Jan04
What is Step-up & Step-down Stencil? Selective Solder Paste Volume Increasing Solution

post on January 4, 2016

Step_down_stencilThe trend in the electronics industry is toward smaller and smaller SMD components, with sizes such as 0402, 0201, and even 01005 becoming common (Note 1). Additionally, the pitch between pins on ICs has decreased to a fine pitch of 0.5mm, and even 0.3mm, posing a challenge for the SMT process.

SMT engineers face the challenge of soldering these thin electronic components onto PCBs without encountering non-wetting or soldering short issues. This task is more difficult when dealing with a mix of larger and smaller parts on a circuit board.

read more…》

Manufacture, SMT, Soldering     WorkingBear    Views (16,232)     comment (0)
, ,

Oct01
Copper Defined vs. Solder Mask Defined pad design for BGA soldering strength

post on October 1, 2015

Cooper Defined vs. Solder Mask Defined pad design for BGA soldering strength

Since the electronic product design moves from desktop to portable devices, the manufacturer also make electronic component as small as possible to meet this popular trend. Besides, the PCB thickness also become thinner and the associated soldering pads on the PCB are tiny size. This  make the SMT manufacturing process more difficult and challenge.

You may know that portable device always has BGA malfunction risk during impact drop test. Most of company dispense the underfill glue to fix this kind of BGA crack issue. My company did the same thing too.  WorkingBear think there shall be another way to enhance the soldering pad strength to eliminate the underfill glue since underfill process spend money and waste labor hours.

read more…》

PCB/FPC/PTF, Reliability, SMT, Soldering     WorkingBear    Views (23,601)     comment (0)
,

Jul01
Why do thinner PCBs will need carrier for reflow process?

post on July 1, 2015

BGA_underfill_crack01BGA_underfill_crack02

As the career of Manufacturing Process Engineering(MPE), WorkingBear has noticed a constant battle between Designers, Marketers, and Manufacturers. Marketers always want  thin, modern design that look thin. Designers think fabrication is simple, while Manufacturers want  strong, robust, sturdy assemblies that won’t be scratch easily on the surface. However, both of parties also want low costs.

This leads to two common questions from R&D and marketing professionals:

  1. Why do thinner PCBs require a special carrier or template for the reflow process?
  2. Aren’t all PCBs reflowed as a panel, requiring a support fixture for de-panelization?

Since WorkingBear is MPE, so I will answer these two questions as manufacturing point.

read more…》

Design, Glue/adhesive/epoxy/underfill,, PCB/FPC/PTF, Process, Quality, SMT, Soldering     WorkingBear    Views (14,409)     comments (2)
,

Jun24
Case study for the mold-in insert screw boss broken

post on June 24, 2015

Case study for the mold-in insert screw boss broken

In a previous discussion, WorkingBear identified potential root causes for screw boss cracking after mold-in screw nut insertion. Following a complaint from the field, we asked EMS and the plastic injection supplier to double-check their inventory and found that approximately 1% of the plastic case had cracked on the screw bosses due to inner stress during the mold-in screw nut insert process, without any additional force or screwdriver. However, the defect rate increased to 30% after the screws were fastened into the plastic case.

read more…》

Design, Plastic, Quality     WorkingBear    Views (13,321)     comment (0)
, ,

Jun17
Selectively/partial increase solder paste volume solutions

post on June 17, 2015

Why is it necessary to partially increase the solder paste volume in SMT soldering?

To meet the demands of smaller and thinner electronic component designs, stencils are made as thin as possible to precisely control the tiny solder paste printed on the PCB.

However, this creates a challenge when smaller and larger electronic surface-mounted devices (SMDs) need to be mounted on the same board. The stencil’s thinness limits the amount of solder paste that can be deposited, and extending the stencil aperture over the pad size is still not  yet enough to fill the necessary volume of solder. To provide sufficient solder paste volume for larger components, as well as for HTD components, EMS has implemented the PIH (Paste in Hole) process.

read more…》

Manufacture, SMT, Soldering     WorkingBear    Views (6,333)     comment (0)
,