantitative change causes qualitative change.

With the increasing function of integrated circuit, the complexity of IC design is also increasing, and the related materials and processes are becoming more and more sophisticated. Among them, I think the most obvious is that the division of labor of IC design is getting finer and finer.

Moreover, a chip design covers too many disciplines, which not only needs to satisfy the design logic and algorithm feasibility, but also needs to verify the logic of the underlying circuit, and also needs to consider the manufacturing issues. A little bit to withhold to improve, if there is no patience and the spirit of inquiry is easy to give up.

And there is a famous law in the IC industry that you have to make mistakes in order to make progress in the next generation of products. Throughout the major CPU or MCU and other logic chips, there are no generations of versions are optimized in power consumption performance, structure and other aspects, and the experience gained from each generation of optimization is precious wealth for the next generation to avoid the pit.

Since this is the case, our country started late, although we are trying to catch up, but there are some holes must be crossed, in fact, there are no corners to overtake, some corners must be taken, and you have to do is to walk fast, walk steadily.

IC design and manufacturing is not difficult, the need is details, is not impetuous people, carrying the dream of revival.