May14
Temperature Environmental Cycle Profile

post on May 14, 2015

temperature cycle storage environmental test profile

The purpose of temperature environmental test is that the good are shipped by various types of carriers and experience a wide range of storage temperatures, depending on the customer environment, hence the need for this kind of testing. Further, certain components and assemblies are sensitive to these temperature extremes and could be weakened due to induced stresses. Therefore, it is important that a logical sequence of testing be followed in order to observe these effects and assure the product’s performance under various temperature conditions and after temperature extremes have been applied.

(Note: This test didn’t include the humidity.)

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Design, Reliability     WorkingBear    Views (5,248)     comment (0)

May12
Humidity Temperature Cycle Profile

post on May 12, 2015

Humidity Temperature Cycle Profile

The humidity test is designed to determine the effects of humidity on the product and assure that the product will meet published specifications while being subjected to high humidity conditions. This is an accelerated test to uncover failure modes in components, assemblies and process, which may appear in the field during normal service, while keeping test time at a minimum. Performance tests are made at various intervals of the test duration and each test must pass for the design to meet the requirements of this section.

Hygroscopic materials (e.g., printed circuit boards, molded plastics, sealed components, etc.) will absorb moisture proportional to the applied vapor pressure and time of application. Excessive moisture penetration may cause swelling of material or contamination actions, destroying functional ability as well as causing leakage paths between sensitive circuits, result when moisture reacts with trapped chemicals from construction processes causing corrosion or severe etching of metal surfaces. In some cases dendritic growth can cause short circuits or high voltage flashover between closely spaced traces or pin spacing. The following humidity test is designed to accelerate the occurrence of these failure mechanisms if they exist.

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Design, Reliability     WorkingBear    Views (6,702)     comment (0)

May05
Why Burn/In(B/I) still cannot screen out the DDR soldering fail?

post on May 5, 2015

We recently encountered a soldering issue with a DDR memory BGA (Ball Grid Array). The problem identified was HIP (Head-In-Pillow) — two balls with non-wetting under the BGA package were affected. To investigate, we sent someone to the field to assess the customer’s operation, discovering that the product failed to power on. Interestingly, applying finger pressure to the DDR memory component would successfully power it on.

Why did this occur? The production line claimed the products underwent a 12-hour power-on Burn/In (B/I) process at 40°C but didn’t screen out the defect. So, why did we still observe this type of BGA soldering defect in the field?

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Manufacture, Quality, Soldering     WorkingBear    Views (6,054)     comment (0)
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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.

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Design, Manufacture, Plastic, Quality     WorkingBear    Views (19,188)     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.

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Design, Manufacture     WorkingBear    Views (4,338)     comment (0)
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