High-end ingredients often adopt the most simple cooking methods.
Complex PCB, often from the design of the solution.
A seemingly reasonable PCB design, just because of the depth control area on the circuit board and copper plating, in the welding strange scene appeared, the board layer bubbles. Is the processing of the design, or welding ignored the process, see today’s case analysis.
Small wave does PCB design in a certain product company, she is a beautiful girl, her mouth is light, she is confident and calm, she is elegant and do not lose sunshine.
Xiaopao is designing a PCB recently. In the area near the edge of the board, there is a device 0.4mm higher than the board. However, the product has strict requirements on the thickness of the PCB, and the device should not exceed the thickness of the PCB.
After discussion with the structural engineer, Xiao Piao decided to solve the problem of the device exceeding the plate thickness from the PCB design.
Firstly, a sinking area is designed on PCB. During molding, the device is sunk through PCB molding depth control to meet the assembly requirements of the product.
After the discussion with the factory process engineer, the plan is feasible, and we will do it immediately.
She made a quick adjustment to the layering scheme and everything was perfect.
Suddenly, she had an idea that she could electroplate copper in the PCB sinking area, which would improve the heat dissipation of the product to some extent.
Her mood was beautiful at the moment. Considering the impact of processing and copper plating thickness, she hummed a ditty and made the following remarks on the original PCB drawing.
The PCB files were soon delivered to the factory, and the boards began to be produced according to Xiao Piao’s design.
The waiting was a long and painful process.
Waiting with hope is called waiting, waiting without hope is called suffering.
Fortunately, the waiting process was over soon.
Made good PCB board soon handed over to the hands of the small wave.
Tomorrow is the day of PCB on-line welding assembly.
Tomorrow is also destined to be an extraordinary day.
Watch the board slowly from the automatic board on the beginning of the assembly journey.
Solder paste printing, SPI, high speed patch, pre-furnace inspection, the last step, reflow soldering through 12 temperature zones.
A miracle is about to happen, and the time to see it is coming.
Small piao this moment of mood, just like the Coca-Cola opened, braving the cheerful bubble.
There are always surprises and surprises in life. Sometimes you wait a long time for the stars to appear and then you look up at them and it’s morning…
The board came out of the moment after the furnace, the small wave could not believe his eyes, you have seen the northerners steamed buns?
Right, now the step area on the board, just like filled with a fresh steamed bread.
With bubbles of gold and gold.
All the disappointment stems from their blind expectations, the small wave do not understand is where a problem.
Suddenly, she saw a familiar figure in the workshop, handsome face, Yushu face wind, that is all corners of the country says omniscient, omnipotent PCB process engineer Wang Daxian.
Small piao originally dim eyes in the moment full of look, she ran happily to the king of the immortal front, excited said:
“Big fairy, quick help me see this is what problem.”
The big fairy picked up the foamed board, looked at it for a moment, smiled slightly, and then said:
“Xiao piao, you have the most powerful copper foil separation of the curse in the PCB, copper foil and the substrate adhesion is not enough, after the thermal impact of the layer bubbles.”
“Big fairy can do a detailed explanation again.” The small wave quickly asks a way.
Big fairy said: “girl, this thing is a little complicated to say, I will make a long story short. It starts with the pressing of the PCB.” There are three musketeers when PCB is pressed – copper foil, core and PP.
The copper foil commonly used for hard plates is electroplated with copper sulfate solution. One Side is smooth, which is called smooth surface, and the other Side is rough crystalline surface, which is called Matte Side. The roughness of both sides is different, and the coarser Side can produce strong bonding force with resin after treatment.
Prepreg is the English abbreviation of pre-pregnant, which is a kind of sheet adhesive material synthesized by resin and glass fiber cloth carrier.
It exists as a rolled solid at room temperature. When laminated, cut into sheets. During compaction, when the temperature in the press reaches above its Tg, over a period of time, it will slowly change from solid to glass, that is, into the shape of glue. Resin is a kind of thermosetting material, which can undergo polymer polymerization reaction. It can be used as a binder between copper foil and fiberglass cloth.
Core is a combination of PP and copper foil after being fully cured. Core is completely cured after pressing under high temperature, high pressure and vacuum. When the PCB is processed in the factory, its shape and thickness are basically stable and will not change much. In PCB production, it has a variety of names, such as core board, core, base board. It’s a mixture of glass fabric, epoxy resin and double-sided copper foil
The following figure shows the lamination of a conventional 6-layer board. The top and bottom surfaces are copper foil with PP and core in the middle. In the press through high temperature and high pressure vacuum, after PP melting, the CORE and copper foil are completely bonded together. When fully cured, it becomes what we often call a multilayer circuit board.
Design and production of circuit boards and small, is in the PCB bonding on board again after deep processing, and control deep area, after the circuit board has been cured, again on the copper plating, the copper foil is simply deposited on the substrate, its binding force no pressure copper foil binding force is good, right in the high temperature impact, electroplating copper and base material layer foaming.
Master you say I still some dizzy, in the workshop Wang Banxian said along while, the small float or some do not understand.
Just went off work at this moment, wang Daxian pulls small wave the bicycle repair stall outside factory park, let small wave see Li uncle mend tire over there. I saw Uncle Li first picked up a file, grinding on the tire, and then coated it with glue, and finally put a piece of rubber on it, a moment later the damaged tire was mended. Then the big fairy asked the little piao what did you see. The small wave excited of say big fairy I understand, li uncle repair tire really not easy, you see him sweating like a pig, I later want to design a good artificial intelligence of repair tire product, let li uncle not so tired. Big fairy instant feeling breath on not to come, hold back for a long time, long say a word, repair tires not grinding, how to increase the binding force of tires and rubber, after filling will leak.
Of the outer part of the circuit board copper by high temperature and high pressure vacuum melting and PP joint together, after the hair surface uranium foils and the combination of gelatinous resins, completely cured, closely unifies in together, is not easy to layered, copper plating and accused of deep area, only by electroplating in deep deposits a layer of copper base material surface area, because there is no glue in sedimentary copper, The binding force between this layer of copper and PCB is far less good than that between copper foil and resin on the wool surface when pressed. In reflow soldering, under the influence of thermal shock, there will be stratified foaming, so the case happened.
After hearing this, Xiao Piao suddenly saw the light. Later, he gave up the copper plating scheme in the deep control area, reevaluated and optimized the design, and finally delivered the board smoothly.
