May01
Why Do Screw Bosses Crack After Mold-In Screw Inserts? Common Causes and Solutions

post on May 1, 2015

screw boss broken

This story is long-standing memory, but WorkingBear is documenting it here for reference and as a learning record.

One day, we received a customer complaint regarding a product with a plastic housing that had cracked. The issue was visually striking, with noticeable cracks on the outside of the plastic casing. The situation called for immediate investigation.

After examining several defective plastic parts, we discovered that all the cracks were located at the screw boss area. The cracks extended from the inside of the plastic housing outward. Interestingly, the screw boss was designed with a mold-in screw insert, which had been installed during the injection molding process. Based on our initial analysis, it appeared that the issue could be related to the screw boss mechanical design or the injection molding conditions.

To help others facing similar issues (and to serve as a personal memo), WorkingBear has compiled a list of potential causes for screw boss cracks for reference.

read more…》

Design, Manufacture, Plastic, Quality     WorkingBear    Views (24,890)     comments (8)
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Apr29
How to design LCM gasket/cushion for manufacture?

post on April 29, 2015

The gasket/cushion went outside of LCM

The LCM (LCD Module) is a common component for the electronic products. Almost of the LCM was made by glass and it is brittle and  break easily while hit or drop on the floor due to handle careless. As product design we will install a rubber gasket or cushion locate between the glass and plastic case or metal bezel to prevent it from squeezing due to press or careless hitting.

Although this kind of rubber gasket is a simple design but if the gasket didn’t design well then the installation will be a big challenge in manufacturer. We often see the gasket go outside of the display view area. If this is a touch panel product then it will result the touch function fail. If this kind of issue happens in filed then we will get big trouble.

Therefore, this article attempts to look for the rubber gasket design methods.

read more…》

Design, Manufacture     WorkingBear    Views (5,905)     comment (0)
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Apr27
How EMS fabricate a PCB Assembly?

post on April 27, 2015

How EMS fabricate a PCB Assembly?

How EMS (Electronic Manufacturing Services) fabricate a PCB (Printed Circuit Board) Assembly?

This article is writing for the people who still not yet really under what is the PCB Assembly. Because WorkingBear found there are many people just come to this EMS area and still not yet well understand what is SMT (Surface Mount Technology) and what is Wave Soldering.

The PCB Assembly is a very popular technology in modem electronic industry.  For example, the cell phone, Tablet, Computer, Television, Remote toy car, etc. all have the PCB Assembly module  inside. The  invention of PCB Assembly technology is really help the electric products development trend to small size and multi-function.

So, how EMS fabricate a PCB Assembly? It is almost automatic production line now through SMT or wave soldering process to solder the electronic components on the board to instead of hand soldering by iron. Of course, you still can hand solder all electronic components on the board as manual by yourself but you must take high risk for the poor solderability quality and can’t do it mass production. Besides, the 0201 small chip are hard to be hand soldered on board and some of the package that design the soldering pads under the package body can’t be hand soldered. For example BGA, QFN, LGA package.

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Manufacture, SMT, Soldering     WorkingBear    Views (15,780)     comments (2)
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Apr24
How to select a good actuator design for right angle connector?

post on April 24, 2015

Right angle connector or flip lock connectorAs my personal feeling that Right-angle FPC ZIF connector is really more easily to use than Drawer type of ZIF connector. Even right-angle connector is good but do you know how to select a good design of this kind of right angle connector?

Recently my company met lots of component broken troubles for the electrical connector call “right angle connector” or “flip lock connector” in manufacturing production line. We found almost the defect connector broke at the ACTUATOR portion while operators first time tried to lift it after SMT high temperature reflow process. I’m sure the connector works fine before reflow.

I did a study on the connector and found it was caused by the connector itself while through SMT high temperature reflow process as below two reasons:

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Connector, Design, Manufacture, Quality     WorkingBear    Views (5,191)     comment (0)

Apr23
The benefit to use shielding clips to instead of shielding frame

post on April 23, 2015

SMT can clipFor almost of the frequency radio apparatus, the Printed Circuit board must design the shielding frame/can to prevent the EMI (Electromagnetic Disturbance Interference) effect. The regular design will apply one shielding frame to mount on PCB by solder and another shielding can to cover on the frame to isolate the RF.

That means there will be two press tools cost before implement this solution. Beside, the shielding frame must be mounted on the PCB by SMT process. It requires lower flatness specification to keep the solder joint well. Most of the shielding frame asks its flatness meet 0.12mm maximum. Some of the shielding frame even asks the flatness must lower than 0.10mm maximum. Because of current stencil thickness is around 0.10~0.127mm only. It brings more difficult to form the shielding frame and raise its cost.

read more…》

Design, SMT, Soldering     WorkingBear    Views (8,082)     comment (0)