LPIM over molding DFM report

Posted on : Oct 21 , 2022 By GREFEE

Directory

1. The requirement of product

2. The analysis of the product feasibility and suggestion

2.1. demould direction for over molding

2.2. The question of A part

I. Locating hole

II. Thickness

III.Tolerance of PCB.

2.3. The question of B part

I. GAP

II. Thickness

III.Sharp edge to round

IV.Tolerance of PCB

V. undercut

2.4. The question of C part

I. Plastic

II. Thickness

III.Sharp edge to round

3. Mould solution project

3.1. Mould and process project 1st:

3.2. Mould and process project 2rd:

1. The requirement of product：

Encapsulation size and weight
A. 31x 13.1x 7.7mm3 0.92 gram
B. 31x 25.6x 11 mm3 3.13 gram
C. 15.5x 8.2x 4 mm3 0.25 gram

2. The analysis of the product feasibility and suggestion

2.1 demould direction for over molding

1. LED light is on core side because it must be located easily and stationery during opening the mould, so that avoid not to be scratched by mould

2.There is no draft-angle on the whole side of 3 parts (A,B,C), suggest to add 3°on it to prevent the sticky and scratch!

2.2 The question of A part

I. locating hole or socket for PCB in over molding is invalid because it is on the cavity side

II. The analysis display that thickness of this part is even now. in order to good filling, suggest to add round R0.5 to avoid the short-shut

III. The 2 same units should be in a plane with high planeness(less±0.05), and the LED should be high tolerance in the position for the mould(less±0.05 too)，otherwise it’s difficult to place the PCB to right site and would have risk to occur the serious flash

Remark: Because of good fluency of material, the bound between pre-part and over molding easily appear
many flash, the tolerance of wires and other causes will affect the flash

2.3 The question of B part

I. There are 4 places that have gaps as following, it’s sharp steel and very nondurable and easy to occur the flash in the mould.

II. The analysis display that thickness of this part is very uneven. suggest make the recess on both side of part to avoid serious sink mark as following.

III. These places have sharp edge and corner to markedly reduce filling of moldflow, suggest add the round radius to improve moldflow and avoid short-shut.

IV. The 4 same units should be in a plane with high planeness (less±0.05),, and the 2 LED should be high tolerance in the position for the mould(less±0.05 too) ，otherwise it’s difficult to place the PCB to right site and would have risk to occur the serious flash

V. There are a undercut between the slope wires and B part, it would make mould and process very complicated, and cause that mould have to take a lot of time to position the wire correctly. The mould and process is on following page 16

Suggest change the slope convex a little to as following, so when make the mould and molding, the wire could be flattened, the mould and process will become easy. The mould and process is on following page 17