It as not until the PCBA assembly that the importance of packaging design silkscreen labeling was realized

    It was not until the PCBA assembly that the importance of packaging design silkscreen labeling was realized

Longlong designs PCB very hard, he has a beautiful girlfriend named Lily.

But the mother-in-law does not agree, but her daughter will not give up,
When her mother's word was nothing, and I gave in 
Then give Longlong an examination period
Examined married Lily, need to examined 
Lily said yes
Longlong pressure is big, but also cannot let mother-in-law see flat from already.
Because if we have hope, we will prevail
All good luck lies in hard work.

Recently, he has a project to bid for the exhibition, and the deadline is very urgent.

Longlong  is the first to build packaging after the drawing board, design to complete production
Longlong is afraid of project problems, personally sent materials to the factory, just breathe a sigh of relief.
But in IQC inspection, or a little incident
Longlong received a call from IQC at noon.
when you checked this material, you found that it could not sink when inserted into the PCB board
Please confirm if there is any problem with this switch device
There is a switch device on the PCB board, IQC inserts the device according to the screen printing frame mark on the board, and it bravely warps on the board
 SWITCH
 

packaging type：KA-0017，specification：sw_4pin，H=4.3mm，H=15mm。 

The logo of the screen printing frame on the PCB board 

If the switch is welded, it cannot sink the edge of the plate, leading to the normal installation of the rear housing
The project is very urgent, the key is still in the mother-in-law's examination period

There should be no problems during the test.
At the thought of this, the cold sweat on longlong's head flowed down.
when the Packaging finish , the most afraid of identification screen printing frame.
Layout ， the most afraid to put sinking encapsulation
PCB design, line drawing is not the most terrible, a person to build packaging, layout, design, is terrible, because packaging design some problems are relatively hidden, careless, all the previous efforts wasted
Long long remembered that when he placed the device, he did not take into account the precise position of the device during assembly, and took the first screen printing frame as the body of the device

And this area is actually going to stick out of the board

How do we normally place the PCB layout? In fact, the position of the first screen printing is to extend the board out, and the second screen printing frame is close to the board edge, as shown 

But there's one problem to be the key to remind, some PCB design engineer in packaging, if the second thread device ontology, is the position in the layout, if the location close to the edge, but behind the assembly, or there is a huge hidden trouble, that is to consider the actual production, the size of the PCB design process of tolerance, Usually, we take the layout position of the device as the reference of the second line, and extend 0.2mm or more to the edge of the PCB, so as to prevent interference in assembly due to excessive shape tolerance during PCB processing. White line is the body of the device, red line is the edge of the PCB. So when packaging, there should be a production margin added. According to the material specification, provide the recommended edge line position, and mark the distance from the physical size tolerance to the edge line in the materials in the packaging information. This should be assessed according to the actual needs of production, professional things should be handed over to professional people to do, because focus so professional. For example, E company's professional packaging team.

the red line is the board edge line position, and the white line is the body. Did you increase the margin in the packaging design?。 

The layout was wrong and the rework was in tears.
Longlong was worried.
But no hurry can make a mistake
If anything goes wrong, I'm sorry for Lily's earnest expectations

As a result, Longlong discussed with Zhang of the factory what emergency measures to take, and assembled PCB first, then tested it and went to the exhibition

Zhang Chang gave a very down-to-earth emergency method, using plastic tooling to re-shape the pin until the switch's sinking area extends out of the plate, and then the housing is assembled. It's a little ugly, but there's no problem with assembly and testing.
As long as the mind does not slide, the method is more than difficult.
PCB board is always ready to dress up the little girl, fitted with a shell, no one knows what hidden inside.
Board later participated in the exhibition, in the standard, longlong smile on the face.
But through this case, Longlong felt that there was a big gap between himself and the big PCB design companies, and there were still many professional skills to improve
In fact, there are many times, because of the packaging screen printing box mark problem, in PCB layout and assembly, there are a lot of confusion
Now, let's take a look at these crime scenes
In case 1

the capacitor screen printing frame of the table paste was drawn too small, not the device body. After the layout, the devices conflicted, and the other one was crowded out after welding. Fortunately, COMPANY E had a material reserve, so it urgently found a device with a small body but similar specifications from the spot warehouse to replace it, which perfectly solved this kind of problem

Case one is that the device body packaging design is smaller, but what is more weird is that the device packaging design is the same size, but the device body is different

In case 2
The size of the screen printing frame on the board was the same, but IQC found that the two devices were not the same when checking. IQC suspected that the customer's device was wrong.

In fact, the device size is not the same, but the packaging design of the screen printing frame is the same, a false alarm

In case 3

Even more dramatic, look at the picture, just from the picture below, you can see where the body of the device is.
Hold your horses

  In the actual assembly, the device is out of the board. According to the size of this device, if the PCB splinter board after welding may be a little trouble, how to solve this trouble? Do you have any good solutions?

Longlong is more see heart more hair, just then his mobile phone suddenly a shock, longlong picked up the mobile phone a look, couldn't help but heart.
Later longlong wrote down the following a speech
Love is confusing
God wants to make it crazy
Must first let its marriage buy a house
That's not the worst part
We don't have chips and we don't have mines,
The mother-in-law and daughter-in-law also test the son

I don't want you to be rich
But you have to be brilliant
You are making circuit board drops
You are making circuit board drops
Design board material purchase plus welding
one-stop service
Everything is brilliant
I lie to my parents
You can't fool your own mother-in-law

You make me,A short period of time,

Know design, know plate making, welding, know materials,
I realized then that my mother-in-law was not testing me.

I have prayed and worshipped,
Who can give me that magic anytime soon.
There is a tangle, there is a loss,
That is until I came across this brochure for a technical seminar

All the conditions are there,
All the requirements,
God helps me be Success and flight
This time the daughter-in-law looked at me,