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Jun10
PCB rework: Selective solder mask removal by laser

PCB rework: Selective solder mask removal by laserDid you ever met a trouble need to rework to remove the solder mask from the PCB?  If yes then how you did?

We usually remove the solder mask manually  by knife or hand grinding tool. But these kinds of rework always damaged and broke the traces on the PCB and result in high scrap rate for PCB or PCB Assembly.

Today WorkingBear will introduce you a new method to remove the solder mask by laser machine. It is high efficiency and high reliability. If the laser power select property  then it will only remove the solder mask and without damage cooper under the solder mask.

Actually my company had never did this kind of PCB rework quite a long time. Unfortunately, new top manager ask to reduce the design phase and roll in the product to mass production from 9 months to 6 moths. Make design quickly will need to pay something. There are about 10K pcs of the PCB need to be reworked to remove the solder mask to improve the ESD issue.

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Jun03
TQRDCE Performance Expectations and Review

This is an example that implement TRQDCE form for vendor survey.

TQRDCE Introduction:

TQRDCE ChecklistThe strategy of company for establishing and maintaining long-term working relationships is through creating and monitoring mutual performance expect ions and measurements. Performance metrics, constructive feedback, as well as prompt corrective action by the supplier and by customer are fundamental to achieving continuous process improvement.

In order to provide customer with the means to measure our suppliers, the TQRDCE (Technology, Quality, Responsiveness, Delivery, Cost, and Environmental) review was developed. It is imperative that supplier maintain a competitive advantage by providing materials of the highest quality and lowest total cost, with the best delivery, responsiveness and technology available. The TQRDCE Review is a tool for measuring and communicating a supplier’s performance and to aid company in determining their place in future business relationships.

This review is being provided two weeks in advance of our scheduled meeting with [SUPPLIER] on [DATE] at [LOCATION]. it should be shared with the appropriate personnel at [SUPPLIER] with a focus on the development objectives. it is company’s expectation that [SUPPLIER] come to the review with a written action plan that addresses all the development objectives listed on the review.

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May27
Improve BGA solderability by partial increase solder paste volume

BGA_X-Ray_pictureHow to improve the BGA (Ball Grid Array) package solderability is always a big challenge for SMT (Surface Mount Technology) process. Especially for the fine pitch (ball pitch less than 0.8mm) BGA is more difficult to be soldered on the PCB. Besides, it’s soldering quality is also hard to be inspected since its solder hide under its body and sometimes even can’t be inspected by 2D X-Ray inspector. (5Dx or angle rotation X-Ray maybe ok to inspect BGA soldering quality but expensive)

As experience tell us that most of BGA solderability fail is caused by the HIP (Head-In-Pillow) soldering defect and over 90% of the HIP defect show on four corners of BGA package. Because of the diagonal distance is longest and greatest impact from board warpage and BGA deformation. There are many senior SMT engineer had done some experiments and prove that Increasing the solder paste volume on the pads under BGA can reduce the HIP defect risk.

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May20
Shipping carton drop/impact test condition

The electronic industry grows quickly. Each vendor takes responsible to his own component only to make it good and low cost. Take a flashlight manufacturer as example. There are bulb, wires, switch, spring, and plastic or metal housing make up the flashlight. The manufacturer buys all the sub-components from each supplier and assembles them together to fabricate the flashlight then sell to end-user.

All the sub-components are delivery by air, ocean, or truck to destination. It is important to prevent the delivery parts without damage during transferring. Most of the packaging uses corrugated paper carton and cardboard to hold inside components and prevent it from damage by falling or throwing down by porter or carrier.

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May14
Temperature Environmental Cycle Profile

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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