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Connectors

10/07/2020

Become a master of mounting! – Measure to avoid the warpage of a hard PC board

This article is the first of a series of articles titled "Become a master of mounting!" In this series, we are going to discuss some key points you need to understand for better connector mounting.

Today, we are going to talk about the warpage of a hard PC board and how to measure so as to avoid the warpage. Avoiding warped sections is important for soldering process, and, to that end, you have to review the location of the connector on the board.

How do you determine the location of the connector on the board?

Perhaps your first concern is the circuit pattern arrangement and the positional relationship between the connector and other parts/elements mounted on the board. So, your decision on the location of the connector, in many cases, depends on the arrangement and positional relationship.
Have you considered the warpage of a board in designing the location of the connector?
To tell you the truth, paying attention to the warpage of the board is a key point to prevent the poor soldering of the connector.

Generally, the hard PC board is manufactured by press rolling a roll of board material.
Because of this process, the board tends to warp vertically relative to the direction of rolling.

Schematic of a hard board manufacturing process

 

If the connector is placed along the direction in which the warp tends to occur, the board's warpage creates a gap between the connector and the board. This gap turns out to be bigger in the case of a large pin-counts connector because a contact portion between the connector and the board is longer.
Such gaps could cause the poorly soldered part to the connector.

Directions in placing a connector

 

So, it is important to place the connector in the direction in which the board has the least amount of warp, that is, the direction matching the direction of rolling. This will be effective to avoid the poor soldering.

This is all we've got for you today. We have discussed in this chapter the warpage of the hard PC board and how to measure so as to avoid the warpage. In the next chapter, we will talk about the warpage of a flexible PC board and measures to avoid the warpage.

 

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